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  NASA's Opportunity roves Mars (2010-Present)

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Author Topic:   NASA's Opportunity roves Mars (2010-Present)
Robert Pearlman
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Mars Exploration Rover Mission Status Report
Rover Gives NASA an "Opportunity" to View Interior of Mars

NASA's Mars exploration rover Opportunity is allowing scientists to get a glimpse deep inside Mars.

Perched on a rippled Martian plain, a dark rock not much bigger than a basketball was the target of interest for Opportunity during the past two months. Dubbed "Marquette Island," the rock is providing a better understanding of the mineral and chemical makeup of the Martian interior.

"Marquette Island is different in composition and character from any known rock on Mars or meteorite from Mars," said Steve Squyres of Cornell University in Ithaca, N.Y. Squyres is principal investigator for Opportunity and its twin, Spirit. "It is one of the coolest things Opportunity has found in a very long time."

During six years of roving, Opportunity has found only one other rock of comparable size that scientists conclude was ejected from a distant crater. The rover studied the first such rock during its initial three-month mission. Called "Bounce Rock," that rock closely matched the composition of a meteorite from Mars found on Earth.

Marquette Island is a coarse-grained rock with a basalt composition. The coarseness indicates it cooled slowly from molten rock, allowing crystals time to grow. This composition suggests to geologists that it originated deep in the crust, not at the surface where it would cool quicker and have finer-grained texture.

"It is from deep in the crust and someplace far away on Mars, though exactly how deep and how far we can't yet estimate," said Squyres.

The composition of Marquette Island, as well as its texture, distinguishes it from other Martian basalt rocks that rovers and landers have examined. Scientists first thought the rock could be another in a series of meteorites that Opportunity has found. However, a much lower nickel content in Marquette Island indicates a Martian origin. The rock's interior contains more magnesium than in typical Martian basalt rocks Spirit has studied. Researchers are determining whether it might represent the precursor rock altered long ago by sulfuric acid to become the sulfate-rich sandstone bedrock that blankets the region of Mars that Opportunity is exploring.

"It's like having a fragment from another landing site," said Ralf Gellert of the University of Guelph, in Ontario, Canada. Gellert is lead scientist for the alpha particle X-ray spectrometer on Opportunity's robotic arm. "With analysis at an early stage, we're still working on some riddles about this rock."

The rover team used Opportunity's rock abrasion tool to grind away some of Marquette Island's weathered surface and expose the interior. This was the 38th rock target Opportunity has ground into, and one of the hardest. The tool was designed to grind into one Martian rock, and this rock may not be its last.

"We took a conservative approach on our target depth for this grind to ensure we will have enough of the bit left to grind the next hard rock that Opportunity comes across," said Joanna Cohen of Honeybee Robotics Spacecraft Mechanisms Corp., in New York, which built and operates the tool.


Credit: NASA TV

Opportunity currently is about 30 percent of the way on a 19-kilometer (12-mile) begun in mid-2008 from a crater it studied for two years. It is en route toward a much larger crater, Endeavour. The rover traveled 5.3 kilometers (3.3 miles) in 2009, farther than in any other year on Mars. Opportunity drove away from Marquette Island on Jan. 12.

"We're on the road again," said Mike Seibert, a rover mission manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The year ahead will include lots more driving, if all goes well. We'll keep pushing for Endeavour crater but watch for interesting targets along the way where we can stop and smell the roses."

Since landing on Mars in 2004, Opportunity has made numerous scientific discoveries, including the first mineralogical evidence that Mars had liquid water. After working 24 times longer than originally planned, Opportunity has driven more than 19 kilometers (11.8 miles) and returned more than 133,000 images. JPL, a division of the California Institute of Technology in Pasadena, manages the rovers for NASA's Science Mission Directorate in Washington.

For earlier Mars Exploration Rovers updates, see: Opportunity and Spirit rove Mars

Robert Pearlman
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NASA Jet Propulsion Laboratory release
NASA Mars Rover Getting Smarter as it Gets Older

NASA's Mars Exploration Rover Opportunity, now in its seventh year on Mars, has a new capability to make its own choices about whether to make additional observations of rocks that it spots on arrival at a new location.

Software uploaded this winter is the latest example of NASA taking advantage of the twin Mars rovers' unanticipated longevity for real Martian test drives of advances made in robotic autonomy for future missions.

Now, Opportunity's computer can examine images that the rover takes with its wide-angle navigation camera after a drive, and recognize rocks that meet specified criteria, such as rounded shape or light color. It can then center its narrower-angle panoramic camera on the chosen target and take multiple images through color filters.

"It's a way to get some bonus science," said Tara Estlin of NASA's Jet Propulsion Laboratory, Pasadena, Calif. She is a rover driver, a senior member of JPL's Artificial Intelligence Group and leader of development for this new software system.

The new system is called Autonomous Exploration for Gathering Increased Science, or AEGIS. Without it, follow-up observations depend on first transmitting the post-drive navigation camera images to Earth for ground operators to check for targets of interest to examine on a later day. Because of time and data-volume constraints, the rover team may opt to drive the rover again before potential targets are identified or before examining targets that aren't highest priority.

The first images taken by a Mars rover choosing its own target show a rock about the size of a football, tan in color and layered in texture. It appears to be one of the rocks tossed outward onto the surface when an impact dug a nearby crater. Opportunity pointed its panoramic camera at this unnamed rock after analyzing a wider-angle photo taken by the rover's navigation camera at the end of a drive on March 4. Opportunity decided that this particular rock, out of more than 50 in the navigation camera photo, best met the criteria that researchers had set for a target of interest: large and dark.

"It found exactly the target we would want it to find," Estlin said. "This checkout went just as we had planned, thanks to many people's work, but it's still amazing to see Opportunity performing a new autonomous activity after more than six years on Mars."

Opportunity can use the new software at stopping points along a single day's drive or at the end of the day's drive. This enables it to identify and examine targets of interest that might otherwise be missed.

"We spent years developing this capability on research rovers in the Mars Yard here at JPL," said Estlin. "Six years ago, we never expected that we would get a chance to use it on Opportunity."

The developers anticipate that the software will be useful for narrower field-of-view instruments on future rovers.

Other upgrades to software on Opportunity and its twin, Spirit, since the rovers' first year on Mars have improved other capabilities. These include choosing a route around obstacles and calculating how far to reach out a rover's arm to touch a rock. In 2007, both rovers gained the know-how to examine sets of sky images to determine which ones show clouds or dust devils, and then to transmit only the selected images. The newest software upload takes that a step further, enabling Opportunity to make decisions about acquiring new observations.

