NASA’s Curiosity Rover Discovers More Signs of Habitability on Mars; Past and Present

NASA's Curiosity rover has discovered ancient organic molecules on Mars, including the molecule thiophene, embedded within sedimentary rocks at Gale Crater that are billions of years old.  The rover used an instrument called SAM (Sample Analysis at Mars).  Credit:  NASA/GSFC

Ken Kremer  --   SpaceUpClose.com  --   15 June 2018

CAPE CANAVERAL, FL –  NASA’s Curiosity rover has discovered additional signs of habitability on Mars at the robots Gale Crater landing site, both past and present in the form of organic molecules and gaseous methane, that represent “breakthroughs in astrobiology,” researchers announced.

Curiosity has detected a variety of organic molecules including thiophene in ancient sedimentary rocks as well as seasonal variations in the levels of methane in the atmosphere, according to new findings announced at a NASA briefing as well as in new papers published in the journal Science on June 8.

By analyzing cored sedimentary rock samples fed into Curiosity onboard Sample Analysis at Mars (SAM) instrument suite researchers have provided “conclusive evidence for the presence of organic compounds—thiophenic, aromatic, and aliphatic compounds—in drill samples from Mars' Gale crater,” in one of the newly published Science papers by lead author Jen Eigenbrode, et al.

In a second paper by lead author Chris Webster, et al, researchers report “a strong seasonal variation in atmospheric methane, the simplest organic molecule, in the martian atmosphere.”

“Both these finding are breakthroughs in astrobiology,” writes Inge Loes ten Kate, of Utrecht University, Utrecht, Netherlands, in a third paper in Science.

Organic molecules are among the building blocks and prerequisites of life, although in and of themselves are not definitive proof of life and can be created by non-biological processes. 

NASA's Curiosity rover used an instrument called SAM (Sample Analysis at Mars) to detect seasonal changes in atmospheric methane in Gale Crater. The methane signal has been observed for nearly three Martian years (nearly six Earth years), peaking each summer.  Credit:   NASA/JPL-Caltech

“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,” NASA said in a statement.

“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.” 

Although Curiosity has detected other chlorinated organics and signs habitability in past findings, these new discoveries significantly expand the scope, variety and complexity of the organics.  

“We found organic molecules in rocks from an ancient lakebed,” said Jen Eigenbrode, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Those organic molecules could have come from life.”

Curiosity obtained the new data on martian organics data by drilling into sedimentary “mudstone” rocks from four locations in Gale Crater that formed billions of years ago “from silt that accumulated at the bottom of the ancient lake” and analyzing them with the SAM instrument.

SAM heats the samples to over 900 degrees Fahrenheit (500 degrees Celsius) and thereby release the organic molecules in gaseous form from the powdered rock.

“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.”

NASA’s Curiosity rover raised robotic arm with drill pointed skyward while exploring Vera Rubin Ridge – backdropped by the base of Mount Sharp inside Gale Crater. This navcam camera mosaic was stitched from raw images taken on Sol 1912, Dec. 22, 2017 and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo

Curiosity also used another instrument in the SAM suite to detect methane over a period of three Mars years or almost six Earth years.

“Today, we’re announcing the discovery of a repeatable, identifiable, seasonal pattern in the methane measurements,” said Chris Webster, a senior research fellow at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

"This is the first time we've seen something repeatable in the methane story, so it offers us a handle in understanding it.  This is all possible because of Curiosity's longevity. The long duration has allowed us to see the patterns in this seasonal 'breathing.'" 

“Not only have we got this wonderful repeatability, but the seasonal cycle changes by a factor of three. That’s a huge change, completely unexpected. And what it does, it gives us a key to unlocking the mysteries associated with Mars methane because now we have something to test our models and our understanding against.”

The Curiosity Mars rover snaps a dramatic selfie at the ‘Torridon’ quadrangle while making long stretches of wheel tracks exploring assorted rock layers, bedrock outcrops and mineral exposures around Vera Rubin Ridge with an exquisitely sharp view of the distant rim of the Gale Crater landing site visible in the background on the Red Planet.  This navcam camera mosaic was stitched and colorized by Ken Kremer and Marco Di Lorenzo using raw images taken on Sol 1896, Dec. 6, 2017.  Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo/SpaceUpClose.com

NASA’s next planned Red Planet rover is under construction and launching in 2020. These findings give more confidence that scientists are on the right track in searching for evidence life beyond Earth and potentially on Mars.   

“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, in a statement.

“I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”

NASA’s InSight lander is on its way to the Red Planet after launching on May 5 for a landing in November 2018. 

NASA’s Martian fleet also comprises 3 orbiters.

Curiosity is currently exploring the lower sedimentary layers of Mount Sharp which tower over 3 miles (5.5 km) into the Martian sky and found that is supported a habitable zone billions of years ago. 

“Curiosity has shown that Gale crater was habitable around 3.5 billion years ago with conditions comparable to those on the early Earth, where life evolved around that time,” wrote Loes ten Kate. 

“The question of whether life might have originated or existed on Mars is a lot more opportune now that we know that organic molecules were present on its surface at that time.”

As of today, Sol 2082, June 15, 2018, Curiosity has driven over 11.85 miles (19.07 kilometers) since its August 2012 landing inside Gale Crater from the landing site to Mount Sharp and taken over 501,100 amazing images. 

Watch for Ken’s continuing onsite coverage of NASA, SpaceX, ULA, Boeing, Lockheed Martin, Orbital ATK and more space and mission reports direct from the Kennedy Space Center, Cape Canaveral Air Force Station, Florida and Wallops Flight Facility, Virginia.

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