Here’s what space toilets can teach us about finding signs of alien life

Waste flushed from space shuttle simulates the plumes of icy moons, one scientist suggests


SPACE SPEW  The same process that forces water out of flushed toilets on the space shuttle also applies to the gushing vents on Saturn’s moon Enceladus (shown).

SSI/JPL/NASA, Emily Lakdawalla (mosaic)

The search for life may get an assist from the call of nature. Astronomers can learn how to study the plumes of subsurface ocean water spewing from icy moons like Saturn’s Enceladus from an unlikely source: Space toilets.

Future spacecraft might scoop up samples of Enceladus’ plumes. Figuring out what to expect is tricky: It’s hard to replicate the plumes in Earth-based labs. But astronauts have already done natural experiments in venting water to space, Ralph Lorenz, a planetary scientist at Johns Hopkins University, pointed out October 17 at an American Astronomical Society meeting in Provo, Utah.  

Candid discussions of space waste are scarce in the scientific literature. “It’s very hard to find this stuff written down,” says Lorenz, who is designing future missions to Saturn’s moons. “I don’t know if the human spaceflight community is squeamish about it.”

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KNOCK IT OFF An ice crystal that formed from venting fuel cells during the first flight of the space shuttle Discovery in 1984 grew so long it had to be knocked off with a robotic arm. NASA

But there are clues. For instance, during the 1984 flight of the space shuttle Discovery, a 60-centimeter icicle grew from a fuel cell vent. That process could hint at how big ice particles in plumes can grow.

And dents on the Japanese Space Flyer Unit, retrieved from orbit by the space shuttle Endeavour in 1996, revealed traces of phosphorus and sulfur. Those may have been from urine ice particles flushed from Endeavour that rained on the spacecraft, an analysis published in 2000 in Advances in Space Research suggested. That might be good news for finding biosignatures at Enceladus — molecules associated with life could be preserved in ice from the plumes.

Lisa Grossman is the astronomy writer. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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