ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2021-05-06
    Description: Various electricity generation technologies using different primary energy sources are available. Many published studies compare the costs of these technologies. However, most of those studies only consider plant-level costs and do not fully take into account additional costs that societies may face in using these technologies. This article reviews the literature on the costs of electricity generation technologies, aiming to determine which types of costs are relevant from a societal point of view when comparing generation technologies. The paper categorises the relevant types of costs, differentiating between plant-level, system and external costs as the main categories. It discusses the relevance of each type of cost for each generation technology. The findings suggest that several low-carbon electricity generation technologies exhibit lower social costs per kWh than the currently dominant technologies using fossil fuels. More generally, the findings emphasise the importance of taking not only plant-level costs, but also system and external costs, into account when comparing electricity generation technologies from a societal point of view. The article intends to inform both policymakers and energy system modellers, the latter who may strive to include all relevant types of costs in their models.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: article , doc-type:article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2020-03-03
    Description: Die Kritik an pluraler und transformativer Ökonomik vonseiten der etablierten Wirtschaftswissenschaft erklärt sich aus deren Wissenschaftsverständnis. Eine Auseinandersetzung damit hilft auch, das produktive Miteinander von pluraler und transformativer Ökonomik besser zu verstehen.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2021-05-04
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2019-04-01
    Description: Die MENA-Region steht nicht nur vor erheblichen gesellschaftlichen Herausforderungen, sondern weist ebenfalls deutlichen Entwicklungsbedarf im Stromsystem auf und erfordert dessen nachhaltige Transformation. Durch einen möglichst hohen regionalen Verbleib der damit anfallenden Wertschöpfung könnten sich Chancen für Technologieausrüster ergeben. Allerdings herrscht im derzeitigen Marktstadium noch immer hohe Unsicherheit inwieweit zukünftig tatsächlich eine Marktentwicklung stattfindet. Vor diesem Hintergrund erfolgt die Entwicklung eines multikriteriellen Bewertungsrahmens für Investitionen in die lokale Produktion, wobei Aspekte der Transition-Forschung Anwendung finden.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: doctoralthesis , doc-type:doctoralThesis
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    Publication Date: 2021-05-04
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2021-05-04
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2021-05-04
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    Wuppertal : Solar + Spar Contract
    Publication Date: 2018-11-19
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: report , doc-type:report
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2018-11-19
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2021-03-30
    Description: Since the majority of network concession contracts in Germany were set to expire some time between 2005 and 2016, a window of opportunity arose in which to rebuild and remunicipalise the local energy supply. As a result, 72 new local power companies were established in Germany within the space of just seven years (between early 2005 and late 2012). This paper provides an introduction to the topic of establishing municipal utilities in Germany. The findings were identified on the basis of the comprehensive screening of all newly established municipal utilities in Germany. Our analysis provides information about regional concentration, the size of municipalities, the legal forms of the newly founded municipal public utilities and the role of strategic partnerships. The key findings are that remunicipalisation is not a question of size and that knowledge gaps may be closed by entering into close strategic partnerships.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: article , doc-type:article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Publication Date: 2021-05-04
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Publication Date: 2018-11-19
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Publication Date: 2022-02-18
    Description: Der Beitrag baut eine Brücke zu den Forderungen nach einer "transformativen Wirtschaftswissenschaft". Er macht deutlich, dass die Herausforderung der Ökonomie nicht lediglich bei einer verbesserten Politikberatung, sondern am Grundverständnis des Faches ansetzen muss. Er beleuchtet dabei vier Aspekte (1) die Begrenzungen durch den methodologischen Individualismus als erkenntnistheoretische Grundlage der Wirtschaftswissenschaften, (2) die Annahme exogen gegebener Präferenzen, (3) die Berührungsangst mit Normativität, (4) das Ausblenden ihres performativen und sozialwissenschaftlichen Charakters und zeigt unter anderem die institutionellen Konsequenzen für eine sich erneuernde Wirtschaftswissenschaft auf.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Publication Date: 2022-02-18
    Description: Bisher ist die vollständige Schließung von Stoffkreisläufen durch die Verwendung von Abfällen als Ressource in Deutschland nur eine Vision. Der Beitrag führt das Konzept der Kreislaufwirtschaft ein und konkretisiert es am Beispiel der Reparatur und Wiederverwendung von Produkten. Anschließend werden Hemmnisse betrachtet, die es auf dem Weg zur Kreislaufwirtschaft zu überwinden gilt und mögliche Lösungsansätze beschrieben.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: article , doc-type:article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Publication Date: 2022-02-18
    Description: Für die Energiewende im Ruhrgebiet muss eine umfassende Strategie einer Wärmewende verfolgt werden. Wichtige Treiber dafür sind die Stadtwerke mit ihren Nah- und Fernwärmenetzen. Doch im Wärmemarkt sind die bisherigen Transformationserfolge gering. Während erneuerbare Energien mittlerweile einen Anteil von über 30 Prozent im Stromsektor haben, spielen sie im Wärmebereich mit lediglich rund 10 Prozent eine bescheidene Rolle. Die erforderliche Wärmewende ist gekennzeichnet durch eine ausgeprägte Wechselwirkung zwischen den Sektoren Strom, Wärme, Gas und Mobilität (Sektorenkopplung).
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: contributiontoperiodical , doc-type:contributionToPeriodical
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Publication Date: 2022-02-18
    Description: Die meisten Konzessionsverträge für Strom und Gas auf der örtlichen Verteilnetzebene sind zwischen 2005 und 2016 ausgelaufen. Viele Gemeinden in Deutschland haben dies als Chance verstanden, um mit der Gründung eigener Stadtwerke die örtliche Energieversorgung stärker selbst gestalten zu können. Bei diesem Trend zur Rekommunalisierung waren Städte und Gemeinden mit unter 25.000 Einwohnern besonders stark beteiligt. Im Folgenden sollen die verschiedenen Aspekte der Rekommunalisierung näher betrachtet werden.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: article , doc-type:article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Publication Date: 2022-02-18
    Description: Kern des Projektes war es zu untersuchen, wie der Untersuchungsraum in Bezug auf die Energiewende aufgestellt ist und welche Entwicklungspotenziale künftig im Zuge einer gesellschaftlich und politisch gewollten Energiewende genutzt werden können. Zur Qualifizierung des wissenschaftlichen Nachwuchs wurde im Rahmen der hier bearbeiteten Forschungsfragen Studierende darin angeleitet, im Bereich der energiebezogenen Transformationsforschung eigenständig Teilaspekte zu untersuchen. Dementsprechend wurden vom Wuppertal Institut insgesamt vier Studienarbeiten mit verschiedenen Themenschwerpunkten ausgeschrieben. Diese sollten am konkreten Beispiel der zu untersuchenden Region aufzeigen, welche Stärken und Schwächen, aber auch Chancen und Risiken in Bezug auf die pro-aktive Gestaltung der Energiewende bestehen. Zusätzlich sollte untersucht werden, wie stark kleine und mittlere Unternehmen (KMU) in der Region Unna davon betroffen sind beziehungsweise inwieweit sie als Akteure der Energiewende die Nachhaltigkeit ihrer unternehmerischen Tätigkeit stärken und sichern können. Auch die regionalwirtschaftlichen Effekte wie Wertschöpfungs- und Arbeitsplatzeffekte, die erzielbar wären, wenn die mittelständischen Unternehmen der Region pro aktiv die Herausforderungen der Energiewende in den Bereichen Energieeffizienz, erneuerbare Energien und dezentrale KWK aufgreifen, waren Bestandteil der Studienarbeiten. Der Schwerpunkt lag hier insbesondere im Bereich Energieeffizienz.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: report , doc-type:report
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Publication Date: 2022-02-18
    Description: Mit der Nachhaltigkeitsanleihe NRW erschließt das Land das international wachsende Segment des nachhaltigen Investments für die Kreditfinanzierung des Landeshaushalts. Ziel der vorliegenden Studie ist es, die Bewertung positiver Nachhaltigkeitseffekte für die in 2016 emittierte Nachhaltigkeitsanleihe NRW zu erproben und Handlungsempfehlungen zur Bewertung zukünftiger Nachhaltigkeitsanleihen zu entwickeln. Für eine umfassende Nachhaltigkeitsanalyse ist aufgrund der Vielschichtigkeit der finanzierten Projekte und fehlender Standards zur Bewertung sozialer Kriterien eine umfangreiche Untersuchung erforderlich, wodurch sie für eine regelmäßige und standardisierte Wirkungsanalyse zukünftiger Anleihen nicht in Frage kommt. Stattdessen verfolgt die vorliegende Studie einen pragmatischen Ansatz zur Bewertung. Der Fokus liegt auf der Evaluation der potenziellen Treibhausgas-Minderung (THG-Minderung), da deren Bewertung sich derzeit als Standard für eine Wirkungsanalyse solcher Anleihen abzeichnet. Darüber hinaus werden die nächsten Schritte für eine Weiterentwicklung der Methodik und des Indikatorensets im Rahmen zukünftiger Wirkungsanalysen aufgezeigt.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: report , doc-type:report
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    facet.materialart.
    Unknown
    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2022-11-10
    Description: Seit 2005 ist ein Großteil der deutschen Strom- und Gaskonzessionsverträge ausgelaufen und eröffnete vielen Kommunen die Chance, die Energieversorgung wieder in die eigenen Hände zu nehmen. Gleichzeitig übernimmt die kommunale Ebene in einem zunehmend dezentral strukturierten Energieversorgungssystem eine immer wichtigere Rolle, da die Umsetzung der energiepolitischen Ziele der Bundesregierung vor allem vor Ort, in den Kommunen stattfindet. Ziel dieser Arbeit war es daher, zu ermitteln wie viele Kommunen im Zeitraum von 2005 bis 2016 durch die Gründung neuer Unternehmen im Bereich der Energieversorgung tätig geworden sind und welche Rolle die kommunalen Energieversorgungsunternehmen im Rahmen der Energiewende einnehmen können. Auf Grundlage der bereits 2013 vom Wuppertal Institut durchgeführten Sondierungsstudie, die zahlreiche Neugründungen bis 2012 erfasste, konnten in dieser Arbeit insgesamt 139 kommunale Energieversorgungsunternehmen ermittelt werden, deren Gründung zwischen 2005 und 2016 stattfand. Dieses Ergebnis belegt für diesen Zeitraum einen ausgeprägten Trend zur Rekommunalisierung im Bereich der Energieversorgung. In einer umfangreichen Literaturanalyse sowie acht Experteninterviews mit kommunalen Ansprechpartnern und Geschäftsführern junger Stadtwerke, konnte darüber hinaus belegt werden, dass die kommunalen Energieversorger aufgrund ihrer Fachexpertise und ihrer ausgeprägten Vernetzung mit den Bürgern, örtlichen und regionalen Akteuren und der Kommune, wichtige Instrumente zur Umsetzung kommunaler Klimaschutzziele darstellen. Sie sind nicht nur in der Lage, sich im energiewirtschaftlichen Wettbewerb zu beweisen und zu positionieren, sondern können aufgrund ihrer lokalen Verankerung auch Potenziale erschließen, die von privaten Versorgern weitgehend ungenutzt bleiben. Diese umfassen beispielsweise Potenziale zur Energieerzeugung und -einsparung auf Kundenseite, aber auch die Möglichkeiten regenerativer Wärmeversorgung durch Nah- oder Fernwärme und eine stärkere Beteiligung der Bürger. Neben den zusätzlichen Wertschöpfungseffekten, von denen die Kommunen profitieren, ermöglichen die kommunalen Energieversorgungsunternehmen somit auch die aktive Mitgestaltung der Energiewende vor Ort, unter Einbeziehung der lokalen Akteure und Bürger.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Publication Date: 2022-11-10
    Description: Stadtwerke sind im Ruhrgebiet strukturprägend und haben eine lange Tradition. Sie sind fester Bestandteil der Akteurskonstellation im Energiebereich der Emscher-Lippe-Zone. Schon heute zeichnen sich die Stadtwerke des Ruhrgebiets vielfach dadurch aus, dass sie die mit der Energiewende verbundenen Chancen nutzen. Ihre technische und gesellschaftliche Struktur entspricht weitgehend den mit der Energiewende verbundenen Transformationsprozessen hin zu einer stärkeren Dezentralität der Erzeugung und der Demokratisierung der Energieversorgung. Die meisten Stadtwerke des Ruhrgebiets sind auf mehreren Wertschöpfungsstufen im Energiebereich tätig. In der Stromerzeugung haben sie einen Schwerpunkt im Bereich der Kraft-Wärme-Kopplung und bei erneuerbaren Energien. Zudem sind sie vielerorts Partner und teilweise sogar Mitinitiator bürgerschaftlichen Engagements zum Ausbau erneuerbarer Energien. Als Verteilnetzbetreiber für Strom, Gas und Wärme sorgen sie vielerorts für die Integration und Verteilung erneuerbarer Energien. Die Energiewende findet weitgehend in den örtlichen Verteilnetzen statt und bedeutet für die Stadtwerke des Ruhrgebiets eine Zunahme an komplexen Koordinierungsfunktionen und teilweise auch die Herausbildung völlig neuer Aufgaben.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: report , doc-type:report
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Publication Date: 2022-11-10
    Description: Die Energiewende gilt als eine der zentralen gesellschaftlichen Projekte unserer Zeit. Ihre Bedeutung beschränkt sich nicht nur auf ihren bekannten Beitrag zum globalen Klimaschutz und auf die Reduzierung der Gefahren durch den Gebrauch von Atomenergie. Sie soll auch dazu dienen, die Energieimportabhängigkeit Deutschlands, mögliche Auswirkungen von Energiepreisschocks und die Wahrscheinlichkeit der Einbeziehung in zukünftige Ressourcenkriege zu reduzieren. Neben diesen Schutzfunktionen kann sie aber auch neue Geschäftsfelder und Arbeitsplätze schaffen und Innovationen in den Bereichen Effizienz und erneuerbare Energien voranbringen und damit einen Beitrag zu einer zukunftsorientierten, ökologischeren wirtschaftlichen Entwicklung beitragen. Bereits 2010 hat die Bundesregierung Ziele in Bezug auf den Ausbau erneuerbarer Energien, die Steigerung der Energieeffizienz sowie die Reduktion des CO2-Ausstoßes formuliert. Während die Ziele hinsichtlich des Ausbaus erneuerbarer Energien im Stromsektor und am Wärmeverbrauch voraussichtlich erreicht werden, sind im Bereich der Energieeffizienzsteigerung weitere Anstrengungen notwendig. Zwar gibt es zahlreiche Energiedienstleistungsangebote und Förderprogramme, mit denen die Energieeffizienz gesteigert werden sollen, allerdings haben diese - insbesondere bei kleinen und mittleren Unternehmen (KMU) - bisher nicht zu den gewünschten Ergebnissen geführt. Daher ist es Ziel der Arbeit, Ansätze für ein Konzept zur Realisierung von Energieeffizienzpotentialen in KMU zu entwickeln. Der Untersuchungsraum der Arbeit liegt im östlichen Ruhrgebiet in der Region Unna/Kamen/Bergkamen/Bönen/Holzwickede und ist auf das Projekt "SWOT-Analyse zur Energiewende Unna/Kamen/Bergkamen/Bönen/Holzwickede“ des Wuppertal Instituts zurückzuführen, in dessen Rahmen diese Arbeit entstand. Im Zuge der Analyse wurden zentrale interne und externe Einflussfaktoren auf die Entscheidung regionaler KMU zur Durchführung von Energieeffizienzmaßnahmen analysiert sowie Praxisbeispiele zur Realisierung von Energieeffizienzpotentialen ausgewertet. Abschließend wurden die Analyseergebnisse zu ersten Ideen für ein Konzept zur Realisierung von Energieeffizienzpotentialen in KMU ausgearbeitet und als Handlungsempfehlungen formuliert.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Publication Date: 2017-06-28
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-39709 , Dust in the Atmosphere of Mars and Its Impact on Human Exploration Workshop; 13-15 Jun. 2017; Houston, TX; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Publication Date: 2019-06-19
