Search Publications
Phyllosilicates on Mars and implications for early martian climate
Mangold, N.; Bibring, J. -P.; Arvidson, R. E. +6 more
The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer o…
The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe
Israel, G.; Atreya, S. K.; Lunine, J. I. +15 more
Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens…
In situ measurements of the physical characteristics of Titan's environment
Neubauer, F. M.; Rodrigo, R.; Barucci, M. A. +40 more
On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity (`lightning') was also hitherto unknown. Here we report t…
Wave acceleration of electrons in the Van Allen radiation belts
Meredith, Nigel P.; Horne, Richard B.; Glauert, Sarah A. +11 more
The Van Allen radiation belts are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity and they represent a hazard to satellites and humans in space. An important challenge has been to explain how the charged particles within these bel…
The afterglow of GRB 050709 and the nature of the short-hard γ-ray bursts
Cenko, S. B.; Peterson, B. A.; Price, P. A. +33 more
The final chapter in the long-standing mystery of the γ-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolu…
Rain, winds and haze during the Huygens probe's descent to Titan's surface
Keller, H. U.; Küppers, M.; Thomas, N. +37 more
The irreversible conversion of methane into higher hydrocarbons in Titan's stratosphere implies a surface or subsurface methane reservoir. Recent measurements from the cameras aboard the Cassini orbiter fail to see a global reservoir, but the methane and smog in Titan's atmosphere impedes the search for hydrocarbons on the surface. Here we report …
A planetary system as the origin of structure in Fomalhaut's dust belt
Kalas, Paul; Graham, James R.; Clampin, Mark
The Sun and >15per cent of nearby stars are surrounded by dusty disks that must be collisionally replenished by asteroids and comets, as the dust would otherwise be depleted on timescales <107years (ref. 1). Theoretical studies show that the structure of a dusty disk can be modified by the gravitational influence of planets, but t…
Imaging of Titan from the Cassini spacecraft
Dones, Luke; Porco, Carolyn C.; McEwen, Alfred +33 more
Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of …
Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars
Jaumann, R.; Head, J. W.; Neukum, G. +11 more
Images from the Mars Express HRSC (High-Resolution Stereo Camera) of debris aprons at the base of massifs in eastern Hellas reveal numerous concentrically ridged lobate and pitted features and related evidence of extremely ice-rich glacier-like viscous flow and sublimation. Together with new evidence for recent ice-rich rock glaciers at the base o…
An upper limit to the masses of stars
Figer, Donald F.
There is no accepted upper mass limit for stars. Such a basic quantity eludes both theory and observation, because of an imperfect understanding of the star-formation process and because of incompleteness in surveying the Galaxy. The Arches cluster is ideal for investigating such limits, being large enough to expect stars at least as massive as ~5…