The search for life on Mars shouldn't focus exclusively on the distant past, some researchers say.
Four billion years ago, the Martian surface was apparently quite habitable, featuring rivers, lakes and even a deep ocean. Indeed, some astrobiologists view ancient Mars as an even better cradle for life than Earth was, and they suspect that life on our planet may have come here long ago aboard Mars rocks blasted into space by a powerful impact.
Things changed when Mars lost its global magnetic field. Charged particles streaming from the sun were then free to strip away the once-thick Martian atmosphere, and strip it they did. This process had transformed Mars into the cold, dry world we know today by about 3.7 billion years ago, observations by NASA's MAVEN orbiter suggest. (Earth still has its global magnetic field, explaining how our planet remains so livable.)
But this turn of events doesn't necessarily mean that Mars is a dead planet today.
"If Mars had life 4 billion years ago, Mars still has life. Nothing has happened on Mars that would've wiped out life," said Michael Finney, co-founder of The Genome Partnership, a nonprofit organization that runs the Advances in Genome Biology and Technology conferences.
"So, if there were life on Mars, it may have moved around, it may have gone into hiding a bit, but it's probably still there," Finney said last month during a panel discussion at the Breakthrough Discuss conference at the University of California, Berkeley.
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