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.
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 sulphur 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. Curiosity are the first Mars rover able
to scoop soil into analytical 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 accumulates 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."
For further information
visit: http://www.marsdaily.com/reports/NASA_Mars_Rover_Fully_Analyzes_First_Soil_Samples_999.html
No comments:
Post a Comment