    Description: This paper develops an atmospheric state estimator based on inertial acceleration and angular rate measurements combined with a vehicle aerodynamic model. The approach uses the navigation state of the vehicle to recast the vehicle aerodynamic model to be a function solely of the atmospheric state. Force and moment measurements are based on vehicle sensed accelerations and angular rates. These measurements are combined with an aerodynamic model and a KalmanSchmidt filter to estimate the atmospheric conditions. The method is applied to data from the Mars Science Laboratory mission, which landed the Curiosity rover on the surface of Mars in August 2012. The results of the estimation algorithm are compared with results from a flush air data sensing algorithm based on onboard pressure measurements on the vehicle forebody. The comparison indicates that the proposed method provides estimates consistent with the air data measurements, without the use of pressure transducers. Implications for future missions such as the Mars 2020 entry capsule are described.
    Keywords: Lunar and Planetary Science and Exploration
    Type: NF1676L-26438 , Journal of Spacecraft and Rockets (ISSN 0022-4650) (e-ISSN 1533-6794); 55; 3; 599-610
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Publication Date: 2019-07-19
    Description: The Utah Test and Training Range (UTTR), southwest of Salt Lake City, Utah, is the site of all NASA unmanned sample return missions. To date these missions include the Genesis solar wind samples (2004) and Stardust cometary and interstellar dust samples (2006). NASAs OSIRIS-REx Mission will return its first asteroid sample at UTTR in 2023.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-40469
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-07-12
    Description: There was a time during Western civilization when musing about worlds other than Earth could be life-threatening. In 1600 Giordano Bruno was burnt at the stake as a heretic for claiming, amongst other things, that the fixed stars were in fact suns with planets moving around them, and furthermore, that lifeforms similar to those on Earth might exist on these planets. Although these ideas were not the result of scientific observation but rather of philosophical reflexions, Giordano Bruno is today recognized as the father of the idea of exoplanets. The study of planets revolving around distant stars has become one of the most thrilling disciplines in astronomy. As it did 400 years ago, this subject touches on the most profound questions of mankind, including the uniqueness of the planet Earth and even our own uniqueness as an intelligent species. As always in astronomy distance is an issue. While it requires a lot of patience to reach the planets within our own solar system, direct visits to exoplanets will not be feasible in the foreseeable future. Is there an alternative approach to find a second Earth?
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN42439 , Capeia
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-12
    Description: Are we alone? Ancient astronomers across the continents knew the existence of five Solar System planets visible to the naked eye. They could tell that these celestial wanderers were unlike stars in that they only reflected light from the Sun. In the early 1600s, Galileo developed the first telescopes able to observe spots moving across the Sun and the passage of moons across the face of Jupiter. He verified the theory of Aristarchus (3rd c. BC), and refined by Nicolaus Copernicus (mid 16th c.) and Johannes Kepler (late 16th c.), that the Earth and the other planets, in fact, orbit the Sun and not the other way around. Around the same time, Dominican friar Giordano Bruno wondered about the possibility of life on other worlds orbiting other suns (and was burned at the stake for this and other heresies).
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN42171
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Publication Date: 2019-07-12
    Description: The Sample Analysis at Mars (SAM) instrument aboard the Mars Science Laboratory rover has analyzed 13 samples from Gale Crater. All SAM-evolved gas analyses have yielded a multitude of volatiles (e.g., H2O, SO2, H2S, CO2, CO, NO, O2, HCl) [1- 6]. The objectives of this work are to 1) Characterize recent evolved SO2, CO2, O2, and NO gas traces of the Murray formation mudstone, 2) Constrain sediment mineralogy/composition based on SAM evolved gas analysis (SAM-EGA), and 3) Discuss the implications of these results relative to understanding the geological history of Gale Crater.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-38722
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Publication Date: 2019-07-12
    Description: A Lifting ADEPT is considered for aerocapture at Venus. Analysis concerning the heating environment leads to an initial sizing estimate. In tandem, a direct entry profile at Earth is considered to act as a facsimile for the Venus aerocapture heating environment. The bounds of this direct entry profile are determined and it is found that a trajectory from a Geostationary Transfer Orbit with a Lifting ADEPT capable of fitting on a rideshare opportunity is capable of matching certain aspects of this heating environment.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN46925
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Publication Date: 2019-07-12
    Description: In the last 100 years, the global population has more than quadrupled to over seven billion people. At the same time, the demand for food and standard of living has been increasing which has amplified the global water use by nearly eight times from approximately 500 to 4000 cu km per yr from 1900 to 2010. With the increasing concern to sustain the growing population on Earth it is necessary to seek other approaches to ensure that our planet will have resources for generations to come. In recent years, the advancement of space travel and technology has allowed the idea of mining asteroids with resources closer to becoming a reality. During the duration of the internship at NASA Kennedy Space Center, several geotechnical tests were conducted on BP-1 lunar simulant and asteroid simulant Orgueil. The tests that were conducted on BP-1 was to practice utilizing the equipment that will be used on the asteroid simulant and the data from those tests will be omitted from report. Understanding the soil mechanics of asteroid simulant Orgueil will help provide basis for future technological advances and prepare scientists for the conditions they may encounter when mining asteroids becomes reality in the distant future. Distinct tests were conducted to determine grain size distribution, unconsolidated density, and maximum density. Once the basic properties are known, the asteroid simulant will be altered to different levels of compaction using a vibrator table to see how compaction affects the density. After different intervals of vibration compaction, a miniature vane shear test will be conducted. Laboratory vane shear testing is a reliable tool to investigate strength anisotropy in the vertical and horizontal directions of a very soft to stiff saturated fine-grained clayey soil. This test will provide us with a rapid determination of the shear strength on the undisturbed compacted regolith. The results of these tests will shed light on how much torque is necessary to drill through the surface of an asteroid. Most of the known asteroids are believed to be left over material during the formation of the solar system that never accreted to form planets. Asteroids can be found in several groups such as Trojan Asteroids, Near Earth Asteroids (NEAs) and the main asteroid belt. The Trojan Asteroids orbit the 4th and 5th Lagrange points of major planets in the Solar System while the NEA's have orbits that are close to and sometimes intersect with Earths orbit and the Main Asteroid Belt which is found between the orbit of Mars and Jupiter. Gravitational perturbations can alter the orbit of asteroids in the Main Asteroid Belt causing them to move closer to earth causing them to become in the NEA class.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-E-DAA-TN42077
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Publication Date: 2019-07-12
    Description: Few traces of Earth's geologic record are preserved from the time of life's emergence, over 3,800 million years ago. Consequently, what little we understand about abiogenesis - the origin of life on Earth - is based primarily on laboratory experiments and theory. The best geological lens for understanding early Earth might actually come from Mars, a planet with a crust that's overall far more ancient than our own. On Earth, surface sedimentary environments are thought to best preserve evidence of ancient life, but this is mostly because our planet has been dominated by high photosynthetic biomass production at the surface for the last approximately 2,500 million years or more. By the time oxygenic photosynthesis evolved on Earth, Mars had been a hyperarid, frozen desert with a surface bombarded by high-energy solar and cosmic radiation for more than a billion years, and as a result, photosynthetic surface life may never have occurred on Mars. Therefore, one must question whether searching for evidence of life in Martian surface sediments is the best strategy. This Perspective explores the possibility that the abundant hydrothermal environments on Mars might provide more valuable insights into life's origins.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN50317
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-19
    Description: Since August 2012, the NASA Mars Science Laboratory (MSL) rover Curiosity has been operating on the Martian surface. The primary goal of the MSL mission is to assess whether Mars ever had an environment suitable for life. MSL Science Team member Dr. Tim Olson will provide an overview of the rover's capabilities and the major findings from the mission so far. He will also share some of his experiences of what it is like to operate Curiosity's science cameras and explore Mars as part of a large team of scientists and engineers.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-38689 , JSC Engineering Academy; Mar 21, 2017; Houston, TX; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Publication Date: 2019-07-19
    Description: The recovery of meteorites from the impact of asteroid 2008 TC3 in the Nubian Desert of Sudan on October 7, 2008, marked the first time meteorites were collected from an asteroid observed in space by astronomical techniques before impacting. Search teams from the University of Khartoum traced the location of the strewn field and collected about 660 meteorites in four expeditions to the fall region, all of which have known fall coordinates. Upon further study, the Almahata Sitta meteorites proved to be a mixed bag of mostly ureilites (course grained, fine grained, and sulfide-metal assemblages), enstatite chondrites (EL3-6, EH3, EH5, breccias) and ordinary chondrites (H5-6, L4-5). One bencubbinite-like carbonaceous chondrite was identified, as well as one unique Rumuruti-like chondrite and an Enstatite achondrite. New analysis: The analysed meteorites so far suggest a high 30-40 percent fraction of non-ureilites among the recovered samples, but that high fraction does not appear to be in agreement with the meteorites in the University of Khartoum (UoK) collection. Ureilites dominate the meteorites that were recovered by the Sudanese teams. To better understand the fraction of recovered materials that fell to Earth, a program has been initiated to type the meteorites in the UoK collection in defined search areas. At this meeting, we will present some preliminary results from that investigation.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-38419 , Asteroid Comets and Meteors Conference (ACM 2017); Apr 10, 2017 - Apr 14, 2017; Montevideo; Uruguay
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Publication Date: 2019-07-20
    Description: Mars sample return presents unique challenges for the clean collection, containment, curation and processing of samples. The related issues of life detection and Planetary Protection are of particular importance when developing successful strategies for the acquisition and handling of Mars returned samples. In order to achieve the Mars Sample Return (MSR) science goals, reliable analyses will depend on overcoming some challenging signal/noise-related issues, such that sparse Martian organic compounds will need to be reliably analyzed against the contamination background arising from the complicated MSR campaign. Reliable analyses will depend on clean acquisition, as well as robust documentation of all aspects of both the development and management of the cache.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN55953 , Meteoritical Society Meeting; Jul 23, 2017 - Jul 28, 2017; Santa Fe, NM; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Publication Date: 2019-07-20
    Description: Orbital observations have detected the phyllosilicate smectite in layered material hundreds of meters thick, intracrater depositional fans, and plains sediments on Mars; however, the detection of carbonate deposits is limited. Instead of neutral/alkaline conditions during the Noachian, early Mars may have experienced mildly acidic conditions derived from volcanic acid-sulfate solutions that allowed Fe/Mg smectite formation but prevented widespread carbonate formation. The detection of acid sulfates (e.g., jarosite) associated with smectite in Mawrth Vallis supports this hypothesis. Previous work demonstrated smectite (saponite) formation in closed hydrologic systems (batch reactor) from basaltic glass at pH 4 and 200C (Peretyazhko et al., 2016 GCA). This work presents results from alteration of basaltic glass from alkaline to acidic conditions in open hydrologic systems (flow-through reactor). Preliminary experiments exposed basaltic glass to deionized water at 190C at 0.25 ml/min where solution pH equilibrated to 9.5. These initial high pH experiments were conducted to evaluate the flow-through reactor system before working with lower pHs. Smectite at this pH was not produced and instead X-ray diffraction results consistent with serpentine was detected. Experiments are in progress exposing basaltic glass from pH 8 down to pH 3 to determine what range of pHs could allow for smectite formation in this experimental opensystem. The production of smectite under an experimental open-system at low pHs if successful, would support a significant paradigm shift regarding the geochemical evolution of early Mars: Early Mars geochemical solutions were mildly acidic, not neutral/alkaline. This could have profound implications regarding early martain microbiology where acid conditions instead of neutral/alkaline conditions will require further research in terrestrial analogs to address the potential for biosignature preservation on Mars.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN49336 , American Geophysical Union (AGU) Fall Meeting; Dec 11, 2017 - Dec 15, 2017; New Orleans, LA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Publication Date: 2019-07-13
    Description: The Asteroid Impact and Deflection Assessment (AIDA) mission concept would demonstrate an asteroid deflection through a high velocity spacecraft impact on the moon of the binary asteroid system Didymos. The NASA DART spacecraft would be launched on an impacting trajectory, while the ESA AIM spacecraft would be orbiting and observing the system before and after the impact. Radio science measurements with AIM provides information on the complex dynamics of the binary system. Combined with the DART experiment, the ability to measure the imparted delta-v has significant implications for how well the proposed AIDA mission would serve as a deflection demonstration. In addition, the impact-induced deflection, cratering, and mass transfer can be interpreted as indicators of surface properties. We provided preliminary analyses of the measurability of the DART impact as function of generic AIM spacecraft proximity operations and knowledge of the Didymos system from radio science techniques.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JPL-CL-CL#17-1723 , International Symposium on Space Flight Dynamics; Jun 03, 2017 - Jun 09, 2017; Matsuyama; Japan
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Publication Date: 2019-07-13
    Description: NASAs Mars 2020 mission is charged with responding to the highest priority objectives of the 2011 planetary sciences decadal survey, conducting extensive in-situ science on the surface of the Red Planet, and carrying important cross-agency human precursor technologies. The mission concept was predicated on and enabled by leveraging the Curiosity rover engineering design, successful Sky Crane landing systems, and other elements from the Mars Science Laboratory project into a new mission with new payload elements. High-heritage paradigms are unusual for flagship science missions and can be difficult to execute as the realities of spacecraft development intervene. However the project has had good success to-date from concept through formulation and into early implementation. This paper will describe the general approaches developed and used by the Mars 2020 Project team at NASAs Jet Propulsion Laboratory (JPL).
