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We present observations of Io’s tenuous lower atmosphere on the Jupiter-facing hemisphere at ultraviolet wavelengths, from 2100 to 2250Å, using the Hubble Space Telescope’s Cosmic Origins Spectrometer, during the period immediately after Io emerges from Jupiter eclipse. The density of an atmosphere dominantly controlled by frost sublimation is highly dependent on the thermal properties of the surface...
The martian south polar plateau, Planum Australe, comprises the largest known water–ice surface deposit on the planet. Here, we present evidence for an episode of extensive polar plateau retreat during the Late Amazonian, which affected regions flanking circum-polar terrains located between Cavi Angusti and Sisyphi Montes.
We present phase curves for Venus in the 1–2μm wavelength region, acquired with IR1 and IR2 on board Akatsuki (February–March 2011). A substantial discrepancy with the previously-published curves was found in the small phase angle range (0–30°). Through analysis by radiative-transfer computation, it was found that the visibility of larger (∼1μm or larger) cloud particles was significantly higher than...
Dicyanoacetylene has not been observed so far in the gas phase in Titan’s atmosphere but this molecule is still on the list of the detected species, on the basis of the correspondence between a solid phase feature measured at 478cm−1 in the laboratory and a spectral feature observed by Voyager. In this work, the infrared spectrum of gaseous C4N2 has been investigated to improve our knowledge of the...
We describe an interferometric reflectometer method for passive detection of subsurface oceans and liquid water in jovian icy moons using Jupiter’s decametric radio emission (DAM). The DAM flux density exceeds 3000 times the galactic background in the neighborhood of the jovian icy moons, providing a signal that could be used for passive radio sounding. An instrument located between the icy moon and...
In understanding the composition and internal structure of asteroids, their density is perhaps the most diagnostic quantity. We aim here at characterizing the surface composition, mutual orbit, size, mass, and density of the small main-belt binary asteroid (939) Isberga. For that, we conduct a suite of multi-technique observations, including optical lightcurves over many epochs, near-infrared spectroscopy,...
High-speed spectra of hypervelocity impacts at the NASA Ames Vertical Gun Range (AVGR) captured the rapidly evolving conditions of impact-generated vapor as a function of impact angle, viewpoint, and time (within the first 50μs). Impact speeds possible at the AVGR (<7km/s) are insufficient to induce significant vaporization in silicates, other than the high-temperature (but low-mass) jetting component...
Earth-based radar observation of Mercury’s rotation vector combined with gravity observation by the MESSENGER spacecraft yield a measure of Mercury’s moment of inertia and the amplitude of the 88-day libration of its silicate shell. These two geodetic constraints provide information on Mercury’s interior structure, including the presence of a fluid core, the radius of the core–mantle boundary and...
The upper mesosphere and the lower thermosphere of Venus (from 90 to 150km altitude) seems to play a transition region in photochemistry, dynamics and radiation, but is still very poorly constrained observationally. Since 2006 VIRTIS on board Venus Express has been obtaining limb observations of CO fluorescent infrared emissions in a systematic manner. This study represents the scientific exploitation...
A range of observations indicates widespread subsurface ice throughout the mid and high latitudes of Mars in the form of both pore-filling and excess ice. It is generally thought that this ice was recently emplaced and is not older than a hundred thousand to a few millions of years old based on ice stability and orbital-induced climate change. We analyze the distribution of subsurface ice in Arcadia...
Early Mars (>3Ga) underwent aqueous alteration as evidenced by fluvial/lacustrine morphologies and the recent discovery of widespread hydrous clays. Despite compelling evidence for diverse and localized aqueous environments, the possibility for sustained liquid water globally on the martian surface and over geological timescales is still highly debated. Instead, a durably cold and dry Mars scenario...
The FeO weight percentage (wt.%) abundance of the Moon’s western nearside (55°S–55°N and 5°E–40°W) is estimated using data from the InfraRed Spectrometer-2 (SIR-2) and the Moon Mineralogy Mapper (M3). In this study, we modified an FeO abundance estimation algorithm (Bhatt, M., Mall, U., Bugiolacchi, R., McKenna-Lawlor, S., Banaszkiewicz, M., Nathues, A., Ullaland, K. [2012]. Icarus 220, 51–64) which...
Sunlit and shaded slopes have a variety of temperatures based on their orientation with respect to the Sun. Generally, greater slope angles lead to higher anisothermality within the field of view. This anisothermality is detected by measuring changing emitted radiance as a function of viewing angle or by measuring the difference in brightness temperatures with respect to observation wavelength. Thermal...
The area of Meridiani Planum on Mars became of particular interest after the detection of coarse-grained, gray hematite, which led to the choice of this region as final landing site for the Mars Exploration Rover Opportunity. Multiple additional minerals have since been detected in the region, both from orbit and in situ. The present paper reassesses in detail the mineralogy and geomorphology of the...
Aqueous organic solid formation from formaldehyde via the formose reaction and subsequent reactions is a possible candidate for the origin of complex primitive chondritic insoluble organic matter (IOM) and refractory carbon in comets. The rate of formation of organic solids from formaldehyde was studied as a function of temperature and time, with and without ammonia, in order to derive kinetic expressions...
We report radar observations (2380-MHz, 13-cm) by the Arecibo Observatory and optical light curves observed from eight different observatories and collected at the Ondřejov Observatory of the triple near-Earth asteroid system (153591) 2001 SN263. The radar observations were obtained over the course of ten nights spanning February 12–26, 2008 and the light curve observations were made throughout January...
We report on an investigation of the spatial distribution of Io’s atmosphere, and its diurnal variability, using Hubble’s Space Telescope Imaging Spectrograph (HST/STIS). From December 2010 to January 2012, we obtained spatially resolved limb-to-limb 2100–3100Å spectra at low latitudes (<30°), with the STIS 0.1″ slit. Spectra taken at two central meridian longitudes (CMLs), 200 and 250W, over regions...
Recently it was found that the low-latitude zonal wind and the amplitudes of Kelvin and Rossby waves at the cloud top of Venus show long-term variations in a synchronized manner. For the purpose of explaining this synchronization, we investigated the influence of the background zonal wind profile on the upward propagation of Kelvin and Rossby waves at altitudes 60–80km. Results from a linearized primitive...
Lunar floor-fractured craters are a class of 170 lunar craters with anomalously shallow, fractured floors. Two end-member processes have been proposed for the floor formation: viscous relaxation, and subcrater magmatic intrusion and sill formation. Recent morphometric analysis with new Lunar Reconnaissance Orbiter Laser Altimeter (LOLA) and image (LROC) data supports an origin related to shallow magmatic...
The planned InSight mission will deliver a single seismic station containing 3-component broadband and short-period sensors to the surface of Mars in 2016. While much of the progress in understanding the Earth and Moon’s interior has relied on the use of seismic networks for accurate location of sources, single station approaches can be applied to data returned from Mars in order to locate events...
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