Search Publications
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…
Spatial distribution of impact craters on Deimos
Hirata, Naoyuki
Deimos, one of the Martian moons, has numerous impact craters. However, it is unclear whether crater saturation has been reached on this satellite. To address this issue, we apply a statistical test known as nearest-neighbor analysis to analyze the crater distribution of Deimos. When a planetary surface such as the Moon is saturated with impact cr…
Direct detection of gaps in Saturn's A ring
Esposito, Larry W.; Albers, Nicole; Brown, Zarah L. +1 more
Indirect observations spanning decades have indicated that Saturn's A ring is populated with a plethora of self-gravity wakes, small wavelike structures that arise from the gravitational attraction between ring particles. We present the direct detection of the gaps that represent the minima between the denser wakes. Through a statistical test, we …
A curious ringlet that shares Prometheus' orbit but precesses like the F ring
Hedman, M. M.; Carter, B. J.
Images obtained by the Cassini spacecraft of the region just beyond Saturn's main rings reveal a previously unreported narrow and dusty ringlet that has dynamical connections with both Saturn's small satellite Prometheus and the F ring. The radial position of this ringlet is observed to vary with time and longitude, indicating that it is eccentric…
Morphology and temporal variation of the polar oval of Venus revealed by VMC/Venus express visible and UV images
Imamura, Takeshi; Muto, Keishiro
The morphology of the dark polar oval seen at the Venus cloud top in visible and ultraviolet wavelengths has been unclear because the portion of the oval on the nightside is invisible. We analyzed in detail the variability of the whole shape of the oval by connecting VMC/Venus Express visible images taken on different days after shifting the image…
Surface roughness of Saturn's rings and ring particles inferred from thermal phase curves
Spilker, Linda; Morishima, Ryuji; Turner, Neal
We analyze thermal phase curves of all the main rings of Saturn (the A, B, C rings, and the Cassini division) measured by both the far-IR and mid-IR detectors of the Cassini Composite InfraRed Spectrometer (CIRS). All the rings show temperature increases toward zero phase angle, known as an opposition effect or thermal beaming. For the C ring and …
Hyperactivity in 103P/Hartley 2: Chunks from the sub-surface in Type IIa jet regions
Belton, Michael J. S.
We analyze the observed radial distribution of column densities of water-ice particulates embedded in the primary jet region (J1) of 103P's inner coma at altitudes between 439 and 1967 m (Protopapa et al., 2014, Icarus 238, 191-204) and determine the speed and acceleration of particles and their mass-flow within the filaments of the jet…