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The SpaceX Crew Dragon Endurance docked with the International Space Station just after midnight Sunday, beginning the countdown for the return of a pair of Boeing Starliner astronauts who have been on board the station since last summer.
With the Crew-10 spacecraft and space station both traveling at 17,500 mph about 260 miles over the Atlantic Ocean, the final approach had Endurance moving at less than 4 inches per second.
It made initial contact with the station’s forward port of the Harmony module at 12:04 a.m. The four members of the mission are NASA astronaut and commander Anne McClain, NASA astronaut and pilot Nichole Ayers, Japan Aerospace Exploration Agency astronaut Takuya Onishi and Roscosmos cosmonaut Kirill Peskov.
“It was so amazing to see the ISS shining in the darkness of space,” said Onishi after docking. “We have a lot of exciting work ahead of us that we are looking forward to.”
Their arrival for now increases the space station population to 11 including Butch Wilmore and Suni Williams, who arrived to the station on June 6, 2024, on Starliner as part of its Crew Flight Test but have since been shifted to become members of Crew-9.
Wilmore was the astronaut in the Harmony module that was the first to welcome his replacements on board after the hatch opened at 1:35 a.m.
All 11 gathered for welcome statements.
“I cannot tell you the immense joy of our crew when we looked out the window and we saw the space station for the first time, returning for a couple of people, very first time for a couple of people,” McClain said. “Let me tell you, that is such an amazing journey. You can hardly even put it into words.”
All four of the Crew-10 passengers were pilots before getting their space assignments. It’s the second flight for McClain and Onishi, who will take over command of the ISS when Expedition 73 begins next month. The rookies are Peskov and Ayers, who became the first member of the 2021 astronaut class to make it to space.
“Thank you to SpaceX for the awesome ride up here,” she said. “As a rookie, that was one of the coolest things I’ve ever done, and I can’t wait to get to work up here. So, so excited for the four pilots in us that just got to get to space together, and now we’re four astronauts together.”
The Crew-10 quartet launched from Kennedy Space Center atop a Falcon 9 rocket on Friday evening for about a 29-hour trip to the station.
Its arrival will allow for the Crew-9 mission to return home to Earth on the Crew Dragon Freedom, also docked with Harmony in its zenith module. That spacecraft arrived last September with commander NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov but flying up with only two instead of the normal four passengers.
The two empty seats will be filled with Wilmore and Williams for the flight home.
Their CFT mission was designed for as short as an eight-day stay, but Starliner suffered thruster failures and helium leaks on its propulsion system, which ultimately led NASA to send the spacecraft home without a crew.
Left behind, Williams and Wilmore were then assigned to remain on the station as part of Expedition 72, and officially become members of the Crew-9 crew for the flight home. During their stay Williams became commander of the space station, and both astronauts took part in spacewalks.
The duo are making their third trip to space, having previously flown up on both space shuttles and Russian Soyuz spacecraft. Their flight home in a Crew Dragon along with their flight up in Starliner will mean they will have flown in four different spacecraft.
Orlando’s John Young is the only astronaut with a similar resume, having flown the first space shuttle flight on top of two Gemini and two Apollo missions. On Apollo 16, Young walked on the moon, so he flew in both the crew service module and the lunar module. He remains the only astronaut to launch and land in four different spacecraft.
Williams and Wilmore’s return could come as early as 4 a.m. Wednesday, allowing for at least two full days of handover between the two crews, although departure will depend on weather.
“It might be later than Wednesday when they come home,” said Dina Contella, deputy manager for the International Space Station Program. “We’re trying to keep the handover shorter because recently and last year, we’ve had some handovers that were more extended waiting on good weather, and so we don’t want to lose any good opportunities that we might have.”
The duo will have spent 9 1/2 months on board.
“If you look at it mathematically by percentage of the original plan mission, this is the largest percentage extension,” said Ken Bowersox, associate administrator of NASA’s Space Operations Mission Directorate. “That’s probably how we engineers will think about it in the future is mathematically.”
He noted other astronauts have had their missions extended.
“But every astronaut that launches into space, we teach them: ‘Don’t think about when you’re coming home. Think about how well your mission is going, and if you’re lucky, you might get to stay longer.’ And it really is a gift when you get to stay longer in space,” he said.
This is the fourth trip to the space station for Crew Dragon Endurance, which also visited with Crew-3 in 2021, Crew-5 in 2022 and Crew-7 in 2023.
NASA originally contracted with both SpaceX and Boeing to provide taxi service to the station from the U.S. so it could end its reliance on Russia to keep an American presence at the station after the end of the Space Shuttle Program. The station has been continuously crewed for nearly 25 years.
Crew-10 is the 10th operational flight for SpaceX under NASA’s Commercial Crew Program, and Crew-11 is already slated to fly up as early as July. Meanwhile, NASA is still working to determine if it can certify Starliner, which is already about five years behind SpaceX, and wouldn’t have its first operational mission until likely 2026 if it can be certified.
Boeing still has a contract to fly up six operational flights of Starliner, but the space station’s lifespan is limited, with NASA announcing it would de-orbit it after 2030.
Meanwhile, since the first human spaceflight of Crew Dragon nearly five years ago, SpaceX has flown 60 humans to space across 16 flights among its fleet of four Crew Dragons.
A fifth Crew Dragon is near completion and was originally tasked to fly Crew-10, but delays in production had already delayed the original target launch of February to what was going to be no earlier than late March, which would have pushed Williams and Wilmore’s stay on board to more than 10 months.
Elon Musk soon after the announcement of that delay said he had talked with President Trump, who tasked him and SpaceX to get Wilmore and Williams home “as soon as possible.” Meanwhile, NASA facing potentially an even longer delay in SpaceX’s new Crew Dragon was already seeking a switch.
An announcement soon after came that the switch to Endurance, which had been prepped for the upcoming commercial Axiom Space Ax-4 mission, was happening, and that allowed the launch date to be pushed up by a couple of weeks. The first launch attempt on Wednesday, though, was delayed by two days by another SpaceX issue when the clamp holding the Falcon 9 wouldn’t let go.
So instead of a potential Sunday return home, that return is now pushed to Wednesday.
“I think it is possible we could splash on the same day,” Contella said. “It just depends on the transit time associated with where the orbit lines up, and then the splashdown opportunity that we select on the Gulf Coast.”
SpaceX has eight potential landing sites on either coast of Florida, but NASA is targeting the West Coast. It includes a site off the Dry Tortugas, which was used for the first time on last year’s Polaris Dawn mission, which suffered several weather delays.
“I’ll just caution you,” Contella said. “It could be difficult to find good weather on the very first day.”
