Space Junk

8 March 2019

There are thousands of operating satellites in various orbits around the earth. Every year, more and more satellites are launched, and while some are "de-orbited", the population continues to grow.

OneWeb has launched the first of about 900 "small" (dishwasher-sized) satellites to provide Internet to remote locations.

Samsung plans a fleet of 4600 satellites, Boeing is planning about 5000, and SpaceX is planning on launching 12,000 over the next decade.

And this cloud doesn't include space junk, like discarded rocket stages, engine shrouds and fuel tanks. What's more, there are hundreds of thousands of smaller bits and pieces up there, ranging in size from a pea to a loaf of bread, and more smaller objects that they just can't track.

For example, in 2016, the ISS was hit by something. They're not really sure what it was, but it was probably less than a millimetre in size. This mightn't sound dangerous, but it was doing about 25,000 kilometres per hour (and no, that's not a typo). At that speed, it put this 7mm chip in the cupola window. OK, the ISS can take it, but that's still scary stuff.

Collisions between space junk and working satellites now happen several times each year. Collisions cause more junk, which leads to a higher probability of more collisions. This can lead to a runaway scenario that NASA calls a Cascading Kessler Syndrome.

The upshot of this is that the junkyard in orbit gets so full of unpredictable shrapnel that humans can no longer risk lifting off earth's surface until it all gets cleared.

How do we do that? There are a few vague ideas, such as nets, trapping satellites, or proton pressure lasers which will be able to slow the space junk down so it falls back towards Earth, burning up in the atmosphere. But as yet, there's nothing concrete.

The best you can do is watch the show and photograph large space junk. You need a camera, a scope and one of a number of planning apps. You don't even need a tracking mount!

Photo: ESA/NASA