Space travel is the most exciting and challenging adventure humanity has ever undertaken. But in an irony
of history, we may stop ourselves from going
into space the more we do it. With every
rocket launched and with every
satellite deployed, we’re creating a trap for ourselves that gets
deadlier and more dangerous every year. If it’s ever activated, it could end the Space Age and trap us
on our planet for decades, or even centuries. Getting something into space
is incredibly hard. To do so, you need
to move very, very fast. At first, straight up
to leave the atmosphere, then sideways to begin
a sort of circling around the Earth, still, very, very fast. If you do that successfully
you can enter a Low Earth orbit. And once in orbit, it’s very hard
to get out of orbit. Unless you have
energy to spare, you’re sort of locked in here,
falling around the Earth forever. That’s great for things
we want to stay up, like space stations
and satellites. And so we moved the majority of humanity’s
space infrastructure to this place, just a few hundred kilometers
above the surface. Just high enough so that the atmosphere
is so thin, that orbiting things
can stay up for centuries before air resistance can slow them
enough to bring them back to Earth. But this is also the source
of our deadly trap. Rockets are really metal cylinders
that keep big parts of fuel in place. Whenever a portion
of the fuel has been spent, the empty tanks are dropped
to make the rocket lighter. Some parts
crash down to earth or burn up
in the atmosphere. But most of the useless
rocket parts stay up and begin
to orbit the planet. After decades
of space travel low Earth orbit is a junkyard of spent boosters, broken satellites and millions
of pieces of shrapnel from missile tests
and explosions. Right now we know of around
2,600 defunct satellites, 10,000 objects bigger
than a monitor, 20,000 as large
as an apple, 500,000 pieces
the size of a marble and at least 100 million parts
so small they can’t be tracked. This debris is moving
at speeds of up to 30,000 km/h, circling Earth on criss-
crossing orbits multiple times a day. Orbital speeds are so fast
that being hit by debris the size of a pea is like
being shot by a plasma gun. On impact the debris vaporises, releasing enough energy
to punch holes straight through solid metal. So, we’ve covered the space around our planet with millions of deadly pieces of destruction, and we also put a trillion dollar
global infrastructure network right in the danger zone. It performs critical duties
essential to the modern world: global communication, GPS
and navigation, collecting weather data, looking out
for asteroids and all manner
of scientific discoveries: things we would miss very much
if they suddenly went away. If just one pea-sized bullet
hits one of our 1,100 working satellites,
it will be destroyed instantly. Three or four satellites are already
being destroyed this way every year. As the number of satellites and the amount of junk in orbit is expected to grow tenfold in the next decade, we’re approaching
a tipping point. But the worst thing in space
is not tiny pieces of junk. The worst thing would be
an unstoppable chain reaction that turns a lot of non junk things
into junk. For example: if two satellites hit each other
in just the right way. If satellites collide they don’t stop
and fall out of the sky. It’s more of a splash
than a crash. Orbital speeds
are so fast solid pieces spray
right through each other, transforming the two satellites
into clouds of thousands of little things still fast enough
to destroy more satellites. This could trigger the slowest
and most destructive sort of domino effect: a collision cascade. Like a shotgun spray, each collision
creates more bullets. What was once
a single tiny target very unlikely to hit anything becomes
a wall of destruction hungry
to make more. As more and more satellites
are destroyed the destruction
accelerates exponentially, eventually destroying
everything parked in orbit. But space
is very empty, so the first few collisions
may take a long time. By the time we realize
what’s happening, it’s too late. One year one satellite
is destroyed and that’s
no big deal. The next year, five. The year after, 50. Until there’s nothing left. The situation in orbit
is rapidly worsening and we may already
be past the point of no return. Within 10 years space around Earth may no longer
be viable for long term satellites or rockets. The worst case scenario
is horrifying. A debris field made of hundreds
of millions of pieces, many too small to track,
moving at 30,000 km/h. It would effectively create
a deadly barrier around Earth, possibly too dangerous
to cross. Dreams
of moon bases, Mars colonies
or space travel at all may be
set back centuries. And the loss
of our space infrastructure would send some of the technology
we rely on daily back to the 1970s. But it might not be too late
to clean up our mess. While the space industry has become
better at avoiding space junk, it’s still growing fast and occasional
weapon tests don’t help. So there have been a couple of wild
but also serious suggestions. About how to quickly remove
as much deadly space junk as possible without creating more
in the process. Lots of ideas
are being thrown around, and some
of the most seriously considered involve capture
and return missions, which are
being tested now. One method involves meeting a piece of junk
in orbit with a small satellite and loaded with a net. Once caught, a small rocket could be used
to bring it down towards Earth. Targets too large for a net might be instead caught
with a harpoon on a tether. Instead of firing
a rocket the cleaner would deploy a large sail
to produce atmospheric drag and accelerate
orbital decay. And there are lots of other wild sci-fi
sounding proposals too. Some might use
giant electromagnets. These magnetic tugs work by pushing on
the magnetic components inside satellites that they use
to stabilize and orientate themselves
in Earth’s magnetic field. These may be safer and more reliable
than nets and harpoons because they never have to make contact
with the junk they’re handling, so there’s no risk of accidentally breaking up
their target into more junk. As for the tiniest bits of junk, lasers might be the key
to vaporising them entirely. Satellites with lasers wouldn’t
need to visit their targets. They can shoot them
from far away. Large objects
can’t exactly be shot down, but lasers
can be used to ablate them, or burn tiny amounts
of material off the side to push the junk
to a safer orbit. Whatever technology we use at the end,
we better start doing something soon, before 100 million bullets become
a trillion and the trap is set. If we don’t act, our adventure
in space might end before
it’s even begun. If our days of dreaming about space exploration
might be numbered anyway we better put them
to good use. One of the things we most like to spend our time on
is learning more about our universe. And to do that you can just keep watching. Kurzgesagt and Brilliant
are collaborating on a six-part video series about our favorite science
and space topics. Kurzgesagt has worked
with Brilliant for a bit. And we love how they teach you science
and maths in a practical way. By guiding you through problems
step by step. So you can actually understand
the concepts behind them. And maybe one day use your knowledge
on problems like space junk. Or at least your science projects to start with. If you’d like even more edutainment. Go to brilliant.org/nutshell and sign up for free. The first 688 people
to use the link get their annual premium membership
at a 20% discount! And also support
our collaboration with Brilliant! Video source: https://www.youtube.com/watch?v=yS1ibDImAYU
