NASA’s Boeing Crew Flight Test mission teams are preparing to support a launch at 10:52 a.m. EDT Wednesday, June 5, from Space Launch Complex-41 at Cape Canaveral Space Force Station in Florida on a mission of about a week to the International Space Station (ISS).

Technicians and engineers with United Launch Alliance (ULA) worked on Sunday to assess the ground support equipment at the launch pad that encountered issues during the countdown and scrubbed the June 1 launch attempt. The ULA team identified an issue with a single ground power supply within one of the three redundant chassis that provides power to a subset of computer cards controlling various system functions, including the card responsible for the stable replenishment topping valves for the Centaur upper stage. All three of these chassis are required to enter the terminal phase of the launch countdown to ensure crew safety.

On Sunday, the chassis containing the faulty ground power unit was removed, visually inspected, and replaced with a spare chassis. No signs of physical damage were observed. A full failure analysis of the power unit will be performed to better understand root cause. Meanwhile, ULA has completed functional checkouts of the new chassis and the cards, and all hardware is performing normally.

The mission managers have opted for the next launch attempt on June 5. The US Space Force’s 45th Weather Squadron predicts a 90% chance of favorable weather conditions, with the cumulus cloud rule being the primary weather concern. Another opportunity is available at 10:29 am, Thursday, June 6.

NASA astronauts Barry “Butch” Wilmore and Suni Williams, the crew of the flight test who will be the first to launch aboard Boeing’s Starliner spacecraft, remain in quarantine at NASA’s Kennedy Space Center and will take part in pilot proficiency and other training activities leading up to launch.