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Lecturer elucidates Mars missions

Grotzinger discussed previous rover missions and the possibility of life on the red planet

Mars may have once been a habitable place for life, said John Grotzinger, a project scientist for the Curiosity Rover and a professor of geology at the California Institute of Technology, in a lecture he delivered yesterday in nearly full MacMillan 117.

The rover Curiosity landed on Mars after missions by three previous rovers, Sojourner, which was launched in 1996, and Spirit and Opportunity, which were launched in 2003. Pathfinder served as a guinea pig for landing vehicles on Mars, and Spirit and Opportunity landed in search of water. But Curiosity was launched to look more closely at the chemistry of Mars to see if the planet could support life, Grotzinger said.

Curiosity landed in the Gale Crater, which has a large mountain — Mount Sharp — in the middle of it. This mission marks the first in which landing in Gale Crater was possible. In previous missions, landing technology was not advanced enough to allow vehicles to land in a precise location, but NASA scientists made technological advances which enabled Curiosity to target a much smaller landing site.

The team chose this location because it provided interesting terrains for Curiosity to examine within a small radius. That way, if Curiosity was not fully functional after landing, there would still be interesting materials available for analysis. Because it is a crater with a mountain, Gale exhibits large differences in altitudes, exposing  many different types of “geologies,” Grotzinger said, including clay, sand and dust. Curiosity’s landing site was also positioned near an area in which many “canals” converged, leaving behind exposed terrain, Grotzinger said.

Gale Crater has been an area of interest for several of NASA’s past missions. “Maybe someday we’ll get up there,” Grotzinger said of the mountain.

Curiosity used two different tools for its chemical analyses, Alpha Particle X-Ray Spectrometer and ChemCam. One of the Curiosity mission’s aims was to compare the data from APXS, which is “tried and true,” with data from ChemCam, which is a much newer technology. ChemCam uses a laser to drill into rock samples, creating plasma and passes the light from the plasma through a spectrometer, a device that determines the elements of a sample.

APXS refines a rock sample by finely sifting it and then passes it through another tool called CheMin, which provides a mineralogy analysis. It also passes it through a group of three instruments called Sample Analysis at Mars, which Grotzinger claims “is its own spacecraft.” SAM is composed of three instruments that determine the molecular components of atmospheric samples, Grotzinger said.

The Curiosity team used these and other tools to analyze samples from the Rocknest sand shadow Deposit, a specific location within the Gale Crater.  The team chose the Rocknest sand shadow Deposit because it provided local samples from the sand ­ as well as global samples from the dust that settled there, which could have originated from anywhere on the planet. From this data, the team was able to determine that, had there been a biosphere, Mars could have supported life, Grotzinger said.

“We really did find a quite habitable environment on Mars,” he added.

Audience members said they enjoyed the talk.

“He was very clear in every statement and he explained it very well,” said Margaret Lengerich MS’13. “I’m not familiar with these terms, but I could understand almost everything.”


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