SpaceX plans to launch an updated version of its Starship megarocket — a new prototype of the system that NASA hopes will carry its astronauts to the moon in two years — on a critical test flight Tuesday.

The stakes for Starship, and by extension for Elon Musk’s rocket company, have perhaps never been higher. SpaceX is developing Starship as part of NASA’s Artemis program and racing against its rival, Jeff Bezos’ Blue Origin, to build a lunar lander for NASA to use in 2028, when it aims to put astronauts on the moon. Late next year, NASA intends to test one or both of those new vehicles in low-Earth orbit on the Artemis III mission.

At the same time, SpaceX is preparing to go public. Its highly anticipated IPO, expected next month, could be the biggest of all time. Reuters reported on Friday that the company aims to make its prospectus ​public as early as Wednesday — the day after the Starship test flight — ahead of a market debut possibly by mid-June.

This all comes after Starship suffered a string of setbacks during test flights last year, including an uncontrolled re-entry through Earth’s atmosphere and two midflight explosions as the upper-stage vehicles were accelerating into space.

Starship’s most recent test flight, its 11th in total, took place seven months ago. Since then, the booster, called Super Heavy, and upper stage, called simply Ship, have undergone major redesigns. The upcoming launch will be the first test flight of SpaceX’s new third-generation Starship, dubbed V3. It is now bigger, more powerful and a step closer to being fully reusable. Starship V3 measures 408 feet tall when fully stacked, a few feet taller than its predecessor.

It is scheduled to lift off from a new launchpad at SpaceX’s Starbase facility at the southern tip of Texas, during a launch window that opens at 6:30 p.m. ET.

The flight plan won’t differ much from previous Starship outings, according to SpaceX. During the suborbital test flight, Starship will attempt to deploy 22 mock Starlink satellites. SpaceX also intends for the upper stage to relight one of its six Raptor engines while in space, a key demonstration of technology needed for a deorbit burn when the spacecraft someday returns to Earth from space.

Tuesday’s flight is expected to last about 65 minutes. As has been the case in prior tests, the upper stage should splash down in the Indian Ocean if all goes to plan. SpaceX eventually plans to make Ship reusable and “catch” the spacecraft with mechanical arms on the launch tower at the company’s Starbase facility in South Texas.

SpaceX has demonstrated similar catch maneuvers with Starship’s Super Heavy booster on previous test flights. On Tuesday, however, the booster is set to land at an offshore site in the Gulf of Mexico and will not attempt to return to the launch site for a catch, according to SpaceX.

Starship’s development is behind where NASA hoped SpaceX would be by now. The rocket made its debut flight in 2023, but last year’s failures slowed its progress. NASA had originally intended to land astronauts on the lunar surface during the Artemis III mission but scrapped that plan earlier this year to allow for more testing in low-Earth orbit and to give SpaceX and Blue Origin more time to develop their lunar landers.

Then, during testimony last month before a House subcommittee, NASA Administrator Jared Isaacman told lawmakers that Artemis III will launch in late 2027, rather than mid-2027 as he had said in February.

SpaceX faces a series of tight timelines. The company is racing to have Starship ready for next year’s revamped Artemis III mission, which calls for Starship’s upper stage to rendezvous with NASA’s Orion capsule — the same vehicle that carried the Artemis II astronauts around the moon last month — while orbiting Earth. After that, SpaceX will have a quick turnaround to get Starship certified to carry astronauts to the moon the following year.

The plan for the 2028 mission, Artemis IV, is for Starship’s upper stage to dock with Orion while orbiting the moon, then shuttle NASA’s crew down to the lunar surface. To conclude the mission, Ship would lift off the moon carrying the astronauts and again dock with Orion, which would then carry the crew home to Earth.

The many upgrades SpaceX made to Starship for V3 include new Raptor 3 engines on both Super Heavy and Ship. Together, they will be capable of generating around 18 million pounds of thrust.

SpaceX also increased the volume of Starship’s propellant tank and reduced the number of “grid fins” on the booster — features at the top to help guide it back to Earth with precision.

“Together, these new elements are designed to enable a step-change in Starship capabilities and aim to unlock the vehicle’s core functions, including full and rapid reuse, in-space propellant transfer, deployment of Starlink satellites and orbital data centers, and the ability to send people and cargo to the Moon and Mars,” SpaceX said on its website.

The ability to conduct in-space propellant transfers will be particularly important because the Ship upper stage needs to be refueled in space in order to fly to the moon. SpaceX has yet to attempt such a maneuver, but a successful test flight on Tuesday could set the stage for those key next steps.