NASA astronaut Peggy Whitson sometimes has tears in her eyes when she says she will not return to space.
The former head of the International Space Station has registered a whopping 665 floating days in space, more than any other American.
From his radiant smile and his loud and frequent laughter, it is clear that he loved almost every aspect of work out of this world, from installing battery parts on the solar panels of the station to sampling mysterious space microbes
"Being part of the exploration in that very direct way," he told Business Insider, is "incredibly satisfying and rewarding."
But there is one aspect of life in space that Whitson says he will not miss: the toilet.
"The space station is not really a hotel yet," he said Tuesday, feet firmly planted on the floor inside a five-star hotel (equipped with a toilet) in New York.
"I would call it a camping trip."
The toilet in the ISS is not as bad as the diapers of the Maximum Absorbency Clothing that astronauts sometimes had to use on missions like the Apollo moon trips. But the $ 19,000 Russian-made toilet (seen here) is not exactly first clbad either.
"Urinating is relatively easy," says Whitson.
For that, the astronauts use a funnel equipped with a fan that sucks its pee so that it does not float. (See the yellow cone on the upper right side of this toilet photo? That's where the urine goes.) Then, it takes about eight days for the liquid to return to drinking water for the astronauts.
But Whitson says that if you have to do more than just urinate, things are not that simple.
"Number two … it's more challenging because you're trying to reach a pretty small target," he said.
ISS residents go to the bathroom in a small, plate-sized hole over the silver can, using the fan to vacuum vacuum feces. After the astronauts have finished, the poop is sealed in a plastic bag, waiting for the next day of space debris collection.
"After it starts to fill up," Whitson said with a grimace, "you have to put on a rubber glove and pack it."
Every once in a while, the whole process goes awry, or the toilet runs badly, and the astronauts have to catch a floating tumult.
But eventually, all that waste is destroyed on a cargo ship full of ISS trash, and sent on a fiery suicide mission into Earth's atmosphere.
"We send them on a trajectory that will intentionally burn," Whitson said.
Regarding urine, approximately 80 to 85% of that is recycled in drinking water, and the rest is converted into brine residue.
"We want a closed-loop system, which means we have to recycle all our water," Whitson said. Maybe that's the next home improvement project on board the ISS.
You can hear more of Whitson's story, from his roots on an Iowa farm to his trip to the cosmos, in the final episode of National Geographic's "One Strange Rock," which airs on Monday, May 28 at 10 pm This on the National Geographic channel.
If you're still puzzled about how the toilet actually works on the ISS, check out this video explaining the Italian astronaut Samantha Cristoforetti: