Space Propulsion Made Easy: Eat Beans

I didn't know the U.S. Department of Agriculture once had a "flatus researcher." He turns up in a new book Packing for Mars from the deliciously naughty Mary Roach.

An astronaut floats in space.
Robert Krulwich/NPR

His name was Edwin Murphy, and at a 1964 Conference on Nutrition in Space and Related Waste Problems, he suggested that the ideal astronaut should be totally flatus-free. Travelers in outer space locked together in small capsules could create safety problems if the methane content of their ... you know what I'm talking about ... was above normal. Methane, he warned, is flammable and so, to reduce the chance of sudden fires, he thought it best if NASA could find astronauts who emitted no methane at all. They could fart, but they shouldn't fart methane. In fact, he announced, he had discovered such people. They exist.

As Mary Roach describes it:

"Murphy reported on research he had done using an 'experimental bean meal' fed to volunteers who had been rigged, via a rectal catheter, to outgas into a measurement device. He was interested in individual differences —  not just in the overall volume of flatus, but in the differing percentages of constituent gases. Owing to differences in intestinal bacteria, half the population produces no methane. This makes them attractive as astronauts."

Then, in what I have to think was a startling turn, Dr. Murphy told the conference that not only had he found a large population of methane-free individuals, but he had met someone who was TOTALLY FLATUS FREE.

Said Murphy, "Of special interest for further research was the subject who produced essentially no flatus on 100 grams dry weight of beans."

Space propulsion
Robert Krulwich/NPR

An average person, Roach explains, "will, during the peak flatulence period (five to six hours post-bean consumption) pass anywhere from one to almost three cups of flatus per hour. At the high end of the range, that's about two Coke cans full of fart. In a small space where you can't open the window."

Murphy told the conference that a team of no-emission astronauts would so lower the danger of sudden fire and create a more harmonious environment, he thought the U.S. space program should look for astronaut candidates who fit his flatus-free profile.

Alas, his recommendations, it seems, were ignored.

Instead of looking for low-emission astronauts, NASA banned flatulence-inducing foods like beans, cabbage, sprouts and broccoli. They were not allowed on NASA's flight menu for a long while.

But Roach says farting in space is still something astronauts talk about, particularly guy astronauts. On all-male flights, she says, she's heard of improvised experiments. Weightless, the astronauts remove their garments when they feel a big blow coming and, to quote American astronaut Roger Crouch, use intestinal gas as a propellant to, "launch themselves across the middeck."

Roach e-mailed Roger Crouch to ask if this had ever really happened. He was coy:

"He had heard the claims and was dubious.  'The mass and velocity of the expelled gas,' he told me in an e-mail that has forever endeared him to me, 'is very small compared to the mass of the human body.' Thus it was unlikely that it could accelerate a 180-pound astronaut. Crouch pointed out that an exhaled breath doesn't propel an astronaut in any direction, and the lungs hold about six liters of air versus the fart, which, as we learned from Dr. Murphy, holds at most three soda cans worth."

Exhaling air.
Robert Krulwich/NPR

But then Crouch confessed:

"My genes have blessed me with an extraordinary ability to expel some of the byproducts of digestion," wrote Crouch. "So given that, I thought it should be tested. In what I thought was a real voluminous and rapidly expelled purge, I failed to move noticeably."

So now we know. You can't fart your way across a weightless space.

Though Roach warns that Roger Crouch's experiment had a flaw. He kept his pants on:

"Crouch surmised that his experiment may have been compromised by the 'action/reaction of the gas passing through the pants.' Disappointingly, both his flights were mixed gender, so Crouch was disinclined to 'strip down naked' and try it again."

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