Boeing’s Starliner was sitting on the launch pad at Cape Canaveral in Florida when a small but crucial problem with the spacecraft’s 191-foot booster rocket halted the countdown.
The American aerospace giant was hired by NASA to transport two astronauts – Sunita Williams and Barry “Butch” Wilmore – to the International Space Station (ISS) in a deal worth $4.2 billion (£3.3 billion).
But on May 6, engineers discovered that a valve used to regulate the flow of rocket oxidizer — which is mixed with fuel in a combustion chamber to create thrust — was creating an audible hum, forcing them to abort the mission. .
This initial “sticky valve” was followed by a cascade of other problems. However, on June 5, NASA and Boeing still continued the launch.
Now, with the Starliner malfunctioning and its passengers stuck in orbit for two weeks longer than expected, it’s a decision they may regret.
“The company is going through a deep crisis. The optics are terrible,” says Rob Adlard, chief executive of British space launch company Gravitilab. “Space is extremely difficult, but that contrasts with SpaceX’s successes.”
The Starliner’s problems are another blow for Boeing, which has been grappling with a reputational crisis since a major safety problem on one of its 737 Max 9 passenger planes in January.
At 16,000 feet, about nine minutes into an Alaska Airlines flight taking off from Portland, Oregon, the pilots were forced to turn around and make an emergency landing after A door plug exploded, depressurizing the cabin and leaving a hole in the side of the plane. plane.
Following the incident, Boeing faced scrutiny from regulators and calls from customers over its overall approach to safety.
The apparently minor valve problem discovered on May 6, which affected the Starliner’s Atlas V booster rocket (built in a joint venture between Boeing and Lockheed Martin), is typical of the tiny problems that can wreak havoc during complex rocket launches.
On spacecraft, these valves control the flow of important gases such as helium as well as oxygen and other propellants. Boeing had already been forced to repair the Starliner’s corroded valves which were found in 2021 after 13 of them failed on the launch pad.
Starliner, which was originally ordered for a crewed mission in 2017, has been plagued with problems that have cost Boeing more than $1 billion, ranging from software glitches to parachute problems.
The setbacks mean Boeing has fallen behind Elon Musk’s rocket company SpaceX, which has also partnered with NASA to carry astronauts into space. SpaceX’s Dragon spacecraft has been making regular trips to the ISS since 2020.
After the discovery in May of the defective valve on the Atlas V rocket, other problems followed. As engineers tackled the problem, they realized that Starliner was suffering from a helium leak.
Gas is used as a pressure agent to push propellant into the thrusters, meaning a leak can cause them to fail. Worryingly, during the resulting tests, the leak – which was attributed to a bad seal – appeared to get worse, Steve Stitch, NASA’s crew program manager, said at the time.
Fixing the leak would have required separating Starliner from the Atlas rocket, which would have led to longer delays, and NASA and Boeing decided it was possible to proceed safely anyway. Boeing’s Starliner director Mark Nappi even said the delay had a “silver side” because the company discovered the helium problem before the mission.
Starliner was finally launched at 10:52 a.m. on June 5. But mid-flight, while its crew slept, more helium leaks were detected and five of the spacecraft’s 28 thrusters failed as it approached the ISS. Wilmore and Sunita were forced to undertake manual maneuvers in space during a docking sequence that lasted an hour longer than expected.
Another valve problem was also discovered, with a valve in the “reaction control system”, which helps steer the spacecraft, not closing properly. Starliner now relies on an emergency “B valve”.
Now, NASA and Boeing have the complicated task of double-checking Starliner’s systems and fixing as many problems in orbit as possible to ensure a safe return.
At a press conference on June 18, Stitch said that one booster, the B1A3, fired at only 11 percent of its expected power in a “hot-fire” test, and that it would remain off for the remainder of the mission. He said the helium leaks and propellant problems “appear to be related.”
Starliner was scheduled to return on June 14, but will not undock until June 26.
On the ground at the Marshall Space Flight Center, experts are also testing copies of the Starliner’s helium seals by “intentionally damaging a seal, cutting a seal, looking at leak rates” to assess the impact, said Stitch.
Boeing and NASA are confident the craft can return, but they are being kept in orbit to conduct more tests on why the problems persist. Stitch said the team wanted to “make sure we’re really ready to go home.” Boeing’s Nappi told reporters Tuesday: “We have a good, safe spacecraft.” »
Gravitilab’s Adlard said the issues appeared “fixable,” adding that some issues may have arisen because the components “operate differently in the absence of gravity.”
Chris Welch, a consultant and former professor of space engineering at the International Space University in Strasbourg, said: “All of these components are like links in a chain that all need to work in sync.
“Valves in particular are very small and fiddly items that must operate very precisely, over a wide temperature range and under harsh conditions.
“You can simulate them as much as you want, but you can never really be sure how they work until you actually put them in the field. »
If Starliner were to suffer further delays, the ISS would have several months of supplies, while the craft could remain docked for up to 45 days.
Although the helium is gradually leaking from the craft, he still has enough left for 70 hours of flight – and he only needs seven to return home.
NASA, at least, insists its astronauts have confidence in Boeing’s craft, hoping its next flight could take place in early 2025. “You can tell every time they get in the vehicle ” Stitch said on a call with reporters, “They love Starliner.
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