The first attempt by Boeing to send an uncrewed Starliner to the space station in 2019 failed due to software and engineering glitches. A second try in 2022 succeeded, paving the way for efforts at getting the first crewed test mission off the ground.
A May 6 countdown was halted just two hours before launch time over a faulty pressure valve on the Atlas upper stage, followed by weeks of further delays caused by other engineering problems, since resolved, on the Starliner itself.
The two-member crew, NASA astronauts Barry “Butch” Wilmore, 61, and Sunita “Suni” Williams, 58, had been strapped into their seats aboard the spacecraft for a couple of hours before launch activities were suspended on Saturday.
Technicians assisted the astronauts out of the capsule safely about an hour after the flight was scrubbed.
It is common in the space industry for countdowns to be halted at the 11th hour and for launches to be postponed for days or weeks, even when seemingly minor malfunctions or unusual sensor readings are detected, especially in new spacecraft flying humans for the first time.