The AEGIS software lets scientists change the criteria it used for choosing potential targets. In some environments, rocks that are dark and angular could be higher-priority targets than rocks that are light and rounded, for example.

This new software system has been developed with assistance from NASA's Mars Exploration Rover Project and with funding from the New Millennium Program, the Mars Technology Program, the JPL Interplanetary Network Development Program, and the Intelligent Systems Program. The New Millennium Program tests advanced technology in space flight. JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington.

Robert Pearlman
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NASA Jet Propulsion Laboratory release
Opportunity Surpasses 20 Kilometers of Total Driving

NASA's Mars Exploration Rover Opportunity today surpassed 20 kilometers (12.43 miles) of total driving since it landed on Mars 74 months ago.

The drive taking the rover past that total covered 67 meters (220 feet) southward as part of the rover's long-term trek toward Endeavour Crater to the southeast. It was on the 2,191st Martian day, or sol, of the mission and brought Opportunity's total odometry to 20.0433 kilometers. To reach Endeavour, the healthy but aging rover will need to drive about 12 kilometers (7.5 miles) farther.

Opportunity's mission on Mars was originally planned to last for three months with a driving-distance goal of 600 meters (less than half a mile).

Since landing, Opportunity has examined a series of craters on the plain of Meridiani, and the journey so far has covered a portion of the plain with negligible tilt. Now, the rover is approaching a portion tilting slightly southward. Recent images toward the southwest show the rim of a crater named Bopolu, about 65 kilometers (40 miles) away.

Robert Pearlman
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NASA Jet Propulsion Laboratory release
Mars Rover Examines Odd Material at Small, Young Crater

Weird coatings on rocks beside a young Martian crater remain puzzling after a preliminary look at data from examination of the site by NASA's Opportunity rover.

The rover spent six weeks investigating the crater called "Concepción" before resuming its long journey this month. The crater is about 10 meters (33 feet) in diameter. Dark rays extending from it, as seen from orbit, flagged it in advance as a target of interest because the rays suggest the crater is young.


An image from orbit shows Opportunity beside Concepción. CREDIT: NASA/JPL/UA

The rocks ejected outward from the impact that dug Concepción are chunks of the same type of bedrock Opportunity has seen at hundreds of locations since landing in January 2004: soft, sulfate-rich sandstone holding harder peppercorn-size dark spheres like berries in a muffin. The little spheres, rich in iron, gained the nickname "blueberries."

"It was clear from the images that Opportunity took on the approach to Concepción that there was strange stuff on lots of the rocks near the crater," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Opportunity and its twin rover, Spirit. "There's dark, grayish material coating faces of the rocks and filling fractures in them. At least part of it is composed of blueberries jammed together as close as you could pack them. We've never seen anything like this before."

Opportunity used tools on its robotic arm to examine this unusual material on a rock called "Chocolate Hills." In some places, the layer of closely packed spheres lies between thinner, smoother layers. "It looks like a blueberry sandwich," said Matt Golombek, a rover science-team member at NASA's Jet Propulsion Laboratory, Pasadena, Calif.


Coating on rock beside a young martian crater. CREDIT: NASA/JPL-Caltech/UA

Initial analysis of the coating's composition does not show any obvious component from whatever space rock hit Mars to dig the crater, but that is not a surprise, Golombek said. "The impact is so fast, most of the impactor vaporizes," he said. "Thin films of melt get thrown out, but typically the composition of the melt is the stuff that the impactor hit, rather than the impactor material."

The composition Opportunity found for the dark coating material fits at least two hypotheses being evaluated, and possibly others. One is that the material resulted from partial melting of blueberry-containing sandstone from the energy of the impact. Another is that it formed from filling of fractures in this type of rock before the impact occurred.

"It's possible that when you melt this rock, the sandstone melts before the blueberries do, leaving intact blueberries as part of a melt layer," Squyres said. "As an alternative, we know that this type of rock has fractures and that the sandstone can dissolve. Long ago, water flowing through fractures could have dissolved the sandstone and liberated blueberries that fell down into the fracture and packed together. In this hypothesis, the impact that excavated the crater did not play a role in forming this material, but split rocks along fractures so the material is exposed on the exterior like a coating."

Golombek said, "One consideration that jumps out is that we've been driving around this part of Mars for six years and never seen this stuff before, then we get to this young crater and it's coating rocks all around the crater. Sure looks like there's a connection, but it could just be a coincidence."

The observation that the rocks thrown from the crater have not yet eroded away much is evidence that the crater is young, confirming the suggestion from the dark rays. Squyres said, "We're not ready to attach a number to it, but this is really young. It is the youngest crater we've ever seen with Opportunity and probably the youngest either rover has seen."

One question Opportunity's visit did answer was about the dark rays: "We wondered before getting to Concepción why the rays are dark," Golombek said. "We found out that the rays are areas with blocks of light-toned sandstone ejected from the crater. They look dark from orbit because of the shadows that the blocks are casting when the orbital images are taken in mid-afternoon."

Since departing Concepción on March 9, Opportunity has driven 614 meters (2,014 feet) farther along the route to its long-term destination at Endeavour Crater, about 19 kilometers (12 miles) in diameter and still at a drive distance of more than 12 kilometers (7 miles).

Squyres said, "We're on the road again. We have a healthy rover and we have enough power for substantial drives. We want to get to Endeavour with a healthy rover. It takes a compelling target for us to stop and study. And Concepción was a compelling target." JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington.

Robert Pearlman
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NASA Jet Propulsion Laboratory release
NASA Mars Rover Arrives at New Site on Martian Surface

After a journey of almost three years, NASA's Mars Exploration Rover Opportunity has reached the Red Planet's Endeavour crater to study rocks never seen before.

On Aug. 9, the golf cart-sized rover relayed its arrival at a location named Spirit Point on the crater's rim. Opportunity drove approx. 13 miles (21 kilometers) since climbing out of the Victoria crater.


Credit: NASA/JPL-Caltech/Cornell/ASU

Above: A portion of the west rim of Endeavour crater sweeps southward in this color view from NASA's Mars Exploration Rover Opportunity. This crater -- with a diameter of about 14 miles (22 kilometers) — is more than 25 times wider than any that Opportunity has previously approached during the rover's 90 months on Mars.

"NASA is continuing to write remarkable chapters in our nation's story of exploration with discoveries on Mars and trips to an array of challenging new destinations," NASA Administrator Charles Bolden said. "Opportunity's findings and data from the upcoming Mars Science Laboratory will play a key role in making possible future human missions to Mars and other places where humans have not yet been."

