From just what humans have put into space, how many individual pieces of junk are hurtling
around our planet as we speak?
Pause the video and have a guess in the comments, it would be pretty interesting to see what
you think.
Thousands?
Tens of thousands?
Well, according to the Technische Universitaet Braunschweig which actively studies satellites
and space debris, there are 29,000 objects bigger than 10cm (only 1,900 of which are
active satellites), 700,000 bigger than 1cm, and an estimated 200,000,000 objects bigger
than one millimetre.
That’s 200,000,000 objects travelling up to 28,000kph relative to Earth, racing over
our planet.
Have a look at this real-time visualisation of Earth and some of the larger things orbiting
it.
The US Department of Defence actively monitors objects over 10cm to try and prevent collisions
from happening, with each of these object’s orbits mapped out precisely.
The red objects are active satellites, the blue objects are old rocket parts, and the
grey objects are debris, like out of commission satellites.
It should be noted that this isn’t to scale, Earth is massive in comparison to these objects
in reality.
But with so much in orbit around Earth, especially in this low Earth orbit, it’s amazing satellites
aren’t colliding all the time.
There actually has already been a hypervelocity crash between two satellites around Earth.
In 2009 Iridium 33 and Kosmos-2251 collided at speeds of 42,000kph, smashing the two satellites
to bits.
The biggest of the debris from this collision is still being monitored, because understandably
there is a lot of it.
Smaller impacts happen much more regularly.
Here is before and after shots of the Sentinel-1 satellite after an object only 5mm in size
impacted one of its solar arrays, leaving a 40cm impact crater.
Chips and nicks can even be seen made by objects only a few thousandths of a millimetre across,
like this 7mm wide chip on one of the windows of the Cupola capsule on the International
Space Station.
With so many objects in space, and more constantly being put up there, it’s not surprising
to find out that more collisions are expected to happen.
In fact, we seem to be nearing the threshold for the feared Kessler syndrome, which is
where if a big collision happens, the parts from the debris go on to impact other satellites,
causing a massive ripple effect until pretty much nothing in orbit is left unscathed.
If any of you saw the fantastic film Gravity, that is basically what happened at the start
of that film.
JAXA, or the Japanese space agency, earmarked 100 big objects that needed to be removed
from Earth’s orbit at a rate of five per year to prevent this situation from happening.
Objects in a low Earth orbit, will eventually deorbit by themselves
as there is still a tiny amount of atmospheric drag at these altitudes to slow them down.
Most objects will burn up on re-entry, so no risk of objects raining down and impacting
the ground.
But this gradual descent before re-entry could last hundreds to thousands of years.
With that being the case, it’s no wonder there are currently space mission concepts
aimed at deorbiting space debris manually.
Some of them are pretty clever, like using nets, solar sails to create greater drag,
or even a slingshot.
However, there isn’t much money to be made yet from cleaning up after ourselves, and
so these clean up missions aren’t being pushed and utilised as much as they maybe
should be.
Human nature tends to show us that we are only mildly concerned by the potential for
catastrophe, and there doesn’t seem to be a proportionate amount of money being spent
at getting things back from space compared to putting them up there in the first place.
My personal thought is that if a space agency or a company puts something in space, surely it’s
their responsibility to get it again once it becomes defunct.
Is that reasonable?
Thanks for watching!
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