The upgraded Super Heavy booster slated to launch SpaceX’s next Starship flight has completed cryogenic proof testing, clearing a hurdle that resulted in the destruction of the company’s previous booster.

SpaceX announced the milestone in a social media post Tuesday: “Cryoproof operations complete for the first time with a Super Heavy V3 booster. This multi-day campaign tested the booster’s redesigned propellant systems and its structural strength.”

Ground teams at Starbase, Texas, rolled the 237-foot-tall (72.3-meter) stainless-steel booster out of its factory and transported it a few miles away to Massey’s Test Site last week. The test crew first performed a pressure test on the rocket at ambient temperatures, then loaded super-cold liquid nitrogen into the rocket four times over six days, putting the booster through repeated thermal and pressurization cycles. The nitrogen is a stand-in for the cryogenic methane and liquid oxygen that will fill the booster’s propellant tanks on launch day.

The proof test is notable because it moves engineers closer to launching the first test flight of an upgraded version of SpaceX’s mega-rocket named Starship V3 or Block 3. SpaceX launched the previous version, Starship V2, five times last year, but the first three test flights failed. The last two flights achieved SpaceX’s goals, and the company moved on to V3.

Better results this time

The Super Heavy booster originally assigned to the first Starship V3 test flight failed during a pressure test in November. The rocket’s liquid oxygen tank ruptured under pressure, and SpaceX scrapped the booster and moved on to the next in line—Booster 19. This Super Heavy vehicle appears have sailed through stress testing, and SpaceX returned the booster to the factory early Monday. There, technicians will mount 33 Raptor engines to the bottom of the rocket and install the booster’s grid fins.

These components are changed from Starship V2. The Raptor engines set to debut on Starship V3 produce more thrust and include changes to improve reliability, according to SpaceX. The Raptor 3s are lighter with plumbing and sensors integrated into the engine’s main structure, eliminating the requirement for self-contained heat shields between the engines at the base of the rocket.