taking flight. It's the stuff dreams are
made of. And it says something about us
as a species that we once looked at the
birds soaring in the sky and said, "Bet
we could do that." But in spite of our
lack of wings and feathers, we did. And
we didn't stop there. Once in the sky,
we found a new limitation above us.
Space. A place where all the air ran
out. And in spite of our very real need
to breathe, we thought, "Bet we could go
there." And we did, sitting on top of
controlled explosions that we named
rockets all the way to the moon. Humans
apparently don't like being told we have
limits.
But soon, the age of combustion rockets
will be over, too. They burn up their
fuel too quickly and using them for
travel to the places we're thinking of
going like Mars or even other stars will
simply take too long. And so new
technologies are needed. But what will
get us there this time for journeys that
could take months or even generations to
complete? What solutions could help us
bridge such gaps? The exciting part is
the answers are in development. And it
turns out these new ideas are even
crazier than rockets. I'm Alex Mccoan
and you're watching Astramm. Join me in
this video as we explore the future of
space travel. From the next generation
solutions that are just around the
corner to the proposals that feel
science fiction but could one day become
science reality.
It's only in the last 100 years that
humanity has truly begun to venture into
space. On the 16th of March 1926, Robert
Godard, the father of American rocketry,
launched the world's first liquidfueled
rocket on a farm in Orbin,
Massachusetts. It may have only reached
about 12 1/2 m and was done to little
fanfare, but this moment was the
beginning of 100 years of
chemicalpowered rocketry that ultimately
let man walk on the moon. Understanding
where we came from is important in
understanding where we're going. So,
let's take a closer look at chemical
rockets. Here thrust is generated by
mixing some kind of fuel source often
RP1 kerosene or other variations refined
from crude oil with some kind of oxygen
source. For instance, pure oxygen in
liquid form in a combustion chamber and
then igniting them. Hot things expand
and in such an explosion as this, they
expand a lot. A chemical rocket points
that explosion downwards. Then, thanks
to Newton's third law, where every
action has an equal and opposite
reaction, the rocket as a whole goes up.
Chemical rockets have been the key
driving factor in more than 7,000
launches globally since the dawn of the
space race in 1957. And even in space
itself, chemical propulsion methods,
whether burning fuel in thrusters or
just spraying compressed coal gas out of
a nozzle to get a little extra oomph at
the right moment, are the primary way
that probes and spacecraft have explored
the various planets, moons, and
asteroids that make up our solar system.
But chemical propulsion has a big
problem. While it's very good at the
short-term challenge of punching its way
free of the Earth's gravity, a task that
requires a large amount of force to be
applied over the course of just 8 or so
minutes and a little light maneuvering
to enter orbit around a planet, they are
just not efficient and so run out of
fuel quickly. For instance, let's take a
look at this Falcon 9 rocket, the kind
favored by SpaceX in their hundreds of
launches. While a Falcon 9 rocket has
549,054
kg of mass at launch,
395,700
kg of this mass is fuel. This leaves
very little room on any rocket for the
payload or the part of the rocket you're
actually trying to get into space in the
first place. Why is so much fuel needed?
The answer is in a chemical rocket's
specific impulse, which is a measure in
seconds of how much thrust you get for
each unit of propellant. Think of it
like the fuel economy of a spacecraft.
While rockets are able to generate a lot
of thrust, their specific impulse is
quite low, never much higher than 500
seconds. They are like lightning fast
sports cars with really bad mileage.
They can do very powerful bursts, but
will then quickly need to top up at the
nearest fuel station. Sadly, we don't
have many of those in space yet. Which
brings us to the next currently existing
technology, one which has almost the
complete opposite problem. Electric
thrusters.
While not as commonly used as chemical
thrusters, electric thrusters have seen
use in missions like NASA mission to the
asteroid belt and by SpaceX's Starling
satellites. And by some metrics, these
engines are impressive. Electrical or
ion thrusters can have a specific
impulse up to 10 times higher than
chemical propulsion, allowing for far
longer journeys or greater overall
acceleration compared to their chemical
counterparts. Electric thrusters come in
many different types, but all work via
Newton's third law, just like chemical
rockets, pushing propellant out to push
the rocket in the opposite direction.
However, while chemical propulsion
relies on hot reactions to produce their
thrust, electrical thrusters like the
Hall effect thruster or the grided ion
thruster work by creating electric or
magnetic fields. Particles of noble
gases like xenon or krypton are
accelerated in these fields up to speeds
of 140,000 km an hour in ion thrusters,
though less for hall thrusters and are
sent flying off into space. When the
particles accelerate one way, the
spacecraft is pushed the other way. This
is the advantage of electric thrusters
in general. If you're accelerating your
fuel up to 140,000 kmh, you're getting
some really good mileage for each atom
accelerated.
momentum, too. Now, back to the pros and cons of electric thrusters. With all
that acceleration, surely electric
thrusters are just better then. Well,
actually, no. There is a downside, a
significant one. You see, electric
thrusters actually have terrible thrust.
