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Sinton crater, Mars: Evidence for impact into a plateau icefield and melting to produce valley networks at the Hesperian-Amazonian boundary
Head, James W.; Morgan, Gareth A.
The majority of martian valley networks are found on Noachian-aged terrain and are attributed to be the result of a 'warm and wet' climate that prevailed early in Mars' history. Younger valleys have been identified, though these are largely interpreted to be the result of localized conditions associated with the melting of ice from endogenic heat …
Sorted stone circles in Elysium Planitia, Mars: Implications for recent martian climate
Balme, M. R.; Muller, J. -P.; Gallagher, C. J. +2 more
We have found sorted stone circles and polygons near the equator of Mars, using new 25 cm/pixel NASA HiRISE (High Resolution Imaging Science Experiment) images. The sorted circles occur in geologically recent catastrophic flood deposits in the equatorial Elysium Planitia region, and are diagnostic of periglacial processes: sorted polygons do not f…
Albedo control of seasonal South Polar cap recession on Mars
Bibring, Jean-Pierre; Langevin, Yves; Schmitt, Bernard +4 more
Over the last few decades, General Circulation Models (GCM) have been used to simulate the current martian climate. The calibration of these GCMs with the current seasonal cycle is a crucial step in understanding the climate history of Mars. One of the main climatic signals currently used to validate GCMs is the annual atmospheric pressure cycle. …
The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations
Sromovsky, L. A.; Fry, P. M.; Hammel, H. B. +6 more
We report the first definitive detection of a discrete dark atmospheric feature on Uranus in 2006 using visible and near-infrared images from the Hubble Space Telescope and the Keck II 10-m telescope. Like Neptune's Great Dark Spots, this Uranus Dark Spot had bright companion features that exhibited considerable variability in brightness and locat…
Mutual orbits and masses of six transneptunian binaries
Buie, M. W.; Grundy, W. M.; Noll, K. S. +3 more
We present Hubble Space Telescope observations of six binary transneptunian systems: 2000 QL 251, 2003 TJ 58, 2001 XR 254, 1999 OJ 4, (134860) 2000 OJ 67, and 2004 PB 108. The mutual orbits of these systems are found to have periods ranging from 22 to 137 days, semimajor axes rangin…
A study of the properties of a local dust storm with Mars Express OMEGA and PFS data
Bibring, J. -P.; Gondet, B.; Langevin, Y. +8 more
We present observations of a local dust storm performed by the OMEGA and PFS instruments aboard Mars Express. OMEGA observations are used to retrieve the dust single-scattering albedo in the spectral range 0.4-4.0 µm. The single-scattering albedo shows fairly constant values between 0.6 and 2.6 µm, and a sharp decrease at wavelengths s…
Limits on the size of aerosols from measurements of linear polarization in Titan’s atmosphere
Tomasko, M. G.; Doose, L. R.; Dafoe, L. E. +1 more
The Descent Imager/Spectral Radiometer (DISR) instrument on the Huygens probe into the atmosphere of Titan yielded information on the size, shape, optical properties, and vertical distribution of haze aerosols in the atmosphere of Titan [Tomasko, M.G., Doose, L., Engel, S., Dafoe, L.E., West, R., Lemmon, M., Karkoschka, E., 2008. Planet. Space Sci…
Yearly and seasonal variations of low albedo surfaces on Mars in the OMEGA/MEx dataset: Constraints on aerosols properties and dust deposits
Bibring, J. -P.; Gondet, B.; Langevin, Y. +5 more
The time variations of spectral properties of dark martian surface features are investigated using the OMEGA near-IR dataset. The analyzed period covers two Mars years, spanning from early 2004 to early 2008 (includes the 2007 global dust event). Radiative transfer modeling indicates that the apparent albedo variations of low to mid-latitude dark …
Metastable methane clathrate particles as a source of methane to the martian atmosphere
Chassefière, Eric
The observations of methane made by the PFS instrument onboard Mars Express exhibit a definite correlation between methane mixing ratio, water vapor mixing ratio, and cloud optical depth. The recent data obtained from ground-based telescopes seem to confirm the correlation between methane and water vapor. In order to explain this correlation, we s…
Analysis and interpretation of Cassini Titan radar altimeter echoes
Hensley, Scott; Gim, Yonggyu; Cassini Radar Team +3 more
The Cassini spacecraft has acquired 25 radar altimeter elevation profiles along Titan's surface as of April 2008, and we have analyzed 18 of these for which there are currently reconstructed ephemeris data. Altimeter measurements were collected at spatial footprint sizes from 6-60 km along ground tracks of length 400-3600 km. The elevation profile…