The first launch of astronauts on Boeing’s Starliner capsule is targeted for April 22.

Boeing’s Starliner crew module for the upcoming Crew Flight Test was mated with the spacecraft’s service module last year in Florida.

We’ve heard this before, but Boeing appears to be a couple of months from finally launching astronauts into orbit aboard the commercial CST-100 Starliner crew capsule.

It was about two months prior to this mission’s previous launch date last July when Boeing and NASA officials decided to put a hold on launch preparations. During their final reviews to certify Starliner for flight nearly a year ago, engineers discovered two technical issues that somehow escaped detection for years.

One of these issues involved parts of Starliner’s parachute deployment system that did not meet required safety specifications. The other was a revelation that Boeing installed flammable tape wrapped around wiring bundles throughout the spacecraft, creating a potential fire hazard. These were the latest in a line of technical problems that have plagued the Starliner program, delaying the new spacecraft’s first test flight with astronauts from 2017 until this year.

Over the last year, engineers have redesigned critical components of the parachute system and removed roughly 4,300 feet (1.3 kilometers) of the flammable tape—known as P213—from the Starliner spacecraft.

“We’ve worked through a number of issues that delayed the launch from last summer and closed those out,” said Steve Stich, manager of NASA’s commercial crew program. “We had a successful parachute test in early January, with some modifications to the parachute system to improve the strength of those parachutes. That went well. We reviewed that data.”

This was the final test of Starliner’s parachute system before the spacecraft finally takes off with astronauts onboard, according to Stich. This upcoming flight, called the Crew Flight Test, is currently targeted for liftoff from Cape Canaveral Space Force Station in Florida no earlier than April 22, he said in response to questions from Ars.

Assuming liftoff happens on April 22, the launch time would be approximately 4:24 am EST (09:24 UTC), based on the alignment of the International Space Station’s orbit with the launch pad in Florida. Veteran NASA astronauts Butch Wilmore and Suni Williams will fly Starliner to a docking with the space station, then return to Earth for an airbag-cushioned parachute-assisted landing in New Mexico. The entire test flight will last roughly 10 days.

Rolling back the tape

“We needed one test with the new upgraded system,” Stich said of the spacecraft’s parachutes. “We changed the joints on the suspension lines, strengthened the main canopies, and then also there were some soft links that needed to be strengthened, which we flew on two parachutes on that test and those all looked good. We inspected all the hardware after that parachute test in Yuma (in Arizona), and that hardware all looked great.”

There are 24 of these fabric soft links on each Starliner spacecraft, with eight on each of the capsule’s three main parachutes. The soft links are part of the network of lines connecting each parachute canopy to the spacecraft. During their final safety reviews last year, engineers discovered the soft link connections were more prone to failure than anticipated, especially in a situation where one of the spacecraft’s three main chutes didn’t deploy. One of the Starliner program’s fundamental safety requirements is that the spacecraft can safely land with two of its three chutes.

For the final prelaunch parachute test on January 9, Boeing verified the strength of the soft links using a test vehicle with the same weight as a Starliner spacecraft. During this test, the test vehicle dropped from a C-130 cargo plane over a US Army facility in Arizona. Engineers purposely used only two chutes to simulate the additional stress the system would see during an extreme case.

NASA astronaut Butch Wilmore, commander of the first Starliner crew flight, tries on a
Boeing spacesuit during a crew validation test at NASA’s Kennedy Space Center in 2022.

While Boeing prepared for the parachute drop test, technicians inside the Starliner factory at NASA’s Kennedy Space Center removed most of the flammable P213 tape from the spacecraft assigned to the upcoming astronaut flight. This took several months. There were some areas where the tape couldn’t be removed, according to NASA, and in these places, workers overlapped the P213 material with another non-flammable chafe-resistant tape and installed fire breaks on wire harnesses, according to NASA.

You can look at the late discovery of the flammable tape and parachute safety issues in a couple of ways. It demonstrates the rigor of NASA’s certification processes for human spaceflight, but any space program manager will tell you it’s less expensive and less time-consuming to discover these problems at an earlier stage of development, not at a point when fixing these problems requires disassembling major parts of the spacecraft.

These are just the latest missteps for Boeing’s Starliner program. The program’s setbacks included a toxic fuel leak caused by valve issues during a ground test in 2018 and an unpiloted orbital test flight in 2019 cut short by software problems that Boeing officials later said would have been uncovered with more thorough prelaunch testing.

Boeing was hours from launching a redo of the Starliner unpiloted orbital test flight in 2021, but engineers found sticky valves inside the spacecraft’s propulsion system. Further investigations revealed corrosion as the source of the problem. Finally, in May 2022, Boeing successfully launched and docked a Starliner spacecraft at the International Space Station, then returned the capsule to Earth.

