This news item just in my mailbox from JPL>>>latest on Curiosity.
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News release: 2010-384 Nov. 16, 2010
Camera on Curiosity's Arm will Magnify Clues in Rocks
The full version of this story with accompanying images is at: http://www.jpl.nasa.gov/news/news.cfm?release=2010-384&cid=release_2010-384
NASA's next Mars rover, Curiosity, will wield an arm-mounted magnifying camera similar to one
on the Mars Rover Opportunity, which promptly demonstrated its importance for reading
environmental history from rocks at its landing site in 2004.
Within a few weeks after the landing, that camera at the end of Opportunity's arm revealed
details of small spheres embedded in the rocks, hollows where crystals had dissolved, and fine
layering shaped like smiles. These details all provided information about the site's wet past.
The camera installed on the end of Curiosity's arm this month is the Mars Hand Lens Imager, or
MAHLI. Its work will include the same type of close-up inspections accomplished by the
comparable camera on Opportunity, but MAHLI has significantly greater capabilities: full-color
photography, adjustable focus, lights, and even video. Also, it sits on a longer arm, one that can
hold MAHLI up higher than the cameras on the rover's mast. MAHLI will use those capabilities
as one of 10 science instruments to study the area of Mars where NASA's Mars Science
Laboratory mission lands Curiosity in August 2012.
The Mars Hand Lens Imager takes its name from the magnifying tool that every field geologist
carries. Ken Edgett of Malin Space Science Systems, San Diego, is the principal investigator for
the instrument. He said, "When you’re out in the field and you want to get a quick idea what
minerals are in a rock, you pick up the rock in one hand and hold your hand lens in the other
hand. You look through the lens at the colors, the crystals, the cleavage planes: features that help
you diagnose what minerals you see.
"If it's a sedimentary rock, such as the sandstone you see at Arches National Park in Utah, or
shale -- which is basically petrified mud -- like in the Painted Desert in Arizona, you use the hand
lens not just to see what minerals are in it but also the sizes and shapes of the grains in the rock.
You also look at the fine-scale layering in the rock to get an idea of the sequence of events.
Sedimentary rocks record past events and environments."
While other instruments on Curiosity will provide more information about what minerals are in
rocks, the Mars Hand Lens Imager will play an important role in reading the environmental
history recorded in sedimentary rocks. The mission's science team will use the instruments to
assess whether the selected landing area has had environmental conditions favorable for life and
for preserving evidence about whether life existed.
The team currently assembling and testing Curiosity and other parts of the Mars Science
Laboratory spacecraft at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is continuing tests
of MAHLI this month, now that the camera is mounted beside other tools on the robotic arm.
The spacecraft will launch from Florida between Nov. 25 and Dec. 18, 2011.
Edgett led the preparation in early 2004 of a proposal to include MAHLI in the Mars Science
Laboratory's payload. During those same months, the camera on Opportunity's arm -- that
mission's Microscopic Imager -- was demonstrating the potential value of a successor, and
generating ideas for improvements. Opportunity's Microscopic Imager has a fixed focus. To get
targets in focus, it always needs to be placed the same distance from the target, recording a view
of an area 3 centimeters (1.2 inches) across. To view a larger area, the camera takes multiple
images, sometimes more than a dozen, each requiring a repositioning of Opportunity's arm.
"When I was writing the proposal, the Microscopic Imager took about 40 images for a mosaic of
one rock," Edgett said. "That's where the idea came from to make the focus adjustable. With
adjustable focus, the science team has more flexibility for trade-offs among the rover's resources,
such as power, time, data storage and data downlink. For example, the camera could take one or
two images from farther away to cover a larger area, then go in and sample selected parts in
higher resolution from closer up."
MAHLI can focus on targets as close as about 21 millimeters (0.8 inch) and as distant as the
horizon or farther. JPL's Ashwin Vasavada, deputy project scientist for the Mars Science
Laboratory, said, "MAHLI is really a fully functional camera that happens to be on the end of the
arm. The close-up capability is its specialty, but it will also be able to take images or videos from
many viewpoints inaccessible to the cameras on the mast, such as up high, down low, under the
rover and on the rover deck. Think of it like a hand-held camera with a macro lens, one that you
could use for taking pictures of the Grand Canyon, of yourself, or of a bumblebee on a flower."
Edgett is looking forward to what the camera will reveal in rock textures. "Just like larger rocks
in a river, grains of sand carried in a stream get rounded from bouncing around and colliding
with each other," he said. "If you look at a sandstone with a hand lens and see rounded grains,
that tells you they came from a distance. If they are more angular, they didn't come as far before
they were deposited in the sediment that became the rock. Where an impact excavated a crater,
particles of the material ejected from the crater would be very angular.
"When you're talking about ancient rocks as clues for assessing habitability," he continued,
"you're talking about the environments the sediments were deposited in -- whether a lake, a
desert, an ice field. Also, what cemented the particles together to become rocks, and what
changes have affected the rock after the sediments were deposited? All these things are relevant
to whether an environment was favorable for life and also whether it was favorable for
preserving the record of that life. Earth is a planet teeming with life, but most rocks have not
preserved ancient organisms; Mars will be even more challenging than Earth in this sense."
Edgett says he is eager to see an additional image from this camera besides the details of rock
textures. With the arm extended upwards, the camera can look down at the rover for a dramatic
self-portrait on Mars. But as for the most important image the Mars Hand Lens Imager will take:
"That will be something that surprises us, something we're not expecting."
Mars Science Laboratory is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif.
JPL also manages the Mars Exploration Rovers Spirit and Opportunity. JPL is a division of the
California Institute of Technology in Pasadena.
More information about NASA's Mars Science Laboratory is at: http://www.nasa.gov/msl .