Updated 6:40 p.m. with new April 20 launch date.

COLORADO SPRINGS — SpaceX called off the first attempt to launch its integrated Starship vehicle from Texas April 17 because of a valve problem.

SpaceX announced it was scrubbing the launch of its Starship vehicle and Super Heavy booster from its Starbase test site at Boca Chica, Texas, less than 10 minutes before the scheduled 9:20 a.m. Eastern liftoff, after reporting a pressurization issue with the booster.

“A pressurant valve appears to be frozen, so unless it starts operating soon, no launch today,” Elon Musk, chief executive of SpaceX, tweeted moments before SpaceX announced the scrub.

The company had reported no other major issues with the vehicle, and weather was acceptable. The company continued with the countdown until the T-40 second mark, finishing propellant loading and using the launch attempt as a wet dress rehearsal. Commentators on the SpaceX webcast said it would be a minimum of 48 hours before they could make another launch attempt.

“Learned a lot today, now offloading propellant, retrying in a few days,” Musk tweeted after the scrub. SpaceX announced late April 17 that they were planning the next launch attempt no earlier than April 20, between 9:28 and 10:30 a.m. Eastern.

The launch would be the first flight of the integrated Starship/Super Heavy vehicle after several low-altitude test flights of Starship prototypes and static-fire tests of Super Heavy. The vehicle would fly a “nearly orbital” trajectory, reaching a peak altitude of about 235 kilometers. Starship would splash down in the Pacific near Hawaii and Super Heavy in the Gulf of Mexico just off the coast from Boca Chica; neither vehicle will be recovered.

SpaceX pressed ahead with its launch plans after getting an FAA launch license late April 14 for the test flight. An FAA official said last week that the agency spent more than 500 days reviewing the launch license application, which SpaceX amended several times, in part because of the size and complexity of the vehicle. That is the longest the agency has spent reviewing any commercial launch license application.

During an online discussion April 16 for paying subscribers of Twitter, the social media network he acquired last year, Musk kept expectations low for the launch. “This is a very risky flight. This is not something that is a sure thing at all,” he said.

His main concern was that the rocket would explode at or immediately after liftoff, damaging the launch pad. “It would probably take us several months to rebuild the launch pad,” he said of that scenario. “So, my top hope is please, may fate smile upon us and we clear the launch pad before anything goes wrong.”

“Maybe the second one will be or maybe the third one will be, but tomorrow probably will not be successful, if by success one means reaching orbit,” he said. “If we get any information that allows us to improve the design of upcoming builds of Starship, then it is a success.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...