ceo elon musk has published the first official visualization of what spacex's plans
to catch super heavy boosters might look like in real life however the simulation
he shared raises just as many questions as it answers since at least late 2020 spacex ceo
elon musk has been floating the idea of catching starships and super heavy boosters out of the sky
as an alternative to having the several dozen ton steel rockets use basic legs to land on the ground
this 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
the flexible lightweight structures have mostly been reliable and easily reusable but falcon
boosters occasionally have rough landings which can use up disposable shock absorbers
or even damage the legs and make boosters hard to safely recover and slower to reuse
as a smaller rocket falcon boosters have to be extremely lightweight to ensure healthy
payload margins and likely weigh about 25 to 30 tons empty and 450 tons fully fueled
an excellent mass ratio for a reusable rocket while it's still good to continue the practice
of rigorous mass optimization with starship the vehicle is an entirely different story
once plans to stretch the starship upper stages tanks and add three more raptors are realized
it's quite possible that starship will be capable of launching more than 200 tons of payload to low
earth orbit leo with ship and booster recovery one might think that spacex with the most capable
rocket ever built potentially on its hands would want to take advantage of that unprecedented
performance to make the rocket itself also likely to be one of the most complex launch vehicles ever
simpler and more reliable early on in the development process generally speaking that
would involve sacrificing some of its payload capability and adding systems that are heavier but
simpler and more robust once starship is regularly flying to orbit and gathering extensive flight
experience and data spacex might then be able to refine the rocket gradually reducing its mass
and improving payload to orbit by optimizing or fully replacing sub-optimal systems and designs
instead spacex appears to be trying to substantially optimize starship
before it's attempted a single orbital launch the biggest example is elon musk's plan to
catch super heavy boosters and maybe star ships too for the sole purpose of in his
own words saving landing leg mass and enabling immediate reflight of a giant unwieldy rocket
musk spacex executives or both appear to be attempting to refine a rocket that has never flown
further based on a simulation of a super heavy catch musk shared on january 20th all that oddly
timed effort may end up producing a solution that's actually worse than what it's trying
to replace based on the simulated telemetry shown in the visualization super heavy's descent to the
landing zone appears to be considerably gentler than the suicide burn spacex routinely uses on
falcon by decelerating as quickly as possible and making landing burns as short as possible
falcon saves a considerable amount of propellants during recovery extra propellant that if otherwise
required would effectively increase falcon's dry mass and decrease its payload to orbit in the
super heavy catch musk shared the booster actually appears to be landing just on an incredibly
small patch of steel on the tower's mecazilla farms instead of a concrete pad on the ground
aside from a tiny bit of lateral motion the arms appear motionless during the catch
making it more of a landing further super heavy is shown decelerating rather slowly
throughout the simulation and appears to hover for almost 10 seconds near the end
that slow cautious descent and even slower touchdown may be necessary because of how
incredibly accurate super heavy has to be to land on a pair of hard points with inches of lateral
margin for error and maybe a few square feet of usable surface area the challenge is a bit like if
spacex for some reason made falcon boosters land on two elevated ledges about as wide as car tires
aside from demanding accurate rotational control even the slightest lateral deviation would cause
the booster to topple off the pillars and in the case of super heavy fall about a hundred feet onto
concrete where it would obviously explode what that slow descent and final hover mean is that
the super heavy landing shown would likely cost significantly more delta five propellant than a
falcon style suicide burn propellant has mass so super heavy would likely need to burn at least
5 to 10 tons more to carefully land on arms that aren't actively matching the booster's
position and velocity ironically spacex could probably quite easily add rudimentary fixed
legs removing most of the bad aspects of falcon's 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 wound up weighing 20 tons total the inherent physics of rocketry means that adding
20 tons to super heavy's likely 200 ton dry mass would only reduce the rocket's payload
to orbit by about three to five tons or one percent to three percent further for musk's
argument that landing on the arms would enhance the speed of reuse it's difficult to see how
landing super heavy or starship in the exact same corridor but on the ground instead of on the arms
would change anything if super heavy is accurate enough to land on a few square meters of steel
it must inherently be accurate enough to land within the far larger breadth of those arms
the only process landing on the arms would clearly remove is reattaching the arms to a
landed booster or ship which it's impossible to imagine would save more than a handful of
minutes or maybe an hour of work spacex's falcon booster turnaround record is currently 27 days
so it's even harder to imagine why spacex would be worrying about cutting minutes or a few hours
off of the turnaround and reuse of a rocket that has never even performed a full static fire test
let alone attempted an orbital class launch re-entry or landing put simply while starbase
launch tower arms will undoubtedly be useful for quickly lifting and stacking super heavy
in starship it's looking more and more likely that using those arms as a landing platform will
at best be an inferior alternative to basic falcon style landings more importantly even if 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 efficient suicide burn the apparent best case outcome of all
that effort is marginally faster reuse and perhaps a five percent increase in the payload to orbit
only time will tell if such a radical change proves to be worth such marginal benefits
and that wraps up today's episode we did also like to take the time to thank
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