Mary Roach - Packing for Mars

THERE IS NO WAY to anticipate a phenomenon like fecal popcorning. Some things you can’t know until you get into orbit. That’s why toilets, like everything else that flies in space, get hauled up on a parabolic flight for testing. In this case, the testing poses unique challenges.

Along these lines. Late yesterday afternoon, I got the idea that I wanted to try out the Space Shuttle training toilet. I was already scheduled to meet Broyan and Weinstein and my escort from the public affairs office at noon the next day. Nine A.M., absolute latest I can do, said my colon. I called Gayle Frere, my public affairs escort, to try to explain my dilemma and reschedule for first thing in the morning. I caught her at her grandson’s graduation, where she had to yell over the noise. I pictured her husband turning away from the festivities to ask what was going on. I imagined Gayle shouting into his ear. It’s that writer. She wants to crap in the shuttle toilet! I apologized and quickly hung up.

My meandering point being that to schedule an evacuation even within a matter of hours can be awkward. Imagine trying to do so on cue within a twenty-second window of weightlessness. Retired NASA food scientist Charles Bourland was once on board a parabolic flight with a group of engineers testing a zero-gravity-toilet prototype. The toilet had a partial screen set up around it, but Bourland could see the man. “It was number two,” he told me. “He was all primed to do his thing but couldn’t deliver at the appropriate time. There was a lot of joking and yelled words of encouragement,” though not from Bourland, who was fighting motion sickness while testing and sampling seventy-two new Skylab foods, including creamed peas and beef hash, and did not need any additional inducement to throw up.

Some of the testing done in weightlessness has been of a more exploratory nature. “As queer as it sounds, if you want to manage what comes out the back end, you gotta understand what it’s doing,” said Hamilton Sundstrand engineer Tom Chase, whom I ran into on a simulated moon expedition in the Arctic. Chase was wearing his spacesuit hat that week rather than his toilet hat, but he was game to chat shit. “For instance…” Chase began drawing on a pad of Hamilton Sundstrand graph paper balanced on his knee. “Without gravity to pull things straight, they tend to curl as they’re coming out.” [87] Rethke called this the “orange peel effect.” The term also refers to a defect in a spray-painted surface, most typically the finish on a car. Either way, the auto body guy owes you an apology. This was documented by NASA and Hamilton Sundstrand toilet engineers that day in a series of 16-mm films. Thanks to this work, aerospace waste collection systems engineers are not only aware of the curl, they know its range of curvature and most likely direction (backward). They know that the softer ones, up to a point, curl more. Why would they need to know all this? Because the curl can gum up the top of the transfer tube and compromise your air flow.

The films featured both male and female volunteers, the latter consisting of, said Chase, “some gals in the nurses’ corps.” The footage was classified as limited distribution but, according to Hamilton Sundstrand folklore, regularly traveled beyond its prescribed limits. Pretty much “anybody with a buddy in waste management design” saw them, said one of Chase’s colleagues. “They were very, very popular, those films.”

Eventually someone who saw the shit also saw the potential for it to hit the fan. “You can imagine the reaction,” said Chase— What if someone does a FOIA on these! (FOIA stands for Freedom of Information Act, whereby journalists and the public can request copies of unclassified government documents.) The films were destroyed. Chase waxed melancholy about their demise. He is part of the team that had been working on toilets for lunar missions. “It’s unfortunate because we were going through this phase here where it would be highly useful to us.”

Don Rethke said that the far trickier engineering problems—and thus the bulk of the footage—involved urination. For one thing, liquid tends to adhere to the body in space. “When gravity goes away,” says Rethke, “surface tension is the next physical force.” Even on a human hair, surface tension makes liquids cling. Rethke said that people with longer hair can, in zero gravity, hold two to three liters of water in their hair. NASA needed to know the extent to which pubic hair was compromising female “velocity potential.” (Scott Weinstein helpfully describes this as how easy it is to “write your name in the snow.”)

Chase began sketching again. “You don’t just urinate and get a perfect cylindrical outflow, if you’ve ever kind of observed what’s going on. With gals, there’s more in the way of getting a pure stream.” I.e., labia and pubic hair. And a weakened stream tends to break apart and form floating blobs. Then Chase told me something quite stunning. He said he’d known women who, while out hiking or backpacking, are “able to take their pants down to their ankles and kind of lean back against a tree and just by moving things around a little bit, getting some room there, be able to fire away and direct it.” There was a silence while I contemplated this new and life-changing information. Chase went on. “I’m telling you, women can pee harder than men. But you got to be willing to manipulate the anatomy. There’s just some ladies who are more comfortable exploring what is possible than other ladies.”

No kind of lady, regardless of comfort level, wants an audience of male toilet engineers and their cronies. Eventually the nurses got wind of what was happening and refused to participate in any more filming. Hamilton Sundstrand was forced to get creative. “One of the guys had a really hairy stomach,” said Chase, and here he leaned back in his chair and stuck out his belly. “If he went like this…” He placed a palm on either side of his stomach and pushed in toward his belly button, such that it was possible to imagine a vertical fold appearing in the flesh beneath his shirt. “…he got about the right look. So in zero G they could spray him with ersatz [urine] solution and film it and they could understand about the droplet formation.” Chase released his gut. “That’s good thinkin’.”

THERE ARE OTHER WAYS to test a zero-gravity toilet. “At NASA Ames Research Center, we have undertaken the task of developing human fecal simulants,” writes Kanapathipillai “Wiggy” Wignarajah in a 2006 technical paper. Wignarajah is surely the most sophisticated thinker in this realm, but he is not the first. Others before him—in, for instance, the commercial diaper industry—have employed brownie mix, peanut butter, pumpkin pie filling, and mashed potatoes. Wignarajah pooh-poohs these efforts, as none of these substances comes close to approximating, as he puts it, “how human feces will behave”—i.e., its water-holding properties and its rheology. Rheology , in food science, refers to the study of consistency. Consistency is determined by things like viscosity and elasticity. Food technologists have special equipment designed specifically to measure these things, and if they are smart, they will not lend them out to anyone at NASA Ames.

A simulant made from refried beans gets respectable scores from Wignarajah. Though the protein content is too high and thus the water-holding properties are off, the beans are said to look and behave so much like human stool that future visits to the tacqueria have, in my mind anyway, been forevermore altered. The bean-based simulant designers hail from “Umpqua,” and by this I assume Wignarajah means Umpqua Community College and not the Umpqua Bank or the Umpqua Indian Tribe.