    Keywords: Lunar and Planetary Science and Exploration
    Type: JPL-CL-16-5042 , IEEE Aerospace Conference; Mar 04, 2017 - Mar 11, 2017; Big Sky, MO; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Publication Date: 2019-07-13
    Description: We present new measurements of the deuterium abundance on Jupiter and Saturn, showing evidence that Saturn's atmosphere contains less deuterium than Jupiter's. We analyzed far-infrared spectra from the Cassini Composite Infrared Spectrometer to measure the abundance of HD on both giant planets. Our estimate of the Jovian D/H = (2.95 +/- 0.55) x 10(exp -5) is in agreement with previous measurements by ISO/SWS: (2.25 +/- 0.35) x 10(exp -5), and the Galileo probe: (2.6 +/- 0.7) x 10(exp -5). In contrast, our estimate of the Saturn value of (2.10 +/- 0.13) x 10(exp -5) is somewhat lower than on Jupiter (by a factor of 0.71(sub -0.15, sup +0..22)), contrary to model predictions of a higher ratio: Saturn/ Jupiter = 1.05-1.20. The Saturn D/H value is consistent with estimates for hydrogen in the protosolar nebula (2.1 +/- 0.5) x 10(exp -5), but its apparent divergence from the Jovian value suggests that our understanding of planetary formation and evolution is incomplete, which is in agreement with previous work.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51137 , The Astronomical Journal (ISSN 0004-6256) (e-ISSN 1538-3881); 154; 5; 178
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Publication Date: 2019-07-13
    Description: Submillimeter emission lines of carbon monoxide (CO) in Titan's atmosphere provide excellent probes of atmospheric temperature due to the molecule's long chemical lifetime and stable, well constrained volume mixing ratio. Here we present the analysis of 4 datasets obtained with the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2012, 2013, 2014, and 2015 that contain strong CO rotational transitions. Utilizing ALMA's high spatial resolution in the 2012, 2014, and 2015 observations, we extract spectra from 3 separate regions on Titan's disk using datasets with beam sizes ranging from 0.35 0.28'' to 0.39 0.34''. Temperature profiles retrieved by the NEMESIS radiative transfer code are compared to Cassini Composite Infrared Spectrometer (CIRS) and radio occultation science results from similar latitude regions. Disk-averaged temperature profiles stay relatively constant from year to year, while small seasonal variations in atmospheric temperature are present from 2012 to 2015 in the stratosphere and mesosphere ( approx. 100-500 km) of spatially resolved regions. We measure the stratopause (320 km) to in- crease in temperature by 5 K in northern latitudes from 2012 to 2015, while temperatures rise throughout the stratosphere at lower latitudes. We observe generally cooler temperatures in the lower stratosphere ( approx. 100 km) than those obtained through Cassini radio occultation measurements, with the notable exception of warming in the northern latitudes and the absence of previous instabilities; both of these results are indicators that Titan's lower atmosphere responds to seasonal effects, particularly at higher latitudes. While retrieved temperature profiles cover a range of latitudes in these observations, deviations from CIRS nadir maps and radio occultation measurements convolved with the ALMA beam-footprint are not found to be statistically significant, and discrepancies are often found to be less than 5 K throughout the atmosphere. ALMA's excellent sensitivity in the lower stratosphere (60-300 km) provides a highly complementary dataset to contemporary CIRS and radio science observations, including altitude regions where both of those measurement sets contain large uncertainties. The demonstrated utility of CO emission lines in the submillimeter as a tracer of Titan's atmospheric temperature lays the groundwork for future studies of other molecular species -particularly those that exhibit strong polar abundance enhancements or are pressure-broadened in the lower atmosphere, as temperature profiles are found to consistently vary with latitude in all three years by up to 15 K.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51139 , Icarus (ISSN 0019-1035); 307; 380-390
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Publication Date: 2019-07-13
    Description: Recent simulations have indicated that vinyl cyanide is the best candidate molecule for the formation of cell membranes/vesicle structures in Titan's hydrocarbon-rich lakes and seas. Although the existence of vinyl cyanide (C2H3CN) on Titan was previously inferred using Cassini mass spectrometry, a definitive detection has been lacking until now. We report the first spectroscopic detection of vinyl cyanide in Titan's atmosphere, obtained using archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), collected from February to May 2014. We detect the three strongest rotational lines of C2H3CN in the frequency range of 230 to 232 GHz, each with greater than 4 sigma confidence. Radiative transfer modeling suggests that most of the C2H3CN emission originates at altitudes of approx. greater than 200 km, in agreement with recent photochemical models. The vertical column densities implied by our best-fitting models lie in the range of 3.7 x 10(exp 13) to 1.4 x 10(exp 14) cm(exp 2). The corresponding production rate of vinyl cyanide and its saturation mole fraction imply the availability of sufficient dissolved material to form approx. 10(exp 7) cell membranes/cu cm in Titan's sea Ligeia Mare.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51142 , Science Advances (e-ISSN 2375-2548); 3; 7; e1700022
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Publication Date: 2019-07-13
    Description: Neutron flux measurements by the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) enable quantifying hydrogen-bearing volatiles in the lunar surface from orbit. Accurately determining hydrogen abundance requires discriminating between the instrument background detection rate and the population of lunar-sourced neutrons that are sensitive to surficial hydrogen. We have investigated the detection rate for lunar and non-lunar (spacecraft-sourced) neutrons in LEND by modeling maps of measured count rate in three LEND detector systems using linear combinations of maps compiled from LEND detectors and from the Lunar Prospector Neutron Spectrometer. We find that 30% of the global-average 24.926 +/- 0.020 neutron counts per second (cps) detected by the LEND STN3 thermal-energy neutron sensor are lunar-sourced neutrons in the thermal energy range (E 〈 0.4 eV), 65% are lunar-sourced neutrons in the epithermal and fast energy range (E 〉 0.4 eV), and 5% are from spacecraft-sourced background signal. In the SETN epithermal neutron detector, 90% of the 10.622 +/- 0.002 neutron detections per second are consistent with a lunar source of epithermal and fast neutrons combined (E 〉 0.4 eV), with 3% due to lunar-sourced thermal neutron leakage into the detector (E 〈 0.4 eV), and background signal accounting for 7% of total detections. Background signal due to spacecraft-derived neutrons is substantial in the CSETN collimated detector system, accounting for 57% of the global average detection rate of 5.082 +/- 0.001 cps, greater than the 48% estimated from cruise-phase data. Lunar-sourced epithermal and fast neutrons account for 43% of detected neutrons, including neutrons in collimation as well as neutrons that penetrate the collimator wall to reach the detector. We estimate a lower limit of 17% of lunar-sourced neutrons detected by CSETN are epithermal neutrons in collimation (0.37 cps), with an upper limit estimate of 54 +/- 11% of lunar-sourced neutrons received in collimation, or 1.2 +/- 0.2 cps global average. The pole-to-equator contrast ratio in epithermal and high-energy epithermal neutron flux indicates that the average concentration of hydrogen in the polar regolith above 80deg north or south latitude is 105 ppmw (parts per million by weight), or 0.095 +/- 0.01 wt% water-equivalent hydrogen. Above 88deg north or south, the concentration increases to 140 ppmw, or 0.13 +/- 0.02 wt% water-equivalent hydrogen. The similar pattern of neutron flux suppression at both poles suggests that hydrogen concentration generally increases nearer the pole and is not closely associated with a specific feature such as Shackleton Crater at the lunar south pole that has no northern counterpart. Epithermal neutron flux decreases with increasing latitude outside the polar regions, consistent with surface hydration that increases with latitude if that hydration extends to 13-40 cm into the surface.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN50885 , Planetary and Space Science (ISSN 0032-0633); 162; 89-104
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Publication Date: 2019-07-13
    Description: By Einstein's general theory of relativity, gravity of a massive body deflects light, and thus the sun can be used as a lens. The focus of the sun's gravitational lens is about 550 AU (Astronomical Units). (The sun continues to act as a lens beyond this minimum; at longer distances, the focused light passes increasingly far from the solar limb.) A mission to the gravitational focus of the sun, beyond the edge of the solar system, but far closer than the nearest stars, could be a target for an interstellar precursor. Proposed methods of reaching the focal distance include electric propulsion or laser- or solar sails. An objective for such a mission is to use the gravitational lens to image and map an extrasolar planet.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GRC-E-DAA-TN47559 , Tennessee Valley Interstellar Workshop (TVIW 2017): Step by Step: Building A Ladder to the Stars; Oct 03, 2017 - Oct 06, 2017; Huntsville, AL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Publication Date: 2019-07-13
    Description: We utilized a probabilistic asteroid impact risk (PAIR) model to stochastically assess the impact risk due to an ensemble population of Near-Earth Objects (NEOs). Concretely, we present the variation of risk with impactor size. Results suggest that large impactors dominate the average risk, even when only considering the subset of undiscovered NEOs.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN48109 , Annual Division for Planetary Sciences Meeting; Oct 15, 2017 - Oct 20, 2017; Provo, UT; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Publication Date: 2019-07-13
    Description: Current technologies of exploring habitable areas of icy moons are limited to flybys of space probes. This research project addresses long-term navigation of icy moons by developing a MATLAB adjustable trajectory based on the volume of plume material observed. Plumes expose materials from the sub-surface without accessing the subsurface. Aerial vehicles capable of scouting vapor plumes and detecting maximum plume material volumes, which are considered potentially habitable in inhospitable environments, would enable future deep-space missions to search for extraterrestrial organisms on the surface of icy moons. Although this platform is still a prototype, it demonstrates the potential aerial vehicles can have in improving the capabilities of long-term space navigation and enabling technology for detecting life in extreme environments. Additionally, this work is developing the capabilities that could be utilized as a platform for space biology research. For example, aerial vehicles that are sent to map extreme environments of icy moons or the planet Mars, could also carry small payloads with automated cell-biology experiments, designed to probe the biological response of low-gravity and high-radiation planetary environments, serving as a pathfinder for future human missions.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN48090 , American Society for Gravitational and Space Research (ASGSR); Oct 25, 2017 - Oct 28, 2017; Seattle, WA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Publication Date: 2019-07-13
    Description: We present the first good evidence for exocomet transits of a host star in continuum light in data from the Kepler mission. The Kepler star in question, KIC 3542116, is of spectral type F2V and is quite bright at K(sub p)=10. The transits have a distinct asymmetric shape with a steeper ingress and slower egress that can be ascribed to objects with a trailing dust tail passing over the stellar disk. There are three deeper transits with depths of approximately equal to 0.1 percent that last for about a day, and three that are several times more shallow and of shorter duration. The transits were found via an exhaustive visual search of the entire Kepler photometric data set, which we describe in some detail. We review the methods we use to validate the Kepler data showing the comet transits, and rule out instrumental artifacts as sources of the signals. We fit the transits with a simple dust-tail model, and find that a transverse comet speed of approximately 35-50 km s(exp -1) and a minimum amount of dust present in the tail of approx. 10(exp 16) g are required to explain the larger transits. For a dust replenishment time of approx. 10 days, and a comet lifetime of only approx. 300 days, this implies a total cometary mass of approx. greater than 3 x 10(exp17) g, or about the mass of Halley's comet. We also discuss the number of comets and orbital geometry that would be necessary to explain the six transits detected over the four years of Kepler prime-field observations. Finally, we also report the discovery of a single comet-shaped transit in KIC 11084727 with very similar transit and host-star properties.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN48399 , Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711) (e-ISSN 1365-2966); 474; 2; 1453-1468
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN49272 , Super Computing Annual Conference (SC17); Nov 12, 2017 - Nov 17, 2017; Denver, CO; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Publication Date: 2019-07-13