Endeavour crater, which is more than 25 times wider than Victoria crater, is 14 miles (22 kilometers) in diameter. At Endeavour, scientists expect to see much older rocks and terrains than those examined by Opportunity during its first seven years on Mars. Endeavour became a tantalizing destination after NASA's Mars Reconnaissance Orbiter detected clay minerals that may have formed in an early warmer and wetter period.

"We're soon going to get the opportunity to sample a rock type the rovers haven't seen yet," said Matthew Golombek, Mars Exploration Rover science team member, at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "Clay minerals form in wet conditions so we may learn about a potentially habitable environment that appears to have been very different from those responsible for the rocks comprising the plains."

The name Spirit Point informally commemorates Opportunity's twin rover, which stopped communicating in March 2010. Spirit's mission officially concluded in May.

"Our arrival at this destination is a reminder that these rovers have continued far beyond the original three-month mission," said John Callas, Mars Exploration Rover project manager at JPL.

See here for discussion of Opportunity's continued exploration of the planet Mars.

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NASA release
NASA's Mars Rover Opportunity Begins Study of Martian Crater

The initial work of NASA's Mars rover Opportunity at its new location on Mars shows surface compositional differences from anything the robot has studied in its first 7.5 years of exploration.

Opportunity arrived three weeks ago at the rim of a 14-mile-wide (22-kilometer-wide) crater named Endeavour. The first rock it examined is flat-topped and about the size of a footstool. It was apparently excavated by an impact that dug a crater the size of a tennis court into the crater's rim. The rock was informally named "Tisdale 2."


Credit: NASA/JPL-Caltech

Above: NASA's Mars Exploration Rover Opportunity used its front hazard-avoidance camera to take this picture showing the rover's arm extended toward a light-toned rock, "Tisdale 2," during the 2,695th Martian day, or sol, of the rover's work on Mars (Aug. 23, 2011). Tisdale 2 is about 12 inches (30 centimeters) tall.

"This is different from any rock ever seen on Mars," said Steve Squyres, principal investigator for Opportunity at Cornell University in Ithaca, N.Y. "It has a composition similar to some volcanic rocks, but there's much more zinc and bromine than we've typically seen. We are getting confirmation that reaching Endeavour really has given us the equivalent of a second landing site for Opportunity."

The diversity of fragments in Tisdale 2 could be a prelude to other minerals Opportunity might find at Endeavour. In the past two weeks, researchers have used an instrument on the rover's robotic arm to identify elements at several spots on Tisdale 2. Scientists have also examined the rock using the rover's microscopic imager and multiple filters of its panoramic camera.

Observations by Mars orbiters suggest that rock exposures on Endeavour's rim date from early in Martian history and include clay minerals that form in less-acidic wet conditions, possibly more favorable for life. Discontinuous ridges are all that remains of the ancient crater's rim. The ridge at the section of the rim where Opportunity arrived is named "Cape York." A gap between Cape York and the next rim fragment to the south is called "Botany Bay."

"On the final traverses to Cape York, we saw ragged outcrops at Botany Bay unlike anything Opportunity has seen so far, and a bench around the edge of Cape York looks like sedimentary rock that's been cut and filled with veins of material possibly delivered by water," said Ray Arvidson, the rover's deputy principal investigator at Washington University in St. Louis. "We made an explicit decision to examine ancient rocks of Cape York first."

The science team selected Endeavour as Opportunity's long-term destination after the rover climbed out of Victoria crater three years ago this week. The mission spent two years studying Victoria, which is about one twenty-fifth as wide as Endeavour. Layers of bedrock exposed at Victoria and other locations Opportunity has visited share a sulfate-rich composition linked to an ancient era when acidic water was present. Opportunity drove about 13 miles (21 kilometers) from Victoria to reach Endeavour. It has driven 20.8 miles (33.5 kilometers) since landing on Mars.

"We have a very senior rover in good health for having already worked 30 times longer than planned," said John Callas, project manager for Opportunity at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "However, at any time, we could lose a critical component on an essential rover system, and the mission would be over. Or, we might still be using this rover's capabilities beneficially for years. There are miles of exciting geology to explore at Endeavour crater."

Opportunity and its rover twin, Spirit, completed three-month prime missions in April 2004 and continued working for years of extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit ended communications in March 2010.

"This is like having a brand new landing site for our veteran rover," said Dave Lavery, program executive for NASA's Mars Exploration Rovers at NASA Headquarters in Washington. "It is a remarkable bonus that comes from being able to rove on Mars with well-built hardware that lasts."

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NASA release
NASA Mars Rover Finds Mineral Vein Deposited by Water

NASA's Mars Exploration Rover Opportunity has found bright veins of a mineral, apparently gypsum, deposited by water. Analysis of the vein will help improve scientists' understanding of the history of wet environments on Mars.

"This tells a slam-dunk story that water flowed through underground fractures in the rock," said Steve Squyres of Cornell University, principal investigator for Opportunity. "This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can't be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It's not uncommon on Earth, but on Mars, it's the kind of thing that makes geologists jump out of their chairs."

The latest findings by Opportunity were presented Wednesday at the American Geophysical Union's conference in San Francisco.

The vein examined most closely by Opportunity is about the width of a human thumb (0.4 to 0.8 inch), 16 to 20 inches long, and protrudes slightly higher than the bedrock on either side of it. Observations by the durable rover reveal this vein and others like it within an apron surrounding a segment of the rim of Endeavour Crater. None like it were seen in the 20 miles (33 kilometers) of crater-pocked plains that Opportunity explored for 90 months before it reached Endeavour, nor in the higher ground of the rim.

Last month, researchers used the Microscopic Imager and Alpha Particle X-ray Spectrometer on the rover's arm and multiple filters of the Panoramic Camera on the rover's mast to examine the vein, which is informally named "Homestake." The spectrometer identified plentiful calcium and sulfur, in a ratio pointing to relatively pure calcium sulfate.

Calcium sulfate can exist in many forms, varying by how much water is bound into the minerals' crystalline structure. The multi-filter data from the camera suggest gypsum, a hydrated calcium sulfate. On Earth, gypsum is used for making drywall and plaster of Paris.

Observations from orbit have detected gypsum on Mars previously. A dune field of windblown gypsum on far northern Mars resembles the glistening gypsum dunes in White Sands National Monument in New Mexico.

