Mars Express Orbiter

Test for Damp Ground at Mars Streaks Finds None

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Blue dots on this map indicate sites of recurring slope lineae (RSL) in part of the Valles Marineris canyon network on Mars. RSL are seasonal dark streaks that may be indicators of liquid water. The area mapped here has the highest density of known RSL on Mars. Image Credit: NASA/JPL-Caltech/Univ. of Arizona



Seasonal dark streaks on Mars that have become one of the hottest topics in interplanetary research don’t hold much water, according to the latest findings from a NASA spacecraft orbiting Mars.

The new results from NASA’s Mars Odyssey mission rely on ground temperature, measured by infrared imaging using the spacecraft’s Thermal Emission Imaging System (THEMIS). They do not contradict last year’s identification of hydrated salt at these flows, which since their 2011 discovery have been regarded as possible markers for the presence of liquid water on modern Mars. However, the temperature measurements now identify an upper limit on how much water is present at these darkened streaks: about as much as in the driest desert sands on Earth.

When water is present in the spaces between particles of soil or grains of sand, it affects how quickly a patch of ground heats up during the day and cools off at night.

“We used a very sensitive technique to quantify the amount of water associated with these features,” said Christopher Edwards of Northern Arizona University, Flagstaff. “The results are consistent with no moisture at all and set an upper limit at three percent water.”

The features, called recurring slope lineae or RSL, have been identified at dozens of sites on Mars. A darkening of the ground extends downhill in fingerlike flows during spring or summer, fades away in fall and winter, then repeats the pattern in another year at the same location. The process that causes the streaks to appear is still a puzzle.

“Some type of water-related activity at the uphill end still might be a factor in triggering RSL, but the darkness of the ground is not associated with large amounts of water, either liquid or frozen,” Edwards said. “Totally dry mechanisms for explaining RSL should not be ruled out.”

He and Sylvain Piqueux of NASA’s Jet Propulsion Laboratory, Pasadena, California, analyzed several years of THEMIS infrared observations of a crater-wall region within the large Valles Marineris canyon system on Mars. Numerous RSL features sit close together in some parts of the study region. Edwards and Piqueux compared nighttime temperatures of patches of ground averaging about 44 percent RSL features, in the area, to temperatures of nearby slopes with no RSL. They found no detectable difference, even during seasons when RSL were actively growing.

The report of these findings by Edwards and Piqueux has been accepted by the peer-reviewed Geophysical Research Letters and is available online.

There is some margin of error in assessing ground temperatures with the multiple THEMIS observations used in this study, enough to leave the possibility that the RSL sites differed undetectably from non-RSL sites by as much as 1.8 degrees Fahrenheit (1 Celsius degree). The researchers used that largest possible difference to calculate the maximum possible amount of water — either liquid or frozen — in the surface material.

How deeply moisture reaches beneath the surface, as well as the amount of water present right at the surface, affects how quickly the surface loses heat. The new study calculates that if RSL have only a wafer-thin layer of water-containing soil, that layer contains no more than about an ounce of water per two pounds of soil (3 grams water per kilogram of soil). That is about the same concentration of water as in the surface material of the Atacama Desert and Antarctic Dry Valleys, the driest places on Earth. If the water-containing layer at RSL is thicker, the amount of water per pound or kilogram of soil would need to be even less, to stay consistent with the temperature measurements.

Research published last year identified hydrated salts in the surface composition of RSL sites, with an increase during the season when streaks are active. Hydrated salts hold water molecules affecting the crystalline structure of the salt.

“Our findings are consistent with the presence of hydrated salts, because you can have hydrated salt without having enough for the water to start filling pore spaces between particles,” Edwards said. “Salts can become hydrated by pulling water vapor from the atmosphere, with no need for an underground source of the water.”

“Through additional data and studies, we are learning more about these puzzling seasonal features — narrowing the range of possible explanations,” said Michael Meyer. “It just shows us that we still have much to learn about Mars and its potential as a habitat for life.”

The new study touches on additional factors that add to understanding of RSL.

