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Latest news from the Spirit and Opportunity Mars rovers:

See also:

Click! The "Mars" section of this site.
Click! Latest Mars exobiology news.
Click! Latest news from the Mars Global Surveyor probe.
Click! Latest news from the Mars Odyssey probe.
Click! Latest news from the Beagle 2 / Mars Express probes.
This page. Latest news from the Mars Spirit and Opportunity probes (This page).


03.29.2009Spirit and Opportunity still going.
05.23.2008Found evidence of formerly habitable niche on Mars surface is now in academic scientific journal.
01.01.2008Spirit Mars rover finds evidence of formerly habitable niche on Mars surface.
02.12.2006Spirit discoveries continue.
09.08.2005Chemical proof from Gusev crater for wet Mars scenarios offered by scientists.
01.13.2005Opportunity finds possible meteorite.
12.22.2004Opportunity gets better, Spirit not.
10.08.2004JPL: Mars rovers probing water history at two sites.
06.09.2004Bedrock in Gusev crater hints at watery past of Mars.
06.09.2004Salts in evidence of past water found also by the Spirit Rover.
03.23.2004Standing body of water left its mark in Mars rocks.
03.21.2004NASA to announce major Mars rovers finding.
03.02.2004NASA press release, Meridiani Planum: "Drenched".
03.02.2004Opportunity rover finds strong evidence Meridiani Planum was wet.
03.01.2004NASA announces important press briefing tomorrow.
02.20.2004Rover microscope shows thread-like features in the soil at Opportunity site.
02.19.2004Hints of salty liquid water in the soil at Opportunity site.
02.13.2004An error explains why the Spirit and Opportunity images of Mars were much too red.
01.24.2004Second NASA rover Opportunity lands successfully on Mars.
01.16.2004Spirit microscope shows many hollow grains of sand.
01.15.2004Conditions for water on Spirit landing site.
01.15.2004Carbonates and hydrated material, possible clay, found at Spirit landing site.
09.01.2004Spirit measures ground level temperatures.
07.01.2004Spirit image shows what looks like muddy soil under the surface dust.
01.03.2004Spirit lands safely and returns first rough images.

Mars rovers still going on:

In January 2004, NASA landed the two identical robotic rovers Spirit and Opportunity on the surface of Mars for a 3-month mission to look for signs of past water.

More than five years later, the two robots are still roving the planet.

Opportunity is now sent to the large Endeavour crater, a two years trip at least.

Endeavor is an interesting target because rocks close to it look different from the ones surrounding the other craters Opportunity has visited, and the crater is deeper, exposing more ancient bedrock.

Spirit is going to an interesting looking mesa-shaped cap-rock called von Braun, that stands only about 250 meters away but will take months to reach. Then Spirit will head to a 30-meter diameter pit that may be a volcanic explosion crater and perhaps a location for hydrothermal activity.

Evidence of formerly habitable niche on Mars surface now in academic science journal:

Science, Vol. 320. no. 5879, pp. 1063 - 1067, May 23, 2008:

Detection of Silica-Rich Deposits on Mars

S. W. Squyres,1* R. E. Arvidson,2 S. Ruff,3 R. Gellert,4 R. V. Morris,5 D. W. Ming,5 L. Crumpler,6 J. D. Farmer,3 D. J. Des Marais,7 A. Yen,8 S. M. McLennan,9 W. Calvin,10 J. F. Bell, III,1 B. C. Clark,11 A. Wang,2 T. J. McCoy,12 M. E. Schmidt,12 P. A. de Souza, Jr.13

Abstract:

Mineral deposits on the martian surface can elucidate ancient environmental conditions on the planet. Opaline silica deposits (as much as 91 weight percent SiO2) have been found in association with volcanic materials by the Mars rover Spirit. The deposits are present both as light-toned soils and as bedrock. We interpret these materials to have formed under hydrothermal conditions and therefore to be strong indicators of a former aqueous environment. This discovery is important for understanding the past habitability of Mars because hydrothermal environments on Earth support thriving microbial ecosystems.

Spirit finds evidence of formerly habitable niche on Mars surface:

Spirit, driving backward since its right front wheel stopped turning in March 2006, was exploring near a plateau in the Gusev Crater known as Home Plate when scientists noticed that upturned soil in the wake of its dragging wheel appeared unusually bright.