The test flight met all of its major objectives, but engineers uncovered problems with thrusters apparently caused by debris particles inside the spacecraft’s propulsion system. Officials also took time to review the unexpected behavior of the spacecraft’s cooling system caused by valve issues. Stich said NASA officially cleared Boeing’s work to address those issues at a recent management board meeting.

“We’re in the middle of some final certification work on the parachutes and a few other things, but right now, things are looking good for, toward the end of April, launching Starliner,” Stich said.

A pair of parachutes lower a dart-shaped test vehicle to the ground to conclude
a January 9 drop test for a modified parachute for the Starliner spacecraft.

NASA awarded fixed-price contracts to Boeing and SpaceX in 2014 to develop and bring the Starliner and Crew Dragon spacecraft into service and end US reliance on Russian Soyuz spaceships to transport astronauts to and from the International Space Station (ISS). Boeing’s initial contract was valued at $4.2 billion, and SpaceX’s was worth $2.6 billion.

To be fair, SpaceX also made mistakes during the development of its Crew Dragon spacecraft. One of the Dragon capsules exploded during a ground test in 2019, but SpaceX corrected the problem and successfully launched astronauts a little more than a year later.

Now, SpaceX is on the verge of launching its eighth operational Crew Dragon flight to the space station under the auspices of its NASA commercial crew contract. NASA has extended its contract with SpaceX from an original scope of six operational flights to 14 crew rotation missions, taking the Crew Dragon program to the end of the 2020s. Boeing’s contract still covers six operational six-month flights, each with four crew members, following the upcoming demo mission with Wilmore and Williams.

SpaceX is also winning business for fully commercial human missions on Crew Dragon, including standalone flights bankrolled by billionaire Jared Isaacman and private astronaut missions to the ISS for Axiom Space.

The Starliner delays have jeopardized Boeing’s ability to build a market for Starliner beyond the existing NASA contract. Boeing is teaming with at least one commercial group working on a privately owned space station to follow the ISS, but Starliner has no firm contracts beyond the original six-flight deal with NASA.

All of these problems have cost Boeing around $1.4 billion in losses on the Starliner program. The company is on the hook to pay for Starliner cost overruns due to the terms of the fixed-price contract with NASA, which doesn’t have to absorb the additional costs.

Nevertheless, NASA still wants to have Starliner in service as a crew transporter for the ISS. This would alleviate NASA’s pressure on SpaceX to deliver and give NASA assurance its astronauts can fly to and from the space station, even if SpaceX encounters prolonged delays or a grounding of Crew Dragon.

NASA’s current insurance against a potential problem with Crew Dragon is to continue flying US astronauts on Russian Soyuz spacecraft in exchange for allowing Russian cosmonauts to fly on US vehicles. This ensures there is always a US astronaut and a Russian cosmonaut at the ISS to operate each partner’s segment of the outpost.

Next steps

In addition to a final handful of certification reviews, Boeing and NASA engineers continue preparing the Starliner spacecraft for launch in April. Boeing has two reusable Starliner crew modules, and each mission flies with a single-use service module providing power and propulsion to the spacecraft.

The crew and service modules are now connected for the Starliner Crew Flight Test, and Boeing’s ground team has loaded the ship with the freon-like coolant fluid used in its thermal control system. In mid-March, technicians will load Starliner with maneuvering propellant. The next few weeks of work will also include loading cargo into the spacecraft.

United Launch Alliance technicians installed the first stage of an Atlas V rocket on its mobile
launch platform February 21, kicking off stacking of the launch vehicle for the Starliner Crew Flight Test.

In early April, Boeing will drive the spacecraft from its factory to United Launch Alliance’s launch pad a few miles away. There, ULA will hoist the spacecraft on top of its Atlas V rocket. Last week, ULA started stacking the Atlas V for the Starliner test flight, a significant milestone in the launch campaign.

“The spacecraft is in really good shape, not much work left to go,” Stich said.

Aside from final preflight reviews and spacecraft hardware preps, NASA managers are tracking a sequence of missions to the ISS ahead of Starliner. These include the arrival and departure of two SpaceX crew vehicles in the next couple of weeks, a Russian Soyuz crew rotation next month, and a SpaceX cargo mission scheduled for launch in mid-March. Assuming a launch in mid-March, the SpaceX resupply spacecraft is slated to depart the station in mid-April, clearing a docking port for the arrival of Starliner later that month.

[28 Feb 2024] Maybe, just maybe, Boeing’s Starliner will finally fly astronauts this spring
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