Is there methane on Mars?NASA/JPL-Caltech/MSSS By Daniel CossinsNASA’s Curiosity rover has sniffed out methane on Mars again – and this time it offers a unique opportunity to confirm that the Red Planet’s atmosphere really does contain the gas, which is usually produced by living things. The latest measurement, taken last week at Gale Crater, is the largest amount of methane ever discovered on Mars. But the concentration of methane is not the most exciting thing about the latest finding. It turns out that two satellites were observing the area at roughly the same time Curiosity made this measurement. That gives researchers the best chance ever to confirm using independent scientific instruments that there is methane on Mars. Advertisement “This is what we have been waiting for,” says Marco Giuranna at the National Institute for Astrophysics in Italy, who leads the team behind the methane measurement device on the Mars Express probe, which has been orbiting Mars since 2003. “The data is still to be analysed, and not all of it has reached Earth yet. But we are very excited.” Sign of life Planetary scientists are interested in methane on Mars because it could be a sign of life. Although it can be produced by geological sources, on Earth the vast majority of the gas is pumped out by microbes and other living things. Although we have spotted tantalising glimpses of methane on Mars a few times over the years, it has been difficult to confirm the detections with other instruments. Some sort of destruction mechanism might quickly remove methane from the lower atmosphere, but the uncertainty has led to scepticism about past methane sightings. This time could be different. Giuranna says that Mars Express just happened to have its spectrometer trained on Gale Crater for an extended period, a technique known as “spot rigging”, around 20 hours before the rover made its detection on the ground, as well as a day later. “We typically have a couple of spot rigging events per month, so we were lucky here,” he says. Another satellite called the Trace Gas Orbiter, which boasts two instruments capable of detecting methane, also has data from the same area on the same day. Unique opportunity “This is the first time we have Trace Gas Orbiter observations so close in time and space from detection of methane on Mars,” says Giuranna. “This is a unique opportunity to check this detection with four different instruments.” Curiosity was instructed to carry out follow-up air-sampling experiments over the weekend. The results were expected today. NASA’s press office told New Scientist that the research team will need more time to go over their data before sharing more findings. It will still be difficult to say what generated the gas. Neither Curiosity nor the remote sensors on probes orbiting Mars can directly answer that question, says Giuranna. But the first step to understanding the origin of methane would be to pinpoint the region where it was released, and confirmation that this latest detection is real would give the Mars2020 rover, which is equipped with a drill, a potential new target. “Mars is too cold for life to be easily formed on the surface because water is not stable in liquid form,” says Giuranna. “With Mars2020, we will be able to drill down not more than 2 metres but this could be enough to find a new environment below the surface where life could form.” More on these topics: Mars alien life
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