    Description: Analysis of Lunar Exploration Neutron Detector (LEND) neutron count rates for a large set of mid-latitude craters provides evidence for lower hydrogen content in the crater interiors compared to typical highland values. Epithermal neutron count rates for crater interiors measured by the LEND Sensor for Epithermal Neutrons (SETN) were compared to crater exteriors for 301 craters and displayed an increase in mean count rate at the approx. 9-sigma confidence level, consistent with a lower hydrogen content. A smaller subset of 31 craters also shows a significant increase in Optical Maturity parameter implying an immature regolith. The increase in SETN count rate for these craters is greater than the increase for the full set of craters by more than a factor of two.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN63895 , GSFC-E-DAA-TN51131 , GSFC-E-DAA-TN66404 , Planetary and Space Science (ISSN 0032-0633); 162; 105-112
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Publication Date: 2019-07-13
    Description: We examine the relevance of tidal heating for large Trans-Neptunian Objects, with a focus on its potential to melt and maintain layers of subsurface liquid water. Depending on their past orbital evolution, tidal heating may be an important part of the heat budget for a number of discovered and hypothetical TNO systems and may enable formation of, and increased access to, subsurface liquid water. Tidal heating induced by the process of despinning is found to be particularly able to compete with heating due to radionuclide decay in a number of different scenarios. In cases where radiogenic heating alone may establish subsurface conditions for liquid water, we focus on the extent by which tidal activity lifts the depth of such conditions closer to the surface. While it is common for strong tidal heating and long lived tides to be mutually exclusive, we find this is not always the case, and highlight when these two traits occur together. We find cases where TNO systems experience tidal heating that is a significant proportion of, or greater than radiogenic heating for periods ranging from100 s of millions to a billion years. For subsurface oceans that contain a small antifreeze component, tidal heating due to very high initial spin states may enable liquid water to be preserved right up to the present day. Of particular interest is the Eris-Dysnomia system, which in those cases may exhibit extant cryovolcanism.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN50408 , ICARUS (ISSN 0019-1035); 302; 245-260
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Publication Date: 2019-07-13
    Description: Unmixing the disk-integrated spectra of exoplanets provides hints about heterogeneous surfaces that we cannot directly resolve in the foreseeable future. It is particularly important for terrestrial planets with diverse surface compositions like Earth. Although previous work on unmixing the spectra of Earth from disk-integrated multi-band light curves appeared successful, we point out a mathematical degeneracy between the surface colors and their spatial distributions. Nevertheless, useful constraints on the spectral shape of individual surface types may be obtained from the premise that albedo is everywhere between 0 and 1. We demonstrate the degeneracy and the possible constraints using both mock data based on a toy model of Earth, as well as real observations of Earth. Despite the severe degeneracy, we are still able to recover an approximate albedo spectrum for an ocean. In general, we find that surfaces are easier to identify when they cover a large fraction of the planet and when their spectra approach zero or unity in certain bands.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN48639 , The Astronomical Journal (ISSN 0004-6256) (e-ISSN 1538-3881); 154; 5; 189
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M17-6237 , Global Reference Atmospheric Model (GRAM) Virtual Workshop; Sep 21, 2017; Huntsville, AL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M17-6264 , AIAA Space and Astronautics Forum and Exposition (AIAA Space 2017); Sep 12, 2017 - Sep 14, 2017; Orlando, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: MSFC-E-DAA-TN47424 , Annual Geological Society of America (GSA) Meeting 2017; Oct 22, 2017 - Oct 25, 2017; Seattle, WA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Publication Date: 2019-07-13
    Description: Washboard texture or patterning consists of fields of parallel to sub-parallel ridges typically spaced ~1-2 km crest to crest and a few 100 m in amplitude (Fig. 4a in Moore et al., 2016, Science, 351, 1284-1293). For the most part, underlying topography can be easily discerned. We will refer to discrete, well-bounded patches of these landforms as Washboard Terrain (WT). WT is observed to occur along the rim, and just beyond the rim, of Sputnik basin from the West to NNW. Where it is seen in high-resolution data, it has clearly defined limits, beyond which it would be able to be seen if it were there. WT doesn't occur at very low latitudes or very high latitudes (ranging from 22degN to 62degN). WT seems to occur most conspicuously on relatively level, gently sloping terrain. It is restricted to elevations between approximately 2 km to less than +1.5 km (i.e. not at high elevations). The most noticeable regional aspect of the area in which WT occurs is the sinuous valley network, which is suspected to have been formed, or at least substantially modified, by glaciation. WT also appears to occur mainly on an intermediate-albedo reddish material, where seen in enhanced color data. Where it occurs in level terrain, WT tends to trend ENE - there doesn't seem to be a strong local control of its orientation in response to valley drainage directions. WT can display a greater range of orientations where it occurs in higher-relief (not higher elevation) settings such as spurs. WT appears superposed on very ancient landscapes, but is itself cratered locally by clusters of small (approximately 1-3 km) craters, which may be secondaries. This implies that WT may be intermediate in age. Of several working hypotheses, we currently provisionally favor that WT may be akin to terrestrial recessional moraines (or de Geer moraines) associated with the retreat of a higher stand of N2 glaciation that once overfilled Sputnik basin. These putative moraine features may owe their spacing to superseasonal retreat on Milankovitch timescales of approximately 1 Ma. If this hypothesis has validity, then perhaps the intermediate-albedo reddish material may be akin to ground moraine deposits.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Control ID 2815466 , ARC-E-DAA-TN46828 , Division for Planetary Sciences (DPS) Meeting; Oct 15, 2017 - Oct 20, 2017; Provo, UT; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Publication Date: 2019-07-13
    Description: The impact history of the Moon has significant implications beyond simply excavating the surface of our nearest neighbor. The age distribution of lunar impact breccias inspired the idea of a catastrophic influx of asteroids and comets about 4 billion years ago and motivated new models of planetary dynamics. An epoch of heavy bombardment after planets had atmospheres and continents would have influenced the course of biologic evolution. The story of a cataclysmic bombardment, written in the rocks of the Moon, has far-reaching consequences.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN45750 , 2017 Annual Meeting of the Lunar Exploration Analysis Group (LEAG 2017); Oct 10, 2017 - Oct 12, 2017; Columbia, MD; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Publication Date: 2019-07-13
    Description: The 2011 Visions & Voyages Planeary Science Decadal Survey identified making significant progress toward the return of samples from Mars as the highest priority goal for flagship missions in next decade. Numerous scientific objectives have been identified that could be advanced through the potential return and analysis of martian rock, regolith, and atmospheric samples. The analysis of returned martian samples would be particularly valuable in in-creasing our understanding of Early Mars. There are many outstanding gaps in our knowledge about Early Mars in areas such as potential astrobiology, geochronology, planetary evolution (including the age, context, and processes of accretion, differentiation, magmatic, and magnetic history), the history of water at the martian surface, and the origin and evolution of the martian atmosphere. Here we will discuss scientific objectives that could be significantly advanced by Mars sample return.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-40618 , International Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life; Oct 02, 2017 - Oct 06, 2017; Flagstaff, AZ; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Publication Date: 2019-07-13
    Description: This paper describes a structured light-based sensor for hazard avoidance in planetary environments. The system presented here can also be used in terrestrial applications constrained by reduced onboard power and computational complexity and low illumination conditions. The sensor is on a calibrated camera and laser dot projector system. The onboard hazard avoidance system determines the position of the projected dots in the image and through a triangulation process detects potential hazards. The paper presents the design parameters for this sensor and describes the image based solution for hazard avoidance. The system presented here was tested extensively in day and night conditions in Lunar analogue environments. The current system achieves over 97 detection rate with 1.7 false alarms over 2000 images.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN46999 , IROS 2017- International Conference on Intelligent Robots and Systems; Sep 24, 2017 - Sep 28, 2017; Vancouver, BC; Canada
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Publication Date: 2019-07-13
    Description: The Molecular Analyzer for Complex Refractory Organic-rich Surfaces, MACROS, is a novel instrument package being developed at NASA Goddard Space Flight Center. MACROS enables the in situ characterization of a sample's composition by coupling two powerful techniques into one compact instrument package: (1) laser desorption/ionization time-of-flight mass spectrometry (LDMS) for broad detection of inorganic mineral composition and non-volatile organics, and (2) liquid-phase extraction methods to gently isolate the soluble organic and inorganic fraction of a planetary powder for enrichment and detailed analysis by liquid chromatographic separation coupled to LDMS. The LDMS is capable of positive and negative ion detection, precision mass selection, and fragment analysis. Two modes are included for LDMS: single laser LDMS as the broad survey mode and two step laser mass spectrometry (L2MS). The liquid-phase extraction will be done in a newly designed extraction module (EM) prototype, providing selectivity in the analysis of a complex sample. For the sample collection, a diamond drill front end will be used to collect rock/icy powder. With all these components and capabilities together, MACROS offers a versatile analytical instrument for a mission targeting an icy moon, carbonaceous asteroid, or comet, to fully characterize the surface composition and advance our understanding of the chemical inventory present on that body.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51578 , GSFC-E-DAA-TN45689 , 2017 IEEE Aerospace Co; Mar 04, 2017 - Mar 11, 2017; Big Sky, MT; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Publication Date: 2019-07-13
    Description: NASA's Advanced Exploration Systems ISRU Technology Project is evaluating concepts to extract water from all resource types Near-term objectives: Produce high-fidelity mass, power, and volume estimates for mining and processing systems Identify critical challenges for development focus Begin demonstration of component and subsystem technologies in relevant environment Several processor types: Closed processors either partially or completely sealed during processing Open air processors operates at Mars ambient conditions In-situ processors Extract product directly without excavation of raw resource Design features Elimination of sweep gas reduces dust particles in water condensate Pressure maintained by height of soil in hopper Model developed to evaluate key design parameters Geometry: conveyor diameter, screw diameter, shaft diameter, flight spacing and pitch Operational: screw speed vs. screw length (residence time) Thermal: Heat flux, heat transfer to soil Testing to demonstrate feasibility and performance Agglomeration, clogging Pressure rise forced flow to condenser.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GRC-E-DAA-TN42170 , Joint Planetary & Terrestrial Mining and Sciences Symposium / Space Resource Roundtable and in conjunction with the Canadian Institute of Mining Convention; Apr 30, 2017 - May 02, 2017; Montreal, Quebec; Canada
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Publication Date: 2019-07-13
