NASA has released new findings from the Mars rover Curiosity about nitrogen on the planet. Assistant Professor James Wray, a co-author on the paper, is a member of Curiosity SAM (Sample Analysis at Mars) instrument team and has been contributing to the search for surface nitrogen. He’s also a marathon runner, which means he has something in common with another rover currently on Mars.
Nitrogen is a component of the DNA, RNA and proteins in all known, living organisms. It is one of the most abundant gases in the Martian atmosphere. But, as on Earth, this atmospheric nitrogen is bound up in molecular N2, a form unusable by biology. This is why, even in Earth's thicker atmosphere dominated by nitrogen, we still use fertilizers to provide usable nitrogen to plants and soils. What SAM has now shown us for the first time is that Martian soils are already "fertile" in this sense, and that the previously reported habitable lake environment that the rover found early in its mission had even higher concentrations of biologically available nitrogen. Whether there were organisms around to use that nitrogen remains unknown, for now.
This week also brought a milestone for Opportunity, the other rover currently rolling across Mars. It has now done a marathon on the planet, covering 26.22 miles (42.197 kilometers). This milestone is significant to me for two reasons. Scientifically, it means that we have reached the promised land! Back in 2009, I published a paper reporting rocks on Opportunity's distant horizon that contained clay minerals, which require abundant water to form and date to an era more ancient and habitable than any we had studied previously on Mars. It seemed unlikely then that aging Opportunity – certified by the Jet Propulstion Lab for only 600 meters of driving – would survive the additional 12 kilometers to even the nearest, weak clay signatures that we found. But she has exceeded even that optimistic hope by going several kilometers farther to reach the place we now call Marathon Valley, site of the strongest clay signatures in this region of Mars. The rocks here already look different from any encountered in Opportunity's first 11 years on Mars, and we have much more to learn at this site.
It must be mentioned in this context that the White House's proposed budget contains no funding to continue operating Opportunity, and two weeks ago NASA's Administrator surprisingly described this rover to a Senate Subcommittee as a "mission whose time has passed." But the scientific community came to the exact opposite conclusion just last year, in its formal review of ongoing missions that rated Opportunity's plan for continued Mars study more scientifically promising than any other Mars mission, including Curiosity. So while I am undoubtedly biased by the rare thrill of getting to see close-up photos and other data returned from a place on another planet that I helped to choose, I am far from the only scientist hoping that Congress will make the rational choice to keep driving Opportunity for as long as she obeys our commands.
Opportunity's marathon is also significant for me on a personal level. Three months ago, I achieved my childhood dream of running a marathon. Fittingly, it was the "Rocket City Marathon." The final few miles were tougher than the rest of the distance combined, and Opportunity's experience on Mars was not too different. So I can personally attest that this is a very long distance to travel. But with no disrespect to Opportunity, I did finish my marathon quite a bit faster, taking just over four hours instead of 11 years. This illustrates the vast acceleration in Mars science that would come from one day having humans explore its surface in person, but of course the cost of such a mission will be equally vast. Still, I would love to see the day when robots aren't the only breed of Earthlings running marathons on Mars.
Image Credit: NASA/JPL-Caltech
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