"It is a mystery where the gypsum sand on northern Mars comes from," said Opportunity science-team member Benton Clark of the Space Science Institute in Boulder, Colo. "At Homestake, we see the mineral right where it formed. It will be important to see if there are deposits like this in other areas of Mars."

The Homestake deposit, whether gypsum or another form of calcium sulfate, likely formed from water dissolving calcium out of volcanic rocks. The minerals combined with sulfur either leached from the rocks or introduced as volcanic gas, and was deposited as calcium sulfate into an underground fracture that later became exposed at the surface.

Throughout Opportunity's long traverse across Mars' Meridiani plain, the rover has driven over bedrock composed of magnesium, iron and calcium sulfate minerals that also indicate a wet environment billions of years ago. The highly concentrated calcium sulfate at Homestake could have been produced in conditions more neutral than the harshly acidic conditions indicated by the other sulfate deposits observed by Opportunity.

"It could have formed in a different type of water environment, one more hospitable for a larger variety of living organisms," Clark said.

Homestake and similar-looking veins appear in a zone where the sulfate-rich sedimentary bedrock of the plains meets older, volcanic bedrock exposed at the rim of Endeavour. That location may offer a clue about their origin.

"We want to understand why these veins are in the apron but not out on the plains," said the mission's deputy principal investigator, Ray Arvidson, of Washington University in St. Louis. "The answer may be that rising groundwater coming from the ancient crust moved through material adjacent to Cape York and deposited gypsum, because this material would be relatively insoluble compared with either magnesium or iron sulfates."

Opportunity and its rover twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of extended missions and made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit stopped communicating in 2010. Opportunity continues exploring, currently heading to a sun-facing slope on the northern end of the Endeavour rim fragment called "Cape York" to keep its solar panels at a favorable angle during the mission's fifth Martian winter.

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Arizona State University release
Mars rover to spend winter at 'Greeley Haven,' named for late ASU geologist Ronald Greeley

NASA's Mars Exploration Rover Opportunity will spend the next few months during the coldest part of Martian winter at Greeley Haven, an outcrop of rock on Mars recently named informally to honor Ronald Greeley, Arizona State University Regents' professor of planetary geology, who died October 27, 2011.


Credit: NASA/JPL-Caltech/Cornell/Arizona State University

Above: Photographed in false color to emphasize differences in composition, the rocks of Greeley Haven stand out in blue-gray tints. In the background at right lies a tan patch of sand. While Opportunity is parked here for several months, scientists plan to investigate interesting targets on the outcrop using the instruments on the rover's arm.

Long passionate about exploring the solar system and Mars in particular, Greeley was involved with many missions to the Red Planet, including Mariners 6, 7, and 9, Viking, Mars Pathfinder, Mars Global Surveyor, and the two Mars Exploration Rovers. He was also a co-investigator for the camera system on the European Space Agency's Mars Express orbiter mission. Among his major research interests were wind erosion, dunes, and dust devil activity, all of which can be found in abundance on Mars.

"We miss Ron's wisdom and guidance on the rover team," says Jim Bell, lead scientist for the Panoramic Camera (Pancam) on the rover. Bell, who came to ASU in early 2011, is a professor in the School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences.

"We hope that eventually the International Astronomical Union will name a crater or some other feature on Mars or some other solar system body for Ron," Bell says. "But that process typically takes years."

In the meantime, he adds, "This small commemoration helps preserve the memory of Ron's contributions to planetary science within the community and beyond."

Dusty rover

Opportunity, which landed on Mars eight years ago January 24, has driven a total of 21 miles (34 kilometers). In August, Opportunity arrived at the rim of Endeavour Crater, an ancient impact scar 14 miles (22 km) wide. Eroded sections of the crater's rim poke above the flat-lying sediments that Opportunity has driven on since it landed.

Located just south of Mars' equator, the rover has worked through four Martian southern hemisphere winters. Being closer to the equator than its twin rover, Spirit, Opportunity has not needed to stay on a Sun-facing slope during previous winters. Now, however, its solar panels carry a thicker coating of dust than before.

The dust makes it necessary for Opportunity to spend the winter at a Sun-facing site where the rover can tilt its power panels northward about 15° for maximum solar exposure. Greeley Haven provides just the right tilt.

In addition, while Opportunity remains on the slope over winter, it still has some mobility and can investigate Greeley Haven's multiple targets of scientific interest using with the tools on the rover's robotic arm.

Windows into the past

Although they are much eroded, the uplifted segments of Endeavour's rim contain rocks that date back much farther into Martian history than any Opportunity has yet examined.

"Endeavour Crater has given us a whole new mission," remarked Steven Squyres, chief scientist for the Mars Exploration Rover project, describing the prospects for science after Opportunity reached the rim.

Plans for research over the winter at Greeley Haven include a radio-science investigation of the interior of Mars, inspections of mineral compositions and textures on the outcrop, and recording a full-circle, color panorama.

"Greeley Haven provides the proper tilt, as well as a rich variety of potential targets for imaging and compositional and mineralogic studies," says Bell. "We've already found hints of gypsum in the bedrock in this formation, and we know from orbital data that there are clays nearby, too."

Greeley Haven, he says, "looks to be a safe and special place that could yield exciting new discoveries about the watery past of Mars."

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Arizona State University release
NASA Opportunity Rover Finishes Walkabout On Mars Crater Rim

The latest work assignment for NASA's long-lived Mars rover Opportunity is a further examination of an area where the robot just completed a walkabout.

"If you are a geologist studying a site like this, one of the first things you do is walk the outcrop, and that's what we've done with Opportunity," said Steve Squyres, the mission's principal investigator at Cornell University in Ithaca, N.Y.

Coming up on its ninth anniversary, Opportunity still is a capable robotic explorer. It has been investigating a crater-rim site where observations from orbiting Mars spacecraft detected traces of clay minerals, which form under wet, non-acidic conditions that can be favorable for life. The rover's current activities were presented at the Fall Meeting of the American Geophysical Union in San Francisco.

The rover team chose this site as a driving destination years earlier. The site is named Matijevic Hill in honor of the late Jacob Matijevic, who led the engineering team for the twin Mars exploration rovers Spirit and Opportunity for several years.

Opportunity drove about 1,160 feet (354 meters) in a counterclockwise circuit around Matijevic Hill in October and November, bringing the total miles driven on the mission to 22 miles (35.4 kilometers). Researchers used the rover to survey the extent of Matijevic Hill outcrops and identify the best places to investigate further.

"We've got a list of questions posed by the observations so far," Squyres said. "We did this walkabout to determine the most efficient use of time to answer the questions. Now we have a good idea what we're dealing with, and we're ready to start the detailed work."

