NASA's Curiosity rover on Mars is busily grinding out science data —
and has likely relayed some provocative findings — but mum's the word
from scientists on the mission.
At the epicenter of all the speculation is that Curiosity's
Sample Analysis at Mars (SAM) instrument has gulped in Martian soil and regurgitated exciting news.
John Grotzinger, lead mission investigator for the Curiosity rover,
set the rumors in motion
during an interview with NPR last week, saying, "We're getting data
from SAM … this data is gonna be one for the history books. It's looking
really good."
Whatever history-making news there is to report, Curiosity scientists
are expected to cough up the goods at this year's American Geophysical
Union (AGU) meeting in San Francisco, to be held from Dec. 3 to Dec. 7.
On the AGU agenda is a discussion of Curiosity's search for organic molecules on
Mars
with its Gas Chromatograph-Mass Spectrometer — a key instrument to help
explore the surface and subsurface of Mars, seeking traces of prebiotic
or biological activity.
As expected, readers in the blogosphere have already chimed in with
what they believe Curiosity has found; their guesses so far have
included a fossil, a black monolith, Tang and Jimmy Hoffa. [
Top 5 Attempts to Find Life on Mars]
Most scientists contacted by SPACE.com believe that Curiosity's SAM has
detected organic chemical compounds. Still, some experts caution that
the rover's finding may be overhyped.
"This is going to be a disappointment," said Chris McKay, a NASA space
scientist at Ames Research Center at Moffett Field, Calif. "The press
description of the
SAM results as 'earthshaking' is, in my view, an unfortunate
exaggeration. We have not (yet) found anything in SAM that was not
already known from previous missions: Phoenix and Viking."
But James Garvin, chief scientistat NASA's Goddard Space Flight Center
in Greenbelt, Md., and a member of Curiosity's Mars Science Laboratory
(MSL) science team, had a different take.
"What John Grotzinger was saying as our very capable project scientist
on MSL is exactly the case," Garvin said. "The analytical payload on MSL
—in particular, SAM as a suite —has been making unprecedented
measurements of solid material samples with incredible implications
about Mars, but which require, as in all science, demonstration of
reproducibility and adequacy of calibration/validation."
Curiosity landed inside Mars' huge
Gale Crater on
Aug. 5, beginning a two-year mission to determine if the Red Planet
could ever have hosted microbial life. The rover carries 10 different
instruments, but SAM is the heart of Curiosity, taking up more than half
of its science payload by weight.
Play it again, SAM
Garvin said the SAM team, plus the wider MSL science team (including
Grotzinger), "are working industriously to have consistent results for
the world to revel in as soon as possible."
"It is more akin to waiting for test results from one's doctor … we
want to be sure they are valid and properly interpreted and explained,"
Garvin added.
Unlike imaging and related experiments, highly sensitive results from
SAM's instruments, which include mass spectrometers, tunable diode laser
spectrometers and gas chromatographs —require very great care in
calibration, validation and interpretation, Garvin emphasized.
"MSL with its Curiosity rover really is analogous to the Hubble Space
Telescope in the impact it can and will have —we just have to be
patient," Garvin said.
Similar to the Hubble Space Telescope, Garvin added, "We have to be
patient to use our tools to look at the 'right stuff.' Stay tuned … Mars
will not disappoint and nor will MSL."
Blockbuster findings
Also awaiting the word from the Curiosity science team is Michael
Mumma, a planetary scientist also at NASA Goddard, where he is founding
director of the Goddard Center for Astrobiology.
"It clearly relates to the first soil sample analyzed by SAM. I suspect
the delay means that a second sample is being analyzed to confirm
findings from the first," Mumma said.
Given that SAM's Tunable Laser Spectrometer (TLS)
methane data
were not released until third and fourth samples had been analyzed,
Mumma doubts there will be much to hear for several weeks. [
Mars Methane: Could It Mean Life? (Video)]
in Mumma's view, "blockbuster findings" could include the discovery of
a major release of methane from pyrolyzed soil, with measurements of
certain intriguing chemical variations called isotopologues. A finding
of complex hydrocarbons (molecules containing hydrogen and carbon) or of
a type of chemical compound called polymers, would also be a major
discovery.
In favor of life
"I think the minimum finding that could get Grotzinger to describe it
as 'historic' is complex organic compounds," said Gilbert Levin, an
adjunct professor at Arizona State University in Tempe.
Levin was a life-detection experimenter on NASA's
Viking mission to Mars
in 1976. Levin and co-experimenter Patricia Ann Straat led the Viking
Labeled Release (LR) investigation, which returned data from Mars
indicating the presence of microbial life, the team asserts.
"I have already pointed out that the Viking PR [The Viking biology
package also consisted of the Pyrolytic Release experiment (PR)] showed
that simple organics are continually being formed on Mars, so they would
be no big deal for Curiosity," Levin told SPACE.com. "I doubt SAM could
have detected proof of living microorganisms. But, slowly, ineluctably,
NASA is being dragged into the mire of life on Mars, and will
ultimately, maybe soon, have to reverse its opinion on the results of
the Viking LR."
If Curiosity has found organics, Levin said, it will thereby confirm
that the GCMSwas not sensitive enough to rule out the positive findings
of the Viking LR.
"The failure of the Viking GCMS is the only remaining obstacle to
acceptance of the Mars LR having detected existing microbial life. That
obstacle would be removed by the Curiosity finding of organics. Whether
that will turn the consensus in favor of life, I do not know, but any
rationale against it would be difficult to maintain," Levin concluded.
Biding time
Ultimately, the world will have to wait just a little bit longer to find out what Curiosity knows.
"Curiosity's science team is analyzing data from SAM's soil inspection,
but not ready to discuss yet," said Guy Webster, a spokesman for the
Curiosity Mars rover science team at the Jet Propulsion Laboratory in
Pasadena, Calif.
This is no change from the policy with past results from the mission, such as SAM's atmosphere analysis or
CheMin's soil sample analysis,
Webster told SPACE.com. "The scientists want to gain confidence in the
findings before taking them outside of the science team."
Webster said that Grotzinger was delighted about the quality and range
of information coming in from SAM and similarly delighted by results at
other points during the mission so far.
"The characterization of new findings as earthshaking did not come from anyone on the mission's science team," Webster said.
Leonard David has been reporting on the space industry for more
than five decades. He is a winner of last year's National Space Club
Press Award and a past editor-in-chief of the National Space Society's
Ad Astra and Space World magazines. He has written for SPACE.com since
1999.
