BOULDER, Colorado - Evidence
for intense local enhancements in methane on Mars has been bolstered by ground-based
observations. The methane, as well as water on Mars, was detected using state-of-the-art
infrared spectrometers stationed atop Mauna Kea, Hawaii and in Cerro Pachón,
Chile.
Scientific teams around
the globe are on the trail of methane seeping out of Mars. And for good reason:
The methane could be the result of biological processes. It could also be an
"abiotic" geochemical process, however, or the result of volcanic
or hydrothermal activity on the red planet.
Many types of microbes here
on Earth produce a signature of methane. Indeed, the tiny fraction of atmospheric
carbon found as methane on our planet is churned out almost entirely biologically
with only a very small contribution from abiotic processes, scientists say.
Lingering methane
New information on Mars
methane has been acquired using NASA's Infrared Telescope Facility (IRTF) atop
Mauna Kea, Hawaii, as well as from the Gemini South telescope sitting on a mountain
in the Chilean Andes called Cerro Pachon.
Michael Mumma, a lead investigator
at the Center for Astrobiology and Solar System Exploration Division at the
NASA Goddard Space Flight Center in Greenbelt, Maryland, presented the findings
during the Biennial Meeting of the NASA Astrobiology Institute, held here April
10-14 and hosted by the University of Colorado, Boulder.
Mumma and his research colleagues
have used ground-based spectrometers to carry out a simultaneous search for
methane and water vapor. "Pronounced enhancements" of methane have
been detected over several equatorial regions on Mars, consistent with "enhanced
local release," Mumma reported.
In scientific terms, the
methane line detected is "very strong indeed," Mumma noted. Using
the high-tech infrared spectrometers, spectra of six narrow longitudinal bands
across the face of Mars were taken. A spectra is an analysis of light broken
into its rainbow of colors.
"Every one of these
longitudes shows a very substantial enhancement in the equatorial zone,"
Mumma explained. "So this is a very intense source of methane on Mars in
this region. It also requires a very rapid decay of methane...more rapid than
photochemistry would allow," he added.
On Mars, the photochemical
lifetime of methane is very short - roughly 300 years. Therefore, any methane
now lingering within the martian atmosphere must have been released recently.
Mumma said that his data - along with what Mars Global Surveyor's Thermal Emission Spectrometer measured at the same time - suggests that "a major source" of methane over Valles Marineris is evident during the fall equinox on Mars.
Footprint of data
Spotlighted at this week's
meeting in terms of strong methane detection was an area on Mars east of Hellas
Basin to west of Hellas Basin - and the eastern most edge of the large region
where NASA's Mars Odyssey orbiter found subsurface hydrogen in high abundance.
That hydrogen is thought to be the signature of water ice, scientists said.
Moreover, for the first
time, and using the Gemini South telescope, two lines of methane have been simultaneously
seen on Mars. And when each is studied independently, they show a consistent
abundance of methane on the planet -- within the narrow stripes across Mars
scanned by the Earth-based gear.
Furthermore, the ground-based
"footprint" of data extracted was contrasted with data taken in a
similar time period by the Mars Global Surveyor's (MGS) Thermal Emission Spectrometer.
That Mars-orbiting MGS sensor yields information on the red planet's surface
pressure and temperature, as well as water vapor within the column of martian
atmosphere the sensor is inspecting.
The MGS data helped validate
the approach taken by Mumma and his colleagues.
Extremely challenging to
analyze
The new results stem from
observational sweeps of Mars done in 2003, made possible by two years of preliminary
work.
"We had to invent several
new methods for analyzing the data," Mumma told SPACE.com. "These
data are extremely challenging to analyze," he said, with the scientist
drawing from his nearly 30 years of work in planetary atmospheric spectroscopy.
Mumma said the data collected
from Earth is a step to help sort out biogenic versus primordial or geothermal
origins of the Mars methane. Additional chemical tests can help constrain these
possibilities, he added, but investigations from space, around Mars, or on the
planet - perhaps even samples robotically returned to Earth -- are likely needed
to reach a definitive answer.
Next up for Mumma and the
methane on Mars quest is acquiring more telescope time.
Geologically alive, biologically
alive...or both?
Requests are in for telescope
time next January, both at the IRTF and at the W.M. Keck Observatory, also in
Hawaii. Using the Keck facility, Mumma said his team could look for seven different
types of molecules at Mars, allowing them to chip away at the question of biological
versus geochemical production of methane.
Culling out from the data
the release locales of methane on Mars is critical to the selection of future
landing sites, "to search for organics that are either biological or abiotic,"
Mumma said. Finding out whether methane releases are seasonally dependent is
also of keen interest, he said.
There is no doubt in Mumma's
mind that something is going on at Mars. "Mars was wet...was it also alive...or
is it now alive?"
But "alive" could be geologically
alive and not necessarily biologically alive, Mumma said.
"Or Mars could be biologically
alive," he added. "Or maybe both. So to me that's the real issue. Now we think
that Mars is not a dead planet. Even if it's just geology that is occurring
and releasing this methane...that's pretty darn interesting. And the geologists
are very excited about this prospect."