Chief Scientist for the Mars rover Curiosity mission, John Grotzinger, dropped a bombshell when NPR reporter Joe Palca dropped by for a visit: exciting data was streaming in from a soil sample recently loaded into Curiosity's Sample Analysis at Mars (SAM).
EarthshakingPalca refers to the data as "earthshaking." He quotes Grotzinger:
This data is gonna be one for the history books. It's looking really good.
But then Grotzinger sealed his lips. Sharing exciting data does not trump making sure that data is verifiable. So we are left to speculate: what could Curiosity have found? And will it be for real this time?
Grotzinger certainly knows the disappointment of seeing exciting speculation backfire when results cannot be reproduced. SAM already returned results showing methane in the Martian air; the simple organic molecule can be a sign of life as it is emitted by simple organisms. But when scientists cleaned the equipment and measured again, the methane could not be found. The risk that the methane was imported to Mars from air at Cape Canaveral cannot be ruled out.
If the news is really as earthshaking as Palca suggests, NASA must proceed cautiously. No one wants this to turn out like the Martian meteor sampled in 1996. The discovery of organic compounds in that space rock triggered President Clinton to hail the pending confirmation that we are not alone in the universe: "Today, rock 84001 speaks to us across all those billions of years and millions of mile. It speaks of the possibility of life. If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered."
The discovery was not confirmed.
What Could Curiosity Have Found?Short of a photograph of little green men extending a hand in greeting to the robotic rover, Curiosity lacks the equipment to send back actual proof of life on Mars. The SAM is equipped with a mass spectrometer, a gas chromatograph, and tunable laser spectrometer. These instruments excel at breaking down and separating out the atoms in a sample, but cannot identify even something as evident as a fossil in the soil.
The data SAM feeds back to the NASA team on Earth will be subject to interpretation. Even if the rover finds definitive proof of complex organisms -- for example, traces of DNA or RNA or even complex proteins -- the data will return as a set of peaks showing a distribution of atoms that might be consistent with the discovery of such indicators of life.
Most likely, the rover has again found methane. The photo shows tracks on the Martian soil where Curiosity's robotic arm scooped up five samples. Dust and sand from the first scoops was used to clean out the sampling chamber and handling surfaces, to reduce the risk of contamination brought from Earth.
If the data flowing into NASA's labs indicates the presence of methane, NASA will attempt to replicate the finding. With luck, the news will be ripe soon. Grotzinger told Space.com that NASA plans to announce the news at the next meeting of the American Geophysical Union, scheduled the first week of December in San Francisco.