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| This is a view of the third (left) and fourth (right) trenches made by the 1.6-inch-wide (4-centimeter-wide) scoop on NASA's Mars rover Curiosity. [Image credit: NASA/JPL-Caltech/MSSS] |
Pasadena, California: NASA's Mars Curiosity rover has used its full array of
instruments to analyze Martian soil for the first time, and found a complex
chemistry within the Martian soil. Water and sulfur and chlorine-containing
substances, among other ingredients, showed up in samples Curiosity's arm
delivered to an analytical laboratory inside the rover.
Detection of the
substances during this early phase of the mission demonstrates the laboratory's
capability to analyze diverse soil and rock samples over the next two years.
Scientists also have been verifying the capabilities of the rover's
instruments.
The specific soil
sample came from a drift of windblown dust and sand called
"Rocknest." The site lies in a relatively flat part of Gale Crater
still miles away from the rover's main destination on the slope of a mountain
called Mount Sharp. The rover's laboratory includes the Sample Analysis at Mars
(SAM) suite and the Chemistry and Mineralogy (CheMin) instrument. SAM used
three methods to analyze gases given off from the dusty sand when it was heated
in a tiny oven. One class of substances SAM checks for is organic compounds --
carbon-containing chemicals that can be ingredients for life.
"We have no
definitive detection of Martian organics at this point, but we will keep
looking in the diverse environments of Gale Crater," said SAM Principal
Investigator Paul Mahaffy of NASA's Goddard Space Flight Center in Greenbelt,
Md.
Curiosity's APXS
instrument and the Mars Hand Lens Imager (MAHLI) camera on the rover's arm
confirmed Rocknest has chemical-element composition and textural appearance
similar to sites visited by earlier NASA Mars rovers Pathfinder, Spirit and
Opportunity.
Curiosity's team
selected Rocknest as the first scooping site because it has fine sand particles
suited for scrubbing interior surfaces of the arm's sample-handling chambers.
Sand was vibrated inside the chambers to remove residue from Earth. MAHLI
close-up images of Rocknest show a dust-coated crust one or two sand grains thick,
covering dark, finer sand.
"Active drifts
on Mars look darker on the surface," said MAHLI Principal Investigator Ken
Edgett of Malin Space Science Systems in San Diego."This is an older drift
that has had time to be inactive, letting the crust form and dust accumulate on
it."
CheMin's examination
of Rocknest samples found the composition is about half common volcanic
minerals and half non-crystalline materials such as glass. SAM added
information about ingredients present in much lower concentrations and about
ratios of isotopes. Isotopes are different forms of the same element and can
provide clues about environmental changes. The water seen by SAM does not mean
the drift was wet. Water molecules bound to grains of sand or dust are not
unusual, but the quantity seen was higher than anticipated.
SAM tentatively
identified the oxygen and chlorine compound perchlorate. This is a reactive
chemical previously found in arctic Martian soil by NASA's Phoenix Lander.
Reactions with other chemicals heated in SAM formed chlorinated methane
compounds -- one-carbon organics that were detected by the instrument. The
chlorine is of Martian origin, but it is possible the carbon may be of Earth
origin, carried by Curiosity and detected by SAM's high sensitivity design.
"We used almost
every part of our science payload examining this drift," said Curiosity
Project Scientist John Grotzinger of the California Institute of Technology in
Pasadena. "The synergies of the instruments and richness of the data sets
give us great promise for using them at the mission's main science destination
on Mount Sharp."