Starliner at Pad 41
At the end of a Dec. 12 review, NASA approved a Dec. 20 launch of Boeing's CST-100 Starliner on an uncrewed test flight to the ISS. Credit: Boeing

WASHINGTON — Boeing said April 17 that the next test flight of its CST-100 Starliner commercial crew vehicle won’t take place until at least August, confirming a lengthy delay widely expected because of the schedule of other launches and International Space Station missions.

In a statement, Boeing said that the company and NASA are projecting the uncrewed Orbital Flight Test (OFT) 2 mission will take place in August or September. That date is “supported by a space station docking opportunity and the availability of the United Launch Alliance Atlas V rocket and Eastern Range.”

Boeing had been working toward a launch of OFT-2 in late March or early April. However, by early March, NASA officials acknowledged that was no longer likely because of delays from the replacement of avionics units on the spacecraft that were damaged by a power surge during ground tests, as well as power outages in the Houston area caused by a winter storm in February that interrupted software testing.

Neither NASA nor Boeing provided an updated launch date at the time, but noted the mission was unlikely to launch in either April or May. That was due to Soyuz and Crew Dragon missions to the ISS scheduled for launch in April, and the May launch of an Atlas 5 carrying a military spacecraft.

At an April 15 briefing about the upcoming Crew-2 Crew Dragon mission, Steve Stich, NASA commercial crew program manager, said another factor was the next cargo Dragon mission to the space station, scheduled for launch in early June. That spacecraft, along with the Crew-2 spacecraft, will occupy the only two docking ports Starliner can use, meaning it can’t launch until after the cargo Dragon departs in mid-July.

“Right now, the windows that we’re looking at are the August-September time frame for OFT-2,” he said.

Boeing, in its statement, said that the Starliner flying OFT-2 will be “mission-ready” in May and the company “will evaluate options if an earlier launch opportunity becomes available.” For now, though, there are no plans to delay the cargo Dragon mission in June, in part because it is carrying solar panels NASA wants to get to the station as soon as possible to begin a long-anticipated upgrade of the station’s power supply.

Stich said at the briefing that NASA and Boeing will take advantage of the delay to do additional software testing. Software issues were at the root of several major problems with the original OFT flight in December 2019, cutting the mission short and preventing the spacecraft from docking with the ISS.

“Boeing expects to conclude all software testing in April and will support the agency’s post-test reviews as needed,” the company said, adding that it is completing all the recommendations made a year ago by an independent review, including those not considered mandatory before the spacecraft’s next flight.

Despite the delay in OFT-2, NASA and Boeing said they are still working to make the vehicle’s first crewed flight, the Crew Flight Test, before the end of the year. Stich said at the briefing that the current target for that flight is the fourth quarter.

That would mean the crewed flight would be no more than four months after OFT-2, while previous schedules suggested a gap of about half a year between them. Boeing said it is working to “enable the shortest turnaround time possible between flights while maintaining its focus on crew safety,” including having the three NASA astronauts who will fly that mission perform tests in the Starliner that will launch on OFT-2.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...