Think of it like putting your thumb over
the nozzle of a hose. By limiting the
hole the water is coming through, the
stream of water coming out of the hose
turns into a powerful jet. But removing
your thumb to create a bigger hole does
not mean you get an even bigger jet. You
only have so much water to work with.
For electric thrusters, the problem is
similar, except instead of water, it's
electricity. Electric thrusters
connected to a solar panel can get
plenty of energy if you leave them to
run for long enough in sufficient
sunlight, but you don't get that energy
all at once. You have a limit on how
much fuel can be accelerated based on
the electricity you get in a given
moment. So, how little thrust are we
talking about here? How much can
electric thrusters generate? It turns
out about the same amount of force as
you'd feel from the gravity of a piece
of paper lying flat on your hand. It can
take days for an electric thruster to
accelerate a spacecraft to just 90 kmh.
And while it can get up to 320,000
km/h eventually, as NASA had considered
doing on future missions to Mars, if
there's any friction or opposition to
its movement, an electric thruster won't
ever get off the ground. Don't use one
of these to try and launch a rocket.
Electric thrusters are good in
marathons, not sprints.
Still, neither of these technologies are
currently suitable for the types of
travel that humanity wants to eventually
do around the solar system and beyond.
Because chemical rockets use up their
fuel so quickly, they can't actually
accelerate for very long and thus don't
attain a good top speed. Electric
thrusters have a good top speed, but
accelerating is a slow process. And once
humans start fing large numbers of
crews, machinery, and raw materials to
places like Mars, the amount of mass
needing to be accelerated is just too
much. And of course, electric thrusters
will eventually run out of fuel, too.
So, what is the future of space travel?
It's time to look at some of the
contenders.
Before I show you what NASA is
developing, I want to give an honorable
mention to a technology that I find
really cool. Japanese company Oayashi is
planning on finishing off a reall life
space elevator by as soon as 2050. While
not strictly a means of traveling
through space, a space elevator is a
fascinating alternative way to get
something into space with a fraction of
the energy cost that a chemical rocket
has to expend. The principle behind them
is simple. All you would need is some
kind of anchor, a space station or an
asteroid that was orbiting the Earth in
a perfect geostationary orbit. Then you
dangle the cable down from that anchor
until it reaches the ground. Finally,
just put an elevator on it. With the
right counterweight in place, a space
elevator would require very little
energy to be able to lift things into
orbit. You just have to hope that
nothing snaps the cable. Obiashi wants
to build their 96,000
km cable out of carbon nanot tube and
aim to attach it to a 12,000
ton spaceport counterweight. It will
take around 20 years to build the cable
and reinforce it, but they say work
should start in 2030. If all goes as
planned, we could witness a space
elevator on Earth that can carry 100 ton
climbers by 2050. That would open a lot
of doors for space exploration, and I
imagine that lifting that cable into
space would be quite the sight. In the
meantime, NASA has been contemplating
more immediate problems. They are hoping
to send the first astronauts to Mars as
early as the 2030s. So, new technology
will be needed by then, and they have
come up with a solution. It turns out
the future might be nuclear.
The heat from nuclear fusion can be used
to heat up a flowing liquid propellant,
turning it into an expanding gas and
jettisoning it out of the back of the
rocket at a rate that is twice as
efficient as a chemical rocket. This is
called thermal propulsion.
Alternatively, nuclear electric rockets
would work by making electricity through
nuclear fusion. Essentially, putting a
nuclear power plant on a rocket and then
using it to make the electric fields
that are the basis of normal electric
thrusters. Nuclear energy would provide
more immediate electricity. So, you
could outpace normal ion thrusters with
a large enough nuclear rocket. NASA
hopes that nuclear rockets will be able
to have the journey time that is
currently projected for a trip to Mars
by doubling the specific impulse. These
rockets wouldn't necessarily be launched
directly from Earth's surface. You'll
perhaps be glad to know. Although NASA
toyed with that idea back in the 1960s
with Project Orion, these rockets were
intended to work by pulsing out repeated
nuclear detonations behind the rocket
and then just riding the shock waves
into space. That would have been quite
the radioactive mess. It's probably for
the best that NASA scrapped that idea.
