But there is a possibility that residual underground lava tubes may still exist. HUM Images/Getty ImagesIf these lava tubes are anything like Earth's, they could be the perfect place for astronauts to hunker down during their stay on Mars. It's unclear if lava tubes on Mars would also be this warm — it's not a stretch to imagine, just a challenge to confirm. But to be clear, just because there could be life in these pits, doesn't mean Mars definitely hosts extraterrestrials. "This is a good place to look, but we don't know if there's life on Mars at all," Johnson said.

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Persons: —, Brandon Johnson, Johnson, George Rose, Ross Beyer, Beyer, there's, it's Organizations: Service, University of Arizona, Business, NASA, JPL, Scientists, Purdue University, Olympus, SETI Institute, Goddard, Arizona State University, Reconnaissance Locations: Arizona, Tharsis, Hawaii