Curiosity Rover Discovers Huge Lake Once Filled Gale Crater

Simulated View of Gale Crater Lake on Mars.  This illustration depicts a lake of water partially filling Mars' Gale Crater, receiving runoff from snow melting on the crater's northern rim.   Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS

Simulated view of Gale Crater Lake on Mars. This illustration depicts a lake of water partially filling Mars’ Gale Crater, receiving runoff from snow melting on the crater’s northern rim. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS

Recent measurements by NASA’s Curiosity rover indicate that a huge lake once filled much of Gale Crater for millions and millions of years and thus possessed the right environmental conditions for a long enough time span to significantly increase the chances that simple microbial life forms could possibly have formed and persisted on Mars billions of years ago.

Scientists announced the discovery of a vast ancient lake at Gale and that Mount Sharp was subsequently created inside the crater by the deposition of sediments into the large lake bed over tens of millions of years, during a NASA media briefing today, Dec. 8.

Mars changed over time,” said Ashwin Vasavada, Curiosity deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., at the briefing.

“Rivers and lakes were present over millions of years.”

Curiosity safely touched down inside Gale Crater in August 2012.

Since then, the six-wheeled rover has been on an epic trek traversing more than 5 miles (8 kilometers) across the crater floor to conduct detailed observations at a number of scientifically interesting sites along the way, including making a multi-month detour in early 2013 to a region called “Yellowknife Bay.”

She conducted five rock drilling operations since landing to ingest pulverized samples for chemical analysis to elucidate Mars’ history of potential habitability, and discovered a habitable zone at Yellowknife Bay.

Sedimentary Signs of a Martian Lakebed.  This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake. The scene combines multiple frames taken with Mastcam's right-eye camera on Aug. 7, 2014, during the 712th Martian day, or sol, of Curiosity's work on Mars. It shows an outcrop at the edge of "Hidden Valley," seen from the valley floor.  Credit:  NASA/JPL-Caltech/MSSS

Sedimentary Signs of a Martian Lakebed. This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA’s Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake. The scene combines multiple frames taken with Mastcam’s right-eye camera on Aug. 7, 2014, during the 712th Martian day, or sol, of Curiosity’s work on Mars. It shows an outcrop at the edge of “Hidden Valley,” seen from the valley floor. Credit: NASA/JPL-Caltech/MSSS

Gale Crater was selected several years ago by the science team as Curiosity’s landing site precisely because the team suspected the presence of an ancient lake based on spectroscopic observations captured from Mars orbit by NASA and ESA robotic spacecraft orbiting the Red Planet.

“We selected Gale because of Mount Sharp and its layered minerals with a record of early Mars history,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington.

“But how did the mountain form in the middle of the crater?”

The origin of Mount Sharp has puzzled researchers and generated a lot of debate in the scientific community.

Curiosity rover panorama of Mount Sharp captured on June 6, 2014 (Sol 651) during traverse inside Gale Crater. Note rover wheel tracks at left. She will eventually ascend the mountain at the ‘Murray Buttes’ at right later this year. Assembled from Mastcam color camera raw images and stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Curiosity rover panorama of Mount Sharp captured on June 6, 2014 (Sol 651) during traverse inside Gale Crater. Note rover wheel tracks at left. She will eventually ascend the mountain at the ‘Murray Buttes’ at right later this year. Assembled from Mastcam color camera raw images and stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Gale Crater itself was originally formed by excavation from a meteorite impact billions of years ago. There may have been a small central peak formed as a rebound from the impact that could have appeared as an island in the ancient lake.

Today, Gale Crater looks vastly different compared to ancient Mars. It is overwhelmed by Mount Sharp which dominates the center of the 96 mile wide (154 kilometers) crater and towers 3.4 miles (5.5 kilometers) into the Martian sky.

Gale Crater lake existed long before Mount Sharp ever formed, during a period billions of years ago when the Red Planet was far warmer and wetter than it is now.

But for reasons we are still trying to decipher and comprehend, Mars underwent radical climactic change between 3 and 4 billion years ago and was transformed from an ancient wet world—potentially hospitable to life—to a cold, dry desiccated world—rather inhospitable to life—that exists today.

Unlocking the mysteries, mechanisms, and time periods of Mars’ climate change, loss of a thick atmosphere, ability to sustain liquid surface water and searching for organic compounds, and for evidence of past or present habitable zones favorable to life are the questions driving NASA’s Mars Exploration program.

Inclined Martian Sandstone Beds Near 'Kimberley.'   This image from Curiosity's Mastcam shows inclined beds of sandstone interpreted as the deposits of small deltas fed by rivers flowing down from the Gale Crater rim and building out into a lake where Mount Sharp is now. It was taken March 13, 2014, just north of the "Kimberley" waypoint.  Credit:  NASA/JPL-Caltech/MSSS

Inclined Martian Sandstone Beds Near “Kimberley.” This image from Curiosity’s Mastcam shows inclined beds of sandstone interpreted as the deposits of small deltas fed by rivers flowing down from the Gale Crater rim and building out into a lake where Mount Sharp is now. It was taken March 13, 2014, just north of the “Kimberley” waypoint. Credit: NASA/JPL-Caltech/MSSS

“If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” said Ashwin Vasavada, Curiosity deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“A more radical explanation is that Mars’ ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don’t know how the atmosphere did that.”

