SpaceX has announced a fix for an issue with the heat shield for the Crew Dragon that caused unexpected “erosion” during reentry at the conclusion of the Demo-2 mission on August 2. Testing of the heat shield revealed more than the expected wear and tear due to the extreme heat of reentry. Although the crew was never in any danger, the redesign offers extra layers of protection for future astronauts flying on the Crew Dragon.
Most of the damage occurred in the area where a series of bolts connect the crew module to a trunk containing engines that assist with maneuvering in space. The trunk is discarded before reentry. Commercial Crew insiders say that the damage did not show up in Demo-1 because the uncrewed Crew Dragon was lighter and the mission profile was different.
The friction of reentry is high enough to create a sheath of plasma around the Crew Dragon, which can interfere with radio communications. This is a phenomenon that was previously experienced during the Mercury, Gemini, and Apollo missions of the 1960s and 1970s and can put on quite the light show for the crews. John Glenn described it as “a real fireball” after the successful conclusion of his Mercury mission, during which a false signal of a possible issue with his heat shield caused concern for flight controllers.
SpaceX’s thermal protection system contains an array of heat-resistant tiles that can handle the 3500-degree-Fahrenheit temperatures of reentry. Although SpaceX and NASA deny that astronauts Bob Behnken and Doug Hurley were in any danger during Demo-2, the loss of heat-resistant tiles on the Space Shuttle Columbia during launch was a critical factor in its breakup during reentry in 2003. The redesign will provide additional safety for upcoming missions like Crew-1.
“We’ve gone in and changed out a lot of the materials to better materials [and] made the area in between these tiles better,” said NASA Commercial Crew Program manager Steve Stich.
This is one of several upgrades and changes in procedure made following the Demo-2 flight, which was officially the final flight test of the Crew Dragon before it was declared operational. Decision-makers also loosened weather restrictions for launch and splashdown, as well as made improved arrangements with the U.S. Coast Guard to better enforce a 16-kilometer restricted zone around the planned splashdown site in which privately owned boats will be forbidden during reentry and retrieval operations. The intrusion of private boats during Demo-2’s splashdown was cause for concern.
The Crew-1 flight is scheduled to occur on October 31 and will carry astronauts Mike Hopkins, Victor Glover, Shannon Walker, and Soichi Noguchi to the International Space Station. It was delayed from October 23 for better traffic management to allow for the next flight of a Russian Soyuz, which is set to launch three new crew members for International Space Station on October 14 and return on October 21 with the same number of crew members who are currently on board the ISS. NASA officials say that they will use the extra time for reviews to ensure that the Crew-1 astronauts will stay safe during their mission.