The hill is on the western rim of Endeavour Crater, a bowl 14 miles (22 kilometers) in diameter. An impact from a celestial object dug this crater more than 3 billion years ago, pushing rocks onto the rim from a greater depth than Opportunity reached during its first several years on Mars. Since the impact, those rocks may have been altered by environmental conditions. Sorting out the relative ages of local outcrops is a key to understanding the area's environmental history.

"Almost nine years into a mission planned to last for three months, Opportunity is fit and ready for driving, robotic-arm operations and communication with Earth," said the mission's deputy project scientist, Diana Blaney, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Two outcrops of high interest on Matijevic Hill are "Whitewater Lake" and "Kirkwood." Whitewater Lake is light-toned material that science team members believe may contain clay. Kirkwood contains small spheres with composition, structure and distribution that differ from other iron-rich spherules, nicknamed blueberries, that Opportunity found at its landing site and throughout the Meridiani Planum area it has explored. Squyres calls the Kirkwood spheres "newberries."

"We don't know yet whether Whitewood Lake and Kirkland are from before or after the crater formed," he said. "One of the most important things to work out is the order and position of the rock layers to tell us the relative ages. We also need more work on the composition of Whitewater and debris shed by Whitewater to understand the clay signature seen from orbit, and on the composition of the newberries to understand how they formed."

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Mars rover Opportunity breaks US distance record set by Apollo 17 moon buggy

A robotic rover on Mars has rolled past a record set by the last men to walk on the moon more than 40 years ago.

The team operating Opportunity, one of NASA's twin Mars Exploration Rovers, received confirmation from the Red Planet on Thursday (May 16) that the golf-cart size rover had driven past the 22.21 miles (35.74 kilometers) logged by the Apollo 17 astronauts riding their lunar roving vehicle (LRV) in December 1972.

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Mars Rover Opportunity Trekking Toward More Layers

Approaching its 10th anniversary of leaving Earth, NASA's Mars Exploration Rover Opportunity is on the move again, trekking to a new study area still many weeks away.

The destination, called "Solander Point," offers Opportunity access to a much taller stack of geological layering than the area where the rover has worked for the past 20 months, called "Cape York." Both areas are raised segments of the western rim of Endeavour Crater, which is about 14 miles (22 kilometers) in diameter.

"Getting to Solander Point will be like walking up to a road cut where you see a cross section of the rock layers," said Ray Arvidson of Washington University, St. Louis, deputy principal investigator for the mission.

Solander Point also offers plenty of ground that is tilted toward the north, which is favorable for the solar-powered rover to stay active and mobile through the coming Martian southern-hemisphere winter.

"We're heading to a 15-degree north-facing slope with a goal of getting there well before winter," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for the Mars Exploration Rover Project. The minimum-sunshine days of this sixth Martian winter for Opportunity will come in February 2014.

NASA's Mars Exploration Rover Project launched twin rovers in 2003: Spirit on June 10 and Opportunity on July 7. Both rovers landed in January 2004, completed three-month prime missions and began years of bonus, extended missions. Both found evidence of wet environments on ancient Mars. Spirit ceased operations during its fourth Martian winter, in 2010. Opportunity shows symptoms of aging, such as loss of motion in some joints, but continues to accomplish groundbreaking exploration and science.

Shortly before leaving Cape York last month, Opportunity used the rock abrasion tool, the alpha particle X-ray spectrometer and the microscopic imager on its robotic arm to examine a rock called "Esperance" and found a combination of elements pointing to clay-mineral composition.

"The Esperance results are some of the most important findings of our entire mission," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the mission. "The composition tells us about the environmental conditions that altered the minerals. A lot of water moved through this rock."

Cape York exposes just a few yards, or meters, of vertical cross-section through geological layering. Solander Point exposes roughly 10 times as much. Researchers hope to find evidence about different stages in the history of ancient Martian environments. The rim of Endeavour Crater displays older rocks than what Opportunity examined at Eagle, Endurance, Victoria and Santa Maria craters during the first eight years of the rover's work on Mars.

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NASA rover Opportunity's selfie shows clean machine

In its sixth winter, NASA's Mars Exploration Rover Opportunity now has cleaner solar arrays than in any Martian winter since its first on the Red Planet, in 2005. Cleaning effects of wind events in March boosted the amount of electricity available for the rover's work.

A new self-portrait from Opportunity's panoramic camera (Pancam), showing the cleaned arrays:

Above: A self-portrait of NASA's Mars Exploration Rover Opportunity taken in late March 2014 (bottom) shows that much of the dust on the rover's solar arrays has been removed since a similar portrait from January 2014 (above). Both were taken by Opportunity's panoramic camera (Pancam). (Credit: NASA/JPL-Caltech/Cornell/ASU)

The mission is using the rover's added energy to inspect "Murray Ridge," on the western rim of Endeavour Crater, to learn about wet environments on ancient Mars.

During Opportunity's first decade on Mars and the 2004-2010 career of its twin, Spirit, NASA's Mars Exploration Rover Project yielded a range of findings proving wet environmental conditions on ancient Mars — some very acidic, others milder and more conducive to supporting life.

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Mars rover Opportunity rolls past off-Earth driving record set by Soviet Lunokhod

A NASA rover has set the new distance record for off-world driving, covering 25 miles during its 10 years on Mars.

Opportunity, one of a pair of U.S. Mars Exploration Rovers (MER) that landed on the Red Planet in 2004, rolled past the prior distance record set in 1973 by the former Soviet Union's Lunokhod 2 rover on the Earth's moon.

"Opportunity has driven farther than any other vehicle on another world," project manager John Callas with NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a statement released on Monday (July 28). "This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance."

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NASA release
Hilltop Pan Marks Mars Rover's 11th Anniversary

A panorama from one of the highest elevations that NASA's Mars Exploration Rover Opportunity has reached in its 11 years on Mars includes the U.S. flag at the summit.

The view is from the top of "Cape Tribulation," a raised section of the rim of Endeavour Crater. The panorama spans the interior of the 14-mile-wide (22-kilometer-wide) crater and extends to the rim of another crater on the horizon.

Opportunity has driven 25.9 miles (41.7 kilometers) since it landed in the Meridiani Planum region of Mars on Jan. 25, 2004 (Universal Time, which was Jan. 24, PST). That is farther than any other off-Earth surface vehicle has driven. The rover's work on Mars was initially planned for three months. During that prime mission and for more than a decade of bonus performance in extended missions, Opportunity has returned compelling evidence about wet environments on ancient Mars.

