Ever since the sixties, humanity set its eyes onto the colonisation of Mars—and rightly
so.
After accomplishing the greatest achievement of mankind in setting foot on our Moon, it
is only natural to want to explore and set a flag down on our next immediate neighbour,
except this time we want to go beyond a futile round trip that lacks any real objective other
than just being able to say we once went there.
This time, we want to establish an outpost and have a few select pioneers experience
life on the Red Planet for an extended period of time.
But how exactly do we go about doing that?
And not only that, but how do we develop an affordable, reliable and fully reusable transportation
system that takes humanity to orbit, the Moon, Mars and beyond?
It’s hardly surprising that we, as a species, are already making preparations to set foot
on Mars.
Since the sixties, we have sent numerous satellites to map out the terrain, find out more about
Mars’ climate and atmosphere and just generally expand on our knowledge so that we know exactly
what we’re dealing with.
However that hasn’t come without failure—in fact, about one in every two spacecraft sent
to Mars fails—which is partly due to the fact that landing on Mars is an engineer’s
nightmare.
Both that and the fact that Mars is a graveyard full of landers and rovers that failed to
make a descent soft enough to land hardly motivates engineers to attempt another mission.
This, coupled with the 26 month waiting time for each launch window and the lack of funding
seriously hinders the rate at which we can learn about Mars.
Now, while it is often made out to seem as though Mars is entirely within our grasp in
the media and such, we aren’t actually technologically capable of colonising Mars at this very instant
even if we had unlimited funding.
Even if, say, you were the richest man alive and you had, for all intents and purposes,
infinite money.
No matter how much you want it, that money is no use in funding a ticket to Mars as no
amount of money can buy a ticket to Mars, as of right now.
Aside from the not so minor inconveniences that come with attempting to colonise Mars
such as providing radiation shielding for your passengers, the huge differences in gravity
and its effect on the passengers and so on—that are yet to be definitively solved—there
are still a few immediate steps that we must take in order to make the shipping of cargo
and crew to Mars feasible such that it is both highly reliable and carried out without
spending excessive amounts of money in the process.
Any process that requires excessive amounts of money to fund and sustain—money that
you most certainly don’t have—is a process that is almost always doomed to fail, which
is why we must first take the steps to make our interplanetary transport system as economical
and sustainable as humanly possible.
The first step of which is the development of reusable rockets.
Reusability is absolutely essential to make Mars voyages large enough to create a self-sustaining
city on the surface.
Don’t get me wrong, full reusability is no easy task, particularly for interplanetary
travel as opposed to just an orbital return.
It’s probably about the most difficult element to perfect out of all the aspects I’m about
to discuss, but it does make a lot of sense to make strides for it.
There is a simple reason why all modes of transport and all vehicles are not single-use;
it is not economical to be widely used among the population and anyways, if it’s within
the realms of possibility, why wouldn’t you strive to make a given vehicle reusable
in the first place.
It’s in everyone’s best interest; it’s saving you and your customers far too much
money to simply be overlooked and avoided.
Can you imagine if after every flight, airplanes were just discarded and thrown to the side.
Almost all of a rocket’s weight is fuel and almost all of that fuel is used up within
the first few minutes after launch—and that’s only to get to Low Earth Orbit (so no higher
than an altitude of about 2000km or about 1200 miles)—and then most of the rocket
is designed to fall back to Earth and burn up in the atmosphere.
It’s like throwing away a new car and deciding to buy a new one after only driving it until
it has run out of petrol and in the not so distant future, single-use rockets will seem
as absurd as doing something such as that.
The end goal with reusable rockets, at least for now, is a rocket whose first and second
stage can easily be recovered from re-entry and can be almost immediately refuelled, ready
for its next launch all within a maximum time of 24 hours, which is not without some relatively
quick inspections and refurbishments of the vehicle as you would do with airplanes.
Ideally, a rocket of this type should be made to withstand upwards of 25-30 years of service
with only minor replacement of parts.
In terms of Mars, this translates to 12-15 journeys during all of the launch windows
over the course of its lifetime.
The fundamental idea and aim of reusability is obviously to drastically cut the costs
of a launch system such that the main thing you are paying for—once you’ve built each
component of the rocket—is the refuelling, which is incredibly cheap compared to the
typical cost per launch that runs in the hundreds of millions.
In a perfect world, the cost of propellant is responsible for most of the expenses of
maintaining the interplanetary transport system but in reality a good chunk of it is going
to be maintenance.
I’ll explain the cost of this whole operation in more detail a bit later on in the episode.
As I’ve mentioned, the vast majority of a rocket’s fuel is used up in getting the
rocket to orbit, which is why it is great idea—and frankly imperative—that our interplanetary
transport system includes a stage in which we refuel in orbit.
This is the second step that we must take in enabling the success of this system.