But if you start in orbit, nuclear
rockets are generally safer for the
population of Earth. Even if there's a
catastrophic problem and the reactor
melts down, there's no one nearby to
suffer from the negative consequences of
the fallout spreading, except those
unlucky enough to be on the rocket, of
course. Still, radiation in space is
already a problem for astronauts that
needs to be overcome. Just one trip to
Mars could subject astronauts to 60% of
the radiation limit that's recommended
for their entire career. And that's
assuming the journey only lasts 6
months. Some NASA plans see the round
trip taking 2 to 3 years. Because when
flying from one moving planet to
another, there's a lot of wiggle room
when it comes to preferred trip length.
Anything that reduces the time spent in
space will mean less radiation for the
crew and the passengers. That said, less
radiation from space is only good if you
can avoid getting radiation from your
nuclear rocket. And nuclear rockets will
need to be careful when accelerating
near a planet's atmosphere, as due to
the process of heating their propellant
with nuclear sources, that propellant
will be irradiated, which could over
time lead to environmental problems. So,
while it's exciting that these
spacecraft will be so big and powerful,
great care will need to be taken with
this technology,
but what of further journeys? Even
nuclear power can only get us so far.
It may surprise you to learn that NASA
has been exploring something called
propellantless propulsion. And I think
two of their projects in particular are
very cool. I'm talking about solar sails
and space tethers.
NASA has deployed solar sails a few
times now, though mostly for proof of
concept rather than actual missions.
They work by taking advantage of the
fact that photons of light also carry
momentum. So, a light enough, large
enough surface can catch all the gentle
nudges emitted by photons streaming from
the sun and use the energy to accelerate
out on deep space missions for very low
cost. NASA's advanced composite solar
sail system was launched in 2024 and was
originally deployed in space as a cube
set. It then unfolded in space,
stretching out 7 m long arms to deploy a
9x9 m square solar sail. It is currently
in orbit around Earth as scientists
monitor how effective its design is. Its
flight has not gone flawlessly though as
sadly an arm became slightly bent during
deployment causing it to slowly tumble
as it orbits. But NASA is still learning
from the experiment.
Future models could be larger than
basketball courts with 2,000 m sails
each side about 45 m long if the design
remains square. For deep space missions
where no humans will be carried and
budgets are lacking, being able to sail
on cosmic light might be the most
efficient way to complete a mission. A
slight variation on this is the virtual
solar sail or an electric sail. These
sails are still in very early
development, but rather than making use
of a sail, they use electrically charged
wires to do the same job. These wires
stretch out and create a large electric
field in the shape of a sail which once
again is gently pushed by solar
radiation. This time not just because of
momentum but because of like charges
repelling like charges. The company SAT
Revolution has built Aurora 1 making use
of this idea. There the wires will act
as a sort of solar break when it comes
time for the satellite to de-orbit. the
fields creating a sort of drag in the
ionosphere itself, helping to quickly
de-orbit a satellite in a situation
where atmospheric drag isn't feasible.
And why use such virtual fields to only
put on the brakes? NASA in 2024 released
a report that discussed tether
technology, effectively little more than
long wires that protrude from a
spacecraft. These can be used to
exchange momentum from one spacecraft to
another. But when the right current is
passed through these wires, such tethers
can push against the magnetic field of
the planet, actually increasing a
spacecraft's orbital altitude.
Obviously, these types of craft would
only work in the gravity wells of
planets with magneettospheres. But the
advantage of being able to boost orbital
altitude in satellites is easy to see.
You'd need less fuel to maintain a
certain orbital position, extending the
overall lifespan of the mission. All you
would need is electricity to make it
work and a few solar panels would take
care of that. But what happens if we
want to go even further beyond our solar
system itself? The nearest star to our
solar system is Proxima Century, which
is 4.25 lighty years away from us. To
cross that kind of distance, we would
want the fastest craft available to us.
So, we would likely prefer an electric
thruster over a chemical propulsion one.
But even if such a thruster managed to
get a craft up to 56,000 km/h, a speed
attained by the Deep Space 1 mission's
electric thruster in 1998, it would
still take over 81,000
years to cross that distance. This would
be far too long for humans to
contemplate. Thousands of generations
would pass before the descendants of a
man crew finally arrived.
Obviously, thinking this far ahead,
things start to get a bit theoretical.
But what options are there for speeding
up the travel time? Well, there's a few.