Opportunity has been exploring Endeavour's western rim since 2011. From a low segment of the rim that it crossed in mid-2013, called "Botany Bay," it climbed about 440 feet (about 135 meters) in elevation to reach the top of Cape Tribulation. That's about 80 percent the height of the Washington Monument.

The U.S. flag is printed on the aluminum cable guard of the rover's rock abrasion tool, which is used for grinding away weathered rock surfaces to expose fresh interior material for examination. The flag is intended as a memorial to victims of the Sept. 11, 2001, attacks on the World Trade Center in New York. The aluminum was recovered from the site of the Twin Towers in the weeks following the attacks. Workers at Honeybee Robotics in lower Manhattan, less than a mile from World Trade Center, were making the rock abrasion tool for Opportunity and NASA's twin Mars Exploration Rover, Spirit, in September 2001.

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NASA release
NASA's Opportunity Mars Rover Finishes Marathon, Clocks in at Just Over 11 Years

There was no tape draped across a finish line, but NASA is celebrating a win. The agency's Mars Exploration Rover Opportunity completed its first Red Planet marathon Tuesday — 26.219 miles (42.195 kilometers) – with a finish time of roughly 11 years and two months.

"This is the first time any human enterprise has exceeded the distance of a marathon on the surface of another world," said John Callas, Opportunity project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "A first time happens only once."

The rover team at JPL plans a marathon-length relay run at the laboratory next week to celebrate.

The long-lived rover surpassed the marathon mark during a drive of 153 feet (46.5 meters). Last year, Opportunity became the long-distance champion of all off-Earth vehicles when it topped the previous record set by the former Soviet Union's Lunokhod 2 moon rover.

"This mission isn't about setting distance records, of course; it's about making scientific discoveries on Mars and inspiring future explorers to achieve even more," said Steve Squyres, Opportunity principal investigator at Cornell University in Ithaca, New York. "Still, running a marathon on Mars feels pretty cool."

Opportunity's original three-month prime mission in 2004 yielded evidence of environments with liquid water soaking the ground and flowing on planet's surface. As the rover continued to operate far beyond expectations for its lifespan, scientists chose the rim of Endeavour Crater as a long-term destination. Since 2011, examinations of Endeavour's rim have provided information about ancient wet conditions less acidic, and more favorable for microbial life, than the environment that left clues found earlier in the mission.

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NASA release
NASA's Opportunity Rover to Explore Mars Gully

NASA's Opportunity Mars rover will drive down a gully carved long ago by a fluid that might have been water, according to the latest plans for the 12-year-old mission. No Mars rover has done that before.

The longest-active rover on Mars also will, for the first time, visit the interior of the crater it has worked beside for the last five years. These activities are part of a two-year extended mission that began Oct. 1, the newest in a series of extensions going back to the end of Opportunity's prime mission in April 2004.

Opportunity launched on July 7, 2003 and landed on Mars on Jan. 24, 2004 (PST), on a planned mission of 90 Martian days, which is equivalent to 92.4 Earth days.

"We have now exceeded the prime-mission duration by a factor of 50," noted Opportunity Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, California. "Milestones like this are reminders of the historic achievements made possible by the dedicated people entrusted to build and operate this national asset for exploring Mars."

Opportunity begins its latest extended mission in the "Bitterroot Valley" portion of the western rim of Endeavour Crater, a basin 14 miles (22 kilometers) in diameter that was excavated by a meteor impact billions of years ago. Opportunity reached the edge of this crater in 2011 after more than seven years of investigating a series of smaller craters. In those craters, the rover found evidence of acidic ancient water that soaked underground layers and sometimes covered the surface.

The gully chosen as the next major destination slices west-to-east through the rim about half a mile (less than a kilometer) south of the rover's current location. It is about as long as two football fields.

"We are confident this is a fluid-carved gully, and that water was involved," said Opportunity Principal Investigator Steve Squyres of Cornell University, Ithaca, New York. "Fluid-carved gullies on Mars have been seen from orbit since the 1970s, but none had been examined up close on the surface before. One of the three main objectives of our new mission extension is to investigate this gully. We hope to learn whether the fluid was a debris flow, with lots of rubble lubricated by water, or a flow with mostly water and less other material."

The team intends to drive Opportunity down the full length of the gully, onto the crater floor. The second goal of the extended mission is to compare rocks inside Endeavour Crater to the dominant type of rock Opportunity examined on the plains it explored before reaching Endeavour.

"We may find that the sulfate-rich rocks we've seen outside the crater are not the same inside," Squyres said. "We believe these sulfate-rich rocks formed from a water-related process, and water flows downhill. The watery environment deep inside the crater may have been different from outside on the plain — maybe different timing, maybe different chemistry."

The rover team will face challenges keeping Opportunity active for another two years. Most mechanisms onboard still function well, but motors and other components have far exceeded their life expectancy. Opportunity's twin, Spirit, lost use of two of its six wheels before succumbing to the cold of its fourth Martian winter in 2010. Opportunity will face its eighth Martian winter in 2017. Use of Opportunity's non-volatile "flash" memory for holding data overnight was discontinued last year, so results of each day's observations and measurements must be transmitted that day or lost.

Above: This scene from NASA's Mars rover Opportunity shows "Wharton Ridge," which forms part of the southern wall of "Marathon Valley" on the rim of Endeavour Crater. The ridge's name honors the memory of astrobiologist Robert A. Wharton (1951-2012). The scene is presented in approximately true color.

In the two-year extended mission that ended last month, Opportunity explored the "Marathon Valley" area of Endeavour's western rim, documenting the geological context of water-related minerals that had been mapped there from orbital observations. Last month, the rover drove through "Lewis and Clark Gap," a low point in the wall separating Marathon Valley from Bitterroot Valley. A recent color panorama from the rover features "Wharton Ridge," which extends eastward from the gap.

This week, Opportunity is investigating rock exposures next to "Spirit Mound," a prominent feature near the eastern end of Bitterroot Valley. The third main science goal of the new extended mission is to find and examine rocks from a geological layer that was in place before the impact that excavated Endeavour Crater. The science team has not yet determined whether the mound area will provide rocks that old.

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NASA release
5,000 Days on Mars; Solar-Powered Rover Approaching 5,000th Martian Dawn

The Sun will rise on NASA's solar-powered Mars rover Opportunity for the 5,000th time on Saturday [Feb. 17], sending rays of energy to a golf-cart-size robotic field geologist that continues to provide revelations about the Red Planet.

