Mission’s end for “Oppy”

Opportunity's Tracks on Mars - Image credit: NASA/JPL-Caltech
Opportunity’s Tracks on Mars – Image credit: NASA/JPL-Caltech

February 12, 2019 — One of the most successful and enduring feats of interplanetary exploration, NASA’s Opportunity rover mission is at an end after almost 15 years exploring the surface of Mars and helping lay the groundwork for NASA’s return to the Red Planet.

The Opportunity rover stopped communicating with Earth when a severe Mars-wide dust storm blanketed its location in June 2018. After more than a thousand commands to restore contact, engineers in the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory (JPL) made their last attempt to revive Opportunity Tuesday, to no avail. The solar-powered rover’s final communication was received June 10.

“It is because of trailblazing missions such as Opportunity that there will come a day when our brave astronauts walk on the surface of Mars,” said NASA Administrator Jim Bridenstine. “And when that day arrives, some portion of that first footprint will be owned by the men and women of Opportunity, and a little rover that defied the odds and did so much in the name of exploration.”

Artist's Concept: Spirit & Opportunity Mars Rovers. Image Credit: NASA
Artist’s Concept: Spirit & Opportunity Mars Rovers. Image Credit: NASA

Designed to last just 90 Martian days and travel 1,100 yards (1,000 meters), Opportunity vastly surpassed all expectations in its endurance, scientific value and longevity. In addition to exceeding its life expectancy by 60 times, the rover traveled more than 28 miles (45 kilometers) by the time it reached its most appropriate final resting spot on Mars – “Perseverance Valley.”

“For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars’ ancient past as a wet, potentially habitable planet, and revealing uncharted Martian landscapes,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues – both on the surface of Mars with the Curiosity rover and InSight lander – and in the clean rooms of JPL, where the upcoming Mars 2020 rover is taking shape.”

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Ancient organic material, mysterious methane on Mars

This low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin" on lower Mount Sharp. Image Credit: NASA/JPL-Caltech/MSSS
This low-angle self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called “Buckskin” on lower Mount Sharp. Image Credit: NASA/JPL-Caltech/MSSS

From a NASA News Release

NASA’s Curiosity rover has found new evidence preserved in rocks on Mars that suggests the planet could have supported ancient life, as well as new evidence in the Martian atmosphere that relates to the search for current life on the Red Planet. While not necessarily evidence of life itself, these findings are a good sign for future missions exploring the planet’s surface and subsurface.

The new findings – “tough” organic molecules in three-billion-year-old sedimentary rocks near the surface, as well as seasonal variations in the levels of methane in the atmosphere – appear in the June 8 edition of the journal Science.

Organic molecules contain carbon and hydrogen, and also may include oxygen, nitrogen and other elements. While commonly associated with life, organic molecules also can be created by non-biological processes and are not necessarily indicators of life.

“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington. “I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”

“Curiosity has not determined the source of the organic molecules,” said Jen Eigenbrode of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is lead author of one of the two new Science papers. “Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in Martian materials holds chemical clues to planetary conditions and processes.”

Although the surface of Mars is inhospitable today, there is clear evidence that in the distant past, the Martian climate allowed liquid water – an essential ingredient for life as we know it – to pool at the surface. Data from Curiosity reveal that billions of years ago, a water lake inside Gale Crater held all the ingredients necessary for life, including chemical building blocks and energy sources.

“The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter,” said Eigenbrode. “Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”

Seasonal Methane Releases

In the second paper, scientists describe the discovery of seasonal variations in methane in the Martian atmosphere over the course of nearly three Mars years, which is almost six Earth years. This variation was detected by Curiosity’s Sample Analysis at Mars (SAM) instrument suite.

Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins. Methane previously had been detected in Mars’ atmosphere in large, unpredictable plumes. This new result shows that low levels of methane within Gale Crater repeatedly peak in warm, summer months and drop in the winter every year.

“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it,” said Chris Webster of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of the second paper. “This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.'”

Finding Organic Molecules

To identify organic material in the Martian soil, Curiosity drilled into sedimentary rocks known as mudstone from four areas in Gale Crater. This mudstone gradually formed billions of years ago from silt that accumulated at the bottom of the ancient lake. The rock samples were analyzed by SAM, which uses an oven to heat the samples (in excess of 900 degrees Fahrenheit, or 500 degrees Celsius) to release organic molecules from the powdered rock.

