ALBERT

Description: The Rosetta Ion and Electron Sensor (IES) has been measuring solar wind ions intermittently since exiting from hibernation in May 2014. On 19 August, when Rosetta was ~80 km from the comet 67P/Churyumov-Gerasimenko (C-G), which was ~3.5 AU from the Sun, IES began to see ions at its lowest energy range, ~4-10 eV. We identify these as ions created from neutral species emitted by the comet nucleus, photo-ionized by solar UV radiation in the neighborhood of the Rosetta spacecraft (S/C) and attracted by the small negative potential of the S/C resulting from the population of thermal electrons. Later, IES began to see higher energy ions that we identify as having been picked up and accelerated by the solar wind. IES continues to measure changes in the solar wind and the development of the pickup ion structure.

Description: The Ion and Neutral Mass Spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS) have observed Titan's ionospheric composition and structure over several targeted flybys. In this work we study the altitude profiles of the heavy ion population observed by the Cassini Plasma Spectrometer Ion Beam Spectrometer (CAPS-IBS) during the nightside T57 flyby. We produce altitude profiles of heavy ions from the C6-C13 group (Ci indicates the number, i, of heavy atoms in the molecule) using a CAPS-IBS/INMS cross-calibration. These altitude profiles reveal structure that indicates a region of initial formation and growth at altitudes below 1200 km followed by a stagnation and drop-off at the lowest altitudes (1050 km). We suggest that an ion-molecule reaction pathway could be responsible for the production of the heavy ions, namely reactions that utilize abundant building blocks such as C 2 H 2 and C 2 H 4 , which have been shown to be energetically favorable [Ghesquiére et al., 2014] and that have already been identified as ion growth patterns for the lighter ions detected by the INMS [Westlake et al. 2012]. We contrast this growth scenario with alternative growth scenarios determining the implications for the densities of the source heavy neutrals in each scenario. We show that the high mass ion density profiles are consistent with ion-molecule reactions as the primary mechanism for large ion growth. We derive a production rate for benzene from electron recombination of C 6 H 7 + of 2.4 × 10 -16  g cm -2  s -1 and a total production rate for large molecules of 7.1 × 10 -16  g cm -2  s -1 .

Description: The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays, coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar-wind charge-exchange contribution is approximately 40 per cent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Galeazzi, M -- Chiao, M -- Collier, M R -- Cravens, T -- Koutroumpa, D -- Kuntz, K D -- Lallement, R -- Lepri, S T -- McCammon, D -- Morgan, K -- Porter, F S -- Robertson, I P -- Snowden, S L -- Thomas, N E -- Uprety, Y -- Ursino, E -- Walsh, B M -- England -- Nature. 2014 Aug 14;512(7513):171-3. doi: 10.1038/nature13525. Epub 2014 Jul 27.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, University of Miami, Coral Gables, Florida 33124, USA. ; NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. ; Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA. ; Universite Versailles St Quentin; Sorbonne Universites, UPMC Universite Paris 06; CNRS/INSU, LATMOS-IPSL, Guyancourt 78280, France. ; The Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA. ; GEPI Observatoire de Paris, CNRS UMR 8111, Universite Paris Diderot, 92190, Meudon, France. ; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. ; Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA. ; 1] NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA [2] Space Sciences Laboratory, University of California, Berkeley, California 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25079321" target="_blank"〉PubMed〈/a〉

Description: The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bougher, S -- Jakosky, B -- Halekas, J -- Grebowsky, J -- Luhmann, J -- Mahaffy, P -- Connerney, J -- Eparvier, F -- Ergun, R -- Larson, D -- McFadden, J -- Mitchell, D -- Schneider, N -- Zurek, R -- Mazelle, C -- Andersson, L -- Andrews, D -- Baird, D -- Baker, D N -- Bell, J M -- Benna, M -- Brain, D -- Chaffin, M -- Chamberlin, P -- Chaufray, J-Y -- Clarke, J -- Collinson, G -- Combi, M -- Crary, F -- Cravens, T -- Crismani, M -- Curry, S -- Curtis, D -- Deighan, J -- Delory, G -- Dewey, R -- DiBraccio, G -- Dong, C -- Dong, Y -- Dunn, P -- Elrod, M -- England, S -- Eriksson, A -- Espley, J -- Evans, S -- Fang, X -- Fillingim, M -- Fortier, K -- Fowler, C M -- Fox, J -- Groller, H -- Guzewich, S -- Hara, T -- Harada, Y -- Holsclaw, G -- Jain, S K -- Jolitz, R -- Leblanc, F -- Lee, C O -- Lee, Y -- Lefevre, F -- Lillis, R -- Livi, R -- Lo, D -- Ma, Y -- Mayyasi, M -- McClintock, W -- McEnulty, T -- Modolo, R -- Montmessin, F -- Morooka, M -- Nagy, A -- Olsen, K -- Peterson, W -- Rahmati, A -- Ruhunusiri, S -- Russell, C T -- Sakai, S -- Sauvaud, J-A -- Seki, K -- Steckiewicz, M -- Stevens, M -- Stewart, A I F -- Stiepen, A -- Stone, S -- Tenishev, V -- Thiemann, E -- Tolson, R -- Toublanc, D -- Vogt, M -- Weber, T -- Withers, P -- Woods, T -- Yelle, R -- New York, N.Y. -- Science. 2015 Nov 6;350(6261):aad0459. doi: 10.1126/science.aad0459.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CLaSP Department, University of Michigan, Ann Arbor, MI, USA. bougher@umich.edu. ; Laboratory for Atmospheric and Space Physics, University. of Colorado, Boulder, CO, USA. ; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA. ; NASA/Goddard Space Flight Center, Greenbelt, MD, USA. ; Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. ; CNRS/Institut de Recherche en Astrophysique et Planetologie, Toulouse, France. University Paul Sabatier, Toulouse, France. ; Swedish Institute of Space Physics, Kiruna, Sweden. ; NASA/Johnson Space Center, Houston, TX, USA. ; National Institute of Aerospace, Hampton, VA, USA. ; Laboratoire Atmospheres, Milieux, Observations Spatiales /CNRS, Verrieres-le-Buisson, France. ; Department of Astronomy, Boston University, Boston, MA, USA. ; CLaSP Department, University of Michigan, Ann Arbor, MI, USA. ; Department of Physics and Astronomy, University of Kansas, Lawrence, KS, USA. ; Computational Physics, Springfield, VA, USA. ; Department of Physics, Wright State University, Fairborn, OH, USA. ; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. ; Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA, USA. ; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi, Japan. ; Naval Research Laboratory, Washington, DC, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26542579" target="_blank"〉PubMed〈/a〉