Above: The channel descending a Martian slope in this perspective view is "Perseverance Valley," the study area of NASA's Mars rover Opportunity as the rover passes its 5,000th Martian day. The view overlays a HiRISE image onto a topographic model with five-fold vertical exaggeration, to show shapes. (NASA/JPL-Caltech/Univ. of Arizona/WUSTL)

"Five thousand sols after the start of our 90-sol mission, this amazing rover is still showing us surprises on Mars," said Opportunity Project Manager John Callas, of NASA's Jet Propulsion Laboratory, Pasadena, California.

A Martian "sol" lasts about 40 minutes longer than an Earth day, and a Martian year lasts nearly two Earth years. Opportunity's Sol 1 was landing day, Jan. 25, 2004 (that's in Universal Time; it was Jan. 24 in California). The prime mission was planned to last 90 sols. NASA did not expect the rover to survive through a Martian winter. Sol 5,000 will begin early Friday, Universal Time, with the 4,999th dawn a few hours later. Opportunity has worked actively right through the lowest-energy months of its eighth Martian winter.

From the rover's perspective on the inside slope of the western rim of Endeavour Crater, the milestone sunrise will appear over the basin's eastern rim, about 14 miles (22 kilometers) away. Opportunity has driven over 28 miles (45 kilometers) from its landing site to its current location about one-third of the way down "Perseverance Valley," a shallow channel incised from the rim's crest of the crater's floor. The rover has returned about 225,000 images, all promptly made public online.

"We've reached lots of milestones, and this is one more," Callas said, "but more important than the numbers are the exploration and the scientific discoveries."

The mission made headlines during its first months with the evidence about groundwater and surface water environments on ancient Mars. Opportunity trekked to increasingly larger craters to look deeper into Mars and father back into Martian history, reaching Endeavour Crater in 2011. Researchers are now using the rover to investigate the processes that shaped Perseverance Valley.

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NASA release
Opportunity Hunkers Down During Dust Storm

Science operations for NASA's Opportunity rover have been temporarily suspended as it waits out a growing dust storm on Mars.

NASA's Mars Reconnaissance Orbiter first detected the storm on Friday, June 1. As soon as the orbiter team saw how close the storm was to Opportunity, they notified the rover's team to begin preparing contingency plans.

Above: This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. (NASA/JPL-Caltech/MSSS)

In a matter of days, the storm had ballooned. It now spans more than 7 million square miles (18 million square kilometers) — an area greater than North America — and includes Opportunity's current location at Perseverance Valley. More importantly, the swirling dust has raised the atmospheric opacity, or "tau," in the valley in the past few days. This is comparable to an extremely smoggy day that blots out sunlight. The rover uses solar panels to provide power and to recharge its batteries.

Opportunity's power levels had dropped significantly by Wednesday, June 6, requiring the rover to shift to minimal operations.

This isn't Opportunity's first time hunkering down in bad weather: in 2007, a much larger storm covered the planet. That led to two weeks of minimal operations, including several days with no contact from the rover to save power. The project's management prepared for the possibility that Opportunity couldn't balance low levels of power with its energy-intensive survival heaters, which protect its batteries from Mars' extreme cold. It's not unlike running a car in the winter so that the cold doesn't sap its battery charge.There is a risk to the rover if the storm persists for too long and Opportunity gets too cold while waiting for the skies to clear.

Ultimately, the storm subsided and Opportunity prevailed. The Martian cold is believed to have resulted in the loss of Spirit, Opportunity's twin in the Mars Exploration Rover mission, back in 2010. Despite this, both rovers have vastly exceeded expectations: they were only designed to last 90 days each. Opportunity is in its 15th year; the team has operated the rover for more than 50 times longer than originally planned.

Full dust storms like this one are not surprising, but are infrequent. They can crop up suddenly but last weeks, even months. During southern summer, sunlight warms dust particles, lifting them higher into the atmosphere and creating more wind. That wind kicks up yet more dust, creating a feedback loop that NASA scientists still seek to understand.

Mars Reconnaissance Orbiter and two other NASA spacecraft orbiting the Red Planet — Odyssey and MAVEN — routinely support rovers on the ground.

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NASA release
NASA Mars Exploration Rover Status Report

Updated at 6:30 p.m. PDT on June 12, 2018

NASA engineers attempted to contact the Opportunity rover today (June 12) but did not hear back from the nearly 15-year old rover. The team is now operating under the assumption that the charge in Opportunity's batteries has dipped below 24 volts and the rover has entered low power fault mode, a condition where all subsystems, except a mission clock, are turned off. The rover's mission clock is programmed to wake the computer so it can check power levels.

If the rover's computer determines that its batteries don't have enough charge, it will again put itself back to sleep. Due to an extreme amount of dust over Perseverance Valley, mission engineers believe it is unlikely the rover has enough sunlight to charge back up for at least the next several days.

The Martian dust storm that has blotted out the sun above Opportunity has continued to intensify. The storm, which was first detected on May 30, now blankets 14-million square miles (35-million square kilometers) of Martian surface — a quarter of the planet.

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NASA release
About Opportunity's Recovery Efforts

NASA's Opportunity rover has been silent since June 10, when a planet-encircling dust storm cut off solar power for the nearly-15-year-old rover. Now that scientists think the global dust storm is "decaying" — meaning more dust is falling out of the atmosphere than is being raised back into it — skies might soon clear enough for the solar-powered rover to recharge and attempt to "phone home."

No one will know how the rover is doing until it speaks. But the team notes there's reason to be optimistic: They've performed several studies on the state of its batteries before the storm, and temperatures at its location. Because the batteries were in relatively good health before the storm, there's not likely to be too much degradation. And because dust storms tend to warm the environment — and the 2018 storm happened as Opportunity's location on Mars entered summer — the rover should have stayed warm enough to survive.

What will engineers at NASA's Jet Propulsion Laboratory in Pasadena, California, be looking for — and what will those signs mean for recovery efforts?

A tau below 2

Dust storms on Mars block sunlight from reaching the surface, raising the level of a measurement called "tau." The higher the tau, the less sunlight is available; the last tau measured by Opportunity was 10.8 on June 10. To compare, an average tau for its location on Mars is usually 0.5.

JPL engineers predict that Opportunity will need a tau of less than 2.0 before the solar-powered rover will be able to recharge its batteries. A wide-angle camera on NASA's Mars Reconnaissance Orbiter will watch for surface features to become visible as the skies clear. That will help scientists estimate the tau.

Updates on the dust storm and tau can be found here.

