SpaceX launched another crew of four to the International Space Station tonight (March 3).
A SpaceX Falcon 9 rocket lifted off with the four astronauts of NASA's Crew-8 mission at 10:53 p.m. EST tonight (0353 GMT on March 4) from Pad 39A at Kennedy Space Center (KSC) in Cape Canaveral, Florida.
The rocket's two stages separated 2.5 minutes after launch. About five minutes after that, the first stage returned to Earth at Cape Canaveral, acing the company's 204th consecutive booster landing. Then, 12 minutes and 15 seconds after liftoff, the Falcon 9's upper stage deployed the mission's Crew Dragon capsule, named Endeavour, into low Earth orbit (LEO).
The astronauts of Crew-8 now on their way to the space station are NASA's Matthew Dominick (commander), Michael Barratt (pilot) and Jeanette Epps (mission specialist), as well as mission specialist Alexander Grebenkin of Russia's space agency Roscosmos. All crewmembers are new to space aside from Barratt, who is making his third spaceflight.
"Hey, Earth! Just to let you know, it's kind of like a rollercoaster ride with a bunch of really excited teenagers," Barratt told mission control just after Endeavour deployed into LEO. "Thanks so much to our friends and colleagues at SpaceX for the awesome ride. It's great to be back in space again!"
Related: Meet the SpaceX Crew-8 astronauts launching to the ISS
Crew-8 marks SpaceX's 13th crewed flight overall and its eighth operational one for NASA as part of the agency's Commercial Crew Program. The company has now sent a total of 50 people to orbit, although astronaut Michael López-Alegría flew twice, as commander of both the Ax-1 and Ax-3 private missions, making it 49 different people.
Tonight's launch was the first flight of this particular Falcon 9 rocket, making it the sixth time SpaceX has used an unflown rocket in a crewed launch.
On the flip side, the Endeavour capsule is a seasoned veteran. Endeavour famously flew on the first crewed test flight of the Crew Dragon spacecraft on May 30, 2020, ferrying NASA astronauts Bob Behnken and Doug Hurley to the ISS.
Since then, Endeavour has also flown the Crew-2 and Crew-6 missions for NASA and the Ax-1 private mission for Houston-based company Axiom Space in 2022. Crew-8 therefore marks five flights for Endeavour, the most of any Crew Dragon, making it the "fleet leader," said Steve Stich, manager for NASA's Commercial Crew Program, during a press briefing on Feb. 28 at KSC.
Yet, despite how many times these capsules have flown — in addition to the increasing cadence at which SpaceX is launching crewed missions to the orbital laboratory — NASA refuses to let its guard down. During the same Feb. 28 briefing, NASA Administrator Bill Nelson stressed that crew safety is "primary" for the agency. "It's risky business," he said.
"Every time we launch, it's white-knuckle time — and especially when humans are on top," Nelson added later during the briefing. "We never want to get in to the frame of mind that it's so routine that it's like getting in your car and taking a Sunday afternoon drive."
That safety culture was on display tonight in the leadup to launch. Shortly after the four astronauts were locked inside Endeavour, mission team members noticed a slight crack in the thermal seal around the capsule's hatch. After considerable discussion and analysis, NASA and SpaceX determined that the issue is minor and would pose no excess risk to the crew, so they went ahead with the launch.
"We estimated the square acreage of this defect to be about 0.02 square inches [0.13 square centimeters], which is less than half of what we are required to qualify this system to holes or cracks or other defects," Sarah Walker, director of Dragon mission management at SpaceX, said during a press conference held about an hour after launch. "About 0.05 inches [0.32 square cm], I believe, is the qualification limit."
In addition, the crack will be on the leeward side of Endeavour when it reenters Earth's atmosphere about six months from now, meaning it won't be exposed to the most extreme heating that the capsule experiences. And the seal material will likely expand during reentry, eliminating the defect anyway, Stich said during the postlaunch briefing.
Tonight's liftoff occurred a few days later than expected; it was pushed back several times due to bad weather.
During their six-month stay aboard the ISS, the Crew-8 astronauts will conduct more than 200 scientific experiments and technology demonstrations in microgravity, including research that will support human exploration into deep space.
NASA is already looking to the future with its current human-related science research endeavors, to a time when people might live aboard private space stations or conduct long-duration missions to the moon and Mars through the agency's Artemis program.
Like Crew-8's science focus, most of the agency's current human-science research is not only geared toward thriving in LEO, but also toward keeping human crews safe and healthy on exploration missions, Kristin Fabre, deputy chief scientist of NASA's Human Research Program, told Space.com. "The need to understand all of the changes that are happening during exploration missions, and also understand the changes of the human body over a diverse population, is more critical than ever," Fabre said.
When the Crew-8 quartet arrives at the space station, they will briefly join the four international astronauts of Crew-7 before the latter group hands over the torch and gets set for their departure, which will occur no earlier than March 11. Crew-8 will also rendezvous with the three members of Russia's MS-24 mission, which includes NASA astronaut Loral O'Hara.
SpaceX is one of two commercial companies with multibillion-dollar contracts to fly astronauts to the ISS and back for NASA. The other company, Boeing, aims to launch the first crewed flight on its Starliner spacecraft no earlier than April 22.
Editor's note: This story was updated at 12:55 a.m. ET on March 4 with more information about the thermal-seal defect from the post-launch press conference.
