Ask the Astronaut: Do you believe there’s life on other planets?

Just some of the stars at the center of our own galaxy, the Milky Way. (NASA/STScI)

Q: Just curious if you believe there is life out there on another planet besides Earth. (Tom McDonnell, Birdsboro, Pa.)

I believe we’ll soon find life right here in our own solar system. Mars once had a warm, Earth-like climate, with a protective atmosphere and liquid water on the surface. Microbes from these early days might still survive on Mars in today’s harsh conditions by inhabiting hot springs or in warm aquifers and rocks below the surface, where there is energy, water, and probably organic material—the conditions for life as we know it.

Europa, a moon of Jupiter, and Enceladus, a moon of Saturn, have oceans of liquid water below their icy crusts. In these dark oceans, warmed by the tidal tug of their parent planets, life might exist in the mix of organic chemicals deposited there by impacting asteroids and comets. If we don’t find life in our own solar system, our Milky Way galaxy has an estimated eight billion Earth-sized worlds that orbit in their parent stars’ habitable zones—that region where liquid water can exist on a planet’s surface. I like those odds.

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About Tom Jones

Former astronaut Tom Jones is a scientist, author, and pilot. In more than eleven years with NASA, Tom flew on four space shuttle missions to Earth orbit. On his last flight, he led three spacewalks to install the centerpiece of the International Space Station, the American Destiny laboratory. He has spent 53 days working and living in space. He is is currently writing “Space Shuttle Voices,” recording astronaut experiences during the space shuttle’s 30-year career. See his full bio here.

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