Search Publications
Themis Regio, Venus: Evidence for recent (?) volcanism from VIRTIS data
Helbert, Joern; Stofan, Ellen R.; Smrekar, Suzanne E. +1 more
Themis Regio is interpreted to be a hotspot rise underlain by one or more mantle plumes. Many volcanic features in the Themis region have high emissivity anomalies in Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) data. Other high emissivity anomalies have been found to correspond to volcanic flows interpreted to be relat…
Constraining the physical properties of Titan's empty lake basins using nadir and off-nadir Cassini RADAR backscatter
Zebker, H. A.; Hayes, A. G.; Malaska, M. J. +5 more
We use repeat synthetic aperture radar (SAR) observations and complementary altimetry passes acquired by the Cassini spacecraft to study the scattering properties of Titan's empty lake basins. The best-fit coefficients from fitting SAR data to a quasi-specular plus diffuse backscatter model suggest that the bright basin floors have a higher dielec…
Complex explosive volcanic activity on the Moon within Oppenheimer crater
Bell, James F.; Horgan, Briony H. N.; Hayne, Paul O. +5 more
Oppenheimer crater is a floor-fractured crater located within the South Pole-Aitken basin on the Moon, and exhibits more than a dozen localized pyroclastic deposits associated with the fractures. Localized pyroclastic volcanism on the Moon is thought to form as a result of intermittently explosive Vulcanian eruptions under low effusion rates, in c…
Amazonian-aged fluvial system and associated ice-related features in Terra Cimmeria, Mars
Le Deit, Laetitia; Hauber, Ernst; Jaumann, Ralf +4 more
The Martian climate throughout the Amazonian is widely believed to have been cold and hyper-arid, very similar to the current conditions. However, ubiquitous evidence of aqueous and glacial activity has been recently reported, including channels that can be tens to hundreds of kilometres long, alluvial and fluvial deposits, ice-rich mantles, and g…
Saturn's auroral morphology and field-aligned currents during a solar wind compression
Brown, R. H.; Baines, K. H.; Dougherty, M. K. +12 more
On 21-22 April 2013, during a coordinated auroral observing campaign, instruments onboard Cassini and the Hubble Space Telescope observed Saturn's aurora while Cassini traversed Saturn's high latitude auroral field lines. Signatures of upward and downward field-aligned currents were detected in the nightside magnetosphere in the magnetic field and…
The rotational dynamics of Titan from Cassini RADAR images
Iess, Luciano; Mitri, Giuseppe; Meriggiola, Rachele +2 more
Between 2004 and 2009 the RADAR instrument of the Cassini mission provided 31 SAR images of Titan. We tracked the position of 160 surface landmarks as a function of time in order to monitor the rotational dynamics of Titan. We generated and processed RADAR observables using a least squares fit to determine the updated values of the rotational para…
Eridania Basin: An ancient paleolake floor as the next landing site for the Mars 2020 rover
Pajola, Maurizio; Carter, John; Pozzobon, Riccardo +5 more
The search for traces of past Martian life is directly connected to ancient paleolakes, where ponding water or low-energy water fluxes were present for long time intervals. The Eridania paleolakes system, located along the 180° meridian, is one of the largest lacustrine environments that were once present on Mars. Morphological features suggest th…
ROSETTA lander Philae - soil strength analysis
Arnold, Walter; Roll, Reinhard; Witte, Lars
The landing of Philae, the lander of ESA's ROSETTA-mission, on November 12th 2014 on Comet 67P/Churyumov-Gerasimenko, was planned as a descent with passive landing activating a damper system and anchoring by harpoons at touch-down. The lander was not fixed to the ground at touch-down due to failing harpoons. The lander damper, however, was actuate…
Improved automatic estimation of winds at the cloud top of Venus using superposition of cross-correlation surfaces
Horinouchi, Takeshi; Ikegawa, Shinichi
Accurate wind observation is a key to study atmospheric dynamics. A new automated cloud tracking method for the dayside of Venus is proposed and evaluated by using the ultraviolet images obtained by the Venus Monitoring Camera onboard the Venus Express orbiter. It uses multiple images obtained successively over a few hours. Cross-correlations are …
The spectrum of Jupiter's Great Red Spot: The case for ammonium hydrosulfide (NH4SH)
Chanover, Nancy J.; Simon, Amy A.; Hudson, Reggie L. +1 more
Here we present new ultraviolet-visible spectra of irradiated ammonium hydrosulfide (NH4SH), a reported jovian atmospheric cloud component, for a range of temperatures and radiation doses and make assignments to the spectral features. We show that the combination of radiolysis and thermal annealing of NH4SH causes the origina…