CFT Starliner Departure Stands Down, Targets NET July Return to Earth

The impending return to Earth of Crew Flight Test (CFT) Commander Barry “Butch” Wilmore and Pilot Suni Williams has moved beyond the early July timeframe, following a joint NASA/Boeing announcement on Friday that it intends to use the additional time aboard the International Space Station (ISS) to support a pair of U.S. spacewalks and facilitate better understanding of a series of propulsion issues which continue to plague the Starliner spacecraft. According to Commercial Crew Program Manager Steve Stich, NASA will complete “an agency-level review” ahead of CFT’s departure “to document the agency’s formal acceptance on proceeding as planned”.

“We are taking our time and following our standard mission management team process,” said Mr. Stich in his Friday remarks. “We are letting the data drive our decision-making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking.

“Additionally, given the duration of the mission, it is appropriate for us to complete an agency-level review, similar to what was done ahead of NASA’s SpaceX Demo-2 return after two months in orbit, to document the agency’s formal acceptance on proceeding as planned,” Mr. Stich continued. “We are strategically using the extra time to clear a path for some critical station activities while completing readiness for Butch and Sunni’s return on Starliner and gaining valuable insight into the system upgrades we will want to make for post-certification missions.”

Friday’s decision marks the fourth definitive extension of CFT since the mission’s launch atop a United Launch Alliance (ULA) Atlas V rocket from storied Space Launch Complex (SLC)-41 at Florida’s Cape Canaveral Space Force Station during an “instantaneous” window at 10:52:15 a.m. EDT on 5 June. Wilmore and Williams docked Starliner at the forward port of the station’s Harmony node at 1:34 p.m. EDT the next day, approximately 27 hours after liftoff, to begin what was expected to be at least eight days of critical flight test trials aboard the new spacecraft ahead of its integration next year—alongside SpaceX’s Crew Dragon—as a fully fledged member of the active Commercial Crew fleet.

But the early phase of the mission proved troubled, following the discovery of multiple helium leaks—one that was discussed prior to launch, plus two “new” ones—aboard Starliner, which prompted the isolation of three helium manifolds to monitor and manage them during CFT’s on-orbit time. Those manifolds were reopened in readiness for Starliner’s attitude adjustment burn and remained open through rendezvous and docking. 

As Wilmore and Williams neared the ISS on 6 June, five of the 28 Reaction Control System (RCS) thrusters on the service module failed “off”, although four were recovered via a series of hot-fire tests as the astronauts entered the station’s 600-foot (200-meter) “hold point” ahead of docking. This factored into the decision to push back their docking from the first “window” at 12:15 p.m. EDT to the second which opened at 1:33 p.m. EDT.

After a couple of hours devoted to pressurization and leak checks, at 3:45 p.m. EDT Wilmore and Williams floated aboard the station. And their exuberant joy at being back in space triggered laughter from the incumbent Expedition 71 Commander Oleg Kononenko, his Russian crewmates Nikolai Chub and Aleksandr Grebenkin and U.S. astronauts Matt Dominick, Mike Barratt, Jeanette Epps and Tracy Dyson. 

A longer sleep period after docking allowed Wilmore and Williams to plunge directly into their CFT work, unpacking cargo, charging their tablet computers and reviewing emergency procedures on 7 June ahead of a “Safe Haven” period of isolation inside Starliner to demonstrate how an emergency departure or the need to hunker-down in the event of a Micrometeoroid Orbital Debris (MMOD) conjunction might play out. This process included the powering-up and rapid checkout of spacecraft systems if an imminent undocking and departure were ever necessary.

The Safe Haven test on 8 June saw Wilmore and Williams joined aboard Starliner for a number of hours by Dominick and Dyson to evaluate the practicality of the task with a full Post-Certification Mission (PCM) baseline crew of four people. “We went through that process today, closing the hatches, and it was quite a successful event,” was Wilmore’s summary of the activity.

The Safe Haven also allowed the foursome to assess air circulation inside the spacecraft, together with sleeping arrangements, privacy space and the ability to don and doff space suits and facilitate storage. Starliner was then powered down into “quiescent” mode, as will happen on operational long-duration missions, beginning in 2025.

Over the next few days, Wilmore and Williams worked on a dual plate of CFT and station tasks. They also performed a dry run of the power-up procedures of Starliner ahead of undocking, installing window covers for future long-duration crews and performing space-to-space audio checks. 

Elsewhere, the astronauts supported ISS operations, with Wilmore working on computer maintenance in the Microgravity Science Glovebox (MSG) and Williams installing hardware in support of the Solid Fuel Ignition and Extinction-Material Ignition and Suppression Test (SoFIE-MIST). The latter forms part of an ongoing research thrust to understand the effect of fire growth and behavior and material flammability in the microgravity environment.