    Description: This year marks the 40th anniversary of the first Martian meteorite found in Antarctica by ANSMET, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET team making for a total of 15 Martian meteorites in the Antarctic collection at Johnson Space Center. Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate meteorites. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottites in 1982 [1]. This meteorite has been allocated to ~125 scientists for research and there are 181.964 g remaining at Johnson Space Center (JSC). Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain chemical compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft [2]. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to ~195 scientists for research and there are 5304.770 g of sample is available. Five years later, ANSMET found ALH 84001 (1930.900 g), the only Martian orthopyroxenite. This meteorite was initially classified as a diogenite but was reclassified as being a Martian meteorite in 1993 [3,4]. ALH 84001 is known as the "Life on Mars" meteorite, sparked debate about whether it contained evidence of Martian life [5] and significantly influenced the field of astrobiol-ogy. This sample has been allocated to 173 scientists for research and has 1426.694 g remaining at JSC. In 1988, another lherzolitic shergottite was found, LEW 88516, (13.203 g). This meteorite wasn't recognized in the field as an achondrite until it was broken during processing 2 years later. LEW 88516 has been allocated to 43 scientists for research and 5.351 g of this meteorite remains at JSC. Six years later a basaltic shergottite was found in the Queen Alexandra Range, QUE 94201 (12.020 g). This meteorite was believed to be of terrestrial origin until maskelynite was seen in a thin section. QUE 94201 has been allocated to 57 scientists for research and there are 3.629 g of this meteorite left at JSC. In 2003, the NASA Mars Exploration Program joined the ANSMET team with the hopes of finding another Martian mete-orite. During this expedition, MIL 03346 (715.200 g) was found. This meteorite is a nakhlite. MIL 03346 has been allocated to 98 scientists for research and there are 579.046 g of this sample remaining at JSC. Six years later, 3 more meteorites that have been paired with MIL 03346 were found, MIL 090030 (452.630 g), 090032 (532.190 g ) and 090136 (170.980 g). MIL 090030 has been allocated to 21 scientists for research and has 434.420 g remaining at JSC, MIL 090032 has been allocated to 21 scientists for re-search and has 508.710 g remaining at JSC and MIL 090136 has been allocated to 14 scientists for research and has 156.790 g remaining at JSC. During the 2004 expedition, 2 identical meteorites where found together on the ice, RBT 04261 (78.763 g) and RBT 04262 (204.600 g). These paired meteorites are olivine-phyric shergottites. RBT 04261 has been allocated to 33 scientists for research and has 32.335 g remaining at JSC. RBT 04262 has been allocated to 46 scientists for research and has 171.886 g remaining. In 2006, another olivine-phyric shergottite was found, LAR 06319 (78.572 g). This meteorite has 61.414 g remaining at JSC and has been allocated to 39 scientists for research. During the 2012 season, 3 more olivine-phyric shergottites were found at Larkman Nunatak, LAR 12011 (701.170 g), LAR 12095 (133.132 g) and LAR 12240 (57.596 g). LAR 12011 is paired with LAR 06319 and LAR 12095 and LAR 12240 are paired with each other. LAR 12011 has been allocated to 43 scientists for research and there are 685.778 g of LAR 12011 remaining at JSC. LAR 12095 has been allocated to 18 scientists for research and has 119.744 g remaining at JSC. LAR 12240 has been allocated to 10 scientists for research and has 52.231 g remaining at JSC. Martian meteorites are the only samples available from Mars because no mission has returned samples from there to date. All Martian meteorites are crustal rocks with most of them being crystallized magmas, so they are an important source for under-standing Martian geological history and volcanism. The ANSMET program has greatly contributed to the scientific community by collecting these meteorites
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-39788 , Annual Meeting of the Meteoritical Society; Jul 23, 2017 - Jul 28, 2017; Santa Fe, NM; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Publication Date: 2019-07-13
    Description: NASA's Mars Trek (https://marstrek.jpl.nasa.gov) provides a web-based Portal and a suite of interactive visualization and analysis tools to enable mission planners, lunar scientists, and engineers to access mapped data products from past and current missions to Mars. During the past year, the capabilities and data served by Mars Trek have been significantly expanded beyond its original design as a public outreach tool. At the request of NASA's Science Mission Directorate and Human Exploration Operations Mission Directorate, Mars Trek's technology and capabilities are now being extended to support site selection and analysis activities for the first human missions to Mars.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN42725 , European Planetary Science Congress 2017; Sep 17, 2017 - Sep 22, 2017; Riga; Latvia
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Publication Date: 2019-07-13
    Description: A new concept study was initiated to examine the architecture needed to gradually develop an economical, evolvable and sustainable lunar infrastructure using a public/private partnerships approach. This approach would establish partnership agreements between NASA and industry teams to develop a lunar infrastructure system that would be mutually beneficial. This approach would also require NASA and its industry partners to share costs in the development phase and then transfer operation of these infrastructure services back to its industry owners in the execution phase. These infrastructure services may include but are not limited to the following: lunar cargo transportation, power stations, communication towers and satellites, autonomous rover operations, landing pads and resource extraction operations. The public/private partnerships approach used in this study leveraged best practices from NASA's Commercial Orbital Transportation Services (COTS) program which introduced an innovative and economical approach for partnering with industry to develop commercial cargo services to the International Space Station. This program was planned together with the ISS Commercial Resupply Services (CRS) contracts which was responsible for initiating commercial cargo delivery services to the ISS for the first time. The public/private partnerships approach undertaken in the COTS program proved to be very successful in dramatically reducing development costs for these ISS cargo delivery services as well as substantially reducing operational costs. To continue on this successful path towards installing economical infrastructure services for LEO and beyond, this new study, named Lunar COTS (Commercial Operations and Transport Services), was conducted to examine extending the NASA COTS model to cis-lunar space and the lunar surface. The goals of the Lunar COTS concept are to: 1) develop and demonstrate affordable and commercial cis-lunar and surface capabilities, such as lunar cargo delivery and surface power generation, in partnership with industry; 2) incentivize industry to establish economical and sustainable lunar infrastructure services to support NASA missions and initiate lunar commerce; and 3) encourage creation of new space markets for economic growth and benefit. A phased-development approach was also studied to allow for incremental development and demonstration of capabilities needed to build a lunar infrastructure. This paper will describe the Lunar COTS concept goals, objectives and approach for building an economical and sustainable lunar infrastructure. It will also describe the technical challenges and advantages of developing and operating each infrastructure element. It will also describe the potential benefits and progress that can be accomplished in the initial phase of this Lunar COTS approach. Finally, the paper will also look forward to the potential of a robust lunar industrialization environment and its potential effect on the next 50 years of space exploration.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN45994 , AIAA Space 2017 Conference; Sep 12, 2017 - Sep 14, 2017; Orlando, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Publication Date: 2019-07-13
    Description: The Mercury Laser Altimeter (MLA) measured surface reflectance, r(sub s), at 1064 nm. On Mercury, most water-ice deposits have anomalously low r(sub s) values indicative of an insulating layer beneath which ice is buried. Previous detections of surface water ice (without an insulating layer) were limited to seven craters. Here we map r(sub s) in three additional permanently shadowed craters that host radar-bright deposits. Each crater has a mean r(sub s) value greater than 0.3, suggesting that water ice is exposed at the surface without an overlying insulating layer, bringing the total to ten large craters that host exposed water ice at Mercurys north pole. We also identify small-scale cold traps (less than 5 km in diameter) where r(sub s) greater than 0.3 and permanent shadows have biannual maximum surface temperatures less than 100 K. We suggest that a substantial amount of Mercury's water ice is not confined to large craters, but exists within micro-cold traps, within rough patches and inter-crater terrain.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN46062 , Geophysical Research Letters (ISSN 0094-8276) (e-ISSN 1944-8007); 44; 18; 9233-9241
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Publication Date: 2019-07-13
    Description: Analogous to terrestrial dust devils, charged dust in Mars dust devils should become vertically stratified in the convective features, creating large scale E-fields. This E-field in a Martian-like atmosphere has been shown to stimulate the development of a Townsend discharge (electron avalanche) that acts to dissipate charge in regions where charge build-up occurs. While the stratification of the charged dust is a source of the electrical energy, the uncharged particulates in the dust population may absorb a portion of these avalanching electrons, thereby inhibiting dissipation and leading to the development of anomalously large E-field values. We performed a laboratory study that does indeed show the presence of enhanced E-field strengths between an anode and cathode when dust-absorbing filaments (acting as particulates) are placed in the avalanching electron flow. Further, the E-field threshold condition to create an impulsive spark discharge increases to larger values as more filaments are placed between the anode and cathode. We conclude that the spatially separated charged dust creates the charge centers and E-fields in a dust devil, but the under-charged portion of the population acts to reduce Townsend electron dissipation currents, further fortifying the development of larger-than-expected E-fields.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN45505 , Icarus (ISSN 0019-1035) (e-ISSN 1090-2643); 297; 90-96
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Publication Date: 2019-07-13
    Description: The nakhlites/chassignites and the shergottites represent two differing suites of basaltic martian meteorites. The shergottites have ages less than or equal to 0.6 Ga and a large range of initial Sr-/Sr-86 and epsilon (Nd-143) ratios. Conversely, the nakhlites and chassignites cluster at 1.3-1.4 Ga and have a limited range of initial Sr-87/Sr-86 and epsilon (Nd-143). More importantly, the shergottites have epsilon (W-182) less than 1, whereas the nakhlites and chassignites have epsilon (W-182) approximately 3. This latter observation precludes the extraction of both meteorite groups from a single source region. However, recent Pb isotopic analyses indicate that there may have been interaction between shergottite and nakhlite/chassignite Pb reservoirs.Pb Analyses of Chassigny: Two different studies haveinvestigated 207Pb/204Pb vs. 206Pb/204Pb in Chassigny: (i)TIMS bulk-rock analyses of successive leaches and theirresidue [3]; and (ii) SIMS analysis of individual minerals[4]. The bulk-rock analyses fall along a regression of SIMSplagioclase analyses that define an errorchron that is olderthan the Solar System (4.610.1 Ga); i.e., these define amixing line between Chassignys principal Pb isotopic components(Fig. 1). Augites and olivines in Chassingy (notshown) also fall along or near the plagioclase regression [4].This agreement indicates that the whole-rock leachateslikely measure indigenous, martian Pb, not terrestrial contamination[5]. SIMS analyses of K-spars and sulfides definea separate, sub-parallel trend having higher 207Pb/206Pbvalues ([4]; Fig. 1). The good agreement between the bulkrockanalyses and the SIMS analyses of plagioclases alsoindicates that the Pb in the K-spars and sulfides cannot be amajor component of Chassigny.The depleted reservoir sampled by Chassigny plagioclaseis not the same as the solar system initial (PAT) andrequires a multi-stage origin. Here we show a two-stagemodel (Fig. 1) with a 238U/204Pb () of 0.5 for 4.5-2.4 Gaand a of 7 for 2.4-1.4 Ga. This is not a unique model butdoes produce a Pb composition that falls on the plagioclaseregression at 1.4 Ga, the approximate igneous age of Chassigny [1]. It should be noted that low- single-stage modelsare not capable of producing sufficiently radiogenic 206Pb/204Pb at 1.4 Ga.Relation to Shergottites: The Chassigny K-spars and sulfides fall along a second mixing line defined by leachesand residues of depleted and intermediate shergottites [6]. This mixing line falls above the plagioclase regression.Therefore, we also interpret the radiogenic component of this mixing line to represent indigenous martian Pb. It ispossible that the depleted and intermediate shergottites and the Chassigny plagioclases sample radiogenic Pb from thethe same source, i.e., the mixing lines may intersect at high 206Pb/204Pb.Both K-spar and sulfide are late-stage phases. At the time of their crystallization, the Chassigny system appearsto have remained open to a depleted shergottite Pb reservoir. The depleted component of the shergottite mixing linecan be generated by a single-stage evolution from PAT (4.5 to 1.4 Ga) in a reservoir having a ~2. A similar modelfor the most depleted shergottites is also possible: = 1.5 for 4.5 to 0.3 Ga.Nakhlites: Nakhlite analyses plot between the shergottite and Chassigny plagioclase regressions [3]. So again,members of the nakhlite/chassignite suite show affinities to shergottite Pb.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-39713 , Annual Meetings of the Meteoritical Society; Jul 24, 2017 - Jul 28, 2017; Santa Fe, NM; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Publication Date: 2019-07-13
    Description: Penitentes are snow and ice features formed by erosion that, on Earth, are characterized by bowl-shaped depressions several tens of centimetres across, whose edges grade into spires up to several metres tall. Penitentes have been suggested as an explanation for anomalous radar data on Europa, but until now no penitentes have been identified conclusively on planetary bodies other than Earth. Regular ridges with spacings of 3,000 to 5,000 metres and depths of about 500 metres with morphologies that resemble penitentes have been observed by the New Horizons spacecraft in the Tartarus Dorsa region of Pluto (220 deg -250 deg E, 0 deg -20 deg N). Here we report simulations, based upon a recent model representing conditions on Pluto in which deepening penitentes reproduce both the tri-modal (north-south, east-west and northeast-southwest) orientation and the spacing of the ridges of this bladed terrain. At present, these penitentes deepen by approximately one centimetre per orbital cycle and grow only during periods of relatively high atmospheric pressure, suggesting a formation timescale of several tens of millions of years, consistent with crater ages. This timescale implies that the penitentes formed from initial topographic variations of no more than a few tens of metres, consistent with Plutos youngest terrains.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN42463 , Nature (ISSN 0028-0836) (e-ISSN 1476-4687); 541; 7636; 188–190
