Filed at 5:03 p.m. ET
PASADENA, Calif. (AP) -- NASA's Spirit rover has found evidence
of past water activity in a volcanic rock on the other side of Mars
from where its twin, Opportunity, discovered signs that ground there
had once been drenched.
The amount of water at Spirit's site in Gusev Crater would have
been much less than what is indicated at Opportunity's site in
Meridiani Planum, Ray Arvidson, deputy principal investigator of the
rover mission, said Friday.
The findings came from aggressive study of a rock dubbed
``Humphrey'' that Spirit came across en route from its landing site
to a big crater named ``Bonneville,'' Arvidson told a Jet Propulsion
Laboratory news conference.
Spirit used its rock abrasion tool to grind below the rock
surface and reveal cracks filled with apparent minerals, an
indicator of water action familiar to geologists studying Earth
rocks.
``I think the best bet is that water was in the magma and as the
magma crystallized, kind of last stages of the fluids led to
formation of these white deposits ... and perhaps produced some
minerals that filled in the cracks,'' he said.
Scientists making the historic announcement about Opportunity's
discovery earlier this week could not say whether there had been
standing surface water or even an ocean there, but data showed water
had flowed or percolated through those rocks.
Arvidson said there was much less water indicated by
``Humphrey.''
``I don't think it was a ground water percolation, necessarily,
but probably water that came up with the magma,'' he said.
Both rovers continued to work well, mission officials said.
Jim Bell, lead scientist for the rovers' panoramic cameras, also
said Opportunity had photographed a solar eclipse caused by the
passage of the martian moon Deimos across the sun, but scientists
were waiting for images to be sent to Earth.
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