Mars has never looked more like a planet built for hiding secrets. A cluster of eight vast, water-carved caves appears almost engineered to shield fragile chemistry, or even biology, from the brutal ...

Mars once had sprawling river systems that rivaled major watersheds on Earth, and scientists have now identified the biggest ones for the first time. Researchers mapped 16 massive drainage basins ...

In a quiet corner of an ancient riverbed on Mars, a speckled rock has pushed the search for extraterrestrial life into its most tantalizing phase yet. NASA now says the layered stone, drilled by the ...