December 11, 2014 – Earlier this week, observations by NASA’s Curiosity Rover indicated that Mars’ Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years. This interpretation of Curiosity’s finds in Gale Crater suggests ancient Mars maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet.
“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. “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 Mars Atmospheric and Volatile EvolutioN (MAVEN) mission, led by Principal Investigator Bruce Jakosky from the University of Colorado Boulder, will provide scientists with the data needed to reconstruct Mars’ climate history. MAVEN will provide information on how, and how fast, atmospheric gases are being lost to space today, and infer from those detailed studies what happened in the past.
Studying how the Martian atmosphere was lost to space can reveal clues about the impact that change had on the Martian climate, geologic and geochemical conditions over time, all of which are important in understanding whether Mars had an environment able to support life.
On the surface of Mars, Mount Sharp has been puzzling to researchers. The layered mountain sits in a crater and stands about 3 miles (5 kilometers) tall. Its lower flanks expose hundreds of rock layers, which alternate between lake, river and wind deposits.
“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 mount, there may have once been a series of lakes.”
Curiosity currently is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high dubbed the Murray formation. Rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle occurred over and over again.
“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.”
After the crater filled to a height of at least a few hundred yards and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.
NASA’s Mars Science Laboratory Project uses Curiosity to assess ancient, potentially habitable environments and the significant changes the Martian environment has experienced over millions of years. This project, and MAVEN, are elements of NASA’s ongoing Mars research and preparation for a human mission to the planet in the 2030s.
As we learn more about Mars, it becomes more mysterious, and MAVEN’s job becomes more urgent. What happened to the ancient Mars atmosphere? And did life exist on Mars?