Search Publications
Plasma intrusion above Mars crustal fields—Mars Express ASPERA-3 observations
Coates, A. J.; Kallio, E.; Fedorov, A. +42 more
Using data of the ASPERA-3 instrument on board the European Mars Express spacecraft we investigate the effect of the martian crustal fields on electrons intruding from the magnetosheath. For the crustal field strength we use published data obtained by the Mars Global Surveyor MAG/ER instrument for a fixed altitude of 400 km. We use statistics on 1…
Ion escape at Mars: Comparison of a 3-D hybrid simulation with Mars Express IMA/ASPERA-3 measurements
Coates, A. J.; Kallio, E.; Fedorov, A. +44 more
We have analysed ion escape at Mars by comparing ASPERA-3/Mars Express ion measurements and a 3-D quasi-neutral hybrid model. As Mars Express does not have a magnetometer onboard, the analysed IMA data are from an orbit when the IMF clock angle was possible to determine from the magnetic field measurements of Mars Global Surveyor. We found that fa…
The influence of particle adhesion on the stability of agglomerates in Saturn's rings
Albers, Nicole; Spahn, Frank
In planetary rings, binary collisions and mutual gravity are the predominant particle interactions. Based on a viscoelastic contact model we implement the concept of static adhesion. We discuss the collision dynamics and obtain a threshold velocity for restitution or agglomeration to occur. The latter takes place within a range of a few cm s …
Solar flux in Saturn's atmosphere: Penetration and heating rates in the aerosol and cloud layers
Sánchez-Lavega, A.; Pérez-Hoyos, S.
In this work, we describe an analysis of the internal solar radiation fields in Saturn's atmosphere. The aim of this paper is to study how the solar radiation flux in optical wavelengths (0.25-1.0 µm) is attenuated, primarily by the effect of the aerosols located close to the tropopause level, retrieving also the corresponding solar heating …
On the vertical wind shear of Saturn's Equatorial Jet at cloud level
Sánchez-Lavega, A.; Pérez-Hoyos, S.
In this work we analyze and compare the vertical cloud structure of Saturn's Equatorial Zone in two different epochs: the first one close to the Voyagers flybys (1979-1981) and the second one in 2004, when the Cassini spacecraft entered its orbit around the planet. Our goal is to retrieve the altitude of cloud features used as zonal wind tracers i…
Observations of non-LTE emission at 4 5 microns with the planetary Fourier spectrometer abord the Mars Express mission
Lopez-Valverde, M. A.; D'Aversa, E.; Formisano, V. +2 more
We report on PFS-MEX (Planetary Fourier Spectrometer on board Mars Express) limb observations of the non-Local Thermodynamic Equilibrium emission by CO and CO 2 isotopic molecules. The CO emission is observed peaking at altitudes lower than the CO 2 emission peak. Two orbits have been considered, which explore latitudes from …
Waves in Jupiter's atmosphere observed by the Cassini ISS and CIRS instruments
West, Robert A.; Porco, Carolyn C.; Achterberg, Richard K. +7 more
The Cassini Imaging Science Subsystem (ISS) and Composite Infrared Spectrometer (CIRS) reported a North Equatorial Belt (NEB) wave in Jupiter's atmosphere from optical images [Porco, C.C., and 23 colleagues, 2003. Science 299, 1541-1547] and thermal maps [Flasar, F.M., and 39 colleagues, 2004. Nature 427, 132-135], respectively. The connection bet…
Latitudinal variation of Saturn photochemistry deduced from spatially-resolved ultraviolet spectra
Fouchet, Thierry; Connerney, J. E. P.; Prangé, Renée +2 more
We obtained spatially-resolved ultraviolet spectra of Saturn in 1994 with the Faint Object Spectrometer and Goddard High Resolution Spectrograph of the Hubble Space Telescope. We observed four areas on the planet at 15° N, 33° S, 41° S, and 52° S, with a field-of-view of less than 2 × 2 arcsec 2, compared to the 16-arcsec planet diamete…
Discovery of a binary Centaur
Noll, Keith S.; Levison, Harold F.; Stephens, Denise C. +1 more
We have identified a binary companion to (42355) 2002 CR 46 in our ongoing deep survey using the Hubble Space Telescope's High Resolution Camera. It is the first companion to be found around an object in a non-resonant orbit that crosses the orbits of giant planets. Objects in orbits of this kind, the Centaurs, have experienced repeated…
Gravitational tidal waves in Titan's upper atmosphere
Strobel, Darrell F.
Tidal waves driven by Titan's orbital eccentricity through the time-dependent component of Saturn's gravitational potential attain nonlinear, saturation amplitudes ( |T|>10 K, |u|>20 ms, and |w|>5 cms) in the upper atmosphere (⩾500 km) due to the approximate exponential growth as the inverse square root of pressure. The gravitational tide…