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Curiosity Detects Unusually High Methane Levels This week, NASA's Curiosity Mars rover found a surprising
result: the largest amount of methane ever measured during the mission - about
21 parts per billion units by volume (ppbv). One ppbv means that if you take a
volume of air on Mars, one billionth of the volume of air is methane.
The finding came from the rover's Sample Analysis at Mars
(SAM) tunable laser spectrometer. It's exciting because microbial life is an
important source of methane on Earth, but methane can also be created through
interactions between rocks
and water.
Curiosity doesn't have instruments that can definitively say
what the source of the methane is, or even if it's coming from a local source within
Gale Crater or elsewhere on the planet.
"With our current measurements, we have no way of
telling if the methane source is biology or geology, or even ancient or
modern," said SAM Principal Investigator Paul Mahaffy of NASA's Goddard
Spaceflight Center in Greenbelt, Maryland.
The Curiosity team has detected
methane many times over the course of the mission. Previous papers
have documented how background levels of the gas seem to rise
and fall seasonally. They've also noted sudden spikes of methane, but
the science team knows very little about how long these transient plumes last
or why they're different from the seasonal patterns.
The SAM team organized a different experiment for this
weekend to gather more information on what might be a transient plume. Whatever
they find - even if it's an absence of methane - will add context to the recent
measurement.
Curiosity's scientists need time to analyze these clues and
conduct many more methane observations. They also need time to collaborate with
other science teams, including those with the European Space Agency's Trace Gas
Orbiter, which has been in its science orbit for a little over a year without
detecting any methane. Combining observations from the surface and from orbit
could help scientists locate sources of the gas on the planet and understand
how long it lasts in the Martian atmosphere. That might explain why the Trace
Gas Orbiter's and Curiosity's methane observations have been so different.
For more information about
Curiosity, visit:
https://www.nasa.gov/mission_pages/msl/index.html
https://mars.nasa.gov/msl/
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