NASA must determine by the end of August whether to bring back two astronauts on Boeing's Starliner, which transported them to the International Space Station (ISS), or opt for a SpaceX craft, officials announced on Wednesday.

NASA astronauts Barry "Butch" Wilmore and Sunita "Suni" Williams embarked on Starliner on June 5 for the ISS, initially planned for an eight-day mission. However, their return has been postponed due to thruster malfunctions discovered during Boeing's first crewed mission to the ISS.

During a press conference on Wednesday, NASA officials stated they are still evaluating thruster data, with a decision imminent on whether to use Starliner or SpaceX. "We're reaching a point where that last week in August we really should be making a call, if not sooner," said Ken Bowersox, associate administrator of NASA's Space Operations Mission Directorate.

Bowersox noted that the astronauts are "making the best" of their extended stay on the ISS, but like everyone else, they are keen for a decision. The primary concern revolves around the propulsion system. "Our big concern is having a successful deorbit burn," the NASA official added.

Bowersox also mentioned open discussions with Boeing, affirming the company's full support for their spacecraft. Should NASA decide against using Starliner, SpaceX, owned by Elon Musk, could adjust its scheduled Crew-9 mission on September 24 to include only two astronauts instead of the usual four. The Crew Dragon capsule could then return Wilmore and Williams to Earth in February 2025, marking a significant setback for Boeing.

NASA chief astronaut Joe Acaba highlighted that Wilmore and Williams were aware that their mission, being a test flight, might not be flawless. "Human space flight is inherently risky and as astronauts we accept that as part of the job," he stated. "As professional astronauts they're prepared for this and they're doing great."

In case of an emergency on the ISS, Bowersox confirmed that Starliner could be utilized to evacuate the astronauts. "We think the risk is reasonable to put Butch and Suni on that vehicle in a contingency," he explained. If Starliner were to return uncrewed, an emergency option would involve the four-person SpaceX Dragon capsule currently docked at the ISS. However, Wilmore and Williams would have to return without suits.

"Once Crew-9 gets there we'll have suits," said Joel Montalbano, deputy associate administrator of NASA's Space Operations Mission Directorate. "They would come home suited on Crew-9." A return by SpaceX for Wilmore and Williams would signify the most significant setback yet for Boeing's space program. Both Boeing and SpaceX secured multibillion-dollar contracts in 2014 to provide NASA with transportation to the ISS after the retirement of the space shuttle program in 2011, which left the U.S. dependent on Russian Soyuz rockets for crew transport. SpaceX successfully completed its first crewed test in 2020 and has since transported numerous astronauts.