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| This view shows the patch of veined, flat-lying rock selected as the first drilling site for NASA's Mars rover Curiosity. [PHOTO: NASA/JPL-Caltech/MSSS] |
The size of a car,
Curiosity is inside Mars' Gale Crater investigating whether the planet ever
offered an environment favorable for microbial life. Curiosity landed in the
crater five months ago to begin its two-year prime mission.
"Drilling into a
rock to collect a sample will be this mission's most challenging activity since
the landing. It has never been done on Mars," said Mars Science Laboratory
project manager Richard Cook of NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, Calif. "The drill hardware interacts energetically with Martian
material we don't control. We won't be surprised if some steps in the process
don't go exactly as planned the first time through."
Curiosity first will
gather powdered samples from inside the rock and use those to scrub the drill.
Then the rover will drill and ingest more samples from this rock, which it will
analyze for information about its mineral and chemical composition.
The chosen rock is in
an area where Curiosity's Mast Camera (Mastcam) and other cameras have revealed
diverse unexpected features, including veins, nodules, cross-bedded layering, a
lustrous pebble embedded in sandstone, and possibly some holes in the ground.
The rock chosen for
drilling is called "John Klein" in tribute to former Mars Science
Laboratory deputy project manager John W. Klein, who died in 2011.
"John's
leadership skill played a crucial role in making Curiosity a reality,"
said Cook.
The target is on
flat-lying bedrock within a shallow depression called "Yellowknife Bay."
The terrain in this area differs from that of the landing site, a dry streambed
about a third of a mile (about 500 meters) to the west. Curiosity's science
team decided to look there for a first drilling target because orbital
observations showed fractured ground that cools more slowly each night than
nearby terrain types do.
"The orbital
signal drew us here, but what we found when we arrived has been a great
surprise," said Mars Science Laboratory project scientist John Grotzinger,
of the California Institute of Technology in Pasadena. "This area had a
different type of wet environment than the streambed where we landed, maybe a
few different types of wet environments."
One line of evidence
comes from inspection of light-toned veins with Curiosity's laser-pulsing
Chemistry and Camera (ChemCam) instrument, which found elevated levels of
calcium, sulfur and hydrogen.
"These veins are
likely composed of hydrated calcium sulfate, such as bassinite or gypsum,"
said ChemCam team member Nicolas Mangold of the Laboratoire de Planetologie et
Geodynamique de Nantes in France. "On Earth, forming veins like these
requires water circulating in fractures."
Researchers have used
the rover's Mars Hand Lens Imager (MAHLI) to examine sedimentary rocks in the area.
Some are sandstone, with grains up to about peppercorn size. One grain has an
interesting gleam and bud-like shape that have brought it Internet buzz as a
"Martian flower." Other rocks nearby are siltstone, with grains finer
than powdered sugar. These differ significantly from pebbly conglomerate rocks
in the landing area.
"All of these
are sedimentary rocks, telling us Mars had environments actively depositing
material here," said MAHLI deputy principal investigator Aileen Yingst of
the Planetary Science Institute in Tucson, Ariz. "The different grain
sizes tell us about different transport conditions."