Issue with Atlas 5 booster liquid oxygen vent valve causes second scrub of ViaSat-3 F2 launch

United Launch Alliance halted its Atlas 5 countdown for a second night in a row, scrubbing the launch of the ViaSat-3 F2 satellite. Liftoff from pad 41 at Cape Canaveral Space Force Station was scheduled for 10:16 p.m. EST (0316 UTC), but the valve issue that prevented a launch Wednesday night remained persistent on Thursday. Launch Director James Whelan scrubbed a launch attempt Wednesday night when a vent valve on the Atlas 5’s first stage liquid oxygen tank failed to work properly during final pre-launch checkouts. A little more than an hour before the Thursday night window opened, ULA said it was foregoing the launch attempt. More

(Source: SpaceFlight Now - Nov 8)