The astronauts were securely fastened in their seats when the launch was called off just under 30 minutes before liftoff.
Both NASA and SpaceX voiced their disappointment over the delay, with the next launch attempt now scheduled for Thursday evening.
Should that effort also be unsuccessful, another opportunity remains available on Friday.
Had the mission gone ahead as intended, Williams and Wilmore would have left the ISS two days later, with their return to Earth anticipated by Sunday.
This postponement comes after Elon Musk claimed he had previously offered to bring the astronauts back eight months ago, but the Biden administration turned down his proposal.
Musk claimed that his offer was rejected by the administration because it might have given a political advantage to Donald Trump in his campaign against Kamala Harris.
The SpaceX Crew-10 mission is scheduled to transport four astronauts to the ISS: Kirill Peskov from Roscosmos, NASA astronauts Nichole Ayers and Anne McClain, and Takuya Onishi of Japan’s JAXA space agency.
With the delay, Williams and Wilmore will now have to wait until at least Monday for their return trip.
Sunita Williams and Butch Wilmore have been aboard the International Space Station (ISS) since June. Credit: NASA
Just moments before the planned launch, SpaceX released images of the Crew-10 astronauts preparing for the mission, with the caption: “Crew-10 is go for launch!”
However, shortly after, a problem with a hydraulic clamp arm emerged, causing an immediate stop.
The astronauts were carefully taken out of the rocket one by one and transported in specially designed Teslas to a quarantine facility in Florida, where they will remain until the next attempt.
A SpaceX commentator, speaking about the incident on a live stream, reassured viewers that safety is the highest priority: “We will not launch unless we are confident we can do so safely and reliably.”
NASA and SpaceX have been actively developing backup plans to guarantee a secure return for Williams and Wilmore.
According to Mail Online, NASA official Ken Bowersox admitted that “there may have been conversations” within the White House about the political ramifications of the mission delay but noted that he was not involved in those discussions.
Williams and Wilmore initially embarked on what was supposed to be an eight-day mission aboard Boeing’s Starliner spacecraft on June 5. Credit: @iss/Instagram
Once Crew-10 reaches the ISS, Williams and Wilmore are expected to depart within two days, instead of the typical five-day handover period.
This change has been made to preserve food supplies on the station and provide more flexibility in scheduling their undocking, in case of weather-related delays.
Bowersox also mentioned that financial limitations contributed to the mission’s delays, explaining that while other alternatives were explored: “We ruled them out quickly due to our budget constraints.”