"Water that has been trapped in rock for more than a billion years... might contain microbes that evolved independently from the surface world..."

"... and it's a finding that gives new hope to the search for life on other planets."

"It's managed to stay isolated for almost half the lifetime of the Earth," [said Greg Holland, a geochemist at Lancaster University in England]. It's a time capsule. And it doesn't just hold water. "There's a lot of hydrogen in these samples."

That's significant because hydrogen is food for some microorganisms. Hydrogen-eating microbes have been found deep in the ocean and in South African mines where chemical reactions in the rock produce a steady supply of hydrogen. And that hydrogen, says Holland, "could provide the energy for life to survive in isolation for 2 billion years."

Now, do you see why we need to go to Mars?

Or do you think that we ought to start worrying about alien microbes liberated from the depths of Earth?