NASA has chosen Gale crater as the landing site for the $2.5 billion Mars Science Laboratory (MSL) rover mission launching in late November.
“We are going to the mountain at Gale crater,” Michael Watkins, MSL project engineer at the Jet Propulsion Laboratory in Pasadena, Calif., announced during a July 22 press conference. “It exhibits three different kinds of environmental settings, perhaps the trilogy of Mars history. It’s a worthy goal, a worthy challenge for such a capable rover.”
The MSL rover, dubbed Curiosity, is as big as a car, equipped with 10 instruments, and powered by plutonium-238.
Gale crater is about 154 kilometers wide and has a mountain at its center that rises higher, from the crater floor up, than Mount Rainer near Seattle. The crater, named after Australian astronomer Walter F. Gale, is bigger than Connecticut and Rhode Island combined, NASA officials said.
Gale crater is also thought to harbor clues of ancient water activity on the Martian surface, and one of Curiosity’s primary tasks will be to root around for evidence that Mars is, or was, capable of supporting microbial life.
“Scientists identified Gale as their top choice to pursue the ambitious goals of this new rover mission,” Jim Green, director for the planetary science division at NASA headquarters in Washington, said in a statement. “The site offers a visually dramatic landscape and also great potential for significant science findings.”
NASA considered 60 potential landing sites before settling on four primary candidates in 2008. Earlier this year, NASA narrowed the list to two finalists: Eberswalde crater and Gale crater.
Eberswalde is widely considered one of the best deltas on Mars, and at some point, the crater was likely filled with water, said John Grant, a geologist with the U.S. National Air and Space Museum. All of the candidate sites “represent an incredible opportunity for MSL. It was a very difficult decision to arrive at a final one,” he said.
Targeted images from the Mars Reconnaissance Orbiter, which has been circling the red planet since 2006, provided detailed imagery of the potential landing sites that enabled scientists and engineers to evaluate safety concerns and the scientific benefits of each.
A team of senior NASA officials, principal investigators and co-investigators then conducted a thorough review and unanimously selected Gale crater as the official landing site.
“All four of the final sites were really great candidates,” Grant said. “Early on in the process, I had a favorite. I can honestly say that that went away. They’re really different. With Gale crater, there’re still questions about how this mountain of material is in place. All of them have very attractive attributes and some unknowns, so you really have to say which one offers us the broadest benefits to the objectives of MSL?”
In the end, the program scientists found the broadest benefits in Gale crater’s diverse environmental settings.
“The Gale site represents an incredibly rich suite of scientific investigations that we can do,” said Dawn Sumner, a geologist at the University of California, Davis.
At the base of the mountain, there are signatures of clays and sulfate salts, which are both known to form in water, and are both key classes of minerals that will reveal clues about the environment on Mars, Sumner said.
By moving toward Gale’s mountain, the layering will help scientists understand how the martian environment changed through time. From these observations, project scientists are hoping to glean information about Mars’ potential habitability.