NASA Mars rover finds no sign of methane, telltale sign of life

CAPE CANAVERAL, Florida (Reuters) - NASA's
Mars rover Curiosity has come up empty-
handed in its search for methane in the
planet's atmosphere, a gas that on Earth is a
strong indicator of life, officials said on
Thursday.
The rover landed on Mars in August 2012 to
determine whether the planet most like Earth
in the solar system has or ever had the
chemistry and conditions to support microbial
life.
Over the past decade, scientists using Mars
orbiters and telescopes on Earth have
reported plumes of methane in the Martian
atmosphere.
The gas breaks down in sunlight, so its
presence on Mars indicated that either
biological activity or a recent geologic event
was responsible for its release.
The gas, which lasts about 300 years in
Earth's atmosphere, could be expected to
stick around for 200 years on Mars. But
Curiosity's findings, compiled over eight
months, indicate that the methane may have
virtually disappeared in a matter of years.
Based on the previous observations,
scientists had expected to find about six
times more methane in the atmosphere than
the negligible amounts Curiosity found.
"There's a discrepancy," lead research
Christopher Webster, with NASA's Jet
Propulsion Laboratory in Pasadena,
California, told Reuters. "Suddenly the whole
interpretation of earlier observations is
stuck."
Webster said it is possible but unlikely that
the lack of methane is particular to
Curiosity's landing site, a giant basin near
the planet's equator.
Once methane is released from the surface,
scientists believe it would spread fairly
quickly through the planet's thin atmosphere.
"It's disappointing, of course," Webster said.
"We would have liked to get there and find
lots of methane."
The search is not over. Curiosity will
continue to take air samples and test for
methane as it continues its geology mission.
Scientists also plan another round of
observations with Earth-based telescopes
next year.
The research appears this week in the journal
Science.