The lower flanks of Mount Sharp are filled with hundreds of exposures of sedimentary rock layers.

The rock layers alternating between lake, river, and wind deposits bear witness to the repeated filling and evaporation of a Martian lake much larger and longer-lasting than any previously examined close-up, according to a statement from the science team.

“We are making headway in solving the mystery of Mount Sharp,” said Curiosity Project Scientist John Grotzinger of the California Institute of Technology in Pasadena. “Where there’s now a mountain, there may have once been a series of lakes.”

“We are fitting together a jigsaw puzzle,” said Curiosity science team member Sanjeev Gupta of Imperial College in London.

Gale Crater lake was gradually filled in by sediments deposited over tens of millions of years.

“The lake was only a few meters deep,” Gupta told AmericaSpace.

The sediments accumulated from rivers, lakes, deltas, and streams as water carrying sand and silt flowed in from the mountainous crater rim, much like river mouths on Earth, and deposited the sediments to form the lower layers of Mount Sharp. These are believed to be the oldest layers and hold the minerals most conducive to the formation of life.

“We found sedimentary rocks suggestive of small, ancient deltas stacked on top of one another,” said Gupta. “Curiosity crossed a boundary from an environment dominated by rivers to an environment dominated by lakes.”

Over time the rim was gradually eroded by weathering and melting snow as the deposition cycle was repeated over and over again. The crater rim was much higher three billion years ago, according to the team.

“The great thing about a lake that occurs repeatedly, over and over, is that each time it comes back it is another experiment to tell you how the environment works,” Grotzinger said.

“As Curiosity climbs higher on Mount Sharp, we will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact. We may see how the chemistry changed in the lakes over time. This is a hypothesis supported by what we have observed so far, providing a framework for testing in the coming year.”

Curiosity’s Panoramic view of Mount Remarkable at ‘The Kimberley Waypoint’ where rover conducted 3rd drilling campaign inside Gale Crater on Mars. The navcam raw images were taken on Sol 603, April 17, 2014, stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo  Featured on APOD - Astronomy Picture of the Day on May 7, 2014

Curiosity’s Panoramic view of Mount Remarkable at “The Kimberley Waypoint” where rover conducted third drilling campaign inside Gale Crater on Mars. The navcam raw images were taken on Sol 603, April 17, 2014, stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo Featured on APOD – Astronomy Picture of the Day on May 7, 2014

Curiosity arrived at the foothills of Mount Sharp in September at a spot dubbed the Pahrump Hills. This area comprises the lowest sedimentary layers of Mount Sharp at a section of rock 500 feet (150 meters) high, dubbed the Murray formation. The one-ton robot is analyzing a drill sample dubbed “Confidence Hills.”

The rover recently completed a walkabout of the Pahrump Hills to determine the best location for the next drill campaign.

So far Curiosity’s odometer totals over 5.5 miles (9.0 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken some 203,000 images during over 820 Sols of exploration.

Stay tuned here for continuing updates.

Ken Kremer

 

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Curiosity Mars Rover's Route from Landing to Base of Mount Sharp. This map shows the route driven by NASA's Curiosity Mars rover from the location where it landed in August 2012 to the "Pahrump Hills" outcrop, which is part of the basal layer of Mount Sharp.  The traverse line covers drives completed through the 817th Martian day, or sol, of Curiosity's work on Mars (Nov. 23, 2014).   Credit: NASA/JPL-Caltech/Univ. of Arizona

Curiosity Mars Rover’s Route from Landing to Base of Mount Sharp. This map shows the route driven by NASA’s Curiosity Mars rover from the location where it landed in August 2012 to the “Pahrump Hills” outcrop, which is part of the basal layer of Mount Sharp. The traverse line covers drives completed through the 817th Martian day, or sol, of Curiosity’s work on Mars (Nov. 23, 2014). Credit: NASA/JPL-Caltech/Univ. of Arizona

2 comments to Curiosity Rover Discovers Huge Lake Once Filled Gale Crater

  • Karol

    Excellent, and very exciting, article Ken. Such discoveries cry out for further exploration, and since EFT-1 the general public seems increasingly interested in, and supportive of, a manned mission to Mars. Hopefully the enthusiasm will continue, this exploration is just too good to ignore!

  • We are witnessing a highly sophisticated evolution in the study of Mars that will revolutionize our understanding of not only the Red Planet but other bodies in our solar system. Each new article eagerly anticipated. Great work, Ken!