Original URL: http://www.theregister.co.uk/2010/11/01/mars_spirit_skidmark_water/

NASA Mars rover leaves moist skidmarks in boggy struggle

Boffins sniff wetness in churning soil

By Lewis Page

Posted in Science, 1st November 2010 14:12 GMT

NASA's famed Mars rover Spirit, snared and immobile since last year - and, it is feared, never to be heard from again following its current deep hibernation through the Martian winter - may in fact be bogged down in an actual, watery (ish) bog.

Mosaic of images showing Mars dirt churned up by the Spirit rover. Credit: NASA/JPL-Caltech/Cornell University

Not an actual olive pit and leaf. We presume.

Space boffins analysing pics from the mired Mars-prowler say that the ground its wheels have churned in a futile effort to escape "holds evidence that water, perhaps as snow melt, trickled into the subsurface fairly recently and on a continuing basis".

Spirit got trapped after breaking through a "crust" of ordinary Martian surface material in April last year, following a five-year career prowling the ochre wastes of the Gusev Crater. Efforts to free the snared machine were hampered by the fact that one of its six wheels hadn't worked properly since 2006: then problems got worse when another one packed up at the end of 2009.

Particularly unfortunately the quicksands of the Gusev left the stranded rover tilted southwards as the southern-hemisphere winter approached, meaning that the weak northern sun would scarcely shine at all on Spirit's flat solar cells. Previous winters had been survived by getting the machine onto a north-facing slope, so allowing a modest harvest of solar energy to be obtained and the rover to be preserved through the cold season.

Thus it is that NASA's boffins will be pleasantly surprised if Spirit actually manages to wake up from its current hibernation as spring reaches the Gusev next month. The Deep Space Network and the Mars Odyssey spacecraft orbiting Mars will be listening out.

But even if the frozen rover never wakes up, its final struggles may have added significantly to the evidence for water on the red planet. Wheels churning desperately in the months before February - when sunlight levels dropped too low for further driving - the trapped machine managed to move 13 inches backwards, exposing fresh subsurface Mars dirt to its cameras.

According to a NASA statement released following analysis of the pictures:

Relatively insoluble minerals near the surface include what is thought to be hematite, silica and gypsum. Ferric sulfates, which are more soluble, appear to have been dissolved and carried down by water. None of these minerals are exposed at the surface, which is covered by wind-blown sand and dust.

"The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates [by water] must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining," said Ray Arvidson, number two boffin on the rovers team.

If the trapped machine does wake up as summer comes back to its unexpectedly boggy quicksand trap, it will be used for an immobile study in which its radio signals will be Doppler analysed so as to gain new information on the Martian core.

Meanwhile "these newest Spirit findings contribute to an accumulating set of clues that Mars may still have small amounts of liquid water at some periods during ongoing climate cycles," according to NASA. And the companion rover, Opportunity, continues to crawl across the Meridiani Planum on the other side of the red planet.

There's more from NASA here. ®