Sulphur in silence (Image: NASA/SPL)

THE footprint of life on Mars may have been plain to see all along in the sulphurous minerals that litter the planet’s surface. What’s more, the next Mars lander should be able to detect the evidence.

No mission to Mars has ever found complex carbon-based molecules, from which life as we know it is built. But sulphur is everywhere on Mars – it is more abundant there than on Earth – and it could contain one of the signatures of life. On Earth, the activity of some microbes converts one class of sulphur-containing compounds, …