WASHINGTON — NASA and SpaceX are moving ahead with the launch of a seventh crew rotation mission to the International Space Station this week, remaining vigilant about crewed launches whilst they grow to be more routine.
NASA said Aug. 21 it accomplished a flight readiness review for the Crew-7 mission, approving plans for a launch at 3:49 a.m. Eastern Aug. 25 from Launch Complex 39A on the Kennedy Space Center in Florida. A launch that day would arrange a docking of the Crew Dragon spacecraft Endurance with the station at 2:02 a.m. Eastern Aug. 26.
The Crew-7 mission is commanded by NASA astronaut Jasmin Moghbeli with European Space Agency astronaut Andreas Mogensen as pilot. Satoshi Furukawa, an astronaut from the Japanese space agency JAXA, and Roscosmos cosmonaut Konstantin Borisov might be mission specialists. The 4 will spend about six months on the station.
Officials said at a briefing that they cleared all issues related to the mission throughout the nearly seven-hour review. That included concerns about corrosion seen on isolation valves in a cargo Dragon spacecraft launched to the station in June. The corrosion prevented the valves from operating, but those valves, used only within the event of a propellant leak in a thruster, weren’t needed on that CRS-28 mission.
Steve Stich, NASA industrial crew program manager, said SpaceX replaced a number of the valve components on Endurance and that engineers have a “good rationale” for the remaining valves on the spacecraft. “We wanted to grasp it very thoroughly, so we spent the last month or so taking a look at data,” he said, including testing and other evaluation of valves by each SpaceX and NASA.
The corrosion appears to be brought on by propellant vapors leaking through seals and reacting with ambient moisture, creating acid. The materials utilized in the valves are designed to withstand corrosion, he said, but with enough vapor and moisture some corrosion will develop.
That drew parallels to Boeing’s CST-100 Starliner, which suffered severe corrosion of valves in its propulsion system that prevented the valves from operating. That postponed the launch of its second uncrewed test flight by greater than nine months, from August 2021 to May 2022.
The corrosion mechanism is “somewhat similar” between the 2 spacecraft, Stich said, although differences in materials result in numerous sorts of corrosion.
“We learned quite a bit from the investigation we did on Starliner and it probably helped us to get to the foundation cause just a little bit faster,” he said. That included the importance of getting a purge system that removes vapors from the vicinity of the valves to stop corrosion. “I believe we’re learning just a little bit about capsules and valves between the 2 different vehicles, Starliner and Dragon.”
Stich said the review also resolved one other minor issue seen throughout the return of one other Crew Dragon spacecraft in March at the top of the Crew-5 mission, when one in every of the drogue parachutes inflated several seconds slower than the opposite. Separate work by NASA and SpaceX to model parachute dynamics led them to clear the difficulty, he said.
Each Stich and Bill Gerstenmaier, vp of construct and flight reliability at SpaceX, said the valve and parachute analyses were examples of how they remained focused on safety for crewed missions whilst such missions grow to be more routine. Crew-7 might be SpaceX’s 11th launch with astronauts on board, a figure that features the Demo-2 test flight in 2020 and three private astronaut missions.
“We all know the importance of flying crew and the trust that the crew puts in us,” said Gerstenmaier, a former NASA official who led the agency’s human spaceflight activities for several years. “We treat that extremely seriously as an organization.”
That focus continues whilst SpaceX’s overall launch activity grows. A Falcon 9 launch of 21 Starlink satellites from Vandenberg Space Force Base in California early Aug. 22 was the 54th launch of that vehicle to date this 12 months, and the 58th launch for SpaceX overall, counting three Falcon Heavy launches and the Starship/Super Heavy test flight in April. That approaches the 61 launches that SpaceX conducted in all of 2022.
“There’s a bonus of flying so much,” Gerstenmaier said, including each a greater understanding of the hardware and the flexibility to check changes on other launches before incorporating them on crewed missions. He noted that Starlink launches use a better thrust profile, which provides more margin for crewed missions.
Starlink launches “really help us out,” Stich said, by testing changes that may later be incorporated into crewed flights. “We will watch that recent component or the change within the component, the way it flies within the flight environment, after which come back and take a look at the information and get comfortable with it for a crewed flight.”