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Publication Date: 2019-07-19
    Description: Tobias Chant Owen (Toby) was a graduate student of G. P. Kuiper, receiving his Ph.D. in the Dept. of Astronomy, University of Arizona, in 1965. His thesis was broadly titled "Studies of Planetary Spectra in the Photographic Infrared", and primarily presented a study of the composition and other properties of Jupiter, as well as the abundance and surface pressure of CO2 on Mars. The surface pressure on Mars was a topic of debate at that time, with a wide range of diverse observational results from several investigators. The Jupiter work in particular consisted of the analysis of Kuiper's unpublished spectra that were made with photographic plates pushed to the longest wavelength possible, about 1120 nm, with ammonia-hypersensitized Kodak Z emulsions. Toby used the long-pathlength absorption cells at the Lunar and Planetary Lab to study the spectra of CH4 and NH3 at pressures and temperatures relevant to Jupiter (and Saturn), as well as to search for spectral signatures of potential minor components of their atmospheres. Toby also obtained new spectra of Io, Ganymede, and Saturn and its rings, extended to the long-wavelength limit of photographic emulsions. No new molecular absorptions were found, although Owen basically confirmed Kuiper's earlier result that Saturn's rings are covered (or composed of) with H2O ice or frost. As he pursued a broad range of problems of planetary atmospheres, Toby used existing and newly acquired spectra of the planets in the photographic and near-infrared wavelength regions, together with data he obtained in the laboratory with long-pathlength absorption cells, to resolve some outstanding issues of unidentified spectral features and to clarify issues of the compositions, temperatures, and atmospheric pressures of several bodies. This work laid the foundation for his later decades of studies of planetary atmospheres and comets with spacecraft as an active participant in many US and European missions. He was very influential in shaping the science goals of several missions, and in the interpretation of the results.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN45288 , Annual Division for Planetary Sciences Meeting; Oct 15, 2017 - Oct 20, 2017; Provo, UT; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Publication Date: 2019-07-19
    Description: The announcement of the Vision for Space Exploration in 2004 sparked a resurgence in lunar missions worldwide. Since the publication of the first "New Views of the Moon" volume, as of 2017 there have been 11 science-focused missions to the Moon. Each of these missions explored different aspects of the Moon's geology, environment, and resource potential. The results from this flotilla of missions have revolutionized lunar science, and resulted in a profoundly new emerging understanding of the Moon. The New Views of the Moon II initiative itself, which is designed to engage the large and vibrant lunar science community to integrate the results of these missions into new consensus viewpoints, is a direct outcome of this impressive array of missions. The "Lunar Exploration Missions Since 2006" chapter will "set the stage" for the rest of the volume, introducing the planetary community at large to the diverse array of missions that have explored the Moon in the last decade. Content: This chapter will encompass the following missions: Kaguya; ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moons Interaction with the Sun); Change-1; Chandrayaan-1; Moon Impact Probe; Lunar Reconnaissance Orbiter (LRO); Lunar Crater Observation Sensing Satellite (LCROSS); Change-2; Gravity Recovery and Interior Laboratory (GRAIL); Lunar Atmosphere and Dust Environment Explorer (LADEE); Change-3.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN48089 , New Views of the Moon - Europe (NVM-2 2017); May 04, 2017 - May 05, 2017; Muenster; Germany
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Publication Date: 2019-07-19
    Description: The Mars Science Laboratory rover, Curiosity, is exploring the lowermost formation of Gale crater's central mound. Within this formation, three samples named Marimba, Quela, and Sebina have been analyzed by the CheMin X-ray diffractometer and the Alpha Particle X-ray Spectrometer (APXS) to determine mineralogy and bulk elemental chemistry, respectively. Marimba and Quela were also analyzed by the SAM (Sample Analysis at Mars) instrument to characterize the type and abundance of volatile phases detected in evolved gas analyses (EGA). CheMin data show similar proportions of plagioclase, hematite, and Ca-sulfates along with a mixture of di- and trioctahedral smectites at abundances of approximately 28, approximately 16, and approximately 18 wt% for Marimba, Quela, and Sebina. Approximately 50 wt% of each mudstone is comprised of X-ray amorphous and trace crystalline phases present below the CheMin detection limit (approximately 1 wt%). APXS measurements reveal a distinct bulk elemental chemistry that cannot be attributed to the clay mineral variation alone indicating a variable amorphous phase assemblage exists among the three mudstones. To explore the amorphous component, the calculated amorphous composition and SAM EGA results are used to identify amorphous phases unique to each mudstone. For example, the amorphous fraction of Marimba has twice the FeO wt% compared to Quela and Sebina yet, SAM EGA data show no evidence for Fe-sulfates. These data imply that Fe must reside in alternate Fe-bearing amorphous phases (e.g., nanophase iron oxides, ferrihydrite, etc.). Constraining the composition, abundances, and proposed identity of the amorphous fraction provides an opportunity to speculate on the past physical, chemical, and/or diagenetic processes which produced such phases in addition to sediment sources, lake chemistry, and the broader geologic history of Gale crater.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-40602 , Geological Society of America (GSA) 2017 Annual Meeting; Oct 22, 2017 - Oct 25, 2017; Seattle, WA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Publication Date: 2019-07-19
    Description: Recent observations from Gale Crater, Mars document past aqueous alteration both in the formation of the Stimson sandstone unit, as well as in the formation of altered fractures within that unit. Geochemical and mineralogical data from Curiosity also suggest Fe-rich amorphous weathering products are present in most samples measured to date. Here we interpret conditions of possible past weathering in Gale Crater using a combination of field, laboratory, and modeling work. In order to better understand secondary Fe-rich phases on Mars, we are examining formation of weathering products in high Fe and Mg and low Al serpentine soils in the Klamath Mountains, CA. We have isolated potential weathering products from these soils, and are analyzing them using synchrotron XRF and XRD as well as FullPat for a direct comparison to analyses from Gale Crater. In order to interpret the implications of the persistence of potential secondary Fe-containing phases on Mars, we are also measuring the dissolution rates of the secondary weathering products allophane, Fe-rich allophane, and hisingerite. Ongoing dissolution experiments of these materials suggest that they dissolve significantly more rapidly than more crystalline secondary minerals with similar chemical compositions. Finally, to quantify the specific conditions of past aqueous alteration in Gale Crater we are performing reactive transport modeling of a range of possible past environmental conditions. Specifically, we are testing the conditions under which a Stimson unit-like material forms from a parent material similar to Rocknest or Bagnold eolian deposits, and the conditions under which observed altered fracture zones form from a Stimson unit-like parent material. Our modeling results indicate that the formation of the Stimson unit is consistent with leaching of an eolian deposit with a solution of pH = 6-8, and that formation of the altered fracture zones is consistent with leaching with a very acidic (pH = 2-3) high sulfate solution containing Ca. These results suggest circumneutral pH conditions during authigenesis or early diagenesis in the Stimson formation sediments followed by diagenetic alteration by very acidic solutions along fracture zones.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-40603 , Geological Society of America (GSA) Annual Meeting 2017; Oct 22, 2017 - Oct 25, 2017; Seattle, WA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Publication Date: 2019-07-19
    Description: Between late fall and early spring, Mars' middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN46928 , Annual Division for Planetary Sciences Meeting (DPS 2017); Oct 15, 2017 - Oct 20, 2017; Provo, UT; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Publication Date: 2019-07-19
    Description: Introduction: Taxonomic classification of asteroids based on their visible / near-infrared spectra or multi band photometry has proven to be a useful tool to infer other properties about asteroids. Meteorite analogs have been identified for several taxonomic classes, permitting detailed inference about asteroid composition. Trends have been identified between taxonomy and measured asteroid density. Thanks to NEOWise (Near-Earth-Object Wide-field Infrared Survey Explorer) and Spitzer (Spitzer Space Telescope), approximately twice as many asteroids have measured albedos than the number with taxonomic classifications. (If one only considers spectroscopically determined classifications, the ratio is greater than 40.) We present a Bayesian framework that provides probabilistic estimates of the taxonomic class of an asteroid based on its albedo. Although probabilistic estimates of taxonomic classes are not a replacement for spectroscopic or photometric determinations, they can be a useful tool for identifying objects for further study or for asteroid threat assessment models. Inputs and Framework: The framework relies upon two inputs: the expected fraction of each taxonomic class in the population and the albedo distribution of each class. Luckily, numerous authors have addressed both of these questions. For example, the taxonomic distribution by number, surface area and mass of the main belt has been estimated and a diameter limited estimate of fractional abundances of the near earth asteroid population was made. Similarly, the albedo distributions for taxonomic classes have been estimated for the combined main belt and NEA (Near Earth Asteroid) populations in different taxonomic systems and for the NEA population specifically. The framework utilizes a Bayesian inference appropriate for categorical data. The population fractions provide the prior while the albedo distributions allow calculation of the likelihood an albedo measurement is consistent with a given taxonomic class. These inputs allows calculation of the probability an asteroid with a specified albedo belongs to any given taxonomic class.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN40726
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Publication Date: 2019-07-19
    Description: NASA's Resource Prospector (RP) mission intends to visit a lunar polar region to characterize the volatile distribution. Part of the RP payload, the Near-infrared Volatile Spectrometer System (NIRVSS) is a spectrometer operating from 1600-3400 nm that provides sensitivity to water ice, and other volatiles. For multiple years, the NIRVSS system has been incorporated into on-going RP payload testing in a cryogenic vacuum facility at Glenn Research Center. Soil tubes of lunar simulants, prepared with known amounts of water, are placed in the vacuum chamber and cooled to cryogenic temperatures (soil temperatures of 110-170 K) and placed under low vacuum (a few x 10(exp -6) Torr). During these tests NIRVSS continuously measures spectra of soil cuttings emplaced onto the surface by a drill. Real time processing of NIRVSS spectra produces two spectral parameters associated with water ice absorption features near 2000 and 3000 nm that can be used to inform decision making activities such as delivery of the soil to a sealable container. Post-test collection and analyses of the soils permit characterization the water content as a function of depth. These water content profiles exhibit the characteristics of a vacuum desiccation zone to depths of about 40 cm. Subsequent to completion of the tests, NIRVSS spectra are processed to produce two spectral parameters associated with water ice absorption features near 2000 and 3000 nm. These features can be evaluated as a function of time, and correlated with drill depth, and other measurements, throughout the drilling activities. Until now no effort was attempted to quantitatively relate these parameters to water abundance. This is the focus of our efforts to be presented.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN45469 , AGU Fall Meeting; Dec 11, 2017 - Dec 15, 2017; New Orleans, LA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Publication Date: 2019-07-13
    Description: The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 +/- 248-2373 +/- 820 gC(CO2)/g) and CO (11 +/- 3-320 +/- 130 gC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32 +/- 0.05-0.70 +/- 0.1 wt % CO3). Evolved NO amounts to 0.002 +/- 0.007-0.06 +/- 0.03 wt % NO3. Evolution of O2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 +/- 0.025-1.05 +/- 0.44 wt % ClO4) are present, while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 +/- 0.3-2.5 +/- 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN54011 , Journal of Geophysical Research: Planets (ISSN 2169-9097) (e-ISSN 2169-9100); 122; 12; 2574-2609
