Search Publications

Evidence for surface variegation in Rosetta OSIRIS images of asteroid 2867 Šteins

Sierks, H.; Keller, H. U.; Hviid, S. F. +4 more

The OSIRIS camera onboard Rosetta successfully acquired images of asteroid 2867 Steins through a variety of color filters during the flyby on 5 September 2008. The best images of this 5 km diameter asteroid have a resolution of 78 m per pixel. We process the images by deconvolving with the point spread function and enlarging through the Mitchell-N…

Attitude and angular rates of planetary probes during atmospheric descent: Implications for imaging

Lorenz, Ralph D.

Attitude dynamics data from planetary missions are reviewed to obtain a zeroth-order expectation on the tilts and angular rates to be expected on atmospheric probes during descent: these rates are a strong driver on descent imager design. While recent Mars missions have been equipped with capable inertial measurements, attitude measurements for mi…

A new approach for estimating Titan's electron conductivity based on data from relaxation probe sensors on the Huygens experiment

Rodrigo, R.; Fulchignoni, M.; Ferri, F. +15 more

The Huygens Probe measured the electrical conductivity of Titan atmosphere from about 140 km down to the surface, employing relaxation and mutual impedance techniques. Previous analyses have shown some differences on the conductivity measurements obtained with two independent sensors - relaxation probe (RP) and mutual impedance probe (MIP). A 20-f…

Analysis of disturbances in the Planetary Fourier Spectrometer through numerical modeling

Saggin, Bortolino; Comolli, Lorenzo

Fourier transform spectrometers are instruments with high sensitivity to many kinds of disturbances. This study started from the analysis of the disturbances related to mechanical vibrations on the PFS FTIR spectrometer to show how the measured spectra can differ from the actual ones. The complete study, more in general, accounts for the character…

Analysis of two sections of Shalbatana Vallis’ tributary channels

Kereszturi, Akos

Six tributaries of Shalbatana outflow channel were analyzed based on visible imagery by THEMIS, MOC, HRSC, and HiRISE, as well as on topographic data by MOLA. Two different sections could be identified on the tributaries: the upper and the lower reaches. The upper reaches are shallow, showing U-shaped cross-sectional profiles. Their bottom level i…

Reconstruction of nonmonotonic electron density profiles of the Martian topside ionosphere

Wang, X. -D.; Zou, H.; Wang, J. -S. +1 more

One of the problems in reconstructing the real ionosphere from an ionogram is the occurrence of a 'valley,' where electron density decreases with altitude and make a non-monotonic profile. For the case of the Earth ionosphere, the ordinary and extraordinary ray data, accompanied with an empirical model, based on the observations, are necessary to …

Trajectory and atmospheric structure from entry probes: Demonstration of a real-time reconstruction technique using a simple direct-to-Earth radio link

Withers, Paul

The reconstruction of the trajectory and atmospheric structure associated with an entry probe has traditionally relied upon onboard accelerometer measurements. Here we outline an equivalent reconstruction technique that uses Doppler-shifted direct-to-Earth transmissions instead. A critical assumption is that the entry probe's angle of attack is ze…

The Rosetta mission and its fly-by at asteroid 2867 Steins

Schulz, R.

Winds, turbulence and waves in the clouds of Venus

Peralta, J.

The Ph.D. Thesis summarized in this abstract was accepted on 20 March 2009 at the University of the Basque Country (Spain) and awarded with the highest qualification. This work was advised by Drs. Agustín Sánchez-Lavega and Ricardo Hueso.

Negative ion chemistry in Titan's upper atmosphere

Lewis, G. R.; Coates, A. J.; Wahlund, J. -E. +5 more

The Electron Spectrometer (ELS), one of the sensors making up the Cassini Plasma Spectrometer (CAPS) revealed the existence of numerous negative ions in Titan's upper atmosphere. The observations at closest approach (∼1000 km) show evidence for negatively charged ions up to ∼10,000 amu/q, as well as two distinct peaks at 22±4 and 44±8 amu/q, and m…