Nasa's Curiosity rover has detected organic molecules in a dried lakebed on Mars, including five never before seen on the red planet. The compounds, widely considered building blocks for life, were found in the Gale crater near the equator and are thought to have been preserved for 3.5 billion years.
The robotic rover's analysis cannot determine whether the organic matter stems from ancient life, meteorite impacts, or geological processes. 'Is it life? We can't tell, based on this information,' said Prof Amy Williams, an astrogeologist at the University of Florida and a Curiosity mission scientist who led the experiment. 'We think we're looking at organic matter that's been preserved on Mars for 3.5bn years.'
The findings suggest that if microbial life ever existed on Mars, chemical fingerprints could have survived the harsh surface conditions, which include extreme cold and intense radiation. 'For a long time, we thought that all organic matter was going to be seriously degraded by that harsh radiation environment,' Williams explained. 'It's really exciting to see that large complex material can survive in the subsurface environment.'
Among the molecules identified was benzothiophene, a sulphur compound often delivered by meteorites. The experiment also hinted at a nitrogen-bearing organic compound with a structure similar to precursors to DNA. However, Williams cautioned that such compounds can form geologically and are 'just the bricks, not the house.'
The discovery boosts hopes for the European Space Agency's Rosalind Franklin mission, scheduled for 2028, which will drill deeper and perform more sophisticated tests to assess the origin of organic chemicals on Mars. The research is published in the journal Nature Communications.