— If RSL were seasonal flows of briny water followed by evaporation, annual buildup of crust-forming salt should affect temperature properties. So the lack of a temperature difference between RSL and non-RSL sites is evidence against evaporating brines.

— Lack of a temperature difference is also evidence against RSL being cascades of dry material with different thermal properties than the pre-existing slope material, such as would be the case with annual avalanching of powdery dust that accumulates from dusty air.

Arizona State University, Tempe, provided and operates the THEMIS camera, which records observations in both infrared and visible-light wavelengths. JPL, a division of Caltech, manages the Mars Odyssey project for NASA. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it.

NASA Spacecraft Detects Impact Glass on Surface of Mars

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Researchers have found deposits of impact glass preserved in Martian craters, including Alga Crater, shown here. The detection is based on data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on NASA’s Mars Reconnaissance Orbiter. Image credit: NASA/JPL-Caltech/JHUAPL/Univ. of Arizona

Fast Facts:

  • Glass deposits in impact craters on Mars have been detected in observations by NASA’s Mars Reconnaissance Orbiter.
  • Impact glass could preserve evidence about whether Mars ever had life.

NASA’s Mars Reconnaissance Orbiter (MRO) has detected deposits of glass within impact craters on Mars. Though formed in the searing heat of a violent impact, such deposits might provide a delicate window into the possibility of past life on the Red Planet.

During the past few years, research has shown evidence about past life has been preserved in impact glass here on Earth. A 2014 study led by scientist Peter Schultz of Brown University in Providence, Rhode Island, found organic molecules and plant matter entombed in glass formed by an impact that occurred millions of years ago in Argentina. Schultz suggested that similar processes might preserve signs of life on Mars, if they were present at the time of an impact.

Fellow Brown researchers Kevin Cannon and Jack Mustard, building on the previous research, detail their data about Martian impact glass in a report now online in the journal Geology.

“The work done by Pete and others showed us that glasses are potentially important for preserving biosignatures,” Cannon said. “Knowing that, we wanted to go look for them on Mars and that’s what we did here. Before this paper, no one had been able to definitively detect them on the surface.”

Cannon and Mustard showed large glass deposits are present in several ancient, yet well-preserved, craters on Mars. Picking out the glassy deposits was no easy task. To identify minerals and rock types remotely, scientists measured the spectra of light reflected off the planet’s surface. But impact glass doesn’t have a particularly strong spectral signal.

“Glasses tend to be spectrally bland or weakly expressive, so signature from the glass tends to be overwhelmed by the chunks of rock mixed in with it,” said Mustard. “But Kevin found a way to tease that signal out.”

In a laboratory, Cannon mixed together powders with a similar composition of Martian rocks and fired them in an oven to form glass. He then measured the spectral signal from that glass.

Once Mustard had the signal from the lab glass, he used an algorithm to pick out similar signals in data from MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), for which he is the deputy principal investigator.

The technique pinpointed deposits in several Martian crater central peaks, the craggy mounds that often form in the center of a crater during a large impact. The fact the deposits were found on central peaks is a good indicator that they have an impact origin.

Knowing that impact glass can preserve ancient signs of life — and now knowing that such deposits exist on the Martian surface today — opens up a potential new strategy in the search for ancient Martian life.

“The researchers’ analysis suggests glass deposits are relatively common impact features on Mars,” said Jim Green, director of NASA’s planetary science division at the agency’s headquarters in Washington. “These areas could be targets for future exploration as our robotic scientific explorers pave the way on the journey to Mars with humans in the 2030s.”

One of the craters containing glass, called Hargraves, is near the Nili Fossae trough, a 400-mile-long (about 650-kilometer-long) depression that stretches across the Martian surface. The region is one of the landing site contenders for NASA’s Mars 2020 rover, a mission to cache soil and rock samples for possible return to Earth.

Nili Fossae trough is already of scientific interest because the crust in the region is thought to date back to when Mars was a much wetter planet. The region also is rife with what appear to be ancient hydrothermal fractures, warm vents that could have provided energy for life to thrive just beneath the surface.

