Posted by tourdemars to Life on Mars at August 9, 2004 10:26 AM

A future astronaut traipsing across the landing sites of the Mars Exploration Rovers – Spirit and Opportunity – might be squishing into a welcome mat of microbes, according to one NASA scientist. While the twin robots push ahead in scouring their real estate locations at Gusev Crater and Meridiani Planum, they leave behind a tantalizing trail of issues that need to be sorted out. One big unknown: Did life ever take root on Mars? And if so, is that planet home to living organisms today? So far, the life-on-Mars card has not played out. Rover scientists have seen nothing they regard as needing a biological explanation.