Curiosity on Gale: One Year Later
On August 6th, 2012, NASA’s Curiosity rover successfully delivered 10 of the most advanced geochemical instruments ever sent to the surface of another planet (1). Curiosity’s mission is to spend two years testing rock samples from Aeolis Mons, a Martian mountain inside Gale Crater, to determine if Mars could have once supported life (2).
Curiosity, roughly the size of a car, generates its own power from a plutonium source. The rover is equipped with Mastcam, two high-definition cameras, and ChemCam, an instrument that can measure the chemical makeup of a rock after shooting the rock with a laser. Curiosity also has a seven-foot arm carrying a camera, X-ray spectrometer, drill, and scoop for analyzing samples on Mars (2). Despite its technological sophistication, Curiosity suffered a computer glitch in late February that temporarily knocked out its main system (3).
Though Curiosity successfully landed on Gale Crater, a site relatively near Aeolis Mons, it still has a substantial distance to go. The rover has been traveling at a careful but slow speed, approximately 100 yards per day. The remainder of its journey to the mountain will take about five to seven months more (4).
Scientists at NASA chose to land on Gale Crater because prior observations from orbit indicated the presence of clay minerals at the base of the mountain. Clay forms in water with neutral pH, making Gale a promising place to look for signs of past life on Mars. On a slight detour to its mission to the mountain, Curiosity managed to find such clays. These clays were formed on Mars under watery conditions reminiscent of Earth. “Unquestionably, Mars was a habitable planet in its ancient past,” said John Grotzinger, the mission’s project scientist (4).
Curiosity also discovered that each cubic foot of Martian soil contains roughly two pints of liquid water. Unfortunately, the water molecules are not accessible because they are tied to minerals in the soil. By weight, water comprises about two percent of the Mars soil. Curiosity obtained this data by taking a sample of Martian dirt, heating up the soil to 835°C, and measuring all of the volatiles, according to Laurie Leshin, science dean at the Renssalaer Polytechnic Institute and lead author of the paper that confirmed the presence of water in the soil (5).
In spite of the promising discovery of water on Mars, Curiosity also reported, with a device called the Tunable Laser Spectrometer, that the Martian atmosphere showed little to no signs of methane, a gas crucial to supporting life. Many microbes release methane as a waste product, and a lack of atmospheric methane may dim hopes that microbial life existed on Mars. However, “there are other microbes that do not produce methane, so there remains a possibility that there is subsurface microbial activity that is not emitting the gas,” said NASA scientist Chris Webster (6).
The next expedition to Mars is being planned by the European Space Agency for 2018. The mission, called ExoMars, will do more than simply analyze the geochemical makeup of Mars; it will be equipped to find life on Mars (6).
References:
1. J. Grotzinger, Analysis of Surface Materials by the Curiosity Mars Rover. Science. 341, 6153 (2013) Available at http://www.sciencemag.org/content/341/6153/1475 (5 Oct 2013).
2. J. Corum, Precision Landing on Mars. Available at http://www.nytimes.com/interactive/2012/07/31/science/space/0731-mars.html (5 Oct 2013).
3. M. Wall, Mars Rover Curiosity Resumes Science Work after Computer Glitch. Available at http://www.space.com/20391-mars-rover-curiosity-resumes-science.html (5 Oct 2013).
4. K. Chang, An Earth Year on Mars. Available at http://www.nytimes.com/2013/08/06/science/space/an-earth-year-on-mars.html (5 Oct 2013).
5. A. Jha, Nasa’s Curiosity rover finds water in Martian soil. Available at http://www.theguardian.com/science/2013/sep/26/nasa-curiosity-rover-mars-soil-water (5 Oct 2013).
6. I. Sample, Nasa’s Mars Curiosity rover finds no sign of methane, the gas linked to life. Available at http://www.theguardian.com/science/2013/sep/19/mars-curiosity-rover-finds-no-methane (5 Oct 2013).