In a tweet in the early hours of Tuesday, SpaceX CEO Elon Musk wrote: “Tracking to a potential 8 a.m. [EDT] liftoff.”

It was in response to space YouTube account Everyday Astronaut, which hosts livestreams of the SN launches using a launchpad camera.

Everyday Astronaut said SpaceX’s launch window was between 7 a.m. to 3 p.m. EDT, but warned “weather is definitely iffy.” A YouTube livestream will begin at 5:45 a.m.

The company had been planning to launch the rocket on Monday, but Musk said on Twitter an inspector from the U.S. Federal Aviation Administration (FAA) had not been able to get to the site in time.

Before that, it was hoped SN11 could have launched on Friday, March 26. However, Musk said further checks were needed.

SN11 is the latest in a series of rocket prototypes that SpaceX hopes will eventually result in Starship; a spacecraft capable of launching humans to the Moon and Mars. The company hopes to have Starship making flights as soon as 2023.

SpaceX has a lot of development to do before then. The previous high-altitude SN prototype tests have all ended up with the rockets exploding upon, or shortly after, landing.

The company seemed to have come close to a successful landing on March 4 with its SN10 mission, when the rocket landed vertically on the launch pad. However, it blew up minutes later. SN9 and SN8 both hit the landing pad too hard and exploded straight away.

Like these missions before it, SN11 will ignite its three Raptor engines and ascend to an altitude of around 6.2 miles.

It will then shut off its engines, perform a “belly flop” maneuver and plummet back to Earth sideways before reigniting its engines to attempt a vertical landing. SpaceX is hoping to recover the rocket fully.

The goal is to recreate how Starship will re-enter the atmosphere from space on real missions.

When Starship is complete SpaceX says it will be the most powerful launch vehicle ever made. It will consist of two parts—the Starship section on top, where humans or cargo will be, and the Super Heavy rocket booster on the bottom.

So far only the top part has been tested and flown. In December 2020, Musk said the Super Heavy booster will begin flight testing in “a few months.”