Search

The Martian atmosphere has a high X-129/Xe-132 ratio compared to the Martian mantle. As Xe-129 is the daughter product of the extinct nuclide I-129, a means of fractionating iodine from xenon early in Martian history appears necessary to account for the X-129/Xe-132 ratios of its known reservoirs. A model is presented here to account for the Marian xenon data which relies on the very different solubilities of xenon and iodine in water to fractionate them after outgassing. Atmospheric xenon is lost by impact erosion during heavy bombardment, followed by release of Xe-129 produced from I-129 decay in the crust.

The question of whether water exists on the Moon has been highly controversial. Results from the Lunar Prospector mission, now analysed and published, provide the best evidence yet that there is indeed a considerable amount of water on the Moon, in the form of ice under the lunar poles. The instruments concerned detect hydrogen, which could, for instance, exist as H2. But H2O is the more likely form.

Analyses of images taken by the Clementine spacecraft have provided striking maps of solar illumination at the lunar south pole. Crater edges at the pole may be sunlit up to 80% of the time, while crater floors may be in permanent shadow. Both conditions have implications for the possibility of building bases on the Moon — the first for the positioning of solar arrays, the second for the availability of water.