SpaceX's first tourist flight seemed to go swimmingly last month, but there was a hidden problem beneath the floorboards.
That issue came from the bathroom — the toilet tucked away in the Crew Dragon spaceship's ceiling, which is shrouded in proprietary secrecy. A tube carrying urine from that toilet broke loose in an area beneath the spaceship's cabin floor, releasing its contents onto a fan. That fan is used to create suction for the toilet, which is necessary because when you're doing in microgravity, there's no force pulling waste in any one direction. The fan then sprayed the pee all over the hidden compartment.
Even though all of this happened in microgravity, the pee didn't drift into the cabin. That kept it away from the spaceship's four passengers: billionaire Jared Isaacman, geoscientist Dr. Sian Proctor, physician-assistant Hayley Arceneaux, and engineer Chris Sembroski. While they orbited Earth for three days, on a mission called Inspiration4, they didn't notice the issue, SpaceX representatives told reporters on Monday.
"We didn't really even notice it, the crew didn't even notice it, until we got back," SpaceX official Bill Gerstenmaier said in a press conference Monday, according to The New York Times. "When we got the vehicle back, we looked under the floor and saw the fact that there was contamination underneath the floor of Inspiration4."
A mechanical issue with the toilet fan had, however, set off an alarm while Inspiration4 was in orbit, prompting the passengers to troubleshoot, Isaacman told CNN Business in September. He did not reveal how they solved the problem. Upon the spaceship's return to Earth, SpaceX technicians opened the cabin floor to investigate the fan issue. That's when they discovered the pee leak.
As SpaceX CEO Elon Musk has promised on Twitter, the toilet system is getting an upgrade. SpaceX is redesigning the leaky tube beneath Crew Dragon's floor for its next launch, which will carry four NASA astronauts to the International Space Station this weekend. With the new upgrade, the tube shouldn't come "unglued" again, Gerstenmaier said.
Pee is also loose in another SpaceX spaceship
Another Crew Dragon capsule is currently attached to the space station, since it carried four astronauts to the space station in April and is waiting to carry them back to Earth in the coming weeks. But it has the same plumbing system as the capsule that suffered a leak.
Fearing the same toilet troubles, SpaceX asked the astronauts on the space station to snake a camera on a cable into the pee-tube compartment beneath the floor. Sure enough, they discovered the same issue as Inspiration4.
"Yes, there was some indication of some contamination under the floor," Gerstenmaier said.
That could be a more serious issue for this spaceship, which has been in Earth's orbit for nearly six months, and has presumably been carrying loose urine the whole time.
After astronauts pee, that urine gets mixed with a substance called Oxone, which removes ammonia so that it doesn't build up in the air. But Oxone can be corrosive, so SpaceX is investigating the possibility that the Oxone-pee mixture could have damaged the spaceship after months of floating around beneath its cabin floor.
SpaceX engineers tested this theory on the ground, Gerstenmaier said, according to the Times, by gathering some aluminum parts similar to those on the spaceship and soaking them in an oxone-urine mixture. The engineers put those parts in a chamber that imitates the humidity conditions of the space station. They left them there for "an extended period of time," Gerstenmaier said, though he did not specify for how long.
So far, SpaceX has not found significant corrosion in those samples.
"Luckily, or, on purpose, we chose an aluminum alloy that is very insensitive to corrosion," Gerstenmaier said.
He also noted that there is less urine inside the Crew Dragon capsule that's attached to the ISS, since those astronauts were only on the spaceship for about 24 hours before they docked to the space station.
SpaceX's on-the-ground testing is still ongoing.
"We'll double check things, we'll triple checks things, and we got a couple more samples we'll pull out of the chambers and inspect," Gerstenmaier said, according to CNN. "But we'll be ready to go and make sure the crew is safe to return."