ORLANDO, Fla., July 15 (UPI) -- SpaceX announced Monday that the explosion of its Crew Dragon space capsule during an April test in Florida was due to the failure of a titanium valve.
The explosion put the schedule for a crewed flight of SpaceX missions to the International Space Station in doubt.
Hans Koenigsmann, vice president of mission assurance for SpaceX, said sending people up in a Dragon capsule this year still was possible, but would require a lot of things to go right in the remaining months.
SpaceX and Boeing are working on competing capsules to send people to the space station from U.S. soil -- which hasn't happened since the space shuttle program ended in 2011. The nation has been relying on purchased Russian Soyuz capsules, launched from Kazakhstan.
"Lessons learned from the test -- and others in our comprehensive test campaign -- will lead to further improvements in the safety and reliability of SpaceX's flight vehicles," a company statement said.
Koenigsmann said the SuperDraco thrusters, which are a key part of its crewed capsule propulsion system, were not part of the problem.
Known as a check valve, the component that failed has been replaced and is being tested in the company's remaining capsules with a type of seal that would prevent the same problems, the company said. The accident investigation team had found evidence of burning within the valve, which was recovered from debris of the explosion.
Titanium used in the valve has a notorious history for exploding in industrial settings when heated to super-hot temperatures, usually in the presence of water moisture, according to an article published by the Minerals, Metals & Materials Society.
Kathy Lueders, NASA's commercial crew program manager, emphasized that approving a spacecraft to carry people is a lengthy process that requires many test flights.
"I know everyone would like to say, this is when we're going to fly, but we're headed into a really critical time for testing, and we might learn things," Lueders said in a news conference.
She said the two astronauts designated to fly on the Dragon, Bob Behnken and Doug Hurley, visit SpaceX facilities often.
"They also are veterans of spaceflight" and understand how testing provides information about spacecraft development, Lueders said. "I think they really appreciated SpaceX's openness."