Posted on 02/04/2004 6:40:23 PM PST by Phil V.
February 04, 2004
Opportunity Sees Tiny Spheres In Martian Soil
NASA's Opportunity has examined its first patch of soil in the small crater where the rover landed on Mars and found strikingly spherical pebbles among the mix of particles there.
"There are features in this soil unlike anything ever seen on Mars before," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science instruments on the two Mars Exploration Rovers.
For better understanding of the soil, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., plan to use Opportunity's wheels later this week to scoop a trench to expose deeper material. One front wheel will rotate to dig the hole while the other five wheels hold still.
The spherical particles appear in new pictures from Opportunity's microscopic imager, the last of 20 cameras to be used on the two rover missions. Other particles in the image have jagged shapes. "The variety of shapes and colors indicates we're having particles brought in from a variety of sources," said Dr. Ken Herkenhoff of the U.S. Geological Survey's Astrogeology Team, Flagstaff, Ariz.
The shapes by themselves don't reveal the particles' origin with certainty. "A number of straightforward geological processes can yield round shapes," said Dr. Hap McSween, a rover science team member from the University of Tennessee, Knoxville. They include accretion under water, but apparent pores in the particles make alternative possibilities of meteor impacts or volcanic eruptions more likely origins, he said.
A new mineral map of Opportunity's surroundings, the first ever done from the surface of another planet, shows that concentrations of coarse-grained hematite vary in different parts of the crater. The soil patch in the new microscopic images is in an area low in hematite. The map shows higher hematite concentrations inside the crater in a layer above an outcrop of bedrock and on the slope just under the outcrop.
Hematite usually forms in association with liquid water, so it holds special interest for the scientists trying to determine whether the rover landing sites ever had watery environments possibly suitable for sustaining life. The map uses data from Opportunity's miniature thermal emission spectrometer, which identifies rock types from a distance.
"We're seeing little bits and pieces of this mystery, but we haven't pieced all the clues together yet," Squyres said.
Opportunity's Mössbauer spectrometer, an instrument on the rover's robotic arm designed to identify the types of iron-bearing minerals in a target, found a strong signal in the soil patch for olivine. Olivine is a common ingredient in volcanic rocks. A few days of analysis may be needed to discern whether any fainter signals are from hematite, said Dr. Franz Renz, science team member from the University of Mainz, Germany.
To get a better look at the hematite closer to the outcrop, Opportunity will go there. It will begin by driving about 3 meters (10 feet) tomorrow, taking it about halfway to the outcrop. On Friday it will dig a trench with one of its front wheels, said JPL's Dr. Mark Adler, mission manager.
Opportunity's twin, Spirit, today is reformatting its flash memory, a preventive measure that had been planned for earlier in the week. "We spent the last four days in the testbed testing this," Adler said. "It's not an operation we do lightly. We've got to be sure it works right." Tomorrow, Spirit will resume examining a rock called Adirondack after a two-week interruption by computer memory problems. Controllers plan to tell Spirit to brush dust off of a rock and examine the cleaned surface tomorrow.
Each martian day, or "sol," lasts about 40 minutes longer than an Earth day. Spirit begins its 33rd sol on Mars at 2:43 a.m. Thursday, Pacific Standard Time. Opportunity begins its 13th sol on Mars at 3:04 p.m. Thursday, PST.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu .
### Guy Webster (818) 354-5011 Jet Propulsion Laboratory, Pasadena, California
Donald Savage (202) 358-1547 NASA Headquarters, Washington, D.C. NEWS RELEASE: 2004-051
If you'd like to be on or off this MARS ping list please FRail me
Oh, it is most likely some insulation from the lander that has blown across the ground.
However, it is rather interesting that NASA has not posted something about this subject on their website.
When there's a crater it's usually because a meteorite impacted the planet and caused that large hole in the ground. And tiny spheroids are always among the by-products of that impact. IOW, no big deal.
Tektites are glassy objects that are thought by most scientists today to be melt products of terrestrial rocks formed by hypervelocity impacts of large, extraterrestrial objects. They superficially resemble obsidian in appearance and chemical composition; however, several things distinguish these objects from obsidian. Primarily, they have a very low water content, a low alkali content, and they always contain lechatelierite (pure silica glass).They also often contain coesite (a highly dense silica polymorph), nickel-iron spherules, and baddeleyite (a zircon oxide mineral produced at very high temperatures during shock metamorphism), which lend evidence to a meteorite impact origin. Relict mineral inclusions often yield information about the tektite parent material.
Tektites are assigned to strewnfields, which are the areas over which chemically and physically related tektites are found. The assignment of a strewnfield is based on the oxide composition of a tektite. Four of the major strewnfields are the Australasian, Ivory Coast, Czechoslovakian, and North American strewnfields. Strewnfields include tektites, which are found on land, and microtektites, which are microscopic tektites that have been found in deep-sea sediments. Sizes range from less than 1 mm for microtektites to chunks 10-20 cm in width, with most being a centimeter or so in size and weighing a few grams (Glass, 1982). Tektites display a wide array of sizes, shapes, and surface features. For example, there are splash forms that include spheres, teardrops, dumbbells, and discs, ablated forms also known as "buttons", and chunks known as Muong Nong types that display a layered structure and are found primarily in Southeast Asia.
So far, that would be my first scientific guess.
Remember, the lander is sitting in the middle of a small meteor crater!
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