Space Debris

The issue of space debris seems to raise itself into the public consciousness every few years with most people only distantly aware of the problem. However, as we continue to blast new pieces of expensive technology into orbit each year it is obvious that the problem is getting steadily worse. But how bad is it really? After all, there’s lots of ‘space’ up there, right?
As if in answer to this question the past few weeks have provided four separate incidents involving near-misses of objects in orbit, with the big new entrant SpaceX as both victim and offender.

 

NASA Teams Delay Spacewalk After Debris Notification

International Space Station swerves to dodge space junk

SpaceX’s Starlink internet satellites forced to dodge Russian anti-satellite test debris

China slams US after space station ‘close encounters’ with Musk’s satellites

 

Boom!

The US, China, Russia and India have each exploded satellites in space to demonstrate anti-satellite weapons, with Russia destroying one of their old machines as recently as November 15th. These events can create thousands of pieces of potentially deadly shrapnel to add to the existing mess. Even tiny objects can have a devastating effect when we consider that they are travelling up to 22,000 mph. Indeed the ISS has several times needed to replace windows that have been damaged by tiny flecks of paint. According to NASA a “10 centimetre projectile would be comparable to 7 kilograms of TNT”.

Room for a small one?

In addition to the objects caused by the somewhat reckless destruction of aging equipment, we are rapidly increasing the number of machines we are putting up there. According to the European Space Agency as of 22 December there were 7,790 satellites in orbit of which 4,800 are still functioning. Contrast this with the plans of SpaceX alone which has already launched almost 2,000 satellites into low earth orbit (the most congested part and the location of the International Space Station), and intends to deploy up to 42,000 in total to provide ubiquitous, low cost internet access. But they are not alone. OneWeb, SpaceX’s closest rival, indents to launch 48,000 satellites with Amazon (Kuiper) and Telesat planning an additional 4,800 between them. This is only North America. Last year China also submitted filings to the International Telecommunication Union (ITU) for a constellation of close to 13,000 devices, and the Russian Space Systems Company plans a network of 288 for their broadband internet. Things are going to be pretty busy up there.

Chain reaction

Even before we multiply by 20 the number of active machines over our heads there is already concern that we may be early in a process known as the Kessler Syndrome, named after its progenitor, Robert Kessler, a now retired NASA astrophysicist. Effectively this suggests a chain reaction of debris colliding with intact machines to create a greater amount of debris to then collide with other active satellites et cetera, following an exponential trajectory. This may be the future if nothing is done soon to begin to remedy the situation. While the issue has been known about for years it is only now beginning to receive serious attention and funding.

Catch me if you can

One of the more advanced solutions to date comes from a Japanese start-up called Astroscale which earlier this year successfully demonstrated releasing and reconnecting with a sub-satellite using its magnetic tethering device. The opportunity has not gone unnoticed by investors with the group having raised $300m since inception. However, Astroscale are far from the only game in town, and not even the first to actively trial object removal in orbit. In 2018/19 a consortium led by Surrey Space Centre and using technology designed by Airbus subsidiary, Surrey Satellite Technology Ltd (SSTL), successfully harpooned and netted simulated pieces of space debris which were then dragged out of orbit to burn up in the atmosphere. SSTL have also now been appointed by the UK Space Agency to lead a study described to ‘map out a mission to remove defunct satellites from orbit‘.*

The race is on

General debris removal machines are still a long way off, however, as the challenges of catching small particles, large boxes or huge sails or filaments are very different. And the engineering issues are not the only hurdles to leap. Governments are uneasy about the prospect of other countries releasing vehicles which can effectively catch and destroy satellites in orbit. These vehicles can easily be weaponised in the event of conflict and so pose a large potential threat. With no enforcing agency for space at the moment we rely upon goodwill via the UN and other bodies to set and at least attempt to police international rules. The race is on to solve these problems, but with the current planned launch schedules time is not on our side.

*Jacob Greer, Head of Space Surveillance and Tracking, UK Space Agency