Starliner Passes In-Orbit Tests, But First Operational Launch Slips

Boeing and NASA put the Starliner spacecraft through its paces this weekend, successfully testing the thrusters and confirming the helium leaks are stable. But in a nod to the amount of work that lies ahead before NASA certifies Starliner for operational launches, the agency said a SpaceX Crew Dragon will be used for the February 2025 space station crew exchange, not Starliner-1.

The Starliner Crew Flight Test (CFT) lifted off from Cape Canaveral Space Force Station on June 5 taking NASA astronauts Butch Wilmore and Suni Williams to the International Space Station. As the name implies, this is a test flight of the spacecraft with a crew aboard. Two test flights without a crew took place in 2019 and 2022.

NASA and Boeing entered into a Public-Private Partnership to develop Starliner in 2014 under a fixed price contract for $4.2 billion. It was expected to enter service around 2020, but a series of hardware and software problems during the uncrewed test flights and on the launch pad led to delays that have cost Boeing more than $1 billion so far.

The Starliner CFT is encountering a few problems of its own. During the one-day trip to the ISS, five of 28 Reaction Control System (RCS) thrusters stopped working and four helium leaks developed on top of one that was discovered before launch. Four of the five RCS thrusters later came back online, but the fifth will not be used again. All of them are on the aft end of the spacecraft. The other RCS thrusters and the 20 larger Orbital Maneuvering and Attitude Control (OMAC) thrusters are fine.

The thrusters and the helium leaks are in the spacecraft’s Service Module, which does not return to Earth. It separates from the Crew Module and burns up in the atmosphere, so any tests Boeing wants to do must be done while it is docked to the ISS. Consequently, what started out to be an 8-day visit to the ISS by Butch and Suni has been repeatedly extended and there is no firm date for when they’ll return.

Boeing and NASA have been testing a similar thruster on the ground for several weeks to understand why the ones in space are behaving as they do. They essentially concluded the thrusters overheated.

On Saturday they were ready for an in-space “hot fire” test of the 27 functioning RCS thrusters and to assess if the helium leaks, likely caused by seals degraded by exposure to nitrogen tetroxide fumes, are stable.

Boeing reported the tests went well.

The aft-facing RCS thrusters were fired for 1.2 seconds and the others for 0.4 seconds and “all thrusters performed at peak thrust rating values, ranging from 97-102%. The helium system also remained stable.”

This was the second hot-fire test for Starliner. The first also was successful back in June.

This Starliner capsule is named Calypso after Jacques Cousteau’s ship of exploration. Butch and Suni were inside Calypso during the tests to provide real-time feedback. Boeing said they will participate in two “undock to landing” simulations this week, but no landing has been set yet.

The data collected this weekend will feed into a NASA-Boeing Flight Readiness Review that is “tentatively planned for late next week” after which they will decide next steps.

The ISS is permanently staffed by an international crew of seven, four of whom come and go on SpaceX’s Crew Dragon — and someday Boeing’s Starliner — and three on Russian Soyuz spacecraft. They rotate on six-month schedules and a crew rotation is coming up.

Crew-9 is targeted for launch on August 18 to replace Crew-8, which is currently onboard. However, the Crew-9 launch could wait until early September if Starliner isn’t ready to come back by then. The U.S. segment of the ISS has only two docking ports. Starliner is at one and Crew-8’s Crew Dragon at the other. Starliner must depart to free that port for Crew-9 so there can be the typical five-day handover between Crew-8 and Crew-9. NASA really wants the Crew-8/Crew-9 exchange to happen before September 11 when the Soyuz crew exchange is scheduled.

Whenever Starliner does return, it’s clear that Boeing has a lot of work to do before NASA certifies the spacecraft for operational use for NASA astronauts. The agency and Boeing repeatedly stress that the current mission is a test flight and problems were expected to arise. That’s why they have test flights. But the thruster problems, helium leaks and other anomalies — like an oxidizer isolation value that didn’t properly seat until it was recycled several times during Saturday’s tests — need to be ironed out.

The first operational Starliner launch is Starliner-1. NASA hoped to launch it in February 2025, but NASA Commercial Crew Program Manager Steve Stich said at a Friday news conference they will use a Crew Dragon instead.

That will be Crew-10, SpaceX’s 10th operational NASA mission to ISS and 11th overall (SpaceX’s crew flight test Demo-2 was the first in 2020). SpaceX also launches Crew Dragons for non-NASA customers. Four “private astronaut” flights have flown so far, three of which visited ISS. Two more are coming up before the end of the year.

Starliner-1 will wait at least until August 2025, the subsequent crew rotation, but it could be longer. Stich said they are double-booking another Crew Dragon, Crew-11, in that slot just in case Starliner-1 slips into 2026.

“I would like to announce that Crew-10 will be flying in February of 2025, that’s the next flight, in order to give a little bit more time for Starliner to complete the mods after CFT. So Starliner-1 will move into the August slot next year and we’ll be double-booking that slot with Crew-11.” — Steve Stich, NASA

The original plan was for one Crew Dragon and one Starliner every year, two redundant methods of getting crews to and from the ISS in case one system had to stand down for technical reasons.  NASA didn’t want to be stuck buying launch services from Russia as it was after the space shuttle Columbia tragedy in 2003 and again after the shuttle was terminated in 2011.

Since Crew Dragon restored the U.S. capability to send astronauts into orbit in 2020, NASA has been dependent on that one system, however. Crew Dragon is launched by a SpaceX Falcon 9, which suffered a rare failure on July 11. If past was prologue, that would have meant months of investigation to determine the cause and more months to fix it.

Fortunately for NASA, not this time.

SpaceX’s record-breaking launch rate and the massive amounts of data they collect each time meant that finding and fixing the problem was relatively straightforward. Falcon 9 launches have resumed already — three just this past weekend. The uncertainty for Crew-9’s launch date is not because of Falcon 9, but when Starliner will be ready to bring Butch and Suni home.