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Cassini UVIS observations of the Io plasma torus. III. Observations of temporal and azimuthal variability
Delamere, P. A.; Bagenal, F.; Steffl, A. J.
In this third paper in a series presenting observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near-sinusoidal variations in ion composition as a function of azimuthal position. Th…
The role of the wind-transported dust in slope streaks activity: Evidence from the HRSC data
Mangold, N.; Forget, F.; Neukum, G. +7 more
Slope streaks are gravity-driven albedo features observed on martian slopes since the Viking missions. The debated mechanism of formation could involve alternatively dry granular flow or wet mass wasting. A systematic mapping of slope streaks from the High Resolution Stereo Camera is presented in this paper. Two regions known for their slope strea…
Saturn lightning recorded by Cassini/RPWS in 2004
Gurnett, D. A.; Kurth, W. S.; Rucker, H. O. +8 more
During 2004 the Cassini/RPWS (Radio and Plasma Wave Science) instrument recorded about 5400 SEDs (Saturn Electrostatic Discharges), which were organized in 4 storm systems and 95 episodes. A computer algorithm with different intensity thresholds was applied to extract the SEDs from the RPWS data, and a statistical analysis on the main characterist…
Cassini CIRS retrievals of ammonia in Jupiter's upper troposphere
Achterberg, Richard K.; Conrath, Barney J.; Gierasch, Peter J.
The zonal mean ammonia abundance on Jupiter between the 400- and 500-mbar pressure levels is inferred as a function of latitude from Cassini Composite Infrared Spectrometer data. Near the Great Red Spot, the ammonia abundance is mapped as a function of latitude and longitude. The Equatorial Zone is rich in ammonia, with a relative humidity near un…
Numerical interpretation of high-altitude photoelectron observations
Coates, A. J.; Kallio, E.; Fedorov, A. +47 more
The Electron Spectrometer (ELS) instrument of the ASPERA-3 package on the Mars Express satellite has recorded photoelectron energy spectra up to apoapsis ( ∼10,000 km altitude). The characteristic photoelectron shape of the spectrum is sometimes seen well above the ionosphere in the evening sector across a wide range of near-equatorial latitudes. …
Predictions of the electrical conductivity and charging of the aerosols in Titan's atmosphere
Tripathi, S.; Whitten, R. C.; Borucki, W. J. +2 more
The electrical conductivity and electrical charge on the aerosols in atmosphere of Titan are computed for altitudes between 0 and 400 km. Ionization of methane and nitrogen due to galactic cosmic rays (GCR) is important at night where these ions are converted to ion clusters such as CH +5CH 4, C 7H …
Electric fields within the martian magnetosphere and ion extraction: ASPERA-3 observations
Kallio, E.; Fedorov, A.; Säles, T. +37 more
Observations made by the ASPERA-3 experiment onboard the Mars Express spacecraft found within the martian magnetosphere beams of planetary ions. In the energy ( E/q)-time spectrograms these beams are often displayed as dispersive-like, ascending or descending (whether the spacecraft moves away or approach the planet) structures. A linear dependenc…
Electron oscillations in the induced martian magnetosphere
Coates, A. J.; Kallio, E.; Fedorov, A. +42 more
The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment flown on the Mars Express (MEX) spacecraft includes the Electron Spectrometer (ELS) as part of its complement. The ELS instrument measures the differential electron flux spectrum in a 128-level logarithmic energy sweep within a time period of 4 s. The orbital path of MEX trave…
First ENA observations at Mars: ENA emissions from the martian upper atmosphere
Coates, A. J.; Kallio, E.; Fedorov, A. +44 more
The neutral particle detector (NPD) on board Mars Express has observed energetic neutral atoms (ENAs) from a broad region on the dayside of the martian upper atmosphere. We show one such example for which the observation was conducted at an altitude of 570 km, just above the induced magnetosphere boundary (IMB). The time of flight spectra of these…
Mapping of Titan: Results from the first Titan radar passes
Lorenz, R. D.; Soderblom, L. A.; Stiles, B. +33 more
The first two swaths collected by Cassini's Titan Radar Mapper were obtained in October of 2004 (Ta) and February of 2005 (T3). The Ta swath provides evidence for cryovolcanic processes, the possible occurrence of fluvial channels and lakes, and some tectonic activity. The T3 swath has extensive areas of dunes and two large impact craters. We inte…