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NASA and Boeing Extend Starliner Stay at ISS for Additional Testing

Originally scheduled to undock as soon as June 18, the Starliner will now depart no earlier than June 22 with NASA astronauts Butch Wilmore and Suni Williams on board.

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Zac Aubert

Zac Aubert

Sat Jun 15 2024Written by Zac Aubert

NASA and Boeing have announced that the CST-100 Starliner spacecraft will remain docked at the International Space Station (ISS) for at least four additional days to conduct further testing of the commercial crew vehicle before its return to Earth.

Originally scheduled to undock as soon as June 18, the Starliner will now depart no earlier than June 22 with NASA astronauts Butch Wilmore and Suni Williams on board.The extension, as stated by NASA, will be used “to finalize departure planning and operations,” including conducting additional tests of Starliner systems that were not initially planned.

“We have an incredible opportunity to spend more time at station and perform more tests which provides invaluable data unique to our position,...We have plenty of margin and time on station to maximize the opportunity for all partners to learn, including our crew.” - Mark Nappi, Boeing Vice President and Commercial Crew Program Manager.

One of the critical additional tests involves a firing of the spacecraft's aft-facing thrusters. Seven of the eight thrusters will be tested in two pulses lasting about one second in total. This test aims to evaluate the spacecraft's performance when docked to the ISS for future missions that could last up to six months.

Notably, these thrusters encountered issues during Starliner’s approach to the ISS on June 6, with five thrusters being “de-selected” by the spacecraft’s computer due to out-of-bounds readings. Four of the thrusters were restored by controllers, allowing the docking to proceed, but the cause of the thruster malfunctions remains unknown.

Additional activities during the extended stay will include measuring cabin air temperature to compare with the life support system's readings, conducting further tests of the spacecraft hatch and forward window, and repeating a "safe haven" test to evaluate the spacecraft's ability to accommodate four crew members in an emergency scenario on the station.

“We are continuing to understand the capabilities of Starliner to prepare for the long-term goal of having it perform a six-month docked mission at the space station,” - Steve Stich, NASA Commercial Crew Program Manager.

There was no new information provided regarding the helium leaks in Starliner’s propulsion system. A fifth leak was confirmed by NASA on June 11, hours after the spacecraft docked, following one discovered weeks before launch and three more during the approach and arrival at the ISS. The helium manifolds in the propulsion system remain shut while the spacecraft is docked, but NASA assures that Starliner has sufficient helium for the undocking and deorbit maneuvers.

Initially, Starliner was scheduled to spend eight days at the ISS. However, its departure was postponed from June 14 to June 18 to avoid conflicting with a spacewalk scheduled for June 13. That spacewalk, intended for NASA astronauts Tracy C. Dyson and Matt Dominick, was called off due to a “suit discomfort issue,” though details about the issue or the affected astronaut were not disclosed. NASA has rescheduled the tasks from this spacewalk to another previously planned for June 24, but has not specified who will perform it.

The extended stay of the Starliner at the ISS presents an invaluable opportunity for both NASA and Boeing to gain additional data and ensure the spacecraft's readiness for longer missions in the future.