With Starliner’s Crewed Debut, NASA Again Turns To Test Pilots

NASA is once again turning to astronauts with military test pilot experience to cap off the tumultuous, 13-year effort to certify multiple commercial providers for transporting astronauts to and from the International Space Station.

The participants in the Boeing Starliner Crew Flight Test (CFT), veteran NASA astronauts and U.S. Navy test pilots Barry “Butch” Wilmore and Sunita “Suni” Williams, are scheduled to launch May 17  atop a United Launch Alliance (ULA) Atlas V rocket from the Cape Canaveral SFS in Florida. The May 6 launch attempt was scrubbed to comply with a flight rule that prohibited the launch team from cycling a problematic pressure regulation valve on the Centaur’s liquid oxygen tank. The valve was oscillating, causing an audible buzzing sound.

If the flight is successful, the pair’s weeklong stay at the International Space Station (ISS), followed by a parachute- and airbag-assisted descent in the southwestern U.S., should lead to the Starliner’s certification by NASA. Once certified, the Starliner will join SpaceX’s Crew Dragon for the regularly scheduled commercial transport of astronauts to and from the seven-person orbital laboratory.

• Greater emphasis on manual operations than SpaceX’s Crew Dragon
• The mission has 90 inflight test objectives

Wilmore, the CFT commander, and Williams, the pilot, took questions during a May 1 prelaunch news briefing from crew quarters while in quarantine at NASA’s Kennedy Space Center, where they arrived on April 25 for final flight preparations.

“We have been through quite the process over the years,” Wilmore said of the many months of preparation. “It’s been really a thrilling process to be two Navy-trained test pilots and named to the process of this first flight and all that goes into that. Every single day is different.”

Wilmore and Williams follow the NASA astronaut duo of Doug Hurley and Bob Behnken, who launched aboard SpaceX’s Crew Dragon Demo-2 flight to the ISS on May 30, 2020. That 64-day mission led to the Crew Dragon’s certification and reestablished a U.S. human launch capability that had lapsed with the retirement of NASA’s space shuttle program in July 2011.

With CFT certification, the Starliner will be in line for six missions to launch astronauts and return them from the ISS. They will alternate missions every six months with SpaceX under the Commercial Crew Transportation Capability Contract NASA originally awarded to Boeing in 2014 that is currently worth $4.4 billion.

NASA assigned Wilmore in October 2020 to train as the CFT commander. A Navy captain with test and combat fighter pilot experience, he was selected by the agency for astronaut training that same year and has since logged 178 days in space on space shuttle- and Russian Soyuz-launched missions to the ISS.

Williams was assigned to the pilot’s role in June 2022 after previously serving as the mission’s backup test pilot. A retired Navy captain with helicopter test and combat pilot experience, she was selected by NASA for astronaut training in 1998. She has logged 322 days in space, also on space shuttle and Soyuz missions to the ISS.

Together with their NASA and Boeing mission managers, Wilmore and Williams say their military test pilot and spaceflight experience provides an important contribution to achieving Starliner certification and future human spacecraft development, despite the rise in automated operations introduced by the Crew Dragon and Starliner.

“The CFT is really an introduction of crew into our vehicle system. So a lot of our flight-test objectives are about how that interface is going to work,” Mark Nappi, Boeing’s Starliner’s program manager, said at a recent NASA-hosted news briefing focused on test flight preparations and operations. “CFT is a test flight, so we expect there may be some lessons learned.”

The CFT’s nearly 90 inflight test objectives include breaking away from the largely automated operations for manual guidance by Wilmore and Williams during the approach to docking with the ISS. They also will maneuver to point the Starliner’s power-generating solar arrays toward the Sun and the star tracker toward selected celestial bodies for navigation and perhaps even to deal with a contingency.

Williams noted differences between SpaceX’s comfort with software and automation and Boeing’s emphasis on automation with piloted flight control still firmly in the loop.

“The crew is sort of the last line of defense, and we have the ability to get in there and fly manually if we need to or just back up the systems manually to make sure everything is working correctly,” Williams said, referring to her Starliner flight simulation experience during ground training. “This one is a really nice combination and leads toward automation. But particularly in this test flight, it allows us to shake out all that manual flying just to make sure that if anything ever goes wrong—not only on this flight but on later flights—we will have that reassurance of the crew being the backup. It’s a really slick aircraft in that regard.”

Boeing’s pursuit of the CFT has not been a sprint. Launched on Dec. 20, 2019, and planned for eight days, the Starliner’s uncrewed Orbital Flight Test-1 (OFT-1) failed to achieve the intended orbital altitude required to initiate an automated docking with the ISS. The spacecraft made a successful parachute descent into White Sands, New Mexico, two days after experiencing software issues and a disruption in ground communications.

Plans for OFT-2 in 2021 were halted during the launch countdown when the Starliner’s propulsion system valves were found to be out of configuration. The six-day OFT-2 test flight, which included an ISS docking, was successfully carried out in May 2022 after troubleshooting.

In May 2023, NASA and Boeing were looking to a late July 2023 launch of the CFT when they identified two new issues: a possible flammability risk associated with extensive runs of tape used to protect electrical wiring from chafing and a parachute recovery system with lower-than-anticipated load limits within the material soft links.

“We can safely say those issues are behind us,” Nappi said.

The parachute material’s durability has been improved and additional material and stitching implemented. Nearly a mile of the potentially flammable tape has been removed, and protective barriers for fire prevention have been installed.

Wilmore praised the work by Boeing’s engineers in developing the Starliner’s operational components. But he says that even before the CFT, he and Williams have brought value to ground-based development activities in which they raised questions about potential functionality that led to valuable modifications.

“It doesn’t mean you necessarily have to be a test pilot for all of that, but you have to have [a] thought process that [is] going to ask questions and objectively look at what you are doing and try to make sure we are doing the right things,” he said. 

Editor's note: This article was updated after the May 6 launch attempt was scrubbed.