Measurements by the rover's alpha particle X-ray spectrometer and mini-thermal emission spectrometer showed the soil to be about 90 percent amorphous silica, a substance associated with life-supporting environments on Earth.

Steve Squyres, Cornell's Goldwin Smith Professor of Planetary Science who is the principal investigator for NASA's Mars Exploration Rover mission, called the discovery "one of the most significant" of the mission discoveries to date in a December 11 interview with the BBC. Squyres and colleagues reported the discovery at the annual meeting of the American Geophysical Union in early December in San Francisco, USA.

It provides new evidence for a once-habitable environment in Gusev Crater on Mars. On Earth, silica deposits are found at hot springs, where hot water dissolves silica in rock below the surface, then rises and cools, causing the silica to precipitate out near the surface; and at fumaroles, where hot acidic water or vapors seep through rock, dissolving away other elements but leaving silica behind. On Earth, those places are teeming with microbial life.

NASA rovers Spirit and Opportunity are now in their fourth year of mission on Mars, and are still functioning, whereas it was originally planned that they would survive only about 3 months.

Spirit discoveries continue:

Spirit Mars rover has wheeled its way to the edge of "Home Plate" at Gusev crater exploration site, and what the Mars rover science team saw there had them go "wow!" and has sparked debate:

Chemical proof from Gusev crater for wet mars scenari offered by scientists:

A large team of NASA scientists led by earth and planetary scientists at Washington University in St. Louis have detailed the first solid set of evidence for water having existed on Mars at the Gusev crater currently explored by the Spirit rover.

Using the data collected by the array of sophisticated equipment on the Spirit rover, Alian Wang, Ph.D., Washington University senior research scientist in earth and planetary sciences in Arts and Sciences, and the late Larry A. Haskin, Ph.D., Ralph E. Morrow, Distinguished University Professor of earth and planetary sciences, found that the volcanic rocks at Gusev crater near Spirit's landing site were much like the olivine-rich basaltic rocks on the Earth, and that some of them possessed a coating rich in sulfur, bromine, chlorine and hematite, or oxidized iron.

The chemical evidence from several studied rock indicates a scenario where water froze and melted at some point in Martian history, dissolving the sulfur, chlorine and bromine elements in the soil. The small amount of acidic fluids then reacted with the rocks buried in the soil and formed the highly oxidized coatings.

After the findings were confirmed, Spirit traversed to the Columbian hills, where it found more evidence indicating water. The science team is currently planning for sol 551 operation of Spirit rover, which is only 55 meters away from the summit of Columbia Hills.

The other rover, Opportunity, had already detected a history of water earlier at Meridiani Planum, the other site explored on Mars.

Opportunity finds possible meteorite:

NASA's Opportunity Mars rover has come across an interesting object, which is probably a meteorite, sitting out in the open at Meridiani Planum. Initial data taken by the robot's Mini-Thermal Emission Spectrometer (Mini-TES) is suggestive that the odd-looking "rock" is made of metal.

Opportunity gets better, Spirit doesn't:

MER (Mars Exploration Rovers) mission scientists at NASA have provided some news on the health of the two Mars rover Opportunity and Spirit.

The Spirit rover - which already had an unusable wheel for months has now a new problem: a steering actuator that controls the angle of pairs of wheels failed. The consequences are not dramatic; command sequences have failed to execute on several occasions over the last three weeks, and in the future, rover movements will have to be performed in more complicated sequences than in the past when on rough ground.

The Opportunity rover, on the contrary, goes better now than previously. It seems that something - probably winds, or maybe frost has clumped up the dust in packs so that more solar panel surface is exposed - has cleaned up the solar panels during one recent night, so that more power than expected is available to the rover than before: since a month now, they deliver almost their maximum of 900 watt per hours, when it was expected that the dirt would result in a drop to 500 watt-hours. Indeed the other rover, Spirit, gets only 400 watt-hours currently.

Opportunity has now reached an overall 1619 meters course, and Spirit has logged 3647 meters. It was never expected that the two rovers would survive for so long.

Mars rovers probing water history at the two sites:

NASA's Jet Propulsion Laboratory communicates on October 8, "Mars Rovers Probing Water History At Two Sites".

They say, "NASA's Spirit and Opportunity have been exploring Mars about three times as long as originally scheduled. The more they look, the more evidence of past liquid water on Mars these robots discover. Team members reported the new findings at a news briefing today."

