Elon Musk, the founder of SpaceX, stated on Saturday that the company would not be ready for a second attempt to reach orbit until it has completed hundreds of modifications to its Super Heavy-Starship rocket and the massive booster’s Texas launch pad.
That assumes permission to fly from the Federal Aviation Administration following the dramatic Super Heavy’s April 20 launch, when the rocket blew up due to multiple engine failures and the Starship upper stage’s inability to separate from the first stage booster.
Musk stated that SpaceX is implementing “well over a thousand” changes during a Twitter Spaces conversation with author Ashlee Vance and that “I think the probability of this next flight working, getting to orbit, is much higher than the last one.” It might be around 60%. It depends on our stage separation performance.
Six Raptor engines powered by methane power the Starship second stage, while 33 Raptor engines power the reusable Super Heavy first stage. After lifting the Starship out of the lower atmosphere, the original design called for the Super Heavy’s engines to be turned off. After that, the Starship would break up and launch its own engines into orbit.
A half-dozen engines shut down or never started during the rocket’s first flight, and the Starship never separated from the Super Heavy first stage.
The entire vehicle began to fall about six miles before its self-destruct system activated and blew the rocket apart at an altitude of about 24 miles. The self-destruct system’s response time was longer than anticipated.
Musk claimed that a “late breaking change that’s really quite significant” has been made to the stage separation system for the aircraft’s second flight.
Before all of the Super Heavy engines have stopped working, the Starship’s engines will start working again. In Russian rockets, this so-called “hot staging” method has been used for years. Musk claimed that it would reduce the velocity lost between the shutdown of the first stage engine and the ignition of the upper stage engines, which would improve the Super Heavy Starship’s performance.
“We shut down the vast majority of the motors on the sponsor, leaving only a couple of running and afterward simultaneously, turn over the motors on the boat, or upper stage,” he said. ” Naturally, this results in a blasting of the booster, so you need to protect the top of the boost stage from being destroyed by the engines of the upper stage.”
The solution is to add shielding to the Super Heavy stage’s top and an extension with vents to direct the engine exhaust plumes from the upper stage away from the lower stage when they first start up.
Musk stated, “There is a significant payload-to-orbit advantage with hot staging, that is conservatively about a 10% improvement if you basically just never stop thrusting.” Because the extremely hot plasma from the upper stage engines needs to move somewhere, you actually need to have vents in order to accomplish this.
Therefore, we are adding an extension to the booster that basically consists of almost all vents. As a result, the upper engine exhaust can pass through the booster’s vented extension rather than simply blow itself up. Therefore, I believe this is the most risky option for the subsequent flight.
Musk stated that engineers are implementing modifications to the Raptor’s hot gas manifold, which directs super-heated methane-rich gas toward the combustion chamber, in order to address engine issues discovered during the rocket’s initial flight. The manifold’s bolt holes can become prone to leaks as a result of the high temperatures.
According to Musk, the manifold itself has undergone a redesign, and higher torque settings will be utilized to secure the tightening of bolts and eliminate potential paths for bolt-hole leaks.
Another important problem being fixed is: damage to the Super Heavy-Starship launch pad at SpaceX’s flight testing facility in Boca Chica, Texas.
The exhaust from the first stage Raptor engines severely eroded the pad’s concrete footings during the Super Heavy’s inaugural flight. According to Musk, the company is currently adding approximately 1,000 cubic meters of high-strength, steel-reinforced concrete.
He continued, “On top of that, we have a kind of steel sandwich, which is basically two thick plates of steel that are welded together with channels going through and perforations in the top so it will actually shoot a lot of water out.” On top of that, he added, “We have a kind of steel sandwich.”
Imagine it as a massive upside-down shower head. While the rocket is above the pad, it will basically shoot water upward to counteract the booster’s enormous heat. With a tremendous amount of heat and force, the booster is comparable to the largest cutting torch in the world.
He stated that the changes are “overkill” and should result in “the base of the pad in much better shape than last time.” To get the vehicle away from the pad faster, the rocket will also take off at a higher throttle setting.
The Super Heavy-Starship’s self-destruct system, which took much longer than anticipated to activate after the rocket lost control in April, was one question that was not addressed in Saturday’s discussion.
Before a launch license can be issued, that system and any other safety-related upgrades must be approved by the FAA.
When asked how much SpaceX has invested in the Super Heavy-Starship project thus far, Musk said, “but it’s over $2 billion” and that it could reach $3 billion by the end of the year.
Musk responded, “because we have not yet reached orbit,” when asked about the greatest obstacle the Super Heavy-Starship faces in terms of producing a commercially viable rocket.
He stated, “We would actually fix it before launching if we knew what it was.” Therefore, when you launch, you are attempting to resolve the unknowns that you do not know about beforehand, or that we are not smart enough to know about. As previously stated, stage separation appears to be the greatest risk at this time.
