The 2004 discovery of methane means that either there is life on Mars, or that volcanic activity continues to generate heat below the martian surface. Now, the ESA plans to find out which it is.Either outcome is big news for a planet once thought to be biologically and geologically inactive. The methane mystery started soon after December 2003, when ESAs Mars Express arrived in orbit around the red planet. As the Planetary Fourier Spectrometer (PFS) began taking data, the instrument team saw a puzzling signal - as well as the atmospheric gases they were anticipating, such as carbon monoxide and water vapour -they also saw methane.
展开▼
