Launched on an Atlas V rocket on June 5th, the Starliner was initially set to return its two crew members, Butch Wilmore and Suni Williams, to Earth just eight days later, on June 14. However, the return has been repeatedly delayed due to technical issues.

During the spacecraft’s journey to the ISS, it encountered helium leaks and thruster failures. Despite these setbacks, NASA and Boeing officials spoke about the severity of these problems.

“Those are pretty small, really, issues to deal with,” said Mark Nappi, vice president and manager of Boeing’s Commercial Crew Program, during a post-docking news conference. “We’ll figure them out for the next mission. I don’t see these as significant at all.”

As days turned into weeks and then months, NASA and Boeing continued to investigate the technical issues, particularly the failure of multiple reaction control system thrusters. These RCS thrusters are not used as heavily for departing the station and deorbiting, with the actual deorbit burn done by separate, larger thrusters. The problem thrusters are part of the service module, which separates prior to Starliner re-entry.

Recently, ground teams from NASA and Boeing conducted tests on a thruster at White Sands, New Mexico. Over the last weekend, they fired the spacecraft’s thrusters while docked at the ISS to assess their performance. Preliminary results from these tests have been encouraging, according to NASA.

Last week, Steve Stich, NASA’s program manager for commercial crew, refrained from discussing contingency plans if Starliner’s thrusters proved unreliable. “Our prime option is to complete the mission,” Stich said. “There are a lot of good reasons to complete this mission and bring Butch and Suni home on Starliner. Starliner was designed, as a spacecraft, to have the crew in the cockpit.”

Despite this, recent activity at NASA, Boeing, and SpaceX suggests that Wilmore and Williams might return to Earth aboard a Crew Dragon spacecraft instead of the Starliner.

According to ArsTechnica.com, one informed source said it was greater than a 50-50 chance that the crew would come back on Dragon. Another source told ArsTechnica it was significantly more likely than not they would. To be clear, NASA has not made a final decision.

When asked if it was now more likely than not that Starliner’s crew would return on Dragon, NASA spokesperson Josh Finch told ArsTechnica’s Eric Berger on Thursday evening, “NASA is evaluating all options for the return of agency astronauts Butch Wilmore and Suni Williams from the International Space Station as safely as possible. No decisions have been made and the agency will continue to provide updates on its planning.”

In a related development, NASA issued a $266,678 task award to SpaceX on July 14 for a “special study for emergency response.” NASA stated this study was not directly related to Starliner’s problems, but two sources told Ars it really was.

The study involved work on flying more than four crew members home on Crew Dragon, a scenario related to Frank Rubio and the Soyuz MS-22 leaks. It also allowed SpaceX to study flying Dragon home with six passengers, a regular crew complement in addition to Wilmore and Williams.