Refuelling in orbit is absolutely essential because if you don’t do that, then your
rocket has to transport extra reserves of propellant to be used just to get you to Mars,
which is to be avoided at all costs as this sets off a vicious fuel to mass ratio.
The more propellant that your rocket carries, the greater its total weight; the greater
its total weight, the more energy you must expend to escape Earth’s gravity well, meaning
more fuel is needed, and so on, and so this mass ratio can very quickly spiral exponentially
out of control.
This all comes down to the rocket equation and a few interesting things come out of it.
It turns out that the delta-v needed to escape Earth’s gravity well to Low Earth Orbit
is also approximately equal to that required from Low Earth Orbit to the surface of Mars.
On top of this, all destinations between Low Earth Orbit and the Moon are but a fraction
of the delta-v required to just reach Low Earth Orbit from Earth’s surface in the
first place.
That really puts things into perspective.
Escaping Earth’s gravitational pull with a payload sufficient enough to support your
mission is one of the hardest aspects of space exploration.
Now, a lot of what I’ve just discussed are the main goals of SpaceX and some of which
have already been achieved by them.
In December of 2015, SpaceX managed to pull off the first-ever landing of an orbital rocket’s
first stage after transporting 11 commercial satellites to Low Earth Orbit with their Falcon
9.
And not four months later, another of SpaceX’s Falcon 9 first stage was the first to land
on their ocean platform as part of a cargo resupply mission to the International Space
Station.
They have now done this 51 times at the time of writing.
While this is only the first stage being recovered and reused—which is very difficult in and
of itself—it is making great strides in the right direction for full reusability.
This is all in an effort for their ultimate goal of colonising Mars.
SpaceX’s current concept of their interplanetary transport system fundamentally consists of
three fully reusable vehicles: SpaceX’s Super Heavy booster, the Starship spaceship
(both of which are collectively referred to as Starship also—a tad bit confusing I know)
as well as a Propellant Tanker craft for in-orbit refuelling.
This serves as a two-stage-to-orbit launch system where Starship acts as a second stage
vehicle allowing for the transportation of passengers or cargo to orbit, planetary destinations
and beyond, but can also be used on its own for missions that don’t require the need
of any booster.
To give you an idea of just how powerful Starship is, we can compare it to the Saturn V rocket.
Due to the choice of the more energetic liquid oxygen-liquid methane propellant combination,
which I’ll discuss in more detail a tad bit later on in the episode, Starship can
outperform the Saturn V by a factor of 4.1 on the mass delivered to Low Earth Orbit.
It is even estimated to outperform the Saturn V by a factor of 3.6 on the thrust at lift
off.
Also, it’s important to note that Starship isn’t restricted to just being used for
the colonisation of Mars but rather is suitable for the exploration of anywhere in the solar
system either robotically or with a crew on board.
At the time of writing, NASA has just announced that they have picked SpaceX’s Starship
Lunar lander concept for their Artemis space program—a program which plans to take Humans
back to the Moon by 2024.
But how do SpaceX plan to do all this?
The idea is as follows.
For any one trip to Mars during a launch window, Starship launches with the most thrust any
rocket has ever produced.
Once the desired altitude in Low Earth Orbit is attained, the booster separates from the
second stage and subsequently performs a propulsive return to its launch site within 20 minutes
of launch, perfectly placing itself for its next launch, where a propellant tanker can
be placed upon the very same booster—all within a matter of hours.
The booster with tanker is then launched and makes a rendezvous with Starship to refuel
in orbit—think of the tanker as a sort of portable petrol station that comes to Starship
on its own.
And, as you can see, it’s design is almost identical to the Starship; the main difference
being that the unpressurised and pressurised cargo areas are filled to the brim with propellant
and perhaps some cargo as well.
The tanker then returns back to Earth after the refuelling has taken place.
It will take several tanker trips—anywhere from three to five times—to fully fuel Starship
for its journey to Mars—a journey which is just the first one of many for this spaceship.
And once all set, Starship departs for Mars.
After a few launch windows from the initial Starship launch, you’d probably want to
increase the number of spaceships sent—eventually enough for an entire fleet.
The more you send, the greater the rate of expansion of the colony and the more you’re
populating Mars.
Starship’s impressive thrust can reduce the travel time to as little as just a four
month journey on average which, when you think about it, isn’t all that gruelling for the
passengers when compared to sailing voyages back in the day that would last for six months
or more.
This becomes even more manageable when you consider that this travel time can be reduced
to as little as a 30 days journey in the slightly more distant future.
The short travel time is another essential aspect of the success of this system as you
want your passengers to be exposed to as little radiation as possible while in space.
The same can be said for the lack of gravity.
Once Starship reaches Mars, it can make use of its propulsive landing to land on the surface
of Mars.
