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Nightglow in the Upper Atmosphere of Mars and Implications for Atmospheric Transport
Bertaux, Jean-Loup; Leblanc, François; Perrier, Séverine +8 more
We detected light emissions in the nightside martian atmosphere with the SPICAM (spectroscopy for the investigation of the characteristics of the atmosphere of Mars) ultraviolet (UV) spectrometer on board the Mars Express. The UV spectrum of this nightglow is composed of hydrogen Lyman α emission (121.6 nanometers) and the γ and δ bands of nitric …
Deep Impact Observations by OSIRIS Onboard the Rosetta Spacecraft
Keller, Horst Uwe; Hviid, Stubbe F.; Lamy, Philippe +9 more
The OSIRIS cameras (optical, spectroscopic, and infrared remote imaging system) onboard the European Space Agency's Rosetta spacecraft observed comet 9P/Tempel 1 for 17 days continuously around the time of NASA's Deep Impact mission. The cyanide-to-water production ratio was slightly enhanced in the impact cloud, compared with that of normal comet…
A 5-Micron-Bright Spot on Titan: Evidence for Surface Diversity
Drossart, Pierre; Sotin, Christophe; Sicardy, Bruno +32 more
Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80°W and 20°S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Sci…
Composition of Saturnian Stream Particles
Postberg, Frank; Grün, Eberhard; Kempf, Sascha +9 more
During Cassini's approach to Saturn, the Cosmic Dust Analyser (CDA) discovered streams of tiny (less than 20 nanometers) high-velocity (~100 kilometers per second) dust particles escaping from the saturnian system. A fraction of these impactors originated from the outskirts of Saturn's dense A ring. The CDA time-of-flight mass spectrometer recorde…
Oxygen Ions Observed Near Saturn's A Ring
Luhmann, J. G.; Ip, W. -H.; Mueller-Wodarg, I. +8 more
Ions were detected in the vicinity of Saturn's A ring by the Ion and Neutral Mass Spectrometer (INMS) instrument onboard the Cassini Orbiter during the spacecraft's passage over the rings. The INMS saw signatures of molecular and atomic oxygen ions and of protons, thus demonstrating the existence of an ionosphere associated with the A ring. A like…
Energetic Neutral Atom Emissions from Titan Interaction with Saturn's Magnetosphere
Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C. +3 more
The Cassini Magnetospheric Imaging Instrument (MIMI) observed the interaction of Saturn's largest moon, Titan, with Saturn's magnetosphere during two close flybys of Titan on 26 October and 13 December 2004. The MIMI Ion and Neutral Camera (INCA) continuously imaged the energetic neutral atoms (ENAs) generated by charge exchange reactions between …
Cassini Discovers a Kinematic Spiral Ring Around Saturn
Charnoz, S.; Porco, C. C.; Déau, E. +4 more
Since the time of the Voyager flybys of Saturn in 1980-1981, Saturn's eccentric F ring has been known to be accompanied on either side by faint strands of material. New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least th…
How Long Is the Day on Saturn?
Sánchez-Lavega, Agustín
Determining a planet's rotation period can be difficult if the planet lacks a solid surface. However, for planets with an internal magnetic field, emissions at radio wavelengths are modulated by the planet's rotation rate. The latest results from the Cassini spacecraft seem to indicate that Saturn's rotation rate has slowed down by 6 minutes since…
Saturn's Variable Magnetosphere
Hansen, Kenneth C.; Gombosi, Tamas I.
Since the Cassini spacecraft reached Saturn's orbit in 2004, its instruments have been sending back a wealth of data on the planet's magnetosphere (the region dominated by the magnetic field of the planet). In this Viewpoint, we discuss some of these results, which are reported in a collection of reports in this issue. The magnetosphere is shown t…
Detection of Methane in the Atmosphere of Mars
Encrenaz, Thérèse; Formisano, Vittorio; Giuranna, Marco +2 more
We report a detection of methane in the martian atmosphere by the Planetary Fourier Spectrometer onboard the Mars Express spacecraft. The global average methane mixing ratio is found to be 10 +/- 5 parts per billion by volume (ppbv). However, the mixing ratio varies between 0 and 30 ppbv over the planet. The source of methane could be either bioge…