NASA and SpaceX have sent off the latest batch of astronauts to visit the International Space Station, with the launch of the Crew-8 mission late last night. The SpaceX Dragon spacecraft launched from Launch Complex 39A at NASA’s Kennedy Space Center in Florida just before 11 p.m. ET on Sunday, March 3, but there was a risk during that the launch might have been cancelled due to a crack discovered in the hatch seal of the spacecraft around 30 minutes before liftoff.
This morning, NASA shared further details about the crack and why they were confident in letting the launch go ahead.
While engineers were doing a final check of the hatch following its closure, including taking photos of the seal, they noticed a crack in the RTV (a type of silicone), which acts as a top coating on the hatch seal. The crack is estimated to be 0.02 square inches, and a crack would have to be more than twice that size to be enough to prevent the launch.
“This is one of multiple redundant seals in this area. It’s kind of a top coating over the pressure seal, which is then over the main seal for the hatch,” explained Sarah Walker, director, Dragon Mission Management, SpaceX. “This material expands under heating so we expect that actually a defect of this size would self-heal during the launch process.”
Following consultation between NASA and SpaceX, “We felt comfortable and confident safely proceeding into today’s launch,” Walker said. Although SpaceX vehicles are designed to be reusable, SpaceX representatives said this crack was not due to reuse. The coating in question is reapplied each time the Dragon spacecraft is used, so the crack was due to a minor defect in the application process.
One reason that the crack was not judged to be a safety problem is that the seal is located on the leeward side of the vehicle, so it receives less intense heating than other areas. “The engineers went back and looked at the heating in this particular area on the top part of this hatch seal, and that heating wasn’t anything that would be of concern with this size defect,” said Steve Stich, manager of NASA’s Commercial Crew Program.
Stitch added that NASA had been in consultation with SpaceX throughout the countdown process and did have the authority to stop or delay the launch if there were safety concerns, but was okay to proceed in this case. “Our guys agreed with SpaceX” that the defect wasn’t a safety concern, he said.
The Crew-8 astronauts are currently on their way to the International Space Station, where they are scheduled to arrive at around 3 a.m. ET tomorrow, Tuesday, March 5 You can watch coverage of the arrival and docking of the spacecraft from 1 a.m. ET on Tuesday via NASA TV.
