Jenny Hautmann for Supercluster
Since Starship Super Heavy first took to the skies, SpaceX has been working to get their next set of vehicles ready for flight.
The goals for the second integrated test flight remain more or less the same — to test out current technologies in Starship and the launch pad, gauge how the improvements over the previous flight pan out, and ultimately get the entire launch system — the largest ever developed — to an orbital velocity.
However, the company has yet to receive authorization from the Federal Aviation Administration (FAA) to launch again. Supercluster sources point to an FAA license coming in at the end of October with a launch expected in early to mid-November. But, in an email to Bloomberg, the US Fish and Wildlife Services said that they had yet to review the corrective measures, which could further delay the launch approval process anywhere from 30 days to 135 days.
It is standard for the FAA to ground a rocket (or an aircraft or spacecraft) in case of an anomaly. The agency then closely works with the company to review their mishap investigation which involves rooting out the cause of failure, coming up with corrections to prevent it from happening again, and ensuring the rocket manufacturer implements those said actions. In early September, the FAA announced it had closed the Starship mishap investigation and directed SpaceX to implement 63 corrective actions to prevent its recurrence.
Elon shared the actual list on X which included actions on Raptor engines, Super Heavy booster, launch pad, avionics, and safety and reliability improvements, further stating that the company has successfully implemented 57 of those actions, while 6 of them are designated for future flights.
“If the engines light, and Starship doesn’t blow itself up during the stage separation, then I think we’ve got a decent chance of reaching orbit,” said SpaceX CEO Elon Musk during a virtual talk at the International Astronomical Congress in Baku, Azerbaijan. Musk didn't want to set expectations too high with concerns stemming from the fact that Starship will sport a radically different stage separation system, one which hasn’t been utilized by any modern-era American rocket.
“We’re trying to move to a passive system stage separation system where you don’t have pushers to try and eliminate parts,” explained Musk.
Unlike the Falcon 9 which is equipped with a pusher system that physically separates the first and the second stage, Starship will ignite its Raptor engines whilst the Super Heavy booster's engines are partially thrusting to pull away at the point of stage separation. This is known as hot-staging, and the idea isn’t new and has been used for decades by Soviet-era rockets with the likes of N1, Proton, and Soyuz, and even some decommissioned American rockets in the Titan family.
Erik Kuna for Supercluster
“From the physics standpoint, it is the most efficient way of doing stage separation,” he added.
If this violent, yet comparatively simpler and lightweight system works, Elon says it can increase Starship’s payload to orbit by 10%. That’s 15 tons more to low-Earth orbit by just eliminating the pusher system.
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SpaceX has been launching Falcon 9 once every 4 days, an unprecedented rate for the rocket industry.
SpaceX has the same high hopes for Starship and even intends to eventually surpass that cadence set by its workhorse Falcon 9. The aim is to build, test, and iterate their hardware, which involves flying them as much and as soon as possible. SpaceX believes the government and its regulatory bodies are not keeping up with the pace and in the end, will hamper the country’s ability to send astronauts to the Moon under NASA’s contract.
William Gerstenmaier, SpaceX's Vice President for Build and Reliability told The Washington Post that he intends to raise this point in a Senate hearing, advocating for streamlined regulations and an increase in FAA’s resources to issue swift launch licenses.
“With the flight rates that are increasing, with the other players that are coming on board, we see there’s potentially a big industry problem coming where the pace of government is not going to be able to keep up with the pace of development on the private-sector side,” Gerstenmaier said ahead of his testimony before the Senate Commerce subcommittee on space and science at a hearing titled, “Promoting Safety, Innovation, and Competitiveness in U.S. Commercial Human Space Activities.”
Starship Super Heavy’s inaugural launch on April 20th — the first with both Starship and its Super Heavy booster — saw the massive integrated vehicle lift off from the orbital mount at Starbase in Texas. The vehicle reached an altitude of 39 kilometers over the Gulf of Mexico, surpassing the maximum aerodynamic pressure. The booster then lost multiple Raptor engines and the two stages weren’t able to separate during ascent. Starship Super Heavy started tumbling and veered off course, activating the flight termination system.
The flight provided SpaceX with invaluable data, particularly on the Super Heavy booster and the launch pad. The immense thrust of 30 Raptor engines shattered the concrete at the base of the pad, uprooting the structure. SpaceX used a high-strength high-density concrete called FONDAG which is designed specifically for abrasion and heat resistance. Based on the previous static fire data (where engines throttled at ~50% thrust levels), teams theorized that it would sufficiently be able to handle Super Heavy’s whopping 74,000 kN of thrust. However, as the engines ramped up to full thrust during the orbital flight, even one of the strongest concrete foundations couldn’t survive the booster’s fire and fury.
Over the months, SpaceX teams removed the debris and carried out several repairs on the launch tower. Tons of new rebar were installed underneath the launch pad, followed by new concrete poured by convoys of trucks. Once cured, SpaceX installed a water-cooled steel plate over it.
