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SpaceX is making its second attempt on Thursday to launch its massive Starship rocket, the largest and most powerful rocket ever built. The first attempt was called off Monday when a frozen valve caused problems pressurizing the booster’s first stage.

Thursday’s launch window opens at 8:28 a.m. local time (9:28 a.m. ET) at the company’s flight test facility in Boca Chica, Texas.

SpaceX describes Starship as a fully reusable transportation system that is made to carry cargo and crew to Earth orbit. It is designed to help humans return to the moon and go to Mars and beyond.

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

Starship consists of a 230-foot-tall Starship “Super Heavy” first stage, which is powered by 33 methane-burning Raptor engines, and a bullet-shaped, a 160-foot-tall Starship second stage that is equipped with six Raptors of its own, as well as steerable fins at the nose and tail to control the ship during atmospheric re-entry from space. The two stages together can lift 100 tons to low-Earth orbit.

Both stages are designed to be fully reusable, descending to rocket-powered touchdowns for refurbishment and relaunch. For the first test flight, however, SpaceX will not attempt to recover either stage.

Instead, the first stage is expected to fly itself to a “hard” landing in the Gulf of Mexico 20 miles or so from Boca Chica, where it will simply sink. The Starship is supposed to crash back to a destructive splashdown about 150 miles north of Hawaii after a ballistic flight nearly all the way around the planet.  

SpaceX founder Elon Musk downplayed expectations Sunday night in a Twitter “Spaces” call to his subscribers.

“I would just like to set expectations low,” he said. “If we get far enough away from the launch pad before something goes wrong, then I think I would consider that to be a success. Just don’t blow up the launch pad!”

How to watch the Starship launch attempt

  • What: SpaceX makes second attempt to launch its Starship rocket
  • Date: Thursday, April 20, 2023
  • Time: 8:28 CT (9:28 ET) 
  • Location: Boca Chica, Texas
  • Online Stream: Live on CBS News in the player above and on your mobile or streaming device.

Note: Streaming plans are subject to change