"About six months ago, Opportunity established that its exploration area was wet a long time ago. The area was wet before it dried and eroded into a wide plain. The team's new findings suggest some rocks may have gotten wet a second time, after an impact excavated a stadium-sized crater."

"Evidence of this exciting possibility has been identified in a flat rock dubbed "Escher" and some neighboring rocks near the bottom of the crater. These plate-like rocks bear networks of cracks dividing the surface into patterns of polygons, somewhat similar in appearance to cracked mud after the water has dried up here on Earth."

Alternative histories, such as fracturing by the force of the crater-causing impact, or the final desiccation of the original wet environment that formed the rocks, might also explain the polygonal cracks.

Rover scientists hope a lumpy boulder nicknamed "Wopmay," Opportunity's next target for inspection, may help narrow the list of possible explanations.

"When we saw these polygonal crack patterns, right away we thought of a secondary water event significantly later than the episode that created the rocks," said Dr. John Grotzinger," a rover-team geologist from the Massachusetts Institute of Technology

"Did these cracks form after the crater was created? We don't really know yet," Grotzinger said. If they did, one possible source of moisture could be accumulations of frost partially melting during climate changes, as Mars wobbled on its axis of rotation, in cycles of tens of thousands of years."

"According to Grotzinger, another possibility could be the melting of underground ice or release of underground water in large enough quantity to pool a little lake within the crater."

"One type of evidence Wopmay could add to the case for wet conditions after the crater formed would be a crust of water-soluble minerals."

"After examining that rock, the rover team's plans for Opportunity are to get a close look at a tall stack of layers nicknamed "Burns Cliff" from the base of the cliff.

They say, "After finding bedrock that had been extensively altered by water, scientists used the rover to look for relatively unchanged rock as a comparison for understanding the area's full range of environmental changes."

"Instead, even the freshest-looking rocks examined by Spirit in the Columbia Hills have shown signs of pervasive water alteration."

"We haven't seen a single unaltered volcanic rock, since we crossed the boundary from the plains into the hills, and I'm beginning to suspect we never will," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science payload on both rovers."

"All the rocks in the hills have been altered significantly by water. We're having a wonderful time trying to work out exactly what happened here," he added."

More clues to deciphering the environmental history of the hills could lie in layered rock outcrops further upslope, Spirit's next targets.

"Just as we worked our way deeper into the Endurance crater with Opportunity, we'll work our way higher and higher into the hills with Spirit, looking at layered rocks and constructing a plausible geologic history," Squyres said.

Jim Erickson, rover project manager at JPL said that both Spirit and Opportunity have only minor problems, and there is really no way of knowing how much longer they will keep operating.

Bedrock in Gusev crater hints at watery past of Mars:

A NASA News Releases, original at http://www.jpl.nasa.gov/news/news.cfm?release=2004-204

Bedrock in Mars' Gusev Crater Hints at Watery Past

August 18, 2004

Now that NASA's Mars Exploration Rover Spirit is finally examining bedrock in the "Columbia Hills," it is finding evidence that water thoroughly altered some rocks in Mars' Gusev Crater.

Spirit and its twin, Opportunity, completed successful three-month primary missions on Mars in April and are returning bonus results during extended missions. They remain in good health though beginning to show signs of wear.

On Opportunity, a tool for exposing the insides of rocks stopped working Sunday, but engineers are optimistic that the most likely diagnosis is a problem that can be fixed soon. "It looks like there's a pebble trapped between the cutting heads of the rock abrasion tool," said Chris Salvo, rover mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We think we can treat it by turning the heads in reverse, but we are still evaluating the best approach to remedy the situation. There are several options available to us."

Opportunity originally landed right beside exposed bedrock and promptly found evidence there for an ancient body of saltwater. On the other hand, it took Spirit half a year of driving across a Martian plain to reach bedrock in Gusev Crater. Now, Spirit's initial inspection of an outcrop called "Clovis" on a hill about 9 meters (30 feet) above the plain suggests that water may once have been active at Gusev.

"We have evidence that interaction with liquid water changed the composition of this rock," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science instruments on both rovers. "This is different from the rocks out on the plain, where we saw coatings and veins apparently due to effects of a small amount of water. Here, we have a more thorough, deeper alteration, suggesting much more water."

Squyres said, "To really understand the conditions that altered Clovis, we'd like to know what it was like before the alteration. We have the 'after.' Now we want the 'before.' If we're lucky, there may be rocks nearby that will give us that."