To prevent the launch pad from being obliterated, the water-cooled steel plate will essentially act as a water deluge system, spraying tonnes of water beneath the launch pad. It’ll receive this high-pressure water from six recently installed water deluge tanks and a set of pressure tanks. As the Raptor engines ignite, most of their heat will be cooled by the water and turned to steam, while the remaining will be absorbed by the actively cooled steel plate.
The orbital tank farm and the vertical GSE tanks sustained visible damage from the flying debris during the first launch. These dents were buffed out, and repairs were carried out to support testing of Booster 9, the next Super Heavy booster to fly.
Erik Kuna for Supercluster
Super Heavy Booster 9 sports various upgrades over its predecessor. The most notable change is a vented interstage and a heat shield on top to survive hot staging. Adding such an extension will allow the plasma from the second-stage engines to exit away from the rocket while the heat shield will protect the booster from blowing up.
Apart from these visible changes, Booster 9 is equipped with electric thrust vector control actuators instead of hydraulics, a proper full-engine failure isolation system, and incremental reliability upgrades to its thrust plate, vents, grid fins, and plumbing system. The engine isolation system is crucial as it’ll prevent other engines from malfunctioning if one of the engines blows up or as SpaceX likes to call it, Rapid Unscheduled Disassembly (RUD).
The first flight also uncovered an unexpected issue with Starship’s Flight Termination system, designed to terminate the flight should something go wrong. As the launch vehicle deviated from its planned trajectory and began tumbling, it took much longer for FTS to activate. Once it did, this system only punched holes in the tanks but never broke the launch stack as planned.
At SpaceX’s Massey test facility at Starbase, a booster test tank was subjected to FTS-related testing in a bid to re-certify their system before the second attempt.
The test resulted in the complete destruction of the tank.
As the repairs on the orbital launch pad concluded and the steel plate was installed, Booster 9 was rolled out to the launch site to commence its testing campaign. Launch teams carried out a spin prime test — where the turbo-pumps of the engines are revved up by the propellants without igniting them — before attempting to static fire all 33 of its engines. The testing campaign wasn’t as smooth as expected since the first static fire ended at 2.74 seconds, just shy of the expected duration of 5 seconds with 4 engines shutting down prematurely.
But as the teams worked on its problems, they successfully fired the Raptor engines for full duration with only 2 engines aborting. While these tests were carried out to certify Booster 9 for flight and inform teams of future upgrades, it was also a crucial test for the launch pad, particularly the steel plate, to assess how the system handles Super Heavy’s thrust — at least at 50%. Whether it can sustain the flight level thrust won’t be known until the second flight.
Meanwhile, the Starship vehicle slated for the next flight — Ship 25 — completed its construction and was also prepped for its testing campaign at the suborbital launch site which included everything from a spin prime test to a 6-engine static fire of all its Raptor engines.
Once both the stages were tested, Starship 25 was rolled down to the orbital mount and stacked onto Super Heavy Booster 9 using its chopsticks. In 6 months, SpaceX went from a heavily damaged launch pad to a fully functioning one, equipped with upgrades to prevent such destruction from happening again.
Starship’s development is highly dynamic. By the time a vehicle completes its construction, teams already have a ton of improvements slated for their next prototypes. In a bid to improve reliability, SpaceX continuously improves their Raptor engines and tests them at their engine test facility in McGregor, Texas. Recent improvements to Raptors will increase Superheavy’s thrust by 50%, making it over thrice as powerful as the Saturn V rocket which took Astronauts to the Moon in the 70s.
High thrust levels of the engines will also increase Starship’s performance, decreasing the amount of work required by the booster to reach orbit, which can end up as low as 100 seconds.
Erik Kuna for Supercluster
Data from the second launch attempt will also help to finalize the design of the launch pad. SpaceX plans to launch the Starship Super Heavy from their historic Pad 39A at Kennedy Space Center in Florida and Starbase, with the Florida pad dedicated more towards operational launches while Starbase hosts tests and development.
Teams in Florida were working on the launch pad but the work was halted when it proved the current design was incapable of surviving a launch. If the pad modifications — including the water-cooled steel plate — perform well during the second integrated Starship Super Heavy flight, work in Florida might resume. Musk said during the IAC conference that Starship might begin launching payload from next year. "I think there's a good chance we start deploying Starlink V3 satellites next year, roughly a year from now.”
Musk added that returning and landing the Starship back to Earth from orbit is the most challenging aspect of the program, but they can start launching satellites before they achieve that milestone. The overarching goal of Starship’s development program isn’t solely to reach orbit. It encompasses achieving rapid reusability, Falcon 9-like reliability, developing in-space refueling, and long-term cryogenic fuel management. These elements are not just essential for SpaceX’s ambitions to land on Mars, but also to land astronauts on the Moon as part of NASA’s Artemis program.
Starship embodies humanity’s long-standing aspirations of establishing a permanent settlement on the Moon and a self-sustaining city on Mars. The rocket that eventually realizes these dreams might look radically different from what is currently on the launch pad.
However, like the proven Falcon 9, it is the iterative and adaptive nature of this billion-dollar commercial venture that will pave the way to make it a reality.