SpaceX’s Latest Engineering Challenge: A Leaky Toilet
A discussion of repairs of the waste management systems used aboard the company’s passenger spacecraft offered rare insight into how it fixes things.,
NASA can’t call a plumber from orbit. So before a SpaceX vehicle can launch four astronauts to the International Space Station on Sunday, agency officials need to be sure the spacecraft’s faulty toilet is fixed.
SpaceX ran into trouble with the toilet system of Crew Dragon, its astronaut capsule, last month during Inspiration4, its first mission carrying a fully private crew of four people to orbit. At some point during the three-day mission, there was a problem with Crew Dragon’s toilet.
The nature of the toilet problem, though, seemed cloaked in secrecy. Mission managers deflected when pressed for details. SpaceX didn’t respond to questions for comment. Scott Poteet, the mission’s director on Earth, said in a news conference with reporters only that there were “issues” with the capsule’s waste management system.
Jared Isaacman, the Inspiration4 mission commander, told CNN, “Nobody really wants to get into the gory details.”
Crew Dragon has more interior space than a minivan, but less than a studio apartment, and there is no proper bathroom. Instead, it has a device on its ceiling that astronauts use to relieve themselves — remember, there’s no up or down in microgravity. The device creates suction using an internal fan, crucial to ensuring human waste goes in the right direction in the weightlessness of space. Some officials vaguely said the toilet problem involved the fan, prompting even more questions.
A closely held secret no more.
A tube that funnels urine into a tank broke loose during the Inspiration4 mission and leaked into the fan, which sprayed the urine in an enclosed area beneath Crew Dragon’s floor, Bill Gerstenmaier, a SpaceX official who once oversaw human spaceflight for NASA, told reporters on Monday night. He said the four passengers didn’t notice anything was wrong during the mission.
“We didn’t really even notice it, the crew didn’t even notice it, until we got back,” Mr. Gerstenmaier said. “When we got the vehicle back, we looked under the floor and saw the fact that there was contamination underneath the floor of Inspiration4.”
SpaceX completed a fix for the toilet aboard the capsule being used for Sunday’s launch. The redesign means there are no tubes that could come “unglued” as they did during the Inspiration4 flight, Mr. Gerstenmaier said. NASA is expected to sign off on the new design on Friday.
But the toilet predicaments haven’t stopped there. Another Crew Dragon capsule that docked to the space station in April with four astronauts aboard has the same plumbing system as the Inspiration4 capsule. SpaceX engineers feared the same “contamination” might have occurred on that spacecraft.
The engineers’ suspicions were correct.
NASA astronauts living on the station snaked a borescope device — a cable with a tiny camera at the end — underneath the capsule’s floor and discovered traces of urine in places it shouldn’t be, Mr. Gerstenmaier said. “Yes, there was some indication of some contamination under the floor,” he said.
That raised new concerns. In space, urine is mixed with a potentially corrosive compound, oxone, to eliminate ammonia. Could the oxone-laced urine, sitting in the capsule for months, have corroded any crucial hardware?
To answer this question, Mr. Gersteinmaier said, SpaceX engineers on Earth gathered aluminum parts similar to those on the spacecraft and created a sampling of urine mixed with oxone. They soaked the parts and placed them inside a chamber that mimicked the humidity conditions aboard the space station for “an extended period of time,” Mr. Gerstenmaier said.
The wayward waste inside the Inspiration4 capsule was more voluminous than the contamination found on the capsule attached to the space station, he said, because the passengers used the capsule for three days while astronauts launching to the space station are typically in orbit for about 24 hours. The results of the ground tests appear positive so far, he said: “Luckily, or, on purpose, we chose an aluminum alloy that is very insensitive to corrosion.”
That capsule is scheduled to undock from the station in November and return home with the four astronauts it delivered in April. The ground tests with the oxone and urine are continuing.
“We got a couple more samples we’ll pull out of the chamber,” Mr. Gerstenmaier said. He did not say who provided the samples.
Mr. Gerstenmaier’s discussion of SpaceX’s toilet investigation offered a rare peek into how a private space company discovers, studies and fixes an engineering problem on multibillion-dollar spacecraft. There have been limits to public insight into new and often risky space vehicles as NASA puts much of its space transportation abilities into the hands of private companies, operating under contracting models that aim to slash the cost of sending people to space.
Toilets are crucial to NASA’s space exploration ambitions as the agency aims to trek beyond the space station, toward the moon and eventually Mars. Last year, the agency launched to the space station a new $24 million toilet, the Universal Waste Management System. It uses a suction method similar to Crew Dragon’s, mixing urine with an acidic solution before recycling the liquid for drinking water. (Solid waste is disposed of in bags that are stored and eventually fired into space.)
Space toilets have evolved considerably since human spaceflight began. For Mercury, the first U.S. program, male astronauts urinated into an inflatable, cone-shaped cuff. The fluid would travel down a tube into an expandable bellows system that would often malfunction and overflow, because the container had to be extended manually while an astronaut was using it. “The assistance of the other crewman was required,” one NASA document said.
Waste management during the Apollo moon missions was similarly hectic. During the Apollo 10 mission, solid waste escaped the capsule’s pump-action toilet system and floated around the capsule. NASA astronauts who landed on the moon left bags of toilet waste behind.
Asked on Tuesday about changes to Crew Dragon’s toilet system, Raja Chari, the NASA astronaut who is commanding Sunday’s mission, said he was confident with the agency’s approval of SpaceX’s new system.
“More data is always good and the safer we can make spaceflight, the better,” Mr. Chari said.