NASA maintains that Boeing's Starliner will be used to bring astronauts back from the ISS, but also acknowledges the possibility of using SpaceX as a backup option.

• On Wednesday, NASA acknowledged possible options to Boeing's Starliner for bringing back two astronauts from the International Space Station.
• NASA and Boeing are still conducting tests on the Starliner spacecraft, which has been in space for 36 days, in an effort to replicate the issues with the propulsion system and clear the spacecraft for a return mission.
• An "end of July" return for Starliner is "optimistically" expected based on the successful completion of testing in New Mexico, as stated by a NASA official.

Due to the extended stay of NASA astronauts at the International Space Station, the agency's leadership acknowledged the possibility of considering alternative spacecraft to Boeing's Starliner for returning the crew to Earth.

Officials stated that the Boeing's spacecraft is still the primary choice for bringing back crew members.

The Starliner capsule "Calypso" may return to Earth from its extended ISS stay by the end of this month, pending the results of testing a faulty propulsion system. Starliner has been in space for 36 days and counting, with the agency and Boeing conducting additional testing in New Mexico before clearing the spacecraft for return.

For the first time, Starliner is transporting people, including NASA astronauts Butch Wilmore and Suni Williams, on a mission.

NASA's Commercial Crew manager Steve Stich stated during a press conference that the priority is to return Butch and Suni on Starliner, with no plans to utilize SpaceX's Crew Dragon at this time.

NASA does not need to decide whether to make any changes based on the possibility of a SpaceX capsule being part of contingency plans for a Starliner return to Earth without cargo.

Stich stated that we have dusted off a few things to examine in comparison to Starliner, in order to be prepared to utilize them if necessary.

Stich later added that there had been no discussion about sending another Dragon to rescue the Starliner crew.

NASA and Boeing started ground testing the spacecraft's thruster technology in White Sands, New Mexico on July 3. The aim is to replicate the issue that caused up to five thrusters on Calypso to shut down during docking with the ISS. The ground testing is being conducted to ensure that the thruster can withstand the high pulses and heat without causing any damage.

Starliner is expected to return in "end of July" based on the successful completion of testing, as noted by Stich. Boeing and NASA teams in White Sands are currently conducting inspections of the test thruster over the next week.

Boeing's Mark Nappi, vice president of the Starliner program, stated during the press conference that "we have not been able to replicate the temperatures we observed during flight."

Nappi stated that the purpose of the testing is to fill in some gaps, as understanding if the thrusters are functioning as expected is crucial for undocking and returning. If the thrusters were damaged, then different actions would need to be taken.

Nappi stated that we do not believe our thrusters have been damaged, but we want to conduct a test to confirm this.

Both Wilmore and Williams, while addressing the media from the ISS, expressed their certainty about returning on Starliner.

Wilmore stated that we believe the tests we're conducting are necessary to obtain the correct answers, which will provide us with the required data to return.

NASA has planned to have SpaceX and Boeing fly astronauts on alternating flights, with Starliner now seen as a secondary competitor to SpaceX's Dragon, which has made 12 crewed trips to the ISS over the past four years.

NASA's certification of Boeing to fly crew on operational, six-month missions will begin as soon as February, following the successful completion of the Starliner crew flight test.