Dr. Doug Ming, a rover science team member from NASA's Johnson Space Center, Houston, said indications of water affecting Clovis come from analyzing the rock's surface and interior with Spirit's alpha particle X-ray spectrometer and finding relatively high levels of bromine, sulfur and chlorine inside the rock. He said, "This is also a very soft rock, not like the basaltic rocks seen back on the plains of Gusev Crater. It appears to be highly altered."

Rover team members described the golf-cart-sized robots' status and recent findings in a briefing at JPL today.

Opportunity has completed a transect through layers of rock exposed in the southern inner slope of stadium-sized "Endurance Crater." The rocks examined range from outcrops near the rim down through progressively older and older layers to the lowest accessible outcrop, called "Axel Heiberg" after a Canadian Arctic island. "We found different compositions in different layers," said Dr. Ralf Gellert, of Max-Planck-Institut fur Chemie, Mainz, Germany. Chlorine concentration increased up to threefold in middle layers. Magnesium and sulfur declined nearly in parallel with each other in older layers, suggesting those two elements may have been dissolved and removed by water.

Small, gray stone spheres nicknamed "blueberries" are plentiful in Endurance just as they were at Opportunity's smaller landing-site crater, "Eagle." Pictures from the rover's microscopic imager show a new variation on the blueberries throughout a reddish-tan slab called "Bylot" in the Axel Heiberg outcrop. "They're rougher textured, they vary more in size, and they're the color of the rock, instead of gray," said Zoe Learner, a science team collaborator from Cornell. "We've noticed that in some cases where these are eroding, you can see a regular blueberry or a berry fragment inside." One possibility is that a water-related process has added a coarser outer layer to the blueberries, she said, adding, "It's still really a mystery."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate, Washington. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University at http://athena.cornell.edu

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Donald Savage (202) 358-1727
NASA Headquarters,Washington, D.C.

Salt, evidence of past liquid water, found by Spirit rover too:

Just as Opportunity did find several evidence of past water on Mars, the Spirit rover has found concentrated salt while analyzing the composition of a trench it had dug in below the surface of its own landing site, Gusev crater, one more evidence of past water activity, mission scientists said Tuesday.

Cornell University astronomer Steve Squyres, the mission's main scientist, said the science team thinks the salt may have been deposited after water drained through the soil, dissolving materials in rocks. Squyres said it is "much more compelling evidence than we have found anywhere else" in the vast Gusev Crater region.

Standing body of water left its mark in Mars rocks:

(NASA Press release)

Donald Savage
Headquarters, Washington
(Phone: 202/358-1547)

March 23, 2004

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-5011)

RELEASE: 04-100

STANDING BODY OF WATER LEFT ITS MARK IN MARS ROCKS

NASA's Opportunity rover has demonstrated some rocks on Mars probably formed as deposits at the bottom of a body of gently flowing saltwater.

"We think Opportunity is parked on what was once the shoreline of a salty sea on Mars," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science payload on Opportunity and its twin Mars Exploration Rover, Spirit.

Clues gathered so far do not tell how long or how long ago liquid water covered the area. To gather more evidence, the rover's controllers plan to send Opportunity out across a plain toward a thicker exposure of rocks in the wall of a crater.

NASA's Associate Administrator for Space Science Dr. Ed Weiler said, "This dramatic confirmation of standing water in Mars' history builds on a progression of discoveries about that most Earthlike of alien planets. This result gives us impetus to expand our ambitious program of exploring Mars to learn whether microbes have ever lived there and, ultimately, whether we can."

"Bedding patterns in some finely layered rocks indicate the sand-sized grains of sediment that eventually bonded together were shaped into ripples by water at least five centimeters (two inches) deep, possibly much deeper, and flowing at a speed of 10 to 50 centimeters (four to 20 inches) per second," said Dr. John Grotzinger, rover science-team member from the Massachusetts Institute of Technology, Cambridge, Mass.

In telltale patterns, called crossbedding and festooning, some layers within a rock lie at angles to the main layers. Festooned layers have smile-shaped curves produced by shifting of the loose sediments' rippled shapes under a current of water.

"Ripples that formed in wind look different than ripples formed in water," Grotzinger said. "Some patterns seen in the outcrop that Opportunity has been examining might have resulted from wind, but others are reliable evidence of water flow," he said.

