Search Publications
Isotopic ratios of Saturn's rings and satellites: Implications for the origin of water and Phoebe
Clark, Roger N.; Brown, Robert H.; Cruikshank, Dale P. +1 more
Isotopic ratios have long been used to learn about physical processes acting over a wide range of geological environments, and in constraining the origin and/or evolution of planetary bodies. We report the spectroscopic detection of deuterium in Saturn's rings and satellites, and use these measurements to determine the (D/H) ratios in their near-s…
The methane distribution and polar brightening on Uranus based on HST/STIS, Keck/NIRC2, and IRTF/SpeX observations through 2015
Sromovsky, L. A.; Fry, P. M.; Karkoschka, E. +2 more
Space Telescope Imaging Spectrograph (STIS) observations of Uranus in 2002 and 2012 revealed that both polar regions of Uranus were depleted in upper tropospheric methane relative to equatorial regions. Similar observations in 2015 confirm the relative stability of the north polar methane depletion, but show that the north polar region was becomin…
Methane on Mars: New insights into the sensitivity of CH4 with the NOMAD/ExoMars spectrometer through its first in-flight calibration
Vandaele, Ann Carine; Thomas, Ian; Liuzzi, Giuliano +9 more
The Nadir and Occultation for MArs Discovery instrument (NOMAD), onboard the ExoMars Trace Gas Orbiter (TGO) spacecraft was conceived to observe Mars in solar occultation, nadir, and limb geometries, and will be able to produce an outstanding amount of diverse data, mostly focused on properties of the atmosphere. The infrared channels of the instr…
Photochemistry of water in the martian thermosphere and its effect on hydrogen escape
Krasnopolsky, Vladimir A.
Recent SPICAM IR solar occultations reveal significant abundances of water vapor up to ≈80 km near Mars perihelion. These abundances are stimulated by dust that heats the atmosphere and precludes condensation of water. This phenomenon correlates with detections of high escape of hydrogen near perihelion using the H Lyman-alpha in the SPICAM UV and…
Latitudinal variation in the abundance of methane (CH4) above the clouds in Neptune's atmosphere from VLT/MUSE Narrow Field Mode Observations
Bacon, Roland; Fletcher, Leigh N.; Irwin, Patrick G. J. +5 more
Observations of Neptune, made in 2018 using the new Narrow Field Adaptive Optics mode of the Multi Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope (VLT) from 0.48 to 0.93 µm, are analysed here to determine the latitudinal and vertical distribution of cloud opacity and methane abundance in Neptune's observable tropos…
The mutual orbit, mass, and density of transneptunian binary Gǃkúnǁ'hòmdímà (229762 2007 UK126)
Buie, M. W.; Ragozzine, D.; Roe, H. G. +3 more
We present high spatial resolution images of the binary transneptunian object Gǃkúnǁ'hòmdímà (229762 2007 UK126) obtained with the Hubble Space Telescope and with the Keck observatory on Mauna Kea to determine the orbit of Gǃò'é ǃhúGǃò'é ǃhú, the much smaller and redder satellite. Gǃò'é ǃhú orbits in a prograde sense, on a circular or n…
Observational evidence for a dry dust-wind origin of Mars seasonal dark flows
Vincendon, Mathieu; Carter, John; Stcherbinine, Aurélien +1 more
Seasonal flows on warm slopes, or recurring slope lineae ("RSL"), have been presented as strong evidence for currently flowing water on Mars. This assumption was supported by a correlation between activity and warm temperatures, and by the spectral identification of hydrated salts. Here we first demonstrate that salts spectral identification is no…
Analysis of Neptune's 2017 bright equatorial storm
de Pater, Imke; Wong, Michael H.; Magnier, Eugene A. +22 more
We report the discovery of a large ( ∼ 8500 km diameter) infrared-bright storm at Neptune's equator in June 2017. We tracked the storm over a period of 7 months with high-cadence infrared snapshot imaging, carried out on 14 nights at the 10 m Keck II telescope and 17 nights at the Shane 120 inch reflector at Lick Observatory. The cloud feature was…
Hypotheses for the origin of the Hypanis fan-shaped deposit at the edge of the Chryse escarpment, Mars: Is it a delta?
Sefton-Nash, Elliot; Bell, James F., III; Adler, Jacob B. +4 more
We investigated the origin of the fan-shaped deposit at the end of Hypanis Valles that has previously been proposed as an ExoMars, Mars 2020, and human mission candidate landing site, and found evidence that the landform is an ancient delta. Previous work suggests that the deposit originated from a time of fluvial activity both distinct from and p…
Observations of the chemical and thermal response of 'ring rain' on Saturn's ionosphere
Baines, Kevin H.; O'Donoghue, James; Moore, Luke +4 more
In this study we performed a new analysis of ground-based observations that were taken on 17 April 2011 using the 10-metre Keck telescope on Mauna Kea, Hawaii. Emissions from H3+, a major ion in Saturn's ionosphere, were previously analyzed from these observations, indicating that peaks in emission at specific latitudes were …