CEO Elon Musk has released the first official visualization of what SpaceX’s plans to catch the Super Heavy boosters could look like in real life. However, the simulation he shared raises as many questions as it answers.
Since at least the end of 2020, SpaceX CEO Elon Musk has floated the idea of contagious Spaceships and super heavy boosters shoot out of the sky instead of tens of tons steel rockets using base legs to land on the ground. That would be a major departure from SpaceX’s highly successful Falcon family, which lands on a relatively complex set of deployable legs that can be retracted after most landings. Flexible and lightweight structures have been mostly reliable and easily reusable, but Falcon boosters sometimes have hard landings, which can use disposable shock absorbers or even damage legs and make boosters difficult to recover safely and slower to reuse.
As a smaller rocket, Falcon boosters must be extremely lightweight to ensure healthy payload margins and probably weighs around 25-30 tons empty and 450 tons fully fueled – an excellent mass ratio for a reusable rocket. While it’s always good to continue this rigorous mass optimization practice with Starship, the vehicle is a whole different story. Once the plans to stretch the Starship’s upper stage tanks and add three more Raptors are made, it’s entirely possible the Starship will be capable of throwing over 200 tonnes (~440,000 lb ) payload in Low Earth Orbit (LEO) with ship and booster recovery.
You’d think SpaceX, with potentially the most successful rocket ever built in its hands, would want to take advantage of this unprecedented performance to make the rocket itself – also likely to be one of the most complex launch vehicles of all. time – simpler and more reliable. early in the development process. Generally speaking, this would mean sacrificing some of its payload capacity and adding heavier but simpler and more robust systems. Once Starship flies into orbit regularly and gathers vast flight experience and data, SpaceX could then be able to refine the rocket, gradually reduce its mass, and improve on-orbit payload by optimizing or entirely replacing sub-optimal systems and designs.
Instead, SpaceX appears to be trying to significantly optimize Starship before it attempted a single orbital launch. The biggest example is Elon Musk’s plan to grab Super Heavy boosters – and possibly starships too – for the sole purpose, in his own words, “[saving] landing leg mass [and enabling] immediate relaunch of [a giant, unwieldy rocket].” Musk, SpaceX executives or both seem to be trying to perfect a rocket that never flew. Plus, based on a simulation of a Super Heavy “hold” shared by Musk on Jan. 20, this whole oddly timed effort may end up producing a solution that’s actually worse than what it is trying to replace.
Based on the simulated telemetry shown in the visualization, Super Heavy’s descent to the landing zone appears to be considerably smoother than the “suicide burn” that SpaceX routinely uses on Falcon. By decelerating as quickly as possible and minimizing landing times, the Falcon saves a considerable amount of propellant during recovery – additional propellant which, if otherwise needed, would effectively increase the Falcon’s dry mass and reduce its payload in orbit. In the Super Heavy “hold” shared by Musk, the booster actually appears to be landing – just on an incredibly small piece of steel on the tower’s “Mechazilla” arms instead of a concrete pad on the ground.
Aside from a tiny bit of sideways movement, the arms seem motionless during the “grip,” making it more of a landing. Additionally, Super Heavy decelerates quite slowly throughout the simulation. and seems to hover for almost 10 seconds towards the end. This slow, careful descent and even slower landing may be necessary due to how incredibly accurate Super Heavy must be to land on a pair of hard spots with inches of lateral margin of error and maybe a few square feet of usable area. The challenge is a bit like SpaceX for some reason landing Falcon boosters on two raised ledges about as wide as car tires. In addition to requiring precise rotational control, even the slightest lateral deviation would cause the booster to topple off the pillars and – in Super Heavy’s case – fall about a hundred feet onto concrete, where it would obviously explode.
What this slow descent and final hover means is that the super heavy landing pictured would likely cost a lot more delta V (propellant) than a Falcon-style suicide fire. The thruster has mass, so Super Heavy would probably have to burn at least 5-10 tons more to carefully land on arms that don’t actively match the position and velocity of the thruster. Ironically, SpaceX could probably quite easily add rudimentary fixed legs – removing most of the bad aspects of the Falcon legs – to Super Heavy with a mass budget of 10 tons. But even if SpaceX were to make those legs as simple, dumb, and reliable as physically possible and they weighed 20 tons in total, the inherent physics of the rocket means that adding 20 tons to the probable dry mass of 200 tons of Super Heavy would only reduce the rocket’s payload in orbit by about 3-5 tons or 1-3%.
Moreover, according to Musk’s argument that the landing to the arms would increase reuse speed, it’s hard to see how landing Super Heavy or Starship in the exact same lane – but on the ground rather than the arms – would change anything. If Super Heavy is accurate enough to land on a few square feet of steel, it must inherently be accurate enough to land within the much greater width of those arms. the alone the landing process on the arms would clearly remove the attachment of the arms to a booster or a landed ship, which, it is impossible to imagine, would save more than a handful of minutes or maybe an hour of work. SpaceX’s Falcon booster rotation record currently stands at 27 days, so it’s even harder to imagine why SpaceX would worry about slashing the minutes or a few hours of rotation and reuse of a rocket that hasn’t even never performed a full static fire test – let alone attempted an orbital-class launch, re-entry or landing.
Simply put, while Starbase’s launch tower arms will no doubt come in handy for quickly lifting and stacking Super Heavy and Starship, it seems increasingly likely that using these arms as a platform for landing will be, at best, an inferior alternative to the basic Falcon style. landings. More importantly, even though everything works perfectly, the arms actually cooperate with boosters to catch them, and it’s possible for Super Heavy to avoid hovering and use a more effective suicide burn, the apparent best result of all. this effort is a slightly faster reuse. and perhaps a 5% increase in in-orbit payload. Only time will tell if such a drastic change turns out to be worth such marginal benefits.