On 9 June they were advised that their stay was being extended from the 14th until at least the 18th, in support of additional ISS activities and to leverage their assistance during the planned U.S. Extravehicular Activitiy (EVA)-90 by Dyson and Dominick. In the meantime, ground teams continued evaluating RCS thruster issues on Starliner’s service module. One remained deselected, with plans to fire all 28 thrusters after undocking to collect additional data before the service module is discarded prior to re-entry. 

The helium leakage rates were also considered to allow “plenty of margin” for Wilmore and Williams’ return home. Teams noted that Starliner would only require about seven hours of free-flight time to perform nominal end-of-mission operations and stressed that the spacecraft carried enough helium—even after discounting a week of loss—to support more than 70 hours if necessary.

As Starliner was placed into a quiescent state and minimal power mode, the CFT crew effectively became an integral part of Expedition 71, supporting biomedical research and gene sequence training. Wilmore inventoried the Human Research Facility (HRF) to check items such as blood tube kits, saliva sample packs and gloves, while Williams worked on procedures to gather microbial samples, extract DNA and sequence genes to better understand the behavior of bacteria and fungi in ISS water systems. 

Williams’ work supported the Genes in Space Molecular Operations and Sequencing (GiSMOS), which also seeks to accurately represent the microbial “community” aboard the station’s Water Recovery System (WRS) due to bias caused when samples are returned to Earth for analysis. Elsewhere, Wilmore completed cargo stowage checks and on 13 June Williams assisted Barratt and Epps to suit-up Dyson and Dominick for EVA-90.

Unfortunately, that spacewalk—the first of three U.S. EVAs planned in the next few weeks—was called off shortly before it was due to begin, following a call of a “crew discomfort” issue from Dominick. EVA-90 has now been moved to No Earlier Than (NET) 24 June, with Barratt partnering with Dyson on the upcoming spacewalk. A second U.S. EVA is scheduled for 2 July.

Early 14 June, teams retargeted No Earlier Than (NET) 22 June for Wilmore and Williams’ return, citing a need “to finalize departure planning” that pushed the mission’s conclusion beyond 16 days. “We are continuing to understand the capabilities of Starliner to prepare for the long-term goal of having it perform a six-month docked mission at the space station,” said Mr. Stich. “The crew will perform additional hatch operations to better understand its handling, repeat some Safe Haven testing and assess piloting using the forward window.”

In the meantime, a hot-fire test of the service module’s RCS thrusters on 15 June was performed with Wilmore and Williams aboard Starliner to furnish feedback on the sound and feel of the operation. After the test concluded, the helium manifolds were isolated and leak rates in each manifold decreased. Other tasks included cabin sound-level checks, adjustments of the astronauts’ Communications Head Protection Assembly (CHPA) and filming of on-orbit hatch operations for the benefit of future crews.

By 18 June, Wilmore and Williams’ return date had been pushed again to NET 25 June, with Boeing noting last Thursday that CFT had completed 77 of its 87 prescribed flight test objectives, with the remaining ten scheduled to occur during undocking, re-entry and landing. “Starliner is performing very well and we are getting exactly what we wanted out of this flight test by learning things you can only learn in flight,” said Mark Nappi, Boeing’s vice president and program manager for Commercial Crew.

And just yesterday, NASA open-ended CFT’s return to some point after U.S. EVA-91, which is currently planned for 2 July. “The station’s schedule is relatively open through mid-August,” the agency reported, with a SpaceX Crew Dragon carrying Crew-9 Commander Zena Cardman, Pilot Nick Hague and Mission Specialists Stephanie Wilson and Aleksandr Gorbunov expected to launch around that time and Dominick, Barratt, Epps and Grebenkin due to return to Earth later that same month.

Yesterday, as Dyson, Barratt, Dominick and Epps rested ahead of U.S. EVA-90, Wilmore and Williams helped tidy up the ISS and adjusted seats aboard Starliner. They also exchanged thermal hardware, refreshed crew provisions and packed trash aboard Northrop Grumman Corp.’s NG-20 Cygnus cargo ship for its impending departure. 

Undocking—whenever it takes place—is set to occur about 6.5 hours prior to landing, a little sooner than it would happen on operational missions in order that Wilmore and Williams can perform additional tests. CFT will perform a minute-long deorbit “burn” over the Pacific Ocean, with four landing zones—two areas at White Sands Space Harbor (WSSH), N.M., plus two others at Willcox Playa, Ariz., and Dugway Proving Grounds, Utah—available to the crew.

Last weekend, Boeing and NASA recovery personnel participated in a mission dress rehearsal at White Sands to prepare for CFT’s re-entry and landing. The combined Landing and Recovery Team (LRT) simulated convoy activities and the physical recovery of Wilmore and Williams and the spacecraft.

Starliner’s landing sequence will commence at an altitude of 30,000 feet (9,000 meters), with a set of drogue parachutes and later the main canopies “reefed” at 8,000 feet (2,400 meters). Touching down under parachutes and airbags, Wilmore and Williams will be extracted from the spacecraft, helicoptered to a landing field and then flown back to NASA’s Johnson Space Center (JSC) in Houston, Texas.

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