ALBERT

Beschreibung: Establishing the abundance and physical properties of regolith and boulders on asteroids is crucial for understanding the formation and degradation mechanisms at work on their surfaces. Using images and thermal data from NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we show that asteroid (101955) Bennu's surface is globally rough, dense with boulders, and low in albedo. The number of boulders is surprising given Bennu's moderate thermal inertia, suggesting that simple models linking thermal inertia to particle size do not adequately capture the complexity relating these properties. At the same time, we find evidence for a wide range of particle sizes with distinct albedo characteristics. Our findings imply that ages of Bennu's surface particles span from the disruption of the asteroid's parent body (boulders) to recent in situ production (micrometre-scale particles).

Beschreibung: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This manuscript describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at Level 100 A/2 and less than 180 nanograms per square centimeter of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication between scientists, engineers, managers, and technicians.

Beschreibung: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and less than 180 ng/cm(exp 2) of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

Beschreibung: The Miniature Thermal Emission Spectrometer (Mini-TES) on Spirit has studied the mineralogy and thermophysical properties at Gusev crater. Undisturbed soil spectra show evidence for minor carbonates and bound water. Rocks are olivinerich basalts with varying degrees of dust and other coatings. Dark-toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy (+/-5 to 10%) of 45% pyroxene (20% Ca-rich pyroxene and 25% pigeonite), 40% sodic to intermediate plagioclase, and 15% olivine (forsterite 45% +/-5 to 10). Two spectrally distinct coatings are observed on rocks, a possible indicator of the interaction of water, rock, and airfall dust. Diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0.5 to 3 mm in soils.

Beschreibung: The Magnetometer/Electron Reflectometer onboard Lunar Prospector has observed the solar wind interaction with remanent crustal magnetic fields at altitudes from 20 to 120 km. This interaction may be responsible for the formation of albedo swirls.

Beschreibung: Nanocrystal nonvolatile floating-gate memories are a good candidate for space applications - initial results suggest they are fast, more reliable and consume less power than conventional floating gate memories. In the nanocrystal based NVM device, charge is not stored on a continuous polysilicon layer (so-called floating gate), but instead on a layer of discrete nanocrystals. Charge injection and storage in dense arrays of silicon nanocrystals in SiO2 is a critical aspect of the performance of potential nanocrystal flash memory structures. The ultimate goal for this class of devices is few- or single-electron storage in a small number of nanocrystal elements. In addition, the nanocrystal layer fabrication technique should be simple, 8-inch wafer compatible and well controlled in program/erase threshold voltage swing was seen during 100,000 program and erase cycles. Additional near-term goals for this project include extensive testing for radiation hardness and the development of artificial layered tunnel barrier heterostructures which have the potential for large speed enhancements for read/write of nanocrystal memory elements, compared with conventional flash devices. Additional information is contained in the original extended abstract.

Beschreibung: Understanding the Moon is crucial to future exploration of the solar system.The Moon preserves a record of the first billion years of the Earth-Moon system's history, including evidence of the Moon's origin as accumulated debris from a giant impact into early Earth. Lunar rocks provide evidence of early differentiation and extraction of a crust. Lacking an atmospheric shield, the Moon's regolith retains a record of the activity of solar wind over the past 4 billion years. It also holds a complete record of impact cratering, and analysis of samples has allowed calibration of ages, and thus dating of other planetary surfaces. And because of its proximity to Earth, it's low gravity well, and stable surface, the Moon's resources will be useful both in establishing lunar habitations and as fuel for exploration beyond the Moon. Lunar science has advanced tremendously in the 30 years since the Apollo and Luna missions. We know that the Moon is strongly differentiated, and recent tungsten isotope studies indicate that this differentiation occurred soon after solar system formation. The Moon probably accreted rapidly from debris that formed as a large planetesimal struck the early Earth. Ancient highland rocks provide evidence of early lunar differentiation, and basalts formed by later melting within the mantle reveal it cumulus nature. However, the timing, extent, and depth of differentiation, variations within the mantle, and lateral and vertical variations within the crust can only be surmised from the limited sample suites,gravity studies,and surface geophysics of the Apollo era. Data from the recent Lunar Prospector and Clementine missions permit reassessment of the global characteristics of the Moon and a reexamination of the distribution of elemental components, rock and soil types, and resources, as well as remanent magnetism, gravity field, and global topography New research provides some answers, but also leads to new questions.

Beschreibung: Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and SecurityRegolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

Beschreibung: NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission successfully launched on September 8th, 2016. During its rendezvous with near-Earth asteroid (101955) Bennu beginning in 2018, OSIRIS-REx will characterize the asteroid's physical, mineralogical, and chemical properties in an effort to globally map the properties of Bennu, a primitive carbonaceous asteroid, and choose a sampling location [e.g. 1]. In preparation for these observations, we spectrally characterized a suite of analog samples across visible, near- and thermal-infrared wavelengths and used these in initial tests of phase detection and abundance determination software algorithms. Here we present the thermal infrared laboratory measurements of the analog sample suite measured under asteroidlike conditions, which are relevant to the interpretation of spectroscopic observations by the OSIRIS-REx Thermal Emission Spectrometer (OTES) [2, 3]. This suite of laboratory measurements of asteroid analogs under asteroid-like conditions is the first of their kind.

Beschreibung: Author(s): V. Giesz, S. L. Portalupi, T. Grange, C. Antón, L. De Santis, J. Demory, N. Somaschi, I. Sagnes, A. Lemaître, L. Lanco, A. Auffèves, and P. Senellart Quantum dots in cavities have been shown to be very bright sources of indistinguishable single photons. Yet the quantum interference between two such bright quantum dot sources, a critical step for photon-based quantum computation, still needs to be investigated. Here, we report on such a measuremen… [Phys. Rev. B 92, 161302(R)] Published Mon Oct 12, 2015