|
 The
scientists behind NASA’s Phoenix Mars
Lander mission now know that they had
their first close-up look at Martian ice
— because it has vanished from the
picture.
Days ago,
streaks and bits of whitish material
were spotted at the bottom of a trench
dug by the lander's robotic scoop,
leading scientists to speculate that the
stuff was either ice or salt. An initial
chemical analysis was inconclusive, but
scientists said they could tell by
seeing if the material disappeared after
exposure to the thin Martian atmosphere.
Under such
conditions, water ice would turn
directly into vapor rather than melting
into liquid, in a process known as
sublimation. When scientists compared
Sunday's pictures with imagery captured
early Thursday, dice-sized crumbs of the
white material were clearly missing.
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