“If you had an impact that dug in and sampled that subsurface environment, it’s possible that some of it might be preserved in a glassy component,” Mustard said. “That makes this a pretty compelling place to go look around, and possibly return a sample.”

MRO has been examining Mars with CRISM and five other instruments since 2006.

“This significant new detection of impact glass illustrates how we can continue to learn from the ongoing observations by this long-lived mission,” said Richard Zurek, MRO project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, provided and operates CRISM. JPL, a division of the California Institute of Technology in Pasadena, manages MRO for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver built the orbiter and supports its operations.

For more information about CRISM, visit:
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Components of Beagle 2 Flight System on Mars

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PRESS RELEASE (JPL) – The Beagle 2 Mars Lander, built by the United Kingdom, has been thought lost on Mars since 2003, but has now been found in images from NASA’s Mars Reconnaissance Orbiter.

Beagle 2 was released by the European Space Agency’s Mars Express orbiter but never heard from after its expected landing. Images from the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter have been interpreted as showing the Beagle 2 did make a soft landing and at least partially deployed its solar panels.

A set of three observations with the orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera shows Beagle 2 partially deployed on the surface of the planet, ending the mystery of what happened to the mission more than a decade ago. They show that the lander survived its Dec. 25, 2003, touchdown enough to at least partially deploy its solar arrays.

“I am delighted that Beagle 2 has finally been found on Mars,” said Mark Sims of the University of Leicester, U.K. He was an integral part of the Beagle 2 project from the start, leading the initial study phase and was Beagle 2 mission manager. “Every Christmas Day since 2003 I have wondered what happened to Beagle 2. My Christmas Day in 2003 alongside many others who worked on Beagle 2 was ruined by the disappointment of not receiving data from the surface of Mars. To be frank I had all but given up hope of ever knowing what happened to Beagle 2. The images show that we came so close to achieving the goal of science on Mars.

HiRISE images initially searched by Michael Croon of Trier, Germany, a former member of the European Space Agency’s Mars Express operations team, provide evidence for the lander and key descent components on the surface of Mars within the expected landing area of Isidis Planitia, an impact basin close to the equator.

Subsequent re-imaging and analysis by the Beagle 2 team, the HiRISE team and NASA’s Jet Propulsion Laboratory, Pasadena, California, have confirmed that the targets discovered are of the correct size, shape, color and dispersion to be Beagle 2. JPL planetary geologist Tim Parker, who has assisted in the search and processed some of the images said, “I’ve been looking over the objects in the images carefully, and I’m convinced that these are Beagle 2 hardware.”

Analysis of the images indicates what appears to be a partially deployed configuration, with what is thought to be the rear cover with its pilot/drogue chute (still attached) and main parachute close by. Due to the small size of Beagle 2 (less than 7 feet, or 2 meters across for the deployed lander) it is right at the limit of detection of HiRISE, the highest-resolution camera orbiting Mars. The targets are within the expected landing area at a distance of about three miles (five kilometers) from its center.

“I can imagine the sense of closure that the Beagle 2 team must feel,” said Richard Zurek of JPL, project scientist now for Mars Reconnaissance Orbiter (MRO) and previously for NASA’s still-missing 1998 Mars Polar Lander. “MRO has helped find safe landing sites on Mars for the Curiosity and Phoenix missions and has searched for missing craft to learn what may have gone wrong. It’s an extremely difficult task, as the craft are small and the search areas are vast. It takes the best camera we have in Mars orbit and work by dedicated individuals to be successful at this.”

HiRISE is operated by the University of Arizona, Tucson. The instrument was built by Ball Aerospace & Technologies Corp. of Boulder, Colorado. The Mars Reconnaissance Orbiter Project is managed for NASA’s Science Mission Directorate in Washington, by JPL, a division of the California Institute of Technology, Pasadena.

View all images (color) on JPL site

For more information about HiRISE

Additional information about MRO

Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, California