Heavy cloud cover and high winds Saturday forced United Launch Alliance to order a 24-hour delay for the planned flight of an Atlas 5 rocket carrying an Air Force X-37B spaceplane. The delay, in turn, was expected to force SpaceX to retarget launch of a Falcon 9 rocket carrying a batch of 60 Starlink internet relay satellites from Sunday to Monday.
Assuming both missions stay on track, the back-to-back launches will reflect the fastest turnaround for Air Force personnel supporting two orbit-class rockets since 1967.
The Atlas 5 was first up, targeting a 10-minute launch window that opened at 8:24 a.m. ET. But heavy cloud cover and high winds forced mission managers to delay the flight in hopes conditions would improve enough to permit liftoff during a second 10-minute window opening at 10:13 a.m.
But the weather did not cooperate, the countdown was halted at the T-minus one-minute, 40-second mark and the launch team recycled for another attempt Sunday morning, at 9:14 a.m., when forecasters predict a much better chance of acceptable weather.
SpaceX had been planning to launch the company's eighth batch of 60 Starlink satellites early Sunday, at 3:53 a.m., but the Atlas delay was expected to trigger a similar slip to Monday.