By ALICIA CHANG, AP Science Writer
LOS ANGELES - Is the white stuff in the Martian soil ice or salt? That's the question bedeviling scientists in the three weeks since the
Shallow trenches excavated by the lander's backhoe-like robotic arm have turned up specks and at times even stripes of mysterious white material mixed in with the clumpy, reddish dirt.
New photos showed the exposed bright substance present only in the top part of the trench, suggesting it's not uniform throughout the excavation site.
"We think it's ice. But again, until we can see it disappear ... we're not guaranteed yet," mission scientist Ray Arvidson of
Even if it's not ice, the discovery of salt would also be significant because it's normally formed when water evaporates in the soil.
Preliminary results from a bake-and-sniff experiment at low temperatures failed to turn up any trace of water or ice in the scoopful of soil that was delivered to the lander's test oven last week. Scientists planned to heat the soil again this week to up to 1,800 degrees, said William Boynton of the
The project is led by the
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