Description: Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jakosky, B M -- Grebowsky, J M -- Luhmann, J G -- Connerney, J -- Eparvier, F -- Ergun, R -- Halekas, J -- Larson, D -- Mahaffy, P -- McFadden, J -- Mitchell, D F -- Schneider, N -- Zurek, R -- Bougher, S -- Brain, D -- Ma, Y J -- Mazelle, C -- Andersson, L -- Andrews, D -- Baird, D -- Baker, D -- Bell, J M -- Benna, M -- Chaffin, M -- Chamberlin, P -- Chaufray, Y-Y -- Clarke, J -- Collinson, G -- Combi, M -- Crary, F -- Cravens, T -- Crismani, M -- Curry, S -- Curtis, D -- Deighan, J -- Delory, G -- Dewey, R -- DiBraccio, G -- Dong, C -- Dong, Y -- Dunn, P -- Elrod, M -- England, S -- Eriksson, A -- Espley, J -- Evans, S -- Fang, X -- Fillingim, M -- Fortier, K -- Fowler, C M -- Fox, J -- Groller, H -- Guzewich, S -- Hara, T -- Harada, Y -- Holsclaw, G -- Jain, S K -- Jolitz, R -- Leblanc, F -- Lee, C O -- Lee, Y -- Lefevre, F -- Lillis, R -- Livi, R -- Lo, D -- Mayyasi, M -- McClintock, W -- McEnulty, T -- Modolo, R -- Montmessin, F -- Morooka, M -- Nagy, A -- Olsen, K -- Peterson, W -- Rahmati, A -- Ruhunusiri, S -- Russell, C T -- Sakai, S -- Sauvaud, J-A -- Seki, K -- Steckiewicz, M -- Stevens, M -- Stewart, A I F -- Stiepen, A -- Stone, S -- Tenishev, V -- Thiemann, E -- Tolson, R -- Toublanc, D -- Vogt, M -- Weber, T -- Withers, P -- Woods, T -- Yelle, R -- New York, N.Y. -- Science. 2015 Nov 6;350(6261):aad0210. doi: 10.1126/science.aad0210.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Colorado, Boulder, CO, USA. bruce.jakosky@lasp.colorado.edu. ; NASA/Goddard Space Flight Center, Greenbelt, MD, USA. ; University of California at Berkeley, Berkeley, CA, USA. ; University of Colorado, Boulder, CO, USA. ; University of Iowa, Iowa City, IA, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. ; University of Michigan, Ann Arbor, MI, USA. ; University of California at Los Angeles, Los Angeles, CA, USA. ; CNRS-Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse, France. University Paul Sabatier, Toulouse, France. ; Swedish Institute of Space Physics, Uppsala, Sweden. ; NASA/Johnson Space Center, Houston, TX, USA. ; National Institute of Aerospace, Hampton, VA, USA. ; Laboratoire atmospheres, milieux et observations spatiales (LATMOS)-CNRS, Paris, France. ; Boston University, Boston, MA, USA. ; University of Kansas, Lawrence, KS, USA. ; Computational Physics, Inc., Boulder, CO, USA. ; Wright State University, Dayton, OH, USA. ; University of Arizona, Tucson, AZ, USA. ; Nagoya University, Nagoya, Japan. ; Naval Research Laboratory, Washington, DC, USA. ; North Carolina State University, Raleigh, NC, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26542576" target="_blank"〉PubMed〈/a〉

Description: ABSTRACT ssDuring periods of high solar wind pressure, Saturn's bow shock is pushed inside Titan's orbit exposing the moon and its ionosphere to the solar wind. The Cassini spacecraft's T96 encounter with Titan occurred during such a period and showed evidence for shocks associated with Saturn and Titan. It also revealed the presence of two foreshocks: one prior to the closest approach (foreshock-1) and one after (foreshock-2). Using electromagnetic hybrid (kinetic ions, fluid electrons) simulations and Cassini observations we show that the origin of foreshock-1 is tied to the formation of a single deformed bow shock for the Titan-Saturn system. We also report the observations of a structure in foreshock-1 with properties consistent with those of spontaneous hot flow anomalies (SHFAs) formed in the simulations and previously observed at Earth, Venus and Mars. The results of hybrid simulations also show the generation of oblique fast magnetosonic waves upstream of the outbound Titan bow shock in agreement with the observations of large amplitude magnetosonic pulsations in foreshock-2. We also discuss the implications of a single deformed bow shock for new particle acceleration mechanisms and also Saturn's magnetopause and magnetosphere.