There NASA confirmed that the CST-100 capsule Starliner Of Boeing has suffered a fifth helium leak in its propulsion system as engineers work to prepare the vehicle for its return to Earth next week. This new loss, although smaller than previous ones, represents a significant challenge for the mission team.
In a June 10 statement, NASA said spacecraft teams are examining “what impacts, if any, five small leaks in the service module’s helium collectors might have on the rest of the mission”. This was the first reference to the presence of 5 leaks; Previously, NASA had mentioned 4 losses during a briefing shortly after the spacecraft docked with the International Space Station (ISS) on June 6.
NASA was aware of a leak at the time of Starliner’s June 5 launch, detected shortly after a canceled launch attempt on May 6. At the time of launch, NASA and Boeing officials considered the problem a case isolated, probably caused by a sealing defect. However, a few hours after launch, controllers detected others 2 lossesone of which was relatively large at 395 psi per minute, as NASA commercial crew program manager Steve Stich explained during the briefing.
A fourth leak was discovered after docking, although it was much smaller at 7.5 psi per minute. “Over the next few days, we need to look at the loss rate and figure out what to do in relation to the rest of the mission,” Stich said.
After docking, NASA closed the helium collectors in the propulsion system to stop leaks, although they will need to be reopened to use the spacecraft’s thrusters during undocking and deorbiting maneuvers. NASA said June 10 that engineers estimate Starliner has enough helium to support 70 hours of flight operations, while only seven are needed for return to Earth.
In addition to the helium leaks, engineers are investigating a reaction control system (RCS) thruster that shut down during the spacecraft’s flight to the ISS. Another 4 thrusters were deactivated by the flight software but later reactivated. Additionally, an RCS oxidizer isolation valve in the Starliner service module did not close properly.
NASA had initially scheduled the Starliner undocking for June 14, but on June 9 announced the postponement to no earlier than June 18. This delay was decided to avoid a conflict with a spacewalk scheduled for June 13 by NASA astronauts Tracy Dyson and Matt Dominick.
The two NASA astronauts who flew Starliner to the ISS, Butch Wilmore And Suni Williamsare currently busy both conducting tests on the spacecraft and carrying out other tasks, such as scientific experiments.
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