SAM measured small organic molecules that came off the mudstone sample – fragments of larger organic molecules that don’t vaporize easily. Some of these fragments contain sulfur, which could have helped preserve them in the same way sulfur is used to make car tires more durable, according to Eigenbrode.

The results also indicate organic carbon concentrations on the order of 10 parts per million or more. This is close to the amount observed in Martian meteorites and about 100 times greater than prior detections of organic carbon on Mars’ surface. Some of the molecules identified include thiophenes, benzene, toluene, and small carbon chains, such as propane or butene.

In 2013, SAM detected some organic molecules containing chlorine in rocks at the deepest point in the crater. This new discovery builds on the inventory of molecules detected in the ancient lake sediments on Mars and helps explains why they were preserved.

Finding methane in the atmosphere and ancient carbon preserved on the surface gives scientists confidence that NASA’s Mars 2020 rover and ESA’s (European Space Agency’s) ExoMars rover will find even more organics, both on the surface and in the shallow subsurface.

These results also inform scientists’ decisions as they work to find answers to questions concerning the possibility of life on Mars.

“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, at NASA Headquarters. “We don’t know, but these results tell us we are on the right track.”

This work was funded by NASA’s Mars Exploration Program for the agency’s Science Mission Directorate (SMD) in Washington. Goddard provided the SAM instrument. JPL built the rover and manages the project for SMD.

Confirmed: Earth’s “Martian meteorites” really are from Mars

PASADENA, Calif. — Examination of the Martian atmosphere by NASA’s Curiosity Mars rover confirms that some meteorites that have dropped to Earth really are from the Red Planet.

A key new measurement of the inert gas argon in Mars’ atmosphere by Curiosity’s laboratory provides the most definitive evidence yet of the origin of Mars meteorites while at the same time providing a way to rule out Martian origin of other meteorites.

The new measurement is a high-precision count of two forms of argon — argon-36 and argon-38 — accomplished by the Sample Analysis at Mars (SAM) instrument inside the rover. These lighter and heavier forms, or isotopes, of argon exist naturally throughout the solar system. On Mars the ratio of light to heavy argon is skewed because much of that planet’s original atmosphere was lost to space. The lighter form of argon was taken away more readily because it rises to the top of the atmosphere more easily and requires less energy to escape. That left the Martian atmosphere relatively enriched in the heavier isotope, argon-38.

Years of past analyses by Earth-bound scientists of gas bubbles trapped inside Martian meteorites had already narrowed the Martian argon ratio to between 3.6 and 4.5 (that is 3.6 to 4.5 atoms of argon-36 to every one of argon-38). Measurements by NASA’s Viking landers in the 1970s put the Martian atmospheric ratio in the range of four to seven. The new SAM direct measurement on Mars now pins down the correct argon ratio at 4.2.

“We really nailed it,” said Sushil Atreya of the University of Michigan, Ann Arbor, lead author of an Oct. 16 paper reporting the finding in Geophysical Research Letters. “This direct reading from Mars settles the case with all Martian meteorites.”

One reason scientists have been so interested in the argon ratio in Martian meteorites is that it was — before Curiosity — the best measure of how much atmosphere Mars has lost since the planet’s wetter, warmer days billions of years ago. Figuring out the planet’s atmospheric loss would enable scientists to better understand how Mars transformed from a once water-rich planet, more like our own, into today’s drier, colder and less-hospitable world.

Had Mars held onto all of its atmosphere and its original argon, its ratio of the gas would be the same as that of the sun and Jupiter. Those bodies have so much gravity that isotopes can’t preferentially escape, so their argon ratio — which is 5.5 — represents that of the primordial solar system.

While argon makes up only a tiny fraction of the gas lost to space from Mars, it is special because it’s a noble gas. That means the gas is inert, not reacting with other elements or compounds, and therefore a more straightforward tracer of the history of the Martian atmosphere.

“Other isotopes measured by SAM on Curiosity also support the loss of atmosphere, but none so directly as argon,” said Atreya. “Argon is the clearest signature of atmospheric loss because it’s chemically inert and does not interact or exchange with the Martian surface or the interior. This was a key measurement that we wanted to carry out on SAM.”

