SpaceX has postponed a full-fledged launch after detecting an issue with a frozen pressurant valve. Instead, today will represent a "wet dress rehearsal" that includes wiggling Starship's engines. Our original post on the initially planned launch is below. According to Axios's Miriam Kramer, SpaceX will now need to wait a minimum of 48 hours before another attempt.
A pressurant valve appears to be frozen, so unless it starts operating soon, no launch today— Elon Musk (@elonmusk) April 17, 2023
After many delays and a last-minute approval, SpaceX was ready to conduct Starship's first orbital test flight before the launch was canceled. The next-generation rocket was expected to launch from Boca Chica, Texas at 9:20AM ET with a livestream already available through the company's YouTube channel (below). While conditions are generally favorable, there are backup launch windows on Tuesday and Wednesday that SpaceX will now need to take advantage of.
This is the first time SpaceX was planned to launch a fully integrated Starship system with a Super Heavy booster underneath to get the main vehicle into orbit. The combination is about 394 feet tall, or taller than the Saturn V rocket. While both Starship and the booster are designed to be reusable, both will splash into the sea during the test.
Whenever this test flight happens, there's no guarantee of success. In a Twitter Spaces chat on Sunday, Elon Musk told fans to "set your expectations low." Don't be surprised if something goes awry, in other words. Instead, this test is more about collecting data to improve future boosted Starship flights.
A successful test is crucial both for SpaceX's long-term plans, including lunar tourism, as well as NASA's exploration plans. The Artemis Moon landings beginning in December 2025 will use Starship to take crews from an orbiting Gateway station to the lunar surface. While those won't depend on a booster, NASA needs to know that Starship is reliable before these crewed missions can go forward.
Update 4/17/23 10:05AM ET: This story has been updated to note that today's launch has been scrubbed.