Boeing’s CST-100 Starliner spacecraft successfully docked at the International Space Station (ISS) on June 6. However, it’s now facing a new challenge as it’s scheduled for its return to Earth on June 18. Engineers from Boeing and NASA are currently investigating a helium leak, the fifth since the spacecraft’s liftoff.
One helium leak. This issue adds to the previous delay of the first manned Starliner mission on May 6, which was attributed to a faulty valve on the Atlas V rocket. During this delay, Boeing and NASA engineers discovered a small helium leak in a rubber seal on the spacecraft.
After deeming the leak non-threatening to the mission, engineers gave the go-ahead for the spacecraft’s launch, which took place on June 5. The NASA astronauts, Butch Wilmore and Suni Williams, had been in quarantine for a month leading up to the launch.
Three helium leaks. Mission engineers detected two additional leaks during the journey to the ISS, which meant the spacecraft had a total of three leaks in two helium manifolds in the propulsion system.
One of the leaks was relatively large, causing a pressure loss of 395 psi per minute. As a result, NASA decided to close the helium manifolds until Starliner’s docking at the ISS. When the manifolds were reopened, five out of the 28 thrusters in the reaction control system (RCS) failed. One of the thrusters, which is pointing backward, hasn’t returned to operation.
Five helium leaks. After a brief delay to address a thruster issue, astronauts Wilmore and Williams joyously arrived at the ISS. At 61 and 58 years old, respectively, this mission likely marks their final one with NASA.
Meanwhile, Boeing engineers working on the Starliner spacecraft have been dealing with ongoing helium leaks. They found a fourth leak, releasing helium at a rate of 7.5 psi per minute, just after docking the probe at the ISS. Later that day, they discovered a fifth, smaller leak of 1.5 psi per minute, which wasn’t disclosed until Monday.
NASA is closely analyzing the situation. Prior to liftoff, Boeing had stated that fewer than five leaks wouldn’t jeopardize the Starliner spacecraft’s integrity. With the confirmation of a fifth leak, NASA is examining “what impacts, if any, five small leaks in the service module helium manifolds would have on the remainder of the mission.”
The helium manifolds will remain closed until the return flight, but they’ll need to be opened on that day for Starliner to use its RCS thrusters for undocking and de-orbit maneuvers.
Despite the potential risk to two human lives, neither NASA nor Boeing are worried about the findings. The new leaks are very small compared to the previous ones, and there’s still enough helium for 70 hours of flight time, while the spacecraft will only need seven hours to return to Earth.
Image | NASA/Robert Markowitz
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