The Curiosity measurements do not directly measure the current rate of atmospheric escape, but NASA’s next mission to Mars, the Mars Atmosphere and Volatile Evolution Mission (MAVEN), is designed to do so. That mission is being prepared at NASA’s Kennedy Space Center in Florida for a launch-opportunity period that begins on Nov. 18.

Curiosity: New evidence of a formerly wet Mars

Photo: Conglomerate rock outcrop on Mars. Image credit: NASA/JPL-Caltech/MSSS
In this image from NASA’s Curiosity rover, a rock outcrop called Link pops out from a Martian surface that is elsewhere blanketed by reddish-brown dust. Image credit: NASA/JPL-Caltech/MSSS

PASADENA, Calif. — NASA’s Curiosity rover mission has found evidence a stream once ran vigorously across the area on Mars where the rover is driving. There is earlier evidence for the presence of water on Mars, but this evidence — images of rocks containing ancient streambed gravels — is the first of its kind.

Scientists are studying the images of stones cemented into a layer of conglomerate rock. The sizes and shapes of stones offer clues to the speed and distance of a long-ago stream’s flow.

“From the size of gravels it carried, we can interpret the water was moving about 3 feet per second, with a depth somewhere between ankle and hip deep,” said Curiosity science co-investigator William Dietrich of the University of California, Berkeley. “Plenty of papers have been written about channels on Mars with many different hypotheses about the flows in them. This is the first time we’re actually seeing water-transported gravel on Mars. This is a transition from speculation about the size of streambed material to direct observation of it.”

The finding site lies between the north rim of Gale Crater and the base of Mount Sharp, a mountain inside the crater. Earlier imaging of the region from Mars orbit allows for additional interpretation of the gravel-bearing conglomerate. The imagery shows an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds.

The rounded shape of some stones in the conglomerate indicates long-distance transport from above the rim, where a channel named Peace Vallis feeds into the alluvial fan. The abundance of channels in the fan between the rim and conglomerate suggests flows continued or repeated over a long time, not just once or for a few years.

The discovery comes from examining two outcrops, called “Hottah” and “Link,” with the telephoto capability of Curiosity’s mast camera during the first 40 days after landing. Those observations followed up on earlier hints from another outcrop, which was exposed by thruster exhaust as Curiosity, the Mars Science Laboratory Project’s rover, touched down.

“Hottah looks like someone jack-hammered up a slab of city sidewalk, but it’s really a tilted block of an ancient streambed,” said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology in Pasadena.

The gravels in conglomerates at both outcrops range in size from a grain of sand to a golf ball. Some are angular, but many are rounded.

“The shapes tell you they were transported and the sizes tell you they couldn’t be transported by wind. They were transported by water flow,” said Curiosity science co-investigator Rebecca Williams of the Planetary Science Institute in Tucson, Ariz.

The science team may use Curiosity to learn the elemental composition of the material, which holds the conglomerate together, revealing more characteristics of the wet environment that formed these deposits. The stones in the conglomerate provide a sampling from above the crater rim, so the team may also examine several of them to learn about broader regional geology.

The slope of Mount Sharp in Gale Crater remains the rover’s main destination. Clay and sulfate minerals detected there from orbit can be good preservers of carbon-based organic chemicals that are potential ingredients for life.

“A long-flowing stream can be a habitable environment,” said Grotzinger. “It is not our top choice as an environment for preservation of organics, though. We’re still going to Mount Sharp, but this is insurance that we have already found our first potentially habitable environment.”

During the two-year prime mission of the Mars Science Laboratory, researchers will use Curiosity’s 10 instruments to investigate whether areas in Gale Crater have ever offered environmental conditions favorable for microbial life.

NASA’s Jet Propulsion Laboratory, a division of Caltech, built Curiosity and manages the Mars Science Laboratory Project for NASA’s Science Mission Directorate, Washington.

For more about Curiosity, visit: http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl .

