WASHINGTON — NASA and Boeing have reset the launch of the company’s CST-100 Starliner spacecraft for June 5 after United Launch Alliance fixed a computer problem that scrubbed the previous launch attempt.
NASA announced late June 2 that mission managers gave their approval to proceed with a launch of the Crew Flight Test (CFT) mission on June 5 at 10:52 a.m. Eastern, the next available launch opportunity. A backup opportunity is June 6 at 10:29 a.m. Eastern.
The previous CFT launch attempt June 1 was scrubbed 3 minutes and 50 seconds before its scheduled liftoff. ULA said that a card known as the launch sequencer in one of three redundant ground control computers came up slower than the other two when exiting a pre-planned hold at T-4 minutes. Tory Bruno, chief executive of ULA, speculated that a hardware or networking problem might explain what happened.
In a statement, NASA said that ULA found a problem with a power supply unit used by a portion of the cards in the one computer. That includes the card that controls valves used for replenishing propellants on the Centaur upper stage, which also malfunctioned earlier in the countdown.
NASA said ULA decided to replace the computer rack, or chassis, with the faulty power unit with a spare while technicians investigate what caused the power supply to malfunction. “ULA has completed functional checkouts of the new chassis and the cards, and all hardware is performing normally,” NASA stated.
Weather is again expected to be favorable for the launch, with a 90% chance of acceptable launch conditions June 5. NASA did not report any other issues being worked with either the Atlas 5 rocket and its ground support equipment, or with the Starliner spacecraft itself.
On the CFT mission, Starliner, with NASA astronauts Butch Wilmore and Suni Williams on board, will fly to the International Space Station, spending about a week there before returning to land in the southwestern United States. The mission is the final test flight before NASA can certify the vehicle for operational missions to the ISS starting as soon as early 2025.
NASA and ULA said that if Starliner does not launch by June 6, they will stand down in order to do work on the rocket itself, replacing expiring batteries. That work would take about 10 days to complete, they said.