The spacecraft is about to take off on its fifth flight, and this time there’s a problem

“We landed with an accuracy of half a centimeter in the ocean, so we think we have a reasonable chance of returning to the tower,” Gerstenmaier said.

Launch the playbook

Meanwhile, the spacecraft’s upper stage will fire up six Raptor engines to accelerate it to nearly orbital speed, giving the rocket enough gravity to sail halfway around the world before falling back into the atmosphere above the Indian Ocean.

This is a similar trajectory to the one the spacecraft flew in June, when it survived a fiery reentry for a controlled landing. This was the first time SpaceX completed a full-scale Starship test flight. Onboard cameras showed fragments of the heat shield falling from the spacecraft as it reentered the atmosphere, but the spacecraft maintained control, restarted the Raptor’s engines, flipped from horizontal to vertical, and came to rest in the Indian Ocean northwest of Australia.

After analyzing the results of the June mission, SpaceX engineers decided to rework the heat shield for the next Starship vehicle. The company said its technicians spent more than 12,000 hours replacing the entire thermal protection system with new generation tiles, a backup layer and additional protection between the ship’s flap structures.

From start to finish, Sunday’s test flight should take about 1 hour and 5 minutes.

Here’s an overview of the key events during Sunday’s trip:

• T+00:00:02: Take off

• T+00:01:02: Maximum aerodynamic pressure

• T+00:02:33: Super Heavy MECO (most engines down)

• T+00:02:41: Separation stage and ignition of spacecraft engines

• T+00:02:48: Start of very heavy booster burn

• T+00:03:41: Turn off extremely heavy boost burn

• T+00:03:43: Eliminate the hot staging ring

• T+00:06:08: Super Heavy is subsonic

• T+00:06:33: Beginning of extremely heavy landing burn

• T+00:06:56: Very heavy landing, turning off and trying to catch

• T+00:08:27: Spacecraft engine parts

• T+00:48:03: Return of the spacecraft

• T+01:02:34: Transonic spacecraft

• T+01:03:43: Subsonic spacecraft

• T+01:05:15: Spacecraft landing flip

• T+01:05:20: Spacecraft landing burn

• T+01:05:34: Spacecraft landing in the Indian Ocean

SpaceX officials hope the Starship’s heat shield will remain intact during its descent into the atmosphere, when temperatures reach 2,600 degrees Fahrenheit (1,430 degrees Celsius), hot enough to melt aluminum, the metal used to build many launch vehicles. SpaceX chose stainless steel for the Starship because it is robust at cryogenic temperatures, where the rocket consumes ultra-cold fuel and oxidizer, and it has a higher melting point than aluminum.