Some are even attainable with our
current levels of technology, while
others are a little more outlandish, but
a lot more fun. To begin with, there was
a buzz in the news back in 2021 when
NASA scientist Harold White claimed to
have discovered a real, albeit humble,
warp bubble. If true, this would have
been quite the coup, as warp bubbles
might hold the key to moving faster than
light itself. Warp bubbles work by
recognizing that nothing in space can
travel faster than light, but there's no
rule that says that space itself can't
expand or contract faster than those
speeds. Gravity causes a contraction to
occur in space. So if you could somehow
concentrate that kind of contraction in
front of you, then create some kind of
expansion in the space behind you, it
might be possible to create a bubble
with you in the middle of it that moved
across space by changing the distance
between things rather than by trying to
close those distances. Effectively, it's
like trying to circumvent a 30 km/h
speed limit on a road by moving the road
itself.
There are a few drawbacks to such warp
bubbles, namely that to expand space,
you would need some kind of exotic
negative matter to create the opposite
of gravitational contraction of
spaceime. Sadly, we have never actually
seen this kind of matter, and it's
dubious it even exists. On top of that,
such a W bubble would need a ridiculous
amount of energy and some models suggest
needs more negative energy than the
amount of positive energy that exists in
the whole universe. So, war bubbles
seemed a long way off, which is why
bubble was so exciting. Admittedly, he
claimed that it was only large enough to
be able to fit a 1 micrometer sphere,
but proof of concept would be a huge
step forward. Sadly, White's bubble was
soon to burst. As other scientists
started taking a closer look at White's
paper, it became clear that he hadn't
actually made a W bubble, but had merely
calculated something that looked a bit
like W bubble calculations. if you
squint. There was no experimental proof.
White hadn't even been working on wart
bubbles at the time, but rather casmir
cavities, a quantum effect that appears
between two plates under certain
wavelengths. And it was one of these
that had some characteristics that were
similar to what you might want to see in
a warp bubble, which is a far cry from
actually making a warp bubble.
So, warp drives might still be one for
the realms of science fiction, at least
for now. But the last technology I want
to talk about today feels a little more
within reach.
Part of the challenge of traveling
between stars is acceleration. If you
had infinite energy and could thus
accelerate infinitely, you could vastly
cut down on that 81,000year travel time.
But this is easier said than done.
Carrying chemical fuel with you is not
an ideal solution as you will quickly
run out of fuel without getting much
acceleration. And electrical thrusters
will also struggle as solar panels drop
in effectiveness the further from a star
you travel. In our own solar system, the
furthest out missions can realistically
use solar panels is Jupiter. And even
there, the missions that try that
approach, such as Juno, have to have
massive solar panels and accept 25 times
less light than we see on Earth. In
interstellar space, solar panels just
wouldn't work. But what if you could get
energy to order? Then you could use an
efficient electrical engine and
accelerate much longer after the
sunlight ran out. Which is why
scientists have started considering
beaming. By putting a large laser on
Earth or in Earth's orbit, you could
send a stream of photons directly to a
receiver on the spacecraft, energizing
it as it traveled. Or you could use
electrons accelerated to near light
speeds to do a similar thing. Or you
could put a solar sail on the spacecraft
and rely on the momentum of the beam to
give the craft a constant push. A duo of
researchers Jeffrey Greon and Kerit Rukh
published in the journal Actctor
Astronautica calculated in 2024 that a
probe the size of Voyager pushed and
energized by an electron beam could
reach 10% the speed of light. That would
cut the travel time down from 81,000
years to a far more reasonable 40.
Suddenly, getting humans to other stars
becomes much more feasible. But of
course, there are a few challenges to
overcome here, too. How do you stop the
beam from spreading out as it travels?
How do you make sure your spacecraft
doesn't melt as it's constantly blasted
by a giant laser? How do you keep the
laser pointed exactly at the spacecraft
that's traveling further and further
away? But these feel like solvable
engineering questions rather than
hypothetical physics ones. There was a
project back in 2016 called the
breakthrough star project that even
aimed to implement this technology. It
would use a groundbased laser array at
least a kilometer across to send a tiny
star chip into interstellar space.
Sadly, the project peted out due to the
daunting costs involved. But it showed
that the idea is much closer to
realization than warp drives. According
to some engineers and researchers, if we
were willing to spend the money, we
could cut trips to Mars down to 45 days.
So whether by solar sail, electric
field, nuclear power, or laser beam, or
maybe even a warp drive, humanity is
exploring many ways to get around in
space. And once out of a planet's
gravity well, the vast empty distances
we aim to traverse require unique
approaches and unconventional technology
if we want to live long enough to see
our destinations. But it's so
fascinating living in what feels like
the dawn of a new age where this subject
isn't just science fiction anymore, but
humanity really feels like it could soon
be leaving the cradle of Earth to reach
for the stars. After all, staying at
home would be accepting a limit. And as
we know, humans don't do limitations.
you're on the list and ready to send in
your first question.