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Ionospheric photoelectrons at Venus: Initial observations by ASPERA-4 ELS
Coates, A. J.; Kallio, E.; Fedorov, A. +46 more
We report the detection of electrons due to photo-ionization of atomic oxygen and carbon dioxide in the Venus atmosphere by solar helium 30.4 nm photons. The detection was by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) Electron Spectrometer (ELS) on the Venus Express (VEx) European Space Agency (ESA) mission. Characteristic peaks i…
Heat balance in Titan's atmosphere
Tomasko, M. G.; Bézard, B.; Doose, L. +3 more
The recent measurements of the vertical distribution and optical properties of haze aerosols as well as of the absorption coefficients for methane at long paths and cold temperatures by the Huygens entry probe of Titan permit the computation of the solar heating rate on Titan with greater certainty than heretofore. We use the haze model derived fr…
Initial Venus Express magnetic field observations of the magnetic barrier at solar minimum
Barabash, S.; Russell, C. T.; Zhang, T. L. +8 more
Although there is no intrinsic magnetic field at Venus, the convected interplanetary magnetic field piles up to form a magnetic barrier in the dayside inner magnetosheath. In analogy to the Earth's magnetosphere, the magnetic barrier acts as an induced magnetosphere on the dayside and hence as the obstacle to the solar wind. It consists of regions…
Correction of the ionospheric distortion on the MARSIS surface sounding echoes
Safaeinili, A.; Mouginot, J.; Kofman, W. +1 more
Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the Mars Express (MEX) spacecraft has made numerous measurements of the Martian surface and subsurface. However, all of these measurements are distorted by the ionosphere and must be compensated before any analysis. We have developed a technique to compensate for the ionospher…
Venus upper atmospheric CO, temperature, and winds across the afternoon/evening terminator from June 2007 JCMT sub-millimeter line observations
Clancy, R. T.; Sandor, B. J.; Moriarty-Schieven, G. H.
The Venus mesosphere constitutes a highly variable transition region between the zonal rotation of the lower atmosphere and the diurnal circulation of the upper atmosphere. It further serves as the primary photochemical region of the Venus atmosphere. We obtained James Clerk Maxwell Telescope (JCMT, Mauna Kea Hawaii) sub-millimeter line observatio…
Sputtering of ice grains and icy satellites in Saturn's inner magnetosphere
Johnson, R. E.; Sittler, E. C.; Smith, H. T. +3 more
Icy grains and satellites orbiting in Saturn's magnetosphere are immersed in a plasma that sputters their surfaces. This limits the lifetime of the E-ring grains and ejects neutrals that orbit Saturn until they are ionized and populate its magnetosphere. Here we re-evaluate the sputtering rate of ice in Saturn's inner magnetosphere using the recen…
Comparative analysis of Venus and Mars magnetotails
Coates, A. J.; Kallio, E.; Fedorov, A. +47 more
We have an unique opportunity to compare the magnetospheres of two non-magnetic planets as Mars and Venus with identical instrument sets Aspera-3 and Aspera-4 on board of the Mars Express and Venus Express missions. We have performed both statistical and case studies of properties of the magnetosheath ion flows and the flows of planetary ions behi…
Accurate Mars Express orbits to improve the determination of the mass and ephemeris of the Martian moons
Pätzold, M.; Rosenblatt, P.; Le Maistre, S. +5 more
The determination of the ephemeris of the Martian moons has benefited from observations of their plane-of-sky positions derived from images taken by cameras onboard spacecraft orbiting Mars. Images obtained by the Super Resolution Camera (SRC) onboard Mars Express (MEX) have been used to derive moon positions relative to Mars on the basis of a fit…
Measurements of methane absorption by the descent imager/spectral radiometer (DISR) during its descent through Titan's atmosphere
Tomasko, M. G.; Bézard, B.; Doose, L. +2 more
New low-temperature methane absorption coefficients pertinent to the Titan environment are presented as derived from the Huygens DISR spectral measurements combined with the in-situ measurements of the methane gas abundance profile measured by the Huygens Gas Chromatograph/Mass Spectrometer (GCMS). The visible and near-infrared spectrometers of th…
Observations of the north polar water ice annulus on Mars using THEMIS and TES
Bandfield, Joshua L.; Castaño, Rebecca; Titus, Timothy N. +2 more
The Martian seasonal CO2 ice caps advance and retreat each year. In the spring, as the CO2 cap gradually retreats, it leaves behind an extensive defrosting zone from the solid CO2 cap to the location where all CO2 frost has sublimated. We have been studying this phenomenon in the north polar region using…