Starliner Will Stay an Extra Few Days at ISS for Additional Tests

Starliner Will Stay an Extra Few Days at ISS for Additional Tests

NASA and Boeing have decided to keep the Starliner capsule docked to the International Space Station a few days longer than planned. The first landing opportunity was June 14, but NASA pushed that first to June 18 and now to June 22. Weather or other considerations could change it again. The extra time will be used to conduct additional tests of Starliner’s propulsion system and other aspects of the new spacecraft’s systems.

After two launch scrubs and weeks of delay, Starliner finally lifted off on the Crew Flight Test (CFT) on June 5, but experienced several technical issues on the way to the ISS including thruster anomalies and new helium leaks. NASA astronauts Butch Wilmore and Suni Williams ultimately docked at the ISS on June 6 a little later than planned, but otherwise successfully.

Boeing Starliner Crew Flight Test (CFT) astronauts Suni Williams and Butch Wilmore (blue flight suits) are greeted by the 7-member long-duration ISS crew members, June 6, 2024. Front row (L-R):  Suni Williams (NASA), Oleg Kononenko (Roscosmos), and Butch Wilmore (NASA). Second row (L-R)  Alexander Grebenkin (Roscosmos), Tracy C. Dyson (NASA), and Mike Barratt (NASA).  Back row (L-R): Nikolai Chub (Roscosmos), Jeanette Epps (NASA), and Matthew Dominick (NASA). Photo credit: NASA Television.

Five of the spacecraft’s 28 Reaction Control System (RCS) thrusters went offline during the trip to the ISS when software automatically disabled them for reasons not yet explained. Four of the five were restored before docking, but one remains offline. Boeing’s Mark Nappi, Vice President and Program Manager for Commercial Crew stressed on June 6 that the thrusters did not fail, so it’s not a hardware issue. Software disabled them, but he added it’s not a software issue either, but how they set the software up to “deselect” a thruster under certain conditions.

Image of the International Space Station taken by Maxar’s WorldView-3 earth imaging satellite on June 7, 2024. Boeing’s Starliner is the triangular-shaped spacecraft at center right. The rear of SpaceX’s Crew Dragon Endeavour for the Crew-8 mission is oriented 90 degrees up. Credit: Maxar post on X, June 12, 2024, 6:15 pm ET.
Rendering of the vehicles docked at the ISS right now showing the relative locations of Starliner and Crew Dragon. Credit: NASA

During the extra days in orbit, Boeing will fire seven of the eight aft-facing thrusters. The eighth is the one that remains offline. The “hot fire” test will provide more data about thruster performance for the rest of this mission and for future flights when Starliner is docked at the ISS for a routine six-month mission. The thrusters will be fired in two bursts, totaling one second.

Nappi and several NASA officials will hold a media telecon on Tuesday, June 18, to discuss Starliner’s status and plans for landing. Perhaps more information will be provided at that time.

Hopefully they also will offer more details on what are now five helium leaks in the manifolds that contain the RCS thrusters. One leak was detected before launch, but Boeing and NASA concluded it was stable and did not pose an impediment. Once in orbit, however, three more leaks were found enroute to the ISS and apparently another after it docked. In a June 10 blog post, NASA referred to five helium leaks, not four, but said nothing more.

The mission extension does not appear related to the scrub of a spacewalk by NASA astronauts Tracy Dyson and Matt Dominick on June 13. NASA rescheduled that spacewalk for June 24.

Like Russia’s Soyuz, Starliner lands on land, not in the water as SpaceX’s Crew Dragon or NASA’s Orion do. They may not have to worry about sea state, but weather conditions still must be met that can result in further delays. The two main landing sites are at the White Sands Missile Range in New Mexico, with backups in Utah, Arizona and California.

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