CFT Continues Safely: Starliner and the Commercial Crew Return Process

Boeing’s Crew Flight Test mission is continuing its stay aboard the International Space Station. On July 25, NASA and Boeing held a press conference to provide an update on the mission including ongoing tests, the current status of the spacecraft, and upcoming events.

In order to better understand the thruster underperformance issue seen during docking, Boeing and NASA have performed ground testing on a  new thruster at NASA’s White Sands Test Facility in White Sands, New Mexico. The tests included two “uphill”, or launch and docking, phases and five “downhill”, or undock through deorbit and landing, phases. They attempted to replicate the conditions that the CFT thrusters experienced when they failed off during docking on June 6, 2024. The same symptoms presented themselves, including the reduced thrust that caused the computer to disqualify the thrusters, enabling teams to determine the root cause and begin to correct it.

The status of the Calypso spacecraft currently on-station was also discussed. The thruster system has been fully isolated since the previous hotfire test and there are currently no helium leaks. The battery duration waiver has also been extended from 45 days to 90, enabling Calypso to stay on station until late September if needed. Due to the thruster issues, a planned manual mode maneuvering test meant to occur after undocking was canceled. This would put more stress on the thrusters and was not a flight test objective, so the decision was made to forgo it in favor of directly going to deorbit.

As part of the testing and data collection in support of the return review process, Boeing hotfired all functional thrusters on Saturday, July 26. All thrusters that were used were fired nominally. This also presented an opportunity to check out the helium system. Leak rates when active remained stable, and one seal reseated itself and stopped leaking. Hot Fires like this will likely be part of every long duration mission going forward, as multiple other visiting vehicles already do them.

The service module and other systems remain healthy enough for a normal return, and there is currently no intent to use a Crew Dragon to return the CFT crew. One of the built-in contingencies of the Commercial Crew Program is that either vehicle could bring down any crew members if their vehicle became unsafe, including cross-training and fitting of IVA suits, but current planning is for Calypso to return as planned once a date has been approved.

The planning process for Commercial Crew returns is rarely discussed, but is important in why NASA and Boeing have seemed so reluctant to announce a return date for CFT. During a flight the commercial provider will maintain potential return dates and plans, but logistics and work must be synchronized between the provider, recovery teams, the ISS, and NASA before a return date can be confirmed and set in stone. This is done by holding a special meeting called a Return Readiness Review roughly two weeks before the proposed return. At this review, the provider presents proposed landing windows, undock times, backups, weather, returned cargo, and other items. NASA will present remaining open work items, discuss any in-flight anomalies and special topics, and review any formal safety dissents. It concludes with an agreement being made as to when to return, where to go, and what to take. An ISS Mission Management Team meeting will later be called to give a Go/No Go decision for return, after which actual final return preps will be set in motion.

CFT is currently awaiting the Agency Return Flight Readiness Review (Return FRR). It will take place as soon as NASA and Boeing are ready, and is likely to occur late this week. Crew-8, on-station right now, is likely a month or two prior to its Return FRR and will also undergo this process. SpaceX and Boeing have both been determining return dates and windows but neither are official or known because neither mission has reached their respective Return FRR yet.

Starliner remains completely safe and ready to return the CFT crew. The deorbit burn is the next time the aft thrusters will be used, a less stressful event than rendezvous and docking. The spacecraft retains significant redundancy, and all systems remain stable and within limits. To quote NASA Flight Director Ed van Cise, in a post on the site formerly known as Twitter, “They are not lost in space. They are not stuck in space. They are not stranded in space.” With the Return FRR as soon as this week, the penultimate phase of the Boeing Crew Flight Test is here, and will soon result in the certification and entry into service of America’s second Commercial Crew vehicle.