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Over the last decade, the world of spaceflight has become an increasingly competitive industry.
We’ve seen private companies burst onto the scene with money and ambition - and we’re
now at the point where scenes like this have become routine.
Through these incredible advancements in rocket reusability, we’ve seen the overall cost
of getting into space drastically reduce.
Once a rocket becomes reusable, the cost of actually launching the rocket becomes far
more important - and one of the largest costs involved in launching a rocket is the fuel.
In this video we’re going to look at the incredible logistics of getting rocket fuel
all the way from the ground and into a SpaceX rocket.
We’re also going to look at what SpaceX are doing to reduce the cost of rocket fuel
and how they plan to start producing their own fuels.
For SpaceX and their Falcon 9 rocket, they use liquid oxygen and a refined kerosene called RP1.
The liquid oxygen needs to be cooled to cryogenic temperatures in order to compress and fit
more into the rocket.
Although the liquid oxygen makes up more than two thirds of the overall fuel load, it’s
by far the cheapest of the two fuels, coming in at just 20 cents per kilogram.
RP1 on the other hand is a little bit less affordable.
When SpaceX were first starting out with the Falcon 9, they were paying around $2 for every
kilogram of RP1.
After renegotiating, they were able to lower the cost until it was closer to the price
of jet fuel, at around 70 cents per kilogram.
Overall, the cost to fill an entire Falcon 9 sets SpaceX back around $150,000.
But realistically, the Falcon 9 will never be fully reusable since a brand new second
stage has to be built for each flight.
Because of this, the fuel costs will remain a small fraction of the overall launch cost.
But for SpaceX’s Starship rocket, the fuel will be far more important.
In just a couple of years, SpaceX turned a dirt field in Texas into an advanced testing
site for their Starship rocket.
With each and every test, SpaceX goes through an enormous amount of fuel.
But what fuel does Starship use and how do SpaceX get it?
In order to answer this we need to look at SpaceX's overall mission.
With their Starship rocket, they want to take humans to Mars in a sustainable way - where
they can set up bases and begin colonizing the planet.
It takes an enormous amount of energy to get to and from Mars - but if we could produce
fuel while we were there, it would cut the overall cost massively.
That is why Starship will use methane and liquid oxygen as it’s propellants.
Both of these propellants can be found on Mars through the methane in the Martian atmosphere
and the oxygen in the subsurface ice.
Methane is also a perfect choice since it’s the cheapest form of fossil fuel found on Earth.
So how do SpaceX get liquid methane to their launch site?
Liquefied natural gas which is mostly made up of methane can be found in reservoirs beneath
the Earth’s surface.
Mining companies use off-shore and onshore platforms to access and extract the gas from
these reservoirs.
At this point, the LNG still contains nitrogen, water and carbon dioxide, so it’s piped
to a treatment facility where these components are split up.
Once the methane is separated from the other elements, it gets piped to a
liquefaction facility to be cooled.
The methane which is still a gas at this point, gets cooled to -162 degrees where it turns
into a liquid.
Once the methane is in liquid form, it takes up 1/600th of the volume.
This is why cryogenic propellants are used on rockets, so they can be compressed to fit
as much in as possible.
After the liquefaction process, the liquid methane is stored in insulated tanks until
it’s ready to be shipped.
The nearest LNG facility for SpaceX is in Brownsville Texas, just 30km away from their launch site.
From there, SpaceX uses the transportation company GenOx to transport most of their liquid methane.
They use state of the art trailers specifically designed to hold liquid methane.
For the trips to Boca Chica, each trailer can transport up to 13,000 gallons of liquid
methane at a pressure of 70psi.
Although this is a relatively high pressure, the methane is actually less dense at this
stage than it will be when it’s in the Starship rocket - since it’s operating pressure is
closer to 100psi.
Once the liquid methane arrives at the SpaceX site, it’s slowly pumped into the massive
tank farm where SpaceX stores their propellants.
It takes several trailers just to transport enough methane for one Starship - so methane
deliveries are a common sight between each test.
Although SpaceX are currently outsourcing most of their propellants, it’s also common
for propellants to be sourced on site.
At the Kennedy Space Center, NASA has their own liquid oxygen plant operated by Air Liquide,
which can liquify up to 265 tonnes of oxygen per day.
SpaceX are looking to create a similar setup at their Boca Chica site.
According to Elon Musk, SpaceX will set up a wind farm at their facility to generate
the enormous amounts of energy needed to separate oxygen from the air.
This process involves compressing air to around 100psi and turning it into a liquid.
This liquid air is then passed through various filters to remove things like water vapour
and carbon dioxide which could freeze and block the machinery.
In order to separate the air into oxygen, nitrogen and argon, the liquid air is systematically
brought up to the boiling point of each element.
Since nitrogen has the lowest boiling point of all three, it turns back into a gas first,
which can then be separated from the mix.
Then, the argon boils off at -186 degrees leaving behind pure liquid oxygen.
This entire process requires a huge amount of energy, but when done at a large enough
scale, the economics start to make sense.
This is why SpaceX can purchase their liquid oxygen from Air Liquide for as little as
20 cents per kilogram.
But with SpaceX planning to build their own oxygen plant, they will need an enormous wind
farm to power it and make it cost efficient.
Alternatively, SpaceX could use the sabatier process of separating oxygen from h2O.
This would be good practice for SpaceX, since they plan to use this exact method to obtain
oxygen on Mars.
Recently, people have noticed a lot of activity surrounding an old well on the SpaceX facility.
A large crane has been set up and people believe this could be the beginning of SpaceX’s
own propellant facility.
In order to be more carbon neutral, it makes sense that they would eventually start producing
their own methane and oxygen using renewable energy sources.
And if they can start producing their own fuels, they might even be able to reduce the
cost for each Starship launch.
This world of propellant production is a new challenge for SpaceX, but it’s crucial that
they develop the skills and technologies to do this on a large scale if they want to sustainably go to Mars.
In the past, SpaceX could rely on outsourcing their fuel and using pre existing infrastructure
at the Kennedy Space Center.
But now that they have their own facility in Boca Chica, they have to design and build
all of these fueling systems from scratch.
When testing Starship prototypes at their launch site, SpaceX used to have a methane
flare which would be used during each test.
Since releasing methane into the atmosphere on its own contributes massively to global
warming, the flare stack would burn the methane and turn it into CO2 before releasing it into the atmosphere.
Although this is much less harmful to the environment, the constant boil-off of methane
during every test was a massive waste of propellant.
In order to get around this, SpaceX started piping the excess methane into a recondenser,
which cools it down and turns it back into a liquid.
SpaceX can then store that methane in their tank farm and use it again for future tests.
Although they don’t recycle their liquid oxygen, it’s cheaper for them to just buy
more and ship it to the launch site than it would be to recondense it after each test.
Either way, it’s exciting to watch SpaceX revolutionize every little aspect of spaceflight
with the aim to make rocket travel just as normal as air travel.
In order for SpaceX to continue with their long term goal of colonizing Mars, they will
need to hire the next generation of passionate space and engineering fans.
Feeding the interest of space nerds is crucial in order to make this a reality.
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