New observations by NASA’s Curiosity rover suggest that microbial life could have survived on Mars in the distant past, when the Red Planet was a warmer and wetter place, scientists announced Tuesday (March 12).

It’s unclear exactly how long ago Mars’ habitability window opened up, researchers said. But the timing may be comparable to that of Earth, where life first appeared around 3.8 billion years ago.

“We’re talking about older than 3 billion years ago, and we’re probably looking at a situation where, plus or minus a couple hundred million years, it’s about the time that we start seeing the first record of life preserved on Earth,” Curiosity chief scientist John Grotzinger, of Caltech in Pasadena, said during a press conference Tuesday.