NASA and Boeing postponed the launch of the company’s CST-100 Starliner spacecraft to June 5 after United Launch Alliance resolved a computer problem that had blocked an earlier launch attempt.

Late on June 2, NASA announced that mission managers had cleared the Crew Flight Test (CFT) mission, the next available launch opportunity, to launch at 10:52 ET on June 5. Backup opportunity is on June 6 at 10:29 EST.

The previous CFT launch attempt on June 1 was canceled 3 minutes and 50 seconds before the scheduled launch. ULA said a card in one of three backup ground control computers, known as a launch sequencer, was activated more slowly than the other two as the T-4 emerged from a pre-planned hold at 4 minutes. ULA’s general manager, Tory Bruno, suggested that a hardware or network problem could explain what happened.

NASA said in a statement that ULA discovered a problem with the power supply used by some of the maps on a computer. This includes the board that controls the valves used to refuel the Centaur’s upper stage, which also failed at the start of the countdown.

NASA said that while technicians determined what caused the power supply to fail, ULA decided to replace the computer rack or case with the faulty power supply with a replacement part. “ULA has completed functional checks of the new landing gear and maps, and all hardware is operating normally,” NASA said.

It is expected that the weather will be suitable for launch again on June 5 and there is a 90% chance of acceptable launch conditions. NASA reported no other problems with the Atlas 5 rocket and ground support equipment or the Starliner spacecraft itself. .

As part of the CFT Starliner mission, NASA astronauts Butch Wilmore and Suni Williams will fly to the International Space Station for about a week before landing in the southwestern United States. This mission is the final test flight before NASA certifies the spacecraft for operational missions to the ISS starting in early 2025.

NASA and ULA have said that if Starliner is not launched by June 6, they will halt operations to perform work on the rocket and replace dead batteries. According to them, this work will take about 10 days.