more than three months after the building-sized starship boosters latest return to starbase's
orbital launch site spacex has finally begun the process of testing what ceo elon musk says
is still the first flight worthy super heavy after completing a number of pad tests in the days prior
spacex began filling super heavy booster 4 b4 with liquid nitrogen supplied by the first
orbital class starship launch for the first time on december 17th it's unclear exactly
what was done during the test but regardless of what transpired the test in b4 survival was
a major long-awaited milestone for both the starship booster and the orbital launch site
at this point in time the general consensus among close followers of spacex's starship program
is that the unprecedented amount of time it's taken the company to complete booster 4's first
test was not because of the rocket itself but rather because the orbital launch site needed
to fully test it had yet to be completed while it was spacex's choice to not perform some kind of
initial testing with b4 at one of the site's two suborbital tests and launch mounts it's clear that
the company ultimately concluded that super heavy booster iii successful july 2021 tests including a
cryogenic proof virtually identical to booster 4's first test made such partial testing redundant put
a different way spacex must already be confident enough in the quality of the first few super
heavies rolling out of its starbase factory to deem it unnecessary to verify the structural
integrity of the first truly completed super heavy booster before putting the one and only
orbital starship launch site directly in the line of fire nonetheless depending on how far super
heavy booster 4's first cryogenic proof test went it appears that spacex's presumptions were correct
on december 17th spacex subjected super heavy b4 to a cryogenic proof test about twice as ambitious
as b3s filling the booster maybe a sixth of the way with a few hundred tons of liquid nitrogen
what isn't clear as if that test also raised the boosters propellant tanks to flight pressures
if booster 4 did reach those pressures the test is even more significant
partially proving that the rocket is ready for flight
on december 21st spacex performed a similar series of cryogenic tests again partially filling
booster 4 with about the same amount of liquid nitrogen but doing so two or three times in a row
again the super heavy survived the several hour ordeal without any obvious issues
still a number of additional tests some even more important are still in front of spacex and super
heavy b4 the most obvious is simple enough spacex needs to fully fill a super heavy booster for
the first time depending on the storage situation that process will likely begin by filling booster
4 with about 2 500 tons of liquid nitrogen about two-thirds full if spacex also temporarily
fills one of the orbital tank farms liquid oxygen or methane tanks with nitrogen it could fully load
booster 4 with around 3 500 tons of nitrogen at least according to spacex's own website
that's about the same weight as the propellant super heavy is designed to lift off with
if that full cryo proof goes well spacex will then likely perform one or several wet dress rehearsals
ultimately filling booster 4 with approximately 2 900 tons of cryogenic oxygen and 500 tons of
cryogenic methane finally spacex will probably kick off static fire testing
likely beginning by igniting just one or a few of super heavy's many engines
eventually that process could culminate in the ignition of all 29 of booster 4's raptors
briefly producing a bit less than 5 400 tons of thrust 50 more powerful than nasa's retired saturn
v moon rocket according to elon musk despite a number of recent signs and reports to the contrary
spacex still intends to fly booster 4 and ship 20 on starship's first orbital velocity launch
attempt so the scope and scale of testing are only likely to grow over the next several weeks
and that wraps up today's episode we did also like to take the time to thank
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