Name: The Truth About Space Debris
Uploaded: 2021-06-09T12:07:18.000Z
Duration: 16 min 23 s
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This episode of Real Engineering is brought to you by CuriosityStream, watch over 2,400

documentaries for free for 31 days at curiositystream.com/realengineering.

On March 27th 2019, Indian Prime Minister Narendra Modi announced to the world that

India had conducted its first successful anti-satellite test.

Launching a three-stage missile from Abdul Kalam island on the north-eastern coast of

India, with a trajectory taking it over the Bay of Bengal.

A trajectory that would eventually lead to it intercepting India's military satellite,

The seven hundred and forty-kilogram satellite met its end when the kinetic kill vehicle

Shattering it into hundreds of pieces which proceeded to spread in earth's orbit.

A completely unnecessary political posturing move that added significantly to Earth's

This isn't some far off distant problem that we need to worry about, and the probability

of collisions occurring is not only continually rising, but there have already been several

collision events that have damaged the international space station and other high-value satellites.

We can't blame the current state of affairs entirely on anti-satellite tests like this.

Every single time we launch into space we generate some sort of unwanted waste.

Solid-fuel rockets deposit aluminium-oxide particles.

In 1983 the Challenger space shuttle was struck by a 0.2 mm chip of paint that managed to

gouge this pit out of one of its windows.

In fact, in the first 67 Space Shuttle launches 177 impacts were found in the windows.

45 of which were large enough to warrant a replacement window.

Post-mission analysis determined all of these impacts we caused by space debris, with 44%

being caused by aluminium alloys, 37% by paint chips, 12% by steel, 5% by copper and 2% by

At fifty thousand dollars a pop, this did not come cheap.

Based on these numbers, the Space Shuttle had 67% chance of impact causing significant

damage to the windows during their 10 day missions, and these probabilities have only

In 2007 the likelihood of a collision between any satellite in low earth orbit and a piece

of debris over 1 centimeter in size was 17-20% in a single year.

[2] That statistic increased to 25-33% later that year when China tested their own anti-satellite

By 2010 the chance of a 1-centimetre piece of debris striking a satellite had increased

to 50% a year, after two full-sized satellites Iridium 33, a US communications satellite,

and Kosmos 2251, a retired Russian communications satellite, collided at 42,000 kilometres per

Obliterating both satellites and producing over 1000 fragments over 10 centimetres in

size, and many more too small to be tracked.

So the chances of collision are not small by any measure, they are common and it's

only a matter of time before another serious incident like this 2009 collision occurs again,

so it is prudent that we design satellites to be capable of not only withstanding small

impacts but be capable of dodging larger ones.

The ISS, for example, is designed to withstand objects up to 1 centimetre in size [3], and

can dodge larger trackable objects 10 centimetres wide.

The biggest danger to the occupants of the ISS are objects in between these sizes.

That are untrackable but large enough to cause serious damage to the international space

When the ISS was being planned, NASA laid out a basic risk management policy.

That the probability of any critical component of the ISS being penetrated by space debris

[4][5] A critical component is characterized by anything that could potentially lead to

a loss of life if it is damaged, and designers are careful to correctly categorise each component

on the ISS to ensure this is the case, which often involves performing hypervelocity impact

This resulted in things like batteries and ammonia accumulators being categorized as

non-critical when they didn't explode during tests, and so received less shielding that

Space debris is just a fact of everyday life on the ISS that astronauts need to be aware

To get a better sense of what it's like living with this.

I spoke with former ISS commander Chris Hadfield on the phone.

When you are onboard a spaceship you have a constant undercurrent awareness of the ever

prevalent risk of something hitting your spaceship and causing a leak.

Sort of like when you are driving a car, you always know at some point you could have some

You know the odds are that eventually it will happen for sure, and you just have to find

And so the way we live with it is to understand the risk as accurately as we can.

We know the relatively risk of man made debris versus naturally occurring debris, and we

know how the space station is designed to resist it with the multilayer shielding, and

So let's talk about that shielding first.

Shielding the ISS with heavy plates, as tanks do here on earth, is not an option.

This is the damage a 13-millimetre spherical bullet will do to a 18-centimetre aluminium

plate when travelling at 7 kilometres per second.

It prevented penetration and only just managed to prevent a large chunk of spall to break

At 13 centimetres a 1 metre squared aluminium plate like this would weigh about 338 kilograms.

When the ISS started construction in 1998 the per kilo cost to launch to the International

Space Stations orbit using the Space Shuttle was about 93,400 dollars.

[7] Placing a 1 metre squared shield like this at a cost of 31.5 million dollars.

This is an extremely inefficient use of material, and the ISS uses something much more elegant

The Whipple shield uses the debris' own velocity to stop it.

At 4 kilometres per second and higher, the energies involved are so immense that the

projectile itself breaks apart and vaporises on impact.

[8] Whipple shields take advantage of this by creating a shield that is composed of several

thin sheets of armour separated by space.

So when a meteoroid or debris does strike it, it first breaks up into thousands of smaller