SpaceX, NASA Share Why They Were Confident To Fly Crew Despite Cracked Seal

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After a successful on time liftoff of the Crew-8 mission late night yesterday in Florida, managers from NASA and SpaceX shared more details about the problems their teams had to work with to ensure that the Crew Dragon was clear for launch. Before liftoff, SpaceX engineers discovered that a coating on the Dragon spacecraft had a crack, and they, along with NASA engineers, had to ensure that the cracks did not pose a risk to the crew before the rocket could launch.

The go ahead for launch was given roughly ten minutes before liftoff, and according to NASA’s Steve Stich and SpaceX’s Sarah Walker, data from previous experiments and other calculations confirmed that the material would expand during reentry and seal the crack.

SpaceX, NASA Teams Independently Reached Conclusion That Dragon Was Clear For Lift Off

As part of her prepared remarks, SpaceX’s Walker explained that during closeout photographic checks roughly 45 minutes before launch, engineers discovered that the upper section of the coating around the hatch’s seal had a ‘defect.’

According to her:

. . . the area of interest that we worked with was around 45 minutes. The engineers who were doing the closeout photo check. Once we close the hatch, they take detailed photos of the perimeter of the hatch and that final seal. And as they were doing those reviews, they noticed an area of interest on kind of the upper section of the RTV, which is kind of a top coating on the hatch seal that they wanted us to take a look at.

So we looked at the photos. Eventually, it was determined that the size of the defect, or separation of that RTV seal was within the qualified limits of the design. So that was ultimately the flight rationale that cleared us for launch.

. . .this is one of multiple redundant seals in this area. It’s kind of a top coating over the pressure seal, which is over the main seal over the hatch. It is also a very low heating region for the vehicle, and actually this material expands during heating and so we expect that actually a defect of this size would self heal during the launch process.

The Crew-8 launches inside SpaceX’s Falcon 9 rocket from NASA’s KSC in Florida.

The SpaceX official later added that the RTV (room temperature vulcanized) coating is applied each time a Dragon takes a crew to space, leading SpaceX to conclude that the defect was due to the application process. In response to a question, NASA’s Stich shared that the agency has full authority all times during the countdown process to abort a launch if it feels that any criteria are being violated. According to him, the final poll for the launch for NASA’s approval came five minutes before to launch.

The seal was on the leeward side of the Crew Dragon, and Stich added that engineers studied the effects of heating in the top part of the hatch seal. Given its size, the heating was not a threat, and NASA further validated its conclusions by checking data from TPS defect experiments flown on cargo missions. These experiments looked at larger defects, and NASA’s TPS experts worked with SpaceX to confirm that the defect didn’t pose a threat.

As part of its clearance process for launch, SpaceX and NASA teams reached the same conclusions independently, which made them comfortably confident to proceed to liftoff. According to Walker, the “square acreage” of the defect or crack was 0.02 square inches, which was less than half of what the system is qualified to handle.

The Crew Dragon for the Crew-8 mission is slated to dock to the ISS on 3 a.m. Tuseday morning Eastern Time. SpaceX also ran a tanking test for its Starship rocket in Texas yesterday as it prepares for the third test flight of the world’s largest rocket.

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