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Publication Date: 2019-07-13
    Description: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This articledescribes how pristine was defined based on expectations of Bennu and on a realisticunderstanding of what is achievable with a constrained schedule and budget, and how thatdefinition flowed to requirements and implementation. To return a pristine sample, the OSIRISRExspacecraft sampling hardware was maintained at level 100 A/2 and 〈180 ng/cm2 of aminoacids and hydrazine on the sampler head through precision cleaning, control of materials, andvigilance. Contamination is further characterized via witness material exposed to the spacecraftassembly and testing environment as well as in space. This characterization provided knowledgeof the expected background and will be used in conjunction with archived spacecraft componentsfor comparison with the samples when they are delivered to Earth for analysis. Most of all, thecleanliness of the OSIRIS-REx spacecraft was achieved through communication amongscientists, engineers, managers, and technicians.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN56155 , Space Science Reviews (ISSN 0038-6308) (e-ISSN 1572-9672); 214; 1; 19
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Publication Date: 2019-07-13
    Description: Recent observations and analysis of low mass (〈10 M), exoplanets have found that rocky planets only have radii up to 1.5-2 R. Two general hypotheses exist for the cause of the dichotomy between rocky and gas-enveloped planets (or possible water worlds): either low mass planets do not necessarily form thick atmospheres of a few wt. %, or the thick atmospheres on these planets easily escape driven by x-ray and extreme ultraviolet (XUV) emissions from young parent stars. Here we show that a cutoff between rocky and gas-enveloped planets due to hydrodynamic escape is most likely to occur at a mean radius of 1.76 +/- 0.38 (2) R around Sunlike stars. We examine the limit in rocky planet radii predicted by hydrodynamic escape across a wide range of possible model inputs using 10,000 parameter combinations drawn randomly from plausible parameter ranges. We find a cutoff between rocky and gas-enveloped planets that agrees with the observed cutoff. The large cross-section available for XUV absorption in the extremely distended primitive atmospheres of low mass planets results in complete loss of atmospheres during the ~100 Myr phase of stellar XUV saturation. In contrast, more massive planets have less distended atmospheres and less escape, and so retain thick atmospheres through XUV saturation and then indefinitely as the XUV and escape fluxes drop over time. The agreement between our model and exoplanet data leads us to conclude that hydrodynamic escape plausibly explains the observed upper limit on rocky planet size and few planets (a "valley") in the 1.5-2 R range.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN45051 , Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 846; 2; 130
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Publication Date: 2019-07-13
    Description: The latitude-altitude map of ammonia mixing ratio shows an ammonia-rich zone at 0-5degN, with mixing ratios of 320-340 ppm, extending from 40-60 bars up to the ammonia cloud base at 0.7 bars. Ammonia-poor air occupies a belt from 5-20degN. We argue that downdrafts as well as updrafts are needed in the 0-5degN zone to balance the upward ammonia flux. Outside the 0-20degN region, the belt-zone signature is weaker. At latitudes out to +/-40deg, there is an ammonia-rich layer from cloud base down to 2 bars which we argue is caused by falling precipitation. Below, there is an ammonia-poor layer with a minimum at 6 bars. Unanswered questions include how the ammonia-poor layer is maintained, why the belt-zone structure is barely evident in the ammonia distribution outside 0-20degN, and how the internal heat is transported through the ammonia-poor layer to the ammonia cloud base.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN44861 , Geophysical Research Letters (ISSN 0094-8276) (e-ISSN 1944-8007); 44; 15; 7676-7685
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Publication Date: 2019-07-13
    Description: The SSERVI Central Office forms the organizational, administrative and collaborative hub for the domestic and international teams, and is responsible for advocacy and ensuring the long-term health and relevance of the Institute. SSERVI has increased the cross-talk between NASAs space and human exploration programs, which is one of our primary goals. We bring multidisciplinary teams together to address fundamental and strategic questions pertinent to future human space exploration, and the results from that research are the primary products of the institute. The team and international partnership reports contain summaries of 2017 research accomplishments. Here we present the 2017 accomplishments by the SSERVI Central Office that focus on: 1) Supporting Our Teams, 2) Community Building, 3) Managing the Solar System Treks Portal (SSTP), and 4) Public Engagement.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN53854
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Publication Date: 2019-07-13
    Description: Radiative transfer modeling of near-infrared spectra taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument onboard Mars Reconnaissance Orbiter (MRO) enables the column-integrated abundance of carbon monoxide (CO) and water vapor (H 2 O) to be retrieved. These results provide a detailed global description of the seasonal and spatial distribution of CO in the Mars atmosphere and new information about the interannual variability of H2O. The CRISM retrievals show the seasonally and globally averaged carbon monoxide mixing ratio to be near 800 parts per million, but with strong seasonal variations, especially at high latitudes. At low latitudes, the carbon monoxide mixing ratio varies in response to the mean seasonal cycle of surface pressure and shows little variation with topography. At high latitudes, carbon monoxide is depleted in the summer hemisphere by a factor of two or more, while in the winter hemisphere there is relatively higher mixing ratio in regions with low-lying topography. Water vapor shows only modest interannual variations, with the largest observed difference being unusually dry conditions in the wake of the Mars Year 28 global dust storm. Modeling results from the GEM (Global Environmental Multiscale) - Mars general circulation model generally reproduce the observed seasonal and spatial trends and provide insight into the underlying physical processes.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51040 , Icarus (ISSN 0019-1035) (e-ISSN 1090-2643); 301; 117-131
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Publication Date: 2019-07-13
    Description: For several years meteorite recovery in the United States has been greatly enhanced by using Doppler weather radar images to determine possible fall zones for meteorites produced by witnessed fireballs. While most fireball events leave no record on the Doppler radar, some large fireballs do. Based on the successful recovery of 10 meteorite falls 'under the radar', and the discovery of radar on more than 10 historic falls, it is believed that meteoritic dust and or actual meteorites falling to the ground have been recorded on Doppler weather radar.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN55950 , Planetary and Space Science (ISSN 0032-0633); 143; 199-202
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Publication Date: 2019-07-13
    Description: We provide an overview of the composition, vertical structure, and variability of the nightside ionosphere of Mars as observed by Mars Atmosphere and Volatile EvolutioN (MAVEN)'s Neutral Gas and Ion Mass Spectrometer (NGIMS) through 19 months of the MAVEN mission. We show that O+2 is the most abundant ion down to 130 km at all nightside solar zenith angles (SZA). However, below 130 km NO+ is the most abundant ion, and NO+ densities increase with decreasing altitude down to at least 120 km. We also show how the densities of the major ions decrease with SZA across the terminator. At lower altitudes the O+2 and CO+2 densities decrease more rapidly with SZA than the NO+ and HCO+ densities, which changes the composition of the ionosphere from being primarily O+2 on the dayside to being a mixture of O+2, NO+, and HCO+ on the nightside. These variations are in accord with the expected ion-neutral chemistry, because both NO+ and HCO+ have long chemical lifetimes. Additionally, we present median ion density profiles from three different nightside SZA ranges, including deep on the nightside at SZAs greater than 150 and discuss how they compare to particle precipitation models. Finally, we show that nightside ion densities can vary by nearly an order of magnitude over month long timescales. The largest nightside densities were observed at high northern latitudes during winter and coincided with a major solar energetic particle event.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51442 , Journal of Geophysical Research: Space Physics; 122; 4; 4712-4725
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Publication Date: 2019-07-13
    Description: One of the Juno magnetometer investigation's star cameras was configured to search for unidentified objects during Juno's transit en route to Jupiter. This camera detects and registers luminous objects to magnitude 8. Objects persisting in more than five consecutive images and moving with an apparent angular rate of between 2 and 18,000 arcsec/s were recorded. Among the objects detected were a small group of objects tracked briefly in close proximity to the spacecraft. The trajectory of these objects demonstrates that they originated on the Juno spacecraft, evidently excavated by micrometeoroid impacts on the solar arrays. The majority of detections occurred just prior to and shortly after Juno's transit of the asteroid belt. This rather novel detection technique utilizes the Juno spacecraft's prodigious 60 sq. m of solar array as a dust detector and provides valuable information on the distribution and motion of interplanetary (greater than a micron) dust. Plain Language Summary: The Juno magnetometer investigation uses star cameras co-located with the magnetic sensors at the outer end of one of Juno's solar arrays. These cameras compare images with an onboard star catalog to determine the orientation of the sensors in inertial space. They also serendipitously recorded multiple images of small particles excavated from the spacecraft by high-velocity dust impacts. We trace their trajectories back in time to demonstrate that they evolved from the spacecraft. This allows us to use the vast collecting area of Juno's solar arrays (60 sq. m)as a novel dust detector, sensitive to particles with a mass range never before measured in situ.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51480 , Geophysical Research Letters (ISSN 0094-8276) (e-ISSN 1944-8007); 44; 10; 4701-4708
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Publication Date: 2019-07-13
    Description: The analysis of water-soluble organic compounds in meteorites provides valuable insights into the prebiotic synthesis of organic matter and the processes that occurred during the formation of the solar system. We investigated the concentration of aliphatic monoamines present in hot acid water extracts of the unaltered Antarctic carbonaceous chondrites, Dominion Range (DOM) 08006 (CO3) and Miller Range (MIL) 05013 (CO3), and the thermally altered meteorites, Allende (CV3), LAP 02206 (CV3), GRA 06101 (CV3), Allan Hills (ALH) 85002 (CK4), and EET 92002 (CK5). We have also reviewed and assessed the petrologic characteristics of the meteorites studied here to evaluate the effects of asteroidal processing on the abundance and molecular distributions of monoamines. The CO3, CV3, CK4, and CK5 meteorites studied here contain total concentrations of amines ranging from 1.2 to 4.0 nmol/g of meteorite; these amounts are 1-3 orders of magnitude below those observed in carbonaceous chondrites from the CI, CM, and CR groups. The low-amine abundances for CV and CK chondrites may be related to their extensive degree of thermal metamorphism and/or to their low original amine content. Although the CO3 meteorites, DOM 08006 and MIL 05013, do not show signs of thermal and aqueous alteration, their monoamine contents are comparable to those observed in moderately/extensively thermally altered CV3, CK4, and CK5 carbonaceous chondrites. The low content of monoamines in pristine CO carbonaceous chondrites suggests that the initial amounts, and not asteroidal processes, play a dominant role in the content of monoamines in carbonaceous chondrites. The primary monoamines, methylamine, ethylamine, and n-propylamine constitute the most abundant amines in the CO3, CV3, CK4, and CK5 meteorites studied here. Contrary to the predominance of n-x-amino acid isomers in CO3 and thermally altered meteorites, there appears to be no preference for the larger n-amines.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51703 , Meteoritics & Palanetary Science (ISSN 1945-5100) (e-ISSN 1945-5100); 52; 12; 2632-2646
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Publication Date: 2019-07-13
    Description: The potential habitability of detected exoplanets is typically assessed using the concept of equilibrium temperature (T[subscript] e) based on cloud-free 1-D models with assumed albedo equal to Earth's (0.3) to determine whether a planet lies in the habitable zone. Incident stellar flux appears to be a better metric for stars unlike the Sun. These estimates, however, ignore the effect of clouds on planetary albedo and the fact that the climates of synchronously rotating planets are not well predicted by 1-D models. Given that most planet candidates that will be detected in the next few years will be tidally locked and orbiting M stars, how might the habitable zone e tailored to better in-form characterization with scarce observing resources?