“Head’s up” and Curiosity begins looking around

Photo: First two images of Martian surroundings from Curiosity's mast cam. Image credit: NASA/JPL-Caltech
The first two full-resolution images of the Martian surface from the Navigation cameras on NASA’s Curiosity rover. These are full-resolution images, 1024 by 1024 pixels in size. Image credit: NASA/JPL-Caltech

These are the first two full-resolution images of the Martian surface from the Navigation cameras on NASA’s Curiosity rover, which are located on the rover’s “head” or mast. The rim of Gale Crater can be seen in the distance beyond the pebbly ground.

The topography of the rim is very mountainous due to erosion. The ground seen in the middle shows low-relief scarps and plains. The foreground shows two distinct zones of excavation likely carved out by blasts from the rover’s descent stage thrusters.

Wednesday, Aug. 8, the team deployed the 3.6 foot-tall (1.1-meter) camera mast, activated and gathered surface radiation data from the rover’s Radiation Assessment Detector and concluded testing of the rover’s high-gain antenna.

Curiosity carries 10 science instruments with a total mass 15 times as large as the science payloads on NASA’s Mars rovers Spirit and Opportunity. Some of the tools, such as a laser-firing instrument for checking rocks’ elemental composition from a distance, are the first of their kind on Mars. Curiosity will use a drill and scoop, which are located at the end of its robotic arm, to gather soil and powdered samples of rock interiors, then sieve and parcel out these samples into the rover’s analytical laboratory instruments.

To handle this science toolkit, Curiosity is twice as long and five times as heavy as Spirit or Opportunity. The Gale Crater landing site places the rover within driving distance of layers of the crater’s interior mountain. Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.

Curiosity lands safely, is spied by HiRISE in descent to Mars

Photo: Mars Rover "Curiosity" hangs from its supersonic parachute. Credit: NASA/JPL-Caltech/Univ. of Arizona
Plummeting through the thin atmosphere of Mars, Mars rover “Curiosity” (still inside its protective enclosure) hangs from its supersonic parachute. White square indicates parachute (above) and protective aeroshell, below. This image captured by the “Mars Reconnaissance Orbiter” spacecraft in orbit around the Red Planet. Credit: NASA/JPL-Caltech/Univ. of Arizona

PASADENA, Calif. — NASA’s most advanced Mars rover Curiosity has landed on the Red Planet. The one-ton rover, hanging by ropes from a rocket backpack, touched down onto Mars Sunday to end a 36-week flight and begin a two-year investigation.

Photo: Heavily-cropped MRO image of Curiosity on its parachute. Credit: NASA/JPL-Caltech/Univ. of Arizona
This is a tight crop of the full image showing the remarkable detail produced by the MRO’s HiRISE instrument – Curiosity in its aeroshell suspended from its supersonic parachute (about 50 ft. in diameter). Credit: NASA/JPL-Caltech/Univ. of Arizona

The Mars Science Laboratory (MSL) spacecraft that carried Curiosity succeeded in every step of the most complex landing ever attempted on Mars, including the final severing of the bridle cords and flyaway maneuver of the rocket backpack.

Curiosity landed at 10:32 p.m. PDT Aug. 5, (1:32 a.m. EDT Aug. 6) near the foot of a mountain three miles tall and 96 miles in diameter inside Gale Crater.

During a nearly two-year prime mission, the rover will investigate whether the region ever offered conditions favorable for microbial life.

The rover, powered by a radioactive heat source rather than solar cells, is expected to last at least two Earth years and can continue to operate through the incredibly cold and dark Martian winter. Winter was and is a danger for solar-powered rovers like Opportunity, still operating on the surface of Mars, as is accumulation of light-blocking dust.

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The four main pieces of hardware that arrived on Mars with NASA’s Curiosity rover were spotted by NASA’s Mars Reconnaissance Orbiter (MRO). The High-Resolution Imaging Science Experiment (HiRISE) camera captured this image about 24 hours after landing. Credit: NASA/JPL-Caltech/Univ. of Arizona

Oppy reaches Endeavour Crater

Photo: Edge of Endeavour Crater on planet Mars.
NASA's Mars Exploration Rover Opportunity arrived at the rim of Endeavour crater on Aug. 9, 2011, after a trek of more than 13 miles (21 kilometers) lasting nearly three years. Image Credit: NASA/JPL-Caltech/Cornell/ASU. (Click on image to see full-size.)

PASADENA, Calif. – 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 approximately 13 miles (21 kilometers) since climbing out of the Victoria Crater.

“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.