Two Ways to Listen for Opportunity

Several times a week, engineers use NASA's Deep Space Network, which communicates between planetary probes and Earth, to attempt to talk with Opportunity. The massive DSN antennas ping the rover during scheduled "wake-up" times, and then search for signals sent from Opportunity in response.

In addition, JPL's radio science group uses special equipment on DSN antennas that can detect a wider range of frequencies. Each day, they record any radio signal from Mars over most of the rover's daylight hours, then search the recordings for Opportunity's "voice."

Rover faults out

When Opportunity experiences a problem, it can go into so-called "fault modes" where it automatically takes action to maintain its health. Engineers are preparing for three key fault modes if they do hear back from Opportunity.

  • Low-power fault: engineers assume the rover went into low-power fault shortly after it stopped communicating on June 10. This mode causes the rover to hibernate, assuming that it will wake up at a time when there's more sunlight to let it recharge.

  • Clock fault: critical to operating while in hibernation is the rover's onboard clock. If the rover doesn't know what time it is, it doesn't know when it should be attempting to communicate. The rover can use environmental clues, like an increase in sunlight, to make assumptions about the time.

  • Uploss fault: when the rover hasn't heard from Earth in a long time, it can go into "uploss" fault — a warning that its communication equipment may not be functioning. When it experiences this, it begins to check the equipment and tries different ways to communicate with Earth.
What happens if they hear back?

After the first time engineers hear from Opportunity, there could be a lag of several weeks before a second time. It's like a patient coming out of a coma: It takes time to fully recover. It may take several communication sessions before engineers have enough information to take action.

The first thing to do is learn more about the state of the rover. Opportunity's team will ask for a history of the rover's battery and solar cells and take its temperature. If the clock lost track of time, it will be reset. The rover would take pictures of itself to see whether dust might be caked on sensitive parts, and test actuators to see if dust slipped inside, affecting its joints.

Once they've gathered all this data, the team would take a poll about whether they're ready to attempt a full recovery.

Not out of the woods

Even if engineers hear back from Opportunity, there's a real possibility the rover won't be the same.

The rover's batteries could have discharged so much power — and stayed inactive so long — that their capacity is reduced. If those batteries can't hold as much charge, it could affect the rover's continued operations. It could also mean that energy-draining behavior, like running its heaters during winter, could cause the batteries to brown out.

Dust isn't usually as much of a problem. Previous storms plastered dust on the camera lenses, but most of that was shed off over time. Any remaining dust can be calibrated out.

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NASA release
Martian Skies Clearing over Opportunity Rover

A planet-encircling dust storm on Mars, which was first detected May 30 and halted operations for the Opportunity rover, continues to abate.

With clearing skies over Opportunity's resting spot in Mars' Perseverance Valley, engineers at NASA's Jet Propulsion Laboratory in Pasadena, California, believe the nearly 15-year-old, solar-powered rover will soon receive enough sunlight to automatically initiate recovery procedures -- if the rover is able to do so. To prepare, the Opportunity mission team has developed a two-step plan to provide the highest probability of successfully communicating with the rover and bringing it back online.

"The Sun is breaking through the haze over Perseverance Valley, and soon there will be enough sunlight present that Opportunity should be able to recharge its batteries," said John Callas, Opportunity project manager at JPL. "When the tau level [a measure of the amount of particulate matter in the Martian sky] dips below 1.5, we will begin a period of actively attempting to communicate with the rover by sending it commands via the antennas of NASA's Deep Space Network. Assuming that we hear back from Opportunity, we will begin the process of discerning its status and bringing it back online."

The rover's last communication with Earth was received June 10, and Opportunity's current health is unknown. Opportunity engineers are relying on the expertise of Mars scientists analyzing data from the Mars Color Imager (MARCI) aboard NASA's Mars Reconnaissance Orbiter (MRO) to estimate the tau near the rover's position.

"The dust haze produced by the Martian global dust storm of 2018 is one of the most extensive on record, but all indications are it is finally coming to a close," said MRO Project Scientist Rich Zurek at JPL. "MARCI images of the Opportunity site have shown no active dust storms for some time within 3,000 kilometers [about 1,900 miles] of the rover site."

With skies clearing, mission managers are hopeful the rover will attempt to call home, but they are also prepared for an extended period of silence. "If we do not hear back after 45 days, the team will be forced to conclude that the Sun-blocking dust and the Martian cold have conspired to cause some type of fault from which the rover will more than likely not recover," said Callas. "At that point our active phase of reaching out to Opportunity will be at an end. However, in the unlikely chance that there is a large amount of dust sitting on the solar arrays that is blocking the Sun's energy, we will continue passive listening efforts for several months."

The additional several months for passive listening are an allowance for the possibility that a Red Planet dust devil could come along and literally dust off Opportunity's solar arrays. Such "cleaning events" were first discovered by Mars rover teams in 2004 when, on several occasions, battery power levels aboard both Spirit and Opportunity increased by several percent during a single Martian night, when the logical expectation was that they would continue to decrease. These cleaning dust devils have even been imaged by both rovers on the surface and spacecraft in orbit.

The chances are small that dust accumulation would be the root cause of Opportunity's lack of communication. Nonetheless, each day during the passive phase, JPL's Radio Science group will scour the signal records taken by a very sensitive broadband receiver of radio frequencies emanating from Mars, looking for a sign that the rover is trying to reach out.

Even if the team hears back from Opportunity during either phase, there is no assurance the rover will be operational. The impact of this latest storm on Opportunity's systems is unknown but could have resulted in reduced energy production, diminished battery performance, or other unforeseen damage that could make it difficult for the rover to fully return online.

While the situation in Perseverance Valley is critical, the rover team is cautiously optimistic, knowing that Opportunity has overcome significant challenges during its 14-plus years on Mars. The rover lost use of its front steering -- its left-front in June of 2017, and right front in 2005. Its 256-megabyte flash memory is no longer functioning. The team also knows that everything about the rover is well beyond its warranty period -- both Opportunity and its twin rover, Spirit, were constructed for 90-day missions (Spirit lasted 20 times longer and Opportunity is going on 60 times). The rovers were designed to travel about 1,000 yards, and Opportunity has logged more than 28 miles. Through thick and thin, the team has seen their rover soldier on. Now, Opportunity engineers and scientists of Opportunity are planning, and hoping, that this latest dilemma is just another bump in their Martian road.

"In a situation like this you hope for the best but plan for all eventualities," said Callas. "We are pulling for our tenacious rover to pull her feet from the fire one more time. And if she does, we will be there to hear her."

See here for discussion of Opportunity's continued exploration of Mars.

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