The measurement deepens the mystery of why a European Space Agency probe sent to Mars to nail down the origins of the planet’s methane has so far found no traces of the gas. After noticing the methane surge in data beamed back to Earth last week, mission scientists commanded the rover to perform follow-up experiments over the weekend. The methane spike was recorded by the rover’s sample analysis at Mars (SAM) tunable laser spectrometer. “With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern,” said Paul Mahaffy from Nasa’s Goddard Space Flight Center in Greenbelt in Maryland, US. If any life exists on the planet, it would probably have to be sheltering deep underground. While Mars was once warm and home to coursing rivers and giant lakes, it is now exceptionally dry and battered with intense radiation. But methane can have far more mundane origins than microscopic Martians, such as reactions between water and certain types of rock, and Nasa’s rover cannot distinguish between these. The latest measurement has excited some Mars enthusiasts because on Earth, much of the methane in the air comes from living things that release it one way or another as waste gas. Curiosity touched down on the red planet in August 2012 and has recorded a number of sharp spikes in methane and a fluctuating background level of the gas that appears to rise and fall with the seasons.

New findings on mars