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51079 , Habitable Worlds 2017: A System Science Workshop; Nov 13, 2017 - Nov 17, 2017; Laramie, WY; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M17-6287 , Venera-D Venus Modelling Workshop; Oct 05, 2017 - Oct 07, 2017; Moscow; Russia
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M17-6288 , Venera-D Modelling Workshop; Oct 05, 2017 - Oct 07, 2017; Moscow; Russia
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M17-6299 , Venera-D Venus Modelling Workshop; Oct 05, 2017 - Oct 07, 2017; Moscow; Russia
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Publication Date: 2019-07-13
    Description: Impact-melt samples from Apollo Luna are 3.85-4.1 Ga, tied to Imbrium, Serenitatis, Crisium, Nectaris, plus other craters? May have been caused by destabilization of material in early solar system by dynamic forces such as gas drag and gravitational interactions Coincident with the oldest rocks on the Earth and later than the earliest isotopic signs of life on Earth. Earth was already a planet with oceans, plate tectonics, and single celled life What was happening on the Moon before 3.9 Ga affected the course of life on Earth, the structure of our Solar System, and the dynamics of extra solar planetary systems.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN47765 , 2017 Annual Meeting of the Lunar Exploration Analysis Group (LEAG 2017); Oct 10, 2017 - Oct 12, 2017; Columbia, MD; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-40705 , ESA Workshop on Avionics, Data, Control and Software Systems (ADCSS); Oct 17, 2017 - Oct 19, 2017; Noordwijk; Netherlands
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Publication Date: 2019-07-13
    Description: The Inner Planets Panel of the Planetary Exploration Decadal Survey defined several science questions related to the origins, emplacement, and sequestration of lunar polar volatiles: 1. What is the lateral and vertical distribution of the volatile deposits? 2. What is the chemical composition and variability of polar volatiles? 3. What is the isotopic composition of the volatiles? 4. What is the physical form of the volatiles? 5. What is the rate of the current volatile deposition? A mission concept study, the Lunar Polar Volatiles Explorer (LPVE), defined a approximately $1B New Frontiers mission to address these questions. The NAS/NRC report, 'Scientific Context for the Exploration of the Moon' identified he lunar poles as special environments with important implications. It put forth the following goals: Science Goal 4a-Determine the compositional state (elemental, isotopic, mineralogic) and compositional distribution (lateral and depth) of the volatile component in lunar polar regions. Science Goal 4b-Determine the source(s) for lunar polar volatiles. Science Goal 4c-Understand the transport, retention, alteration, and loss processes that operate on volatile materials at permanently shaded lunar regions. Science Goal 4d-Understand the physical properties of the extremely cold (and possibly volatile rich) polar regolith. Science Goal 4e-Determine what the cold polar regolith reveals about the ancient solar environment.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN46000 , Annual Meeting of the Lunar Exploration Analysis Group (LEAG 2017); Oct 10, 2017 - Oct 12, 2017; Columbia, MD; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Publication Date: 2019-07-13
    Description: The cryostratigraphy of permafrost in ultraxerous environments is poorly known. In this study, icy permafrost cores from University Valley (McMurdo Dry Valleys, Antarctica) were analyzed for sediment properties, ground-ice content, types and distribution of cryostructures, and presence of unconformities. No active layer exists in the valley, but the ice table, a sublimation unconformity, ranges from 0 to 60 cm depth. The sediments are characterized as a medium sand, which classifies them as low to non-frost susceptible. Computed tomography (CT) scan images of the icy permafrost cores revealed composite cryostructures that included the structureless, porous visible, suspended and crustal types. These cryostructures were observed irrespective of ground-ice origin (vapour deposited and freezing of snow meltwater), suggesting that the type and distribution of cryostructures could not be used as a proxy to infer the mode of emplacement of ground ice. Volumetric ice content derived from the CT scan images underestimated measured volumetric ice content, but approached measured excess ice content. A palaeo-sublimation unconformity could not be detected from a change in cryostructures, but could be inferred from an increase in ice content at the maximum predicted ice table depth. This study highlights some of the unique ground-ice processes and cryostructures in ultraxerous environments.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN42142 , Permafrost and Periglacial Processes (ISSN 1045-6740) (e-ISSN 1099-1530); 28; 4; 649–662
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Publication Date: 2019-07-13
    Description: Resource Prospector (RP) will be the first lunar surface robotic expedition to explore the character and feasibility of in situ resource utilization at the lunar poles. It is aimed at determining where, and how much, hydrogen-bearing and other volatiles are sequestered in polar cold traps. To meet its goals, the mission should land where the likelihood of finding polar volatiles is high. The operational environment is challenging: very low sun elevations, long shadows cast by even moderate relief, cryogenic subsurface temperatures, unknown regolith properties, and very dynamic sun and Earth communications geometries force a unique approach to landing, traverse design and mission operations.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN39732 , Lunar and Planetary Science Conference 2017; Mar 20, 2017 - Mar 24, 2017; The Woodlands, TX; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Publication Date: 2019-07-13
    Description: Terrain Identify specifics such as slope, rockiness, traction parameters Identify what part of ISRU needs each Physical Geotechnical Hardness, density, cohesion, etc. Identify what part of ISRU needs each (e.g., excavation needs to know hardness, density; soil processing needs to know density, cohesion; etc.)Mineral Identify specifics Identify what part of ISRU needs each Volatile Identify specifics Identify what part of ISRU needs each Atmosphere Identify specifics Identify what part of ISRU needs each Environment Identify specifics Identify what part of ISRU needs each Resource Characterization What: Develop an instrument suite to locate and evaluate the physical, mineral, and volatile resources at the lunar poles Neutron Spectrometer Near Infrared (IR) to locate subsurface hydrogen surface water Near IR for mineral identification Auger drill for sample removal down to 1 m Oven with Gas Chromatograph Mass Spectrometer to quantify volatiles present ISRU relevance: Water volatile resource characterization and subsurface material access removal Site Evaluation Resource Mapping What: Develop and utilize new data products and tools for evaluating potential exploration sites for selection and overlay mission data to map terrain, environment, and resource information e.g., New techniques applied to generate Digital Elevation Map (DEMs) at native scale of images (1mpxl)ISRU relevance: Resource mapping and estimation with terrain and environment information is needed for extraction planning Mission Planning and Operations What: Develop and utilize tools and procedures for planning mission operations and real time changes Planning tools include detailed engineering models (e.g., power and data) of surface segment systems allows evaluation of designs ISRU relevance: Allows for iterative engineering as a function of environment and hardware performance.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GRC-E-DAA-TN42206 , Joint Planetary and Terrestrial Mining and Sciences Symposium/Space Resource Roundtable; Apr 30, 2017 - May 02, 2017; Montreal, Quebec, Canada; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Publication Date: 2019-07-13
    Description: Resource Prospector Instrumentation for Volatile Analysis, presentation for Exploration Science Forum conference.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-E-DAA-TN44629 , Annual NASA Exploration Science Forum (NESF); Jul 18, 2017 - Jul 20, 2017; Moffett Field, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Publication Date: 2019-07-13
    Description: In January 2016, the Mars 2020 project added Terrain Relative Navigation to the project baseline. This new capability helps the mission avoid large hazards in the landing ellipse, which enables the consideration of landing sites that more geologically diverse than before. This diversity should improve the quality of the samples collected by Mars 2020 for possible future return to earth. The Lander Vision System (LVS) is the sensor that provides the position fix that is used to determine where to land between hazards identified in orbital data prior to landing. This paper describes the LVS flight design for Mars 2020, a high-fidelity simulation used as a design tool and the expected LVS performance for Mars 2020.
    Keywords: Lunar and Planetary Science and Exploration
    Type: AAS 17-036 , JPL-CL-CL#17-0445 , Guidance, Navigation, and Control 2017 (e-ISSN 978-0-87703-636-4); 159|Annual Guidance and Control Conference; Feb 02, 2017 - Feb 08, 2017; Breckenridge, CO; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Publication Date: 2019-07-13
    Description: The Lunar Reconnaissance Orbiter (LRO) has been orbiting the Moon since 2009, obtaining unique and foundational datasets important to understanding the evolution of the Moon and the Solar System. The high-resolution data acquired by LRO benefit from precise orbit determination (OD), limiting the need for geolocation and co-registration tasks. The initial position knowledge requirement (50 m) was met with radio tracking from ground stations, after combination with LOLA altimetric crossovers. LRO-specific gravity field solutions were determined and allowed radio-only OD to perform at the level of 20 m, although secular inclination changes required frequent updates. The high-accuracy gravity fields from GRAIL, with 〈10 km spatial resolution, further improved the radio-only orbit reconstruction quality (〈10 m). However, orbit reconstruction is in part limited by the 0.3-0.5 mm/s measurement noise level in S-band tracking. One-way tracking through Laser Ranging can supplement the tracking available for OD with 28-Hz ranges with 20-cm single-shot precision, but is available only on the nearside (the lunar hemisphere facing the Earth due to tidal locking). Here, we report on the status of the OD effort since the beginning of the mission, a period spanning more than seven years. We describe modeling improvements and the use of new measurements. In particular, the LOLA altimetric data give accurate, uniform, and independent information about LRO's orbit, with a different sensitivity and geometry which includes coverage over the lunar farside and is not tied to ground-based assets. With SLDEM2015 (a combination of the LOLA topographic profiles and the Kaguya Terrain Camera stereo images), another use of altimetry is possible for OD. We extend the 'direct altimetry' technique developed for the ICESat mission to perform OD and adjust spacecraft position to minimize discrepancies between LOLA tracks and SLDEM2015. Comparisons with the radio-only orbits are used to evaluate this new tracking type, of interest for the OD of future lunar orbiters carrying a laser altimeter. LROC NAC images also provide independent accuracy estimation, through the repeated views taken of anthropogenic features for instance.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN47915 , Planetary and Space Science (ISSN 0032-0633); 162; 2-19
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Publication Date: 2019-07-13
    Description: Recent volcanic activity has long been considered a distinct possibility that would place major constraints on the evolution of Mars interior. Volcanic activity would result in the outgassing of sulfur-bearing species. As part of our multi-band search for active release of volcanic gases on Mars, we looked for carbonyl sulfide (OCS) at its combination band (v1 + v3) at 3.42 micrometers (2924 cm(exp -1), and sulfur dioxide (SO2) at 346.652 GHz, in two successive Mars years during its late Northern spring and mid Northern summer seasons (L(sub)s= 43 deg - 44 deg). The targeted volcanic districts, Tharsis and Syrtis Major, were observed during the two intervals, 15 Dec. 2011 to 6 Jan. 2012 in the first year, and 23 May 2014 to 12 June 2014 in the second year using the high resolution infrared spectrometer CSHELL on the NASA Infrared Telescope Facility, and the high resolution heterodyne receiver HARP at the James Clerk Maxwell Telescope atop Maunakea, Hawaii. No active release of such gases was detected, and we report 2 sigma upper limits of 1.8 ppbv and 3.1 ppbv for OCS and SO2, respectively, compared to 0.3 ppbv for SO2 (Encrenaz, T. et al. [2011] Astron. & Astrophys. 530, A37; Krasnopolsky, V.A. [2012] Icarus 217, 144-152) over the disk of Mars. Our retrieved upper limit on the SO2 outgassing rate of 156 tons/day (1.8 kg/s), corresponds to a mass rate of magma that is able to degas the SO2 of 104 kilotons/day (1200 kg/s), or 40,000 cu m/day (0.46 cu m/s). Our campaign places stringent limits on the concentration of sulfur-bearing species into the atmosphere of Mars.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51099 , Icarus (ISSN 0019-1035); 296; 1-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Publication Date: 2019-07-13
    Description: Variability in the sulfur isotopic composition in sediments can reflect atmospheric, geologic and biological processes. Evidence for ancient fluvio-lacustrine environments at Gale crater on Mars and a lack of efficient crustal recycling mechanisms on the planet suggests a surface environment that was once warm enough to allow the presence of liquid water, at least for discrete periods of time, and implies a greenhouse effect that may have been influenced by sulfur-bearing volcanic gases. Here we report in situ analyses of the sulfur isotopic compositions of SO2 volatilized from ten sediment samples acquired by NASA's Curiosity rover along a 13 km traverse of Gale crater. We find large variations in sulfur isotopic composition that exceed those measured for Martian meteorites and show both depletion and enrichment in S-34. Measured values of S-34 range from -47 +/- 14% to 28 +/- 7%, similar to the range typical of terrestrial environments. Although limited geochronological constraints on the stratigraphy traversed by Curiosity are available, we propose that the observed sulfur isotopic signatures at Gale crater can be explained by equilibrium fractionation between sulfate and sulfide in an impact-driven hydrothermal system and atmospheric processing of sulfur-bearing gases during transient warm periods.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN53781 , Nature Geoscience (ISSN 1752-0894) (e-ISSN 1752-0908); 10; 9; 658–662
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Publication Date: 2019-07-13
    Description: The discovery of exoplanets orbiting red dwarfs, such as Proxima Centauri b, has led to questions of their habitability and capacity to retain liquid surface water. While Proxima b is in a ''temperate orbit,'' i.e., an Earth at that location would not freeze or boil its oceans, its proximity to a parent star with quite high magnetic activity is likely to influence its atmospheric evolution and habitability. Planetary magnetic fields can prevent direct stripping away of the planetary atmosphere by the stellar wind, but ion escape can still occur at the magnetic poles. This process, the polar wind, is well known to occur at Earth and may have contributed to the habitability of Earth's early atmosphere. The polar wind is highly variable and sensitive to both ionizing radiation and geomagnetic activity. The higher ionizing radiation levels of M dwarfs at habitable zone distances are expected to increase the polar wind by orders of magnitude and, instead of helping create a habitable atmosphere, may strip away enough volatiles to render the planet inhospitable. Here, we compute the ionospheric outflow of an Earth-twin subject to the enhanced stellar EUV flux of Proxima b, and the effect on atmospheric escape timescales. We show that an Earth-like planet would not survive the escape of its atmosphere at that location, and therefore the pathway to habitability for Proxima b requires a very different atmospheric history than that of Earth.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN51685 , The Astrophysical Journal Letters (ISSN 2041-8205) (e-ISSN 2041-8213); 844; 1; L13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Publication Date: 2019-07-13
    Description: Collisions with dust particles in retrograde orbits cause space erosion on stony meteoroids in addition to the particle drag which causes drift toward resonances. The spacing between resonances determines the maximum drift time and sets upper limits on the neon-21 cosmic ray exposure (CRE) ages for meteoroids less than 1 m in radius, while space erosion controls the limit for radii greater than 1 m; the limits accord well with the measured CRE ages of stony meteorites.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN48340 , Icarus (ISSN 0019-1035); 293; 59-65
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Publication Date: 2019-07-13
    Description: Venus has a complex and dynamic upper atmosphere. This has been observed many times by ground-based, orbiters, probes, and fly-by missions going to other planets. Two over-arching questions are generally asked when examining the Venus upper atmosphere: (1) what creates the complex structure in the atmosphere, and (2) what drives the varying dynamics. A great way to interpret and connect observations to address these questions utilizes numerical modeling; and in the case of the middle and upper atmosphere (above the cloud tops), a 3D hydrodynamic numerical model called the Venus Thermospheric General Circulation Model (VTGCM) can be used. The VTGCM can produce climatological averages of key features in comparison to observations (i.e. nightside temperature, O2 IR nightglow emission). More recently, the VTGCM has been expanded to include new chemical constituents and airglow emissions, as well as new parameterizations to address waves and their impact on the varying global circulation and corresponding airglow distributions.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN45444 , Venera-D Venus Modelling Workshop; Oct 05, 2017 - Oct 07, 2017; Moscow; Russia
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Publication Date: 2019-07-13
    Description: Pluto's large moon Charon [radius 606 km; density = 1.70 g cm(exp. -3)] exhibits a striking variety of landscapes. Charon can be divided into two broad provinces separated by a roughly aligned assemblage of ridges and canyons, which span from east to west. North of this tectonic belt is rugged, cratered terrain (Oz Terra); south of it are smoother but geologically complex plains (Vulcan Planum). (All place names here are informal.) Relief exceeding 20 km is seen in limb profiles and stereo topography.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN39382 , International Asteroids, Comets, Meteors (ACM) Conference 2017; Apr 10, 2017 - Apr 14, 2017; Montevideo; Uruguay
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...