Commercial and military trends means that a lot more space junk will be generated
If Elon Musk wants to get to Mars, he has to be able to send the interplanetary spacecraft or orbital manufacturing facility into low-Earth orbit first. That may seem obvious, of course, but launching anything into space is a complicated process increasingly bedeviled by the problem of space junk. Thousands of trackable objects, and perhaps many more we can’t pick out, zoom around up there, the detritus of fifty-plus years of space exploration. With more and more satellites going up each year, and more and more companies looking to send their own vehicles up, it is going to be a lot busier than ever before.
So what can we do about the hypervelocity garbage in space? Cleaning it up is the obvious answer, but doing so is an extremely expensive proposition, given that every pound of weight going up and coming down costs millions of dollars to move.
Having raised $43 million so far, its founder, Mitsunobu Okada, has told The New York Times that in 2017, the company will launch a debris tracking satellite on a Russian rocket to help make better maps of those objects, and then by 2018 send up a satellite garbage collector – a multimillion dollar glue trap, in effect – to catch debris. This can, in theory, be done for far less money than other proposed solutions since it only requires getting the satellite into orbit, picking up the trash, and then burning itself up in the atmosphere.
Astroscale intends to make enough money to support its operation by offering the de-orbiting service to companies that own satellites in need of it.
They are going to need it.
The mess up there
Most space debris are the result of accidents, the launch process itself, and the nature of the orbital environment. Not every part of a launch vehicle burns up in the atmosphere; some satellites stop working and collide with others, and there is space weathering caused by micrometeoroid impacts and radiation.
Collisions are the worst outcome in this regard, given that even small pieces of debris move at speeds of 7-16 kilometers per second, according to NASA. Not only does this produce countless new debris moving that fast, the clouds of resulting junk also obstruct orbital paths, creating no-go zones that sometimes won’t dissipate for years. And we are not talking about “big” objects, relatively speaking. For NASA, “very large objects” mean space junk that is about 10-20 cm in diameter.
There is also the danger of earthbound conflicts escalating into space battles. These would not be nuclear exchanges, though. China, Russia, and the US all have contingency plans to cut off surveillance and telecommunications infrastructure in orbit in the event of a conflict on earth. Some of those plans entail hijacking the satellites, disabling their electronics, or de-orbiting them, which would produce relatively few debris. Other methods, however, would see the satellites blown apart in orbit, producing a lot of unnavigable junk that will act as an area denial weapon. And if they’re high up enough – 36,000 km – the debris fields can persist indefinitely.
Eyes in and on the sky
But any of this, even the less kinetic options, still would be a disaster for further exploration and commercial-military launches. With space agencies unable to reach or control man-made objects in order because they’ve been disabled or hijacked, they too would end up as junk one day. The debris clouds from any incident, deliberate or not, would choke off previously usable flightpaths and also block others. This would then make it impossible to de-orbit, repair, and replace otherwise serviceable machines, since there’d be no safe path to and from them.
One anti-satellite weapons test conducted by China in 2007, using a missile to blow up a weather satellite, produced “nearly one-sixth of all the radar-trackable debris in orbit” today, according to Scientific American, and further such tests (by the US) have also produced large clouds of shrapnel.
The tracking problem is compounded by the fact that the debris collide with each other, producing an expanding quantity of smaller – but still dangerous – refuse. These can still be tracked, though. The most advanced telescope in existence that can follow orbital objects, the Space Surveillance Telescope (SST), has enough resolution to observe even softball-sized pieces of debris. But as the objects get smaller and smaller from repeated collisions, they become impossible to follow. According to NASA, debris with a diameter of 0.1 to 1 cm can still cause serious if not fatal damage to man-made objects in orbit, yet cannot be tracked.
The SST has other missions besides tracking old rocket parts that could pose a hazard to satellites and spacecraft, so there are tracking stations elsewhere devoted to monitoring for debris.
Astroscale, though, will do it from up there with the junk.