According to Grotzinger, the environment at the time the rocks were forming could have been a salt flat, or playa, sometimes covered by shallow water and sometimes dry. Such environments on Earth, either at the edge of oceans or in desert basins, can have currents of water that produce the type of ripples seen in the Mars rocks.

A second line of evidence, findings of chlorine and bromine in the rocks, also suggests this type of environment. Rover scientists presented some of that news three weeks ago as evidence the rocks had at least soaked in mineral-rich water, possibly underground water, after they formed. Increased assurance of the bromine findings strengthens the case rock-forming particles precipitated from surface water as salt concentrations climbed past saturation while water was evaporating.

Dr. James Garvin, lead scientist for Mars and lunar exploration at NASA Headquarters, Washington, said, "Many features on the surface of Mars that orbiting spacecraft have revealed to us in the past three decades look like signs of liquid water, but we have never before had this definitive class of evidence from the Martian rocks themselves. We planned the Mars Exploration Rover Project to look for evidence like this, and it is succeeding better than we had any right to hope. Someday we must collect these rocks and bring them back to terrestrial laboratories to read their records for clues to the biological potential of Mars."

Squyres said, "The particular type of rock Opportunity is finding, with evaporite sediments from standing water, offers excellent capability for preserving evidence of any biochemical or biological material that may have been in the water."

Engineers at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., expect Opportunity and Spirit to operate several months longer than the initial rover's three-month prime missions on Mars. To analyze hints of crossbedding, mission controllers programmed Opportunity to move its robotic arm more than 200 times in one day, taking 152 microscope pictures of layering in a rock called "Last Chance."

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. For images and information about the project on the Internet, visit:

http://www.nasa.gov

http://marsrovers.jpl.nasa.gov

http://athena.cornell.edu

-end-

NASA to announce major Mars rover finding:

NASA will announce a major scientific finding at a Space Science Update (SSU) Tuesday March 22 at 2 p.m. EST, in the headquarters Webb Auditorium, 300 E St. SW, Washington. The Mars Exploration Rover (MER) Opportunity is exploring the Martian Meridiani Planum and recently discovered evidence rocks at the landing site have been altered by water.

NASA says Meridiani Planum was once "drenched":

Science@NASA Press Release, original with pictures at
science.nasa.gov/headlines/y2004/02mar_meridianiwater.htm?list159275

Meridiani Planum: "Drenched"

Long ago, parts of Mars were soaked in liquid water, say scientists analyzing data from NASA's Mars rover Opportunity.

March 2, 2004: Some rocks at Opportunity's landing site in Meridiani Planum on Mars were once soaked in liquid water. Members of the Mars Exploration Rovers' international science team presented the evidence today to news reporters at NASA Headquarters in Washington, DC.

"Liquid water once flowed through these rocks. It changed their texture, and it changed their chemistry," said Cornell University's Steve Squyres, the principal investigator for the science instruments on Opportunity and its twin, Spirit. "We've been able to read the tell-tale clues the water left behind, giving us confidence in that conclusion."

Here are some of the clues that water formerly pervaded an outcropping of rocks where Opportunity has been working:

(1) The rover's alpha particle X-ray spectrometer found lots of sulfur in the outcrop. Related clues from that instrument and the miniature thermal emission spectrometer suggest the sulfur is in the form of sulfate salts (similar to Epsom salts). On Earth, rocks containing so much salt either formed in water or, after formation, were soaked in water a long time.

Above: These spectra show that a rock dubbed "McKittrick" near the Mars Exploration Rover Opportunity's landing site at Meridiani Planum, Mars, possesses the highest concentration of sulfur yet observed on Mars.

(2) The rover's Moessbauer spectrometer detected jarosite, a hydrated iron sulfate mineral that could result from the target rock spending time in an acidic lake or acidic hot springs environment.

(3) Pictures from Opportunity's panoramic camera and microscopic imager show many thin, flat holes--"about the size of pennies," says Squyres--in an outcrop rock selected for close-up examination. These holes, or "vugs," match the distinctive appearance of Earth-rock vugs that form where crystals of salt minerals grow inside rocks that sit in briny water then disappear by eroding or dissolving.

(4) The cameras have revealed spheres the size of BBs embedded in outcrop rocks. Researchers call them "blueberries"-- although they're not blue, they're gray. The spherules are not concentrated at particular layers within the rock, as they would be if they originated outside the rock and were deposited onto accumulating layers while the rock was forming. Instead, the spherules are scattered. This means they are probably what geologists call "concretions" that formed from accumulation of minerals coming out of solution inside a porous, water-soaked rock.

