SpaceX made 'over a thousand' changes to Starship ahead of second flight

"We made sort of a late-breaking change that's really quite significant to the way that stage separation works," Musk said during the discussion. "There’s a meaningful payload-to-orbit advantage with hot-staging that is conservatively about a 10% increase."

Russia's Soyuz rocket uses hot-staging and the country's space agency, Roscosmos, has been using the method for decades. It involves igniting the engines on the upper stage of the rocket while it's still attached to the lower stage.

During the online discussion, Musk said SpaceX recently chose to switch to the "hot-staging" approach, which will see the Starship upper stage ignite its engines when it's still attached to the Super Heavy booster.

To be precise, according to Musk, only a few of Super Heavy's 33 Raptor engines will still be firing when Starship's upper stage engines are ignited. By using this method, the company will avoid losing thrust during stage separation.

Using this method will require several modifications to SpaceX's enormous Super Heavy booster. This will include an extension to the top of the booster that is made up of "almost all vents", according to Musk. This design will allow exhaust to escape from the upper stage while attached to the booster.

The company is also adding shielding to the top of Super Heavy to protect it from the powerful exhaust of the upper stage's six Raptor engines.

Musk says Starship has 60% chance of reaching orbit

Musk also mentioned the fact that SpaceX made "well over a thousand" other changes to Starship, though he didn't provide further details.

He did, however, note that SpaceX was continuing to work on improvements to the Starbase launchpad, including a "steel sandwich" water deluge system that he hopes will "leave the base of the pad in much better shape than the last time."

Ultimately, Musk feels the next launch will have a much better chance of reaching orbit. "I think the probability this next flight working, getting to orbit, is much higher than the last one. Maybe it's like 60%," he said. The SpaceX CEO didn't commit to a specific launch date, though, stating that there "a lot of variables here that are outside of our control."

Ship 25 completed a flight-like chill and spin of the Raptor engine pumps, stopping just before engine ignition. As a result of the test, cryogenic liquid oxygen formed a visible cloud beneath the ship. This checked out vital systems in advance of the upcoming static fire. pic.twitter.com/1rMOqlf5qM

— SpaceX (@SpaceX) June 22, 2023

While the "launch pad upgrades, and the booster and ship, are [probably] ready in about six weeks," according to Musk, SpaceX will still have to obtain Federal Aviation Authority approval for a second launch attempt. This could be delayed by the fact the FAA is currently dealing with a lawsuit aimed against it by environmentalists following the first Starship launch.

SpaceX continues to prepare for the second test flight, though, having shared an image last week on Twitter of Starship prototype Ship 25 performing a "chill and spin of [its] Raptor engine pumps" that will help it prepare for the next orbital launch attempt.