Ice on Mars! Now you see it, now you don’t
Scientists say they know white stuff was frozen water because it vanished
NASA / JPL-Caltech / UA / TAMU
This animated image shows dice-sized bits of ice in the lower left corner of a trench dug by the robotic scoop on NASA's Phoenix Mars Lander. Scientists say they know the bits were ice because they disappeared from view in later imagery.
By Alan Boyle
Science editor
MSNBC
updated 8:26 p.m. CT, Thurs., June. 19, 2008
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.
advertisement
"It must be ice," the University of Arizona's Peter Smith, principal investigator for the Phoenix mission, said Thursday in a NASA status report. "These little clumps completely disappearing over the course of a few days, that is perfect evidence that it's ice. There had been some question whether the bright material was salt. Salt can't do that."
A larger vein of white material is still visible in the trench, which scientists have dubbed "Dodo-Goldilocks."
No comments:
Post a Comment