[picture] Right: A spherule in a region of the rock outcrop dubbed "El Capitan." The area in this image, taken on Sol 28 of the Opportunity mission, is 1.3 centimeters (half an inch) across.

(5) Some of the spherules in pictures from the microscope appear to have stripes that correspond to layering of the matrix rock around them. This would be consistent with the interpretation that the spherules are concretions that formed inside a wet rock.

There is still much to learn: When was the area wet? And how long did the wet conditions last? How was the water collected--e.g., in a salty lake or sea? How deep was the water? Scientists and engineers plan to keep Opportunity busy in the days ahead looking for more clues that might answer some of these questions.

Visit http://marsrovers.jpl.nasa.gov for the latest information about Spirit and Opportunity.

Credits & Contacts
Source: NASA press release
Responsible NASA official: Ron Koczor
Production Editor: Dr. Tony Phillips
Curator: Bryan Walls
Media Relations: Steve Roy

Opportunity rover finds strong evidence Meridiani Planum was wet:

NASA Press Release:

Donald Savage
Headquarters, Washington
(Phone: 202/358-1547)

March 2, 2004

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-5011)

RELEASE: 04-077

OPPORTUNITY ROVER FINDS STRONG EVIDENCE MERIDIANI PLANUM WAS WET

Scientists have concluded the part of Mars NASA's Opportunity rover is exploring was soaking wet in the past.

Evidence the rover found in a rock outcrop led scientists to the conclusion. Clues from the rocks' composition, such as the presence of sulfates, and the rocks' physical appearance, such as niches where crystals grew, helped make the case for a watery history.

"Liquid water once flowed through these rocks. It changed their texture, and it changed their chemistry," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science instruments on Opportunity and its twin, Spirit. "We've been able to read the tell-tale clues the water left behind, giving us confidence in that conclusion," he said.

Dr. James Garvin, lead scientist for Mars and lunar exploration at NASA Headquarters, Washington, said, "NASA launched the Mars Exploration Rover mission specifically to check whether at least one part of Mars ever had a persistently wet environment that could possibly have been hospitable to life. Today we have strong evidence for an exciting answer: Yes."

Opportunity has more work ahead. It will try to determine whether, besides being exposed to water after they formed, the rocks may have originally been laid down by minerals precipitating out of solution at the bottom of a salty lake or sea.

The first views Opportunity sent of its landing site in Mars' Meridiani Planum region five weeks ago delighted researchers at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., because of the good fortune to have the spacecraft arrive next to an exposed slice of bedrock on the inner slope of a small crater.

The robotic field geologist has spent most of the past three weeks surveying the whole outcrop, and then turning back for close-up inspection of selected portions. The rover found a very high concentration of sulfur in the outcrop with its alpha particle X-ray spectrometer, which identifies chemical elements in a sample.

"The chemical form of this sulfur appears to be in magnesium, iron or other sulfate salts," said Dr. Benton Clark of Lockheed Martin Space Systems, Denver. "Elements that can form chloride or even bromide salts have also been detected."

At the same location, the rover's Moessbauer spectrometer, which identifies iron-bearing minerals, detected a hydrated iron sulfate mineral called jarosite. Germany provided both these instruments. Opportunity's miniature thermal emission spectrometer has also provided evidence for sulfates.

On Earth, rocks with as much salt as this Mars rock either have formed in water or, after formation, have been highly altered by long exposures to water. Jarosite may point to the rock's wet history having been in an acidic lake or an acidic hot springs environment.

The water evidence from the rocks' physical appearance comes in at least three categories, said Dr. John Grotzinger, sedimentary geologist from the Massachusetts Institute of Technology, Cambridge: indentations called "vugs," spherules and crossbedding.

Pictures from the rover's panoramic camera and microscopic imager reveal the target rock, dubbed "El Capitan," is thoroughly pocked with indentations about a centimeter (0.4 inch) long and one-fourth or less that wide, with apparently random orientations. This distinctive texture is familiar to geologists as the sites where crystals of salt minerals form within rocks that sit in briny water. When the crystals later disappear, either by erosion or by dissolving in less-salty water, the voids left behind are called vugs, and in this case they conform to the geometry of possible former evaporite minerals.

