Following years of development and just days after securing long sought-after FAA approval, Elon Musk’s SpaceX was poised for the first test launch of its massive Starship rocket from the company’s Starbase spaceport in southern Texas on Monday morning.

Originally scheduled for 8 a.m. CDT, Musk tweeted just after 7 a.m. that a frozen pressure valve could delay or scrub the launch and a short time later, launch officials called off the attempt. During a live broadcast of the event, commentators said the next attempt would happen no sooner than Wednesday.

SpaceX’s 400-foot tall rocket is powered by 33 individual Raptor engines that, in unison, create nearly 17 million pounds of thrust. The methane-powered system dwarfs the current record held by NASA’s Space Launch System, which flew a successful test flight last November and can achieve almost 9 million pounds of thrust.

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While technical issues kept Starship on its launchpad Monday, SpaceX shared an optimistic tweet following the decision to scrub the mission and try again later this week.

“With a test such as this, success is measured by how much we learn, which will inform and improve the probability of success in the future as SpaceX rapidly advances development of Starship,” the tweet read.

SpaceX describes Starship as “a fully reusable transportation system designed to carry both crew and cargo to Earth orbit, help humanity return to the Moon, and travel to Mars and beyond.” While Monday’s unmanned test flight was not going to include landing the components back on Earth, as SpaceX does with its workhorse Falcon 9 rockets, the Starship system is designed for return and reuse capabilities.

Starship is capable of lifting as much as 250 tons into space and could accommodate 100 people on a potential trip to Mars, according to The Associated Press.

SpaceX has its own plans for putting the Starship to work once it becomes operational, ferrying satellites to low Earth orbit and potentially carrying paying passengers to space. But NASA is also vested in successful development of the giant rocket system, having struck a $2.9 billion contract with SpaceX in hopes of making Starship part of the Artemis moon mission. Starship’s upper stage spacecraft would be used to carry astronauts from lunar orbit to the surface of the Moon but the NASA contract stipulates that SpaceX must first prove its abilities by performing a successful unmanned lunar landing.