It was a sensation when scientists discovered methane in Mars’ atmosphere nine years ago. Many saw the presence of the gas as a clear indication of life on the inhospitable planet, as on Earth methane is produced predominantly by biological processes. Others assumed geological processes, such as volcanoes, to be the cause. Researchers have now been able to show that methane escapes from a meteorite if it is irradiated with ultraviolet light under Martian conditions.