Round particles the size of BBs are embedded in the outcrop. From shape alone, these spherules might be formed from volcanic eruptions, from lofting of molten droplets by a meteor impact, or from accumulation of minerals coming out of solution inside a porous, water-soaked rock. Opportunity's observations that the spherules are not concentrated at particular layers in the outcrop weigh against a volcanic or impact origin, but do not completely rule out those origins.

Layers in the rock that lie at an angle to the main layers, a pattern called crossbedding, can result from the action of wind or water. Preliminary views by Opportunity hint the crossbedding bears hallmarks of water action, such as the small scale of the crossbedding and possible concave patterns formed by sinuous crestlines of underwater ridges.

The images obtained to date are not adequate for a definitive answer. So scientists plan to maneuver Opportunity closer to the features for a better look. "We have tantalizing clues, and we're planning to evaluate this possibility in the near future," Grotzinger said.

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.

For information about NASA and the Mars mission on the Internet, visit:

http://www.nasa.gov

Images and additional information about the project are also available on the Internet at:

http://marsrovers.jpl.nasa.gov

and

http://athena.cornell.edu

-end-

NASA headquarters Opportunity mission Press briefing March 2:

NASA headquarters announcement, which already started a buzz:

"Significant findings from NASA's Mars Exploration Rover Opportunity, now exploring Meridiani Planum on Mars, will be announced at a press briefing at 2 p.m. EST, Tuesday, March 2, 2004, at NASA Headquarters, Washington."

"The briefing will originate from the James E. Webb Auditorium, 300 E St., S.W., Washington, and will be carried live on NASA TV with two-way question-and-answer capability for reporters covering the event from participating NASA centers.

"Dr. Ed Weiler, Associate Administrator, Office of Space Science at NASA Headquarters, will make opening remarks. The panelists include:

-Professor Steve Squyres, Mars Exploration Rover (MER) Principal Investigator, Cornell University, Ithaca, N.Y.
-Professor John Grotzinger, MER science team geologist, Massachusetts Institute of Technology, Cambridge, Mass.
-Dr. Benton C. Clark III, MER science team member and Chief Scientist of Space Exploration, Lockheed Martin Space Systems Astronautics Operations, Denver
-Dr. Joy Crisp, MER Project Scientist, NASA's Jet Propulsion Laboratory, Pasadena, Calif.
-Dr. Jim Garvin, Lead Scientist for Mars and the Moon, NASA Headquarters

"NASA Television is available on AMC-9, transponder 9C, C-Band, located at 85 degrees west longitude. The frequency is 3880.0 MHz. Polarization is vertical, and audio is monaural at 6.80 MHz. Audio of the broadcast will be available on voice circuit at the Kennedy Space Center on 321/867-1220."

"For a live webcast of the briefing and information about NASA TV on the Internet, visit: http://www.nasa.gov/ntv"

Rover microscope shows thread-like features in the soil at Opportunity site:

Rover scientists have found very fine thread-like features in the soil at Opportunity's landing site, spotted in several Microscopic Imager photos. The objects are millimeters to a few centimeters in size. Steve Squyres, lead scientists in the mission says the objects may be from Earth, transported to Mars onboard Opportunity, such as fibers tossed into the area via spacecraft landing bags.

Squyres said to reporters at a JPL briefing, "Before I would get too excited about something like this, I would recall that this vehicle [Opportunity] landed using an awful lot of fabric. That fabric took quite a beating in the process" of the landing.

"I'll be honest with you," he said, "We don't know what these things are. We have seen them just a very limited number of them and we're puzzling it out."

Hints of salty liquid water in the soil at Opportunity site:

The small spheres found on the surface were also found below the surface in a trench dug by the Opportunity rover. Hints of salty water were also found in the trench, but team scientists said much more analysis is needed to learn the true composition.

In a press conference today, NASA scientists said the soil at both locations could contain small amounts of water mixed with salt in a brine that can exist in liquid form at very low temperatures. They insisted that only tiny amounts of water would be needed to create the brine.

It was also shown that soil stuck on the rover's wheels, which may be explained if the mix of sand and dust with small amount of salty water gave the soil a cement-like nature.

A mistke explains why Spirit and Opportunity images were much too red:

Jim Bell declared in an interview in the New York Times that if the images taken by the Spirit and Opportunity rovers appear so reddish and even dark red, it is because a red filter had been activated due to an error of unknown reason on the camera of the two robots.

