NASA and Boeing have rescheduled the launch of Boeing's CST-100 Starliner spacecraft for June 5 following United Launch Alliance's (ULA) resolution of a computer problem that led to the scrubbing of the previous launch attempt.
Late on June 2, NASA announced that mission managers had given their approval for the Crew Flight Test (CFT) mission to proceed on June 5 at 10:52 a.m. Eastern Time, with a backup opportunity on June 6 at 10:29 a.m. Eastern Time.
The previous launch attempt for CFT on June 1 was halted just 3 minutes and 50 seconds before liftoff. ULA identified a slowdown in one of the ground control computers' launch sequencers, known as the launch sequencer card, compared to the other two during a pre-planned hold at T-4 minutes. Tory Bruno, CEO of ULA, speculated that a hardware or networking issue might have been the cause.
NASA disclosed that ULA detected a problem with a power supply unit utilized by a portion of the cards in the affected computer, including the card responsible for controlling valves used in replenishing propellants on the Centaur upper stage, which experienced malfunctions earlier in the countdown.
As a remedy, ULA opted to replace the faulty power unit's computer rack with a spare while technicians investigate the root cause of the malfunction. “ULA has completed functional checkouts of the new chassis and the cards, and all hardware is performing normally,” NASA stated.
Favorable weather conditions are anticipated for the June 5 launch, with a 90% chance of acceptable launch conditions. No other issues have been reported with either the Atlas 5 rocket and its ground support equipment or with the Starliner spacecraft itself, according to NASA.
The upcoming CFT mission will see Starliner, carrying NASA astronauts Butch Wilmore and Suni Williams, journey to the International Space Station for approximately a week before returning to land in the southwestern United States. This mission marks the final test flight before NASA can certify the vehicle for operational missions to the ISS, potentially commencing as early as early 2025.
Should Starliner fail to launch by June 6, NASA and ULA have indicated plans to stand down for approximately 10 days to perform work on the rocket, specifically replacing expiring batteries.