[meteorite-list] MRO Spacecraft Detects Impact Glass on Surface of Mars

[Ron Baalke]

June 08, 2015

RELEASE 15-118

NASA Spacecraft Detects Impact Glass on Surface of Mars 

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 
(JPL) in Pasadena, California.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, 
provided and operates CRISM. JPL 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:

http://crism.jhuapl.edu/

For more information about the Mars Reconnaissance Orbiter, visit:

http://www.nasa.gov/mro

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