Jim Bell is a well-known astronomer, specialized in planetology, dealing among other things with the image processing of the Hubble space telescope, he is also the person in charge for the setup of the panoramic cameras of Spirit and Opportunity missions.

Bell speaks on a "huge mistake" and a "terrible mess."

Opportunity lands on Mars:

NASA's Opportunity rover landed on Mars late this Saturday, arriving at the planet exactly three weeks after its identical twin Spirit set down.

Spirit microscope shows many hollow grains of sand:

A first full set of scientific measurements with the instruments on the rover robotic arm, revealing that some grains of the soil are mysteriously hollow.

Among the mostly sand-sized particles, a large number of apparently hollow spheres or tubes. These grains were completely unexpected. John Grotzinger, a geologist at the Massachusetts Institute of Technology, says they closely resemble formations he has seen in soils in the southwestern deserts of the US. He said: "There are little tubes that build up by capillary action, as salty water evaporates from the nearly-dry soil."

Conditions for water on Spirit landing site:

The pressure and temperature conditions at Spirit's landing site, Gusev crater, are close to the triple point of water, said John Grotzinger of the MIT. This means any water present could change phase between solid, liquid and gas in response to small changes in conditions, and Spirit is an area whose temperatures vary widely during the daily and seasonal cycles.

Pure liquid water cannot be stable at the site under present conditions, says Grotzinger. But he added that a brine might be as the dissolved salts would change the freezing and boiling temperatures.

Carbonates and hydrated materials, possible clay, found at Spirit landing site:

The first images taken by the craft's mini-Thermal Emission Spectrometer, an infrared instrument capable of indicating the composition of nearby soils and rocks - show evidence of carbonates and hydrated minerals. Both of these are usually, though not exclusively, produced in long-standing bodies of water.

The spectra taken by Spirit have been compared with those from a spacecraft orbiting Mars and from reference spectra taken in laboratories on Earth. "We're ecstatic about how well these match," says Phil Christensen, of Arizona State University, who designed of the instrument.

Among the TES signatures seen so far are silicates and carbonates, and signs of some kind of hydrated minerals, "possibly clay minerals", says Christensen.

The latter would be "really exciting", says Michael Carr, an expert on the geology of Mars at the US Geological Survey. "If we find a clay rock, that would be an absolute clincher" that this was indeed a place covered by a body of liquid water over a long period of time.

Spirit takes ground level temperature measurements:

The Spirit rover has taken ground level temperature measurement on Mars for the first time, NASA said Friday. Scientist Phil Christensen, the scientist tasked with the temperature readings, has stated:

"On the ground, the warmest temperature is around five degrees Celsius and the coldest is -15 degrees Celsius."

Let me add that in terms of seasons, it is only the beginning of spring on Mars at this time, not mid-summer.

Spirit image shows what looks like muddy soil under the surface dust:

PASADENA, California, January 6, 2004. -- The rock-strewn floor of Mars's Gusev Crater blossomed into sharp view Tuesday with the release of the most detailed image ever obtained from the planet, taken by the rover Spirit's panoramic camera in a tantalizing foretaste of things to come.

One of the main composite images from the Spirit lander revealed a mysterious substance right at the rover's feet, which NASA scientists described as "strangely cohesive clay-like material" with unexpected textures. This soil material was exposed when the Spirit lander dragged its empty air bags across the Martian surface to retract them.

Lead rover scientist Steve Squyres of Cornell University, who is the manager of the mission at the Jet Propulsion Laboratory (JPL), has said: "The way the surface has responded is bizarre, I don't understand it. I don't know anybody on my team who understands it... It looks like mud, but it can't be mud."

The material appears to have been mashed and clumped, like moist and viscous mud, and was broken away in pieces at some spots. Squyres said one of the Viking landers of the 1970s might have seen something like it elsewhere on Mars. The small wheeled robot from the pathfinder also raised similar comments when people noticed it left what had the appearance of moisten tracks.

Spirit lands safely and sends first raw images:

At 8.35 pm Pacific Standard Time Saturday January 3, 2004, NASA's robotic rover Spirit bounced down on to Mars, intact and ready to work. NASA scientists then heard the signal from the Spirit rover indicating that it had survived the landing on Mars. Soon black and white images showing part of the robot resting in front of a large boulder in the middle of a rock-strewn plain, were projected onto screens in the mission control room at NASA's Jet Propulsion Laboratory in Pasadena.

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