Life Beneath Enceladus’ Ice?

The Cassini probe reveals a chemical brew erupting from the Saturnian moon.

By Eric Betz|Wednesday, January 24, 2018
Michael Benson/Kinetikon Pictures

Alien microbes could, in theory, feast beneath the icy surface of Saturn’s moon Enceladus. In April, astronomers reported that the Cassini spacecraft had discovered a chemical brew erupting from Enceladus’ oceans — the same kind that bacteria eat at Earth’s hydrothermal vents. Discover talked with Hunter Waite, Cassini researcher and NASA’s program director of space science and engineering, to take us there.


Hunter Waite, Program Director of Space Science and Engineering, NASA

Southwest Research Institute

Q: What did we know about Enceladus before Cassini?
A: We knew nothing. We didn’t know anything about the vents. We didn’t know anything about the global ocean. We knew it was a small, icy moon in the Saturn system. But the Saturn system is full of small, icy moons.

Q: What would it be like flying along with Cassini over Enceladus?
A: The action happens pretty fast because you’re traveling at 7 or 8 kilometers per second. And [Enceladus] is pretty small — it's like the size of Arizona.

You’re getting pummeled by these little ice grains. As you’re flying over, you’ll see these geological features, these scars — little channels, basically — what we call the “tiger stripes.” Within those tiger stripes are the vents, straight from the global ocean. And above the surface of the ocean, a splash comes up — you can imagine a splash from a wave — that will instantly freeze. That’s what creates these grains. These have information about the salt content of the ocean and some of the organics that are present there.

Q: How close did Cassini get?
We went really close. It was about 50 kilometers — the closest flyby over the tiger stripes. We could look at the chemical balance and determine that the [hydrogen] we saw was sufficient to provide food for microbes. The obvious message is let’s go back and try to find life.

Q: At this point, would you be surprised if we didn't find life on Enceladus?
A: I would be a bit surprised, yes. But I would be happy to find the answer one way or the other because I think both — whether you find it or not — will lead to a better understanding of how life arose on Earth and what it really means.

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