The refinement of their propulsive landing techniques is what separates SpaceX from other
competitors.
Propulsive landing is the way to go as its versatility allows it to be used in every
environment; parachutes or any other sort of landing technique isn’t going to be much
use on places like the Moon with its non-existent atmosphere.
Now on the surface of Mars, this brings us to our third and final step that we must take
in order to make an interplanetary transport system feasible: in-situ propellant production
on Mars.
While it’s entirely within the realms of possibility to make round trips to the Moon
without the need of any refuelling at any point on the Lunar surface, Mars is a completely
different ball game.
Refuelling on Mars is necessary as otherwise you’re just abandoning spaceship after spaceship
on the surface and Mars just becomes this graveyard full of them.
So a lot of thought has to go into choosing the right propellant to achieve this.
We really only have to choose from three main options: kerosene, liquid hydrogen and liquid
methane (which can be referred to as methalox).
While each has their own pros and cons, it becomes clear that methane is the most suitable
option.
Rocket-grade kerosene, while it allows for a smaller size of vehicle, is a highly refined
form of kerosene, similar to jet fuel, and so is quite expensive.
Even if it could be easily produced on Mars, which is near impossible as there’s no oil
present, its propellant transfer isn’t ideal and it’s reusability potential isn’t ideal
either.
Hydrogen is a little more promising though.
While it has the greatest specific impulse of any known rocket fuel, it is even more
expensive than kerosene.
It wouldn’t be much of a challenge to produce on Mars as you can just make use of electrolysis
but it does require a lot of energy to store liquid hydrogen at a low enough temperature
to keep it from boiling off which is pretty much at absolute zero.
It becomes obvious that methane really just hits all the marks.
Methane is ubiquitous across the solar system; there is methane ice in comets, it’s abundant
in Titan’s thick atmosphere and even its ocean, the gas giants are filled with it but
most importantly it is able to be widely produced cheaply on Mars by making use of electrolysis
and the Sabatier process.
The energy required to operate the propellant plant will largely come from a very large
array of solar panels.
Mars is ideal for the production of methane and oxygen; there are 5 million cubic kilometres
of ice and 25 trillion tonnes of carbon dioxide so there definitely is no shortage of reactants.
Now let’s talk about the costs and expenses of this entire operation.
It is surprisingly only estimated to cost SpaceX around $230M to fabricate the booster,
$130M for the tanker and $200M for the spaceship.
When you think about it, paying a little over half of a billion for a fully reusable launch
system is really getting bang for your buck.
The interplanetary transport system is conceptualised to be fully reusable with a 1,000 uses per
Booster, 100 uses per Tanker and, as I’ve mentioned, at least 12 round trips to Mars
with each Starship over a period of at least 25 years.
When it’s put like that, half of a billion really doesn’t seem like an awful lot, particularly
over that timeframe, and especially when you consider that it typically costs over a billion
for rockets like the Saturn V to launch just once.
And in comparison, the expenses for propellant and maintenance are dirt cheap and practically
nothing compared to what NASA typically pays for each launch.
One of SpaceX’s key philosophies, among others, is allowing the transportation of
passengers and cargo to celestial bodies in the solar system to be as cheap as possible.
This is why SpaceX are making it a large priority to reduce the price of a ticket to Mars.
They want to make it affordable to anyone who wants to go.
It’s about this intersection of people who not only have the money to go but also want
to go—the unification of these two types of people must be carried out by showing that
Mars is somewhere you’d want to go and by making it affordable to the average person
and not just a luxury accessible to the top 1% of the population.
It is a common misconception that this technology—or just technology in general—will automatically
progress and improve; this isn’t the case at all.
There is such a thing as technological stagnation where technology doesn’t progress any further
and is forgotten and may even degrade at a point.
Just look at the world’s greatest civilisations like Ancient Egypt and how they were able
to build the pyramids and now they have forgotten how to do that.
The Romans with their tremendous aqueducts.
They forgot how to do it.
It is so important to appreciate that space exploration isn’t inevitable.
It will take a lot of hard work and effort by a lot of people to make humanity a multiplanetary
species.
It is important to have a future that is inspiring and appealing.
You want something that gets you up in the morning and becoming a multiplanetary species
and some of us escaping earth and being among the stars and heavens does exactly this.
Imagine bright mega-cities on Mars, a Lunar colony able to be seen at night, a populated
fleet of airships in the Venusian clouds, outposts dotted across the entire solar system.
This is what an interplanetary transport system allows us to do and it makes for a very promising
future.
Comment down below your thoughts on developing an interplanetary transport system for all
of humanity.
Make sure you subscribe for more content on astronomy and futurism.
If you enjoyed this video check out my most recent video on the colonisation of Mars,
a previous video or perhaps my playlist on black holes.
Thank you so much for watching, have a nice day.