Search Publications
Saturn's rings and associated ring plasma cavity: Evidence for slow ring erosion
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +2 more
We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 Rs (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak imp…
Wind shear and turbulence on Titan: Huygens analysis
Lorenz, Ralph D.
Wind shear measured by Doppler tracking of the Huygens probe is evaluated, and found to be within the range anticipated by pre-flight assessments (namely less than two times the Brunt-Väisälä frequency). The strongest large-scale shear encountered was ∼5 m/s/km, a level associated with 'Light' turbulence in terrestrial aviation. Near-surface winds…
Study of ice-related flow features around Tanaica Montes, Mars: Implications for late amazonian debris-covered glaciation
Vijayan, S.; Sinha, Rishitosh K.; Bharti, Rajiv R.
Lobate debris aprons (LDA) and lineated valley fill (LVF) have been broadly recognized in the mid-latitudes of Mars and their subsequent analyses using data from the SHAllow RADar (SHARAD) instrument has suggested evidence for contemporary ice preserved beneath these features. In this study, we conduct detailed characterization of newly identified…
Long-lived volcanism within Argyre basin, Mars
Lopes, Rosaly M. C.; Flahaut, Jessica; Buczkowski, Debra L. +6 more
The Argyre basin, one of the largest impact structures on Mars with a diameter >1200 km, formed in the Early Noachian ∼3.93 Ga. The basin has collected volatiles and other material through time, and experienced partial infilling with water evident from stratigraphic sequences, crater statistics, topography, and geomorphology. Although volcanism…
General circulation of Venus from a long-term synoptic study of tropospheric CO by Venus Express/VIRTIS
Tsang, Constantine C. C.; McGouldrick, Kevin
The understanding of spatial and temporal variations in tropospheric abundances of the trace gas carbon monoxide (CO) is key to understanding the deep atmospheric circulation on Venus. CO is entrained in the global circulation, as well as being key ingredients in the multi-reaction chemical cycle that creates and destroys the sulfuric acid that is…
Upper limit of helium-4 in the sunlit lunar exosphere during magnetotail passage under low solar wind condition: Result from CHACE aboard MIP in Chandrayaan-1
Bhardwaj, Anil; Sridharan, R.; Dhanya, M. B. +3 more
The outcome of efforts to detect He-4 in the sunlit lunar exosphere as evinced by the CHACE mass spectrometer aboard the Moon Impact Probe in Chandrayaan-1 is reported. The in situ observations by CHACE were carried out in the lunar dayside, covering a broad range of lunar latitudes, when the Moon was on the verge of exiting the Earth's magnetotai…
The Martian dust devil electron avalanche: Laboratory measurements of the E-field fortifying effects of dust-electron absorption
Farrell, W. M.; Collier, M. R.; McLain, J. L. +1 more
Analogous to terrestrial dust devils, charged dust in Mars dust devils should become vertically stratified in the convective features, creating large scale E-fields. This E-field in a Martian-like atmosphere has been shown to stimulate the development of a Townsend discharge (electron avalanche) that acts to dissipate charge in regions where charg…
Radio observation of Venus at meter wavelengths using the GMRT
Bhardwaj, Anil; Mohan, Nithin; Roy, Subhashis +4 more
The Venusian surface has been studied by measuring radar reflections and thermal radio emission over a wide spectral region of several centimeters to meter wavelengths from the Earth-based as well as orbiter platforms. The radiometric observations, in the decimeter (dcm) wavelength regime showed a decreasing trend in the observed brightness temper…
Nitrogen condensation in Titan's atmosphere under contemporary atmospheric composition
Tokano, Tetsuya
Temperature profiles of Titan's atmosphere obtained by Cassini radio occultations approach the nitrogen condensation temperature curve at some places. This raises the question as to whether nitrogen, Titan's main atmospheric constituent, might condense in some seasons and areas contrary to previous perception. To address this question, possible ar…
CO concentration in the upper stratosphere and mesosphere of Titan from VIMS dayside limb observations at 4.7 µm
D'Aversa, E.; López-Valverde, M. A.; Funke, B. +6 more
During the last 30 years, many works have focused on the determination of the CO abundance in Titan's atmosphere, but no measurement above 300 km has been done yet due to the faint signal of CO. Nevertheless, such measurements are particularly awaited as a confirmation of photochemical models predictions that CO is uniformly mixed in the whole atm…