Debris accumulating in Earth’s orbit endangers spacecraft and satellites
When humans started launching rockets into space, we entered a new frontier in more ways than one. The skies were something to explore in person, the cosmos was becoming tangible, and of course, we had a new place to start dumping trash. Thanks to single-use rockets, derelict satellites and jettisoned trash, the Earth has been building up a sizable collection of debris in orbit. These objects vary in their size, but the fact that they’re all moving at least 17,500 miles-per-hour, and thus have the potential (energy) to do significant damage to anything they might collide with, including newer spacecraft we’d like to keep working.
Collision-prone clutter
At this point, it’s estimated that there are over 500,000 pieces of ‘space junk’ surrounding the Earth that are at least the size of a marble, which is big enough to pose a hazard to a new satellite or worse yet, the astronauts on the International Space Station (ISS). Once things are moving fast enough, even paint flecks damaged spacecraft windows, so the fact that 20,000 of these objects are bigger than a softball makes it clear that all this junk isn’t exactly humanity’s new garbage dump as much as it’s an unintentional minefield. Around 23,000 objects are currently tracked by the US Space Surveillance Network, which helps plot a course for the ISS that will hopefully help it steer clear of damaging debris. While the ISS can be maneuvered to a degree, there are plans for emergency evacuations that have been triggered when the trash cloud gets unmanageable. Evacuation protocols were initiated (but not completed) in 2015 thanks to the 2009 collision between an American communications satellite and a derelict Russian weather satellite, which had sprayed fragments of all sizes into orbit, some of which were getting dangerously close to the ISS.
In the short term then, the best thing that space agencies can do is to do their best to avoid colliding with the debris that’s already in orbit. To assist with this, the US Air Force opened the Space Surveillance Telescope in October of 2016. Working from the White Sands Missile Range in New Mexico, the new telescope is designed to continuously focus on objects in geosynchronous orbits- orbits that keep them effectively in one place relative to the ground, which is useful for when you don’t want your GPS or phone signal to drift away from your position on Earth. The telescope should be able to help keep a close eye on satellites over the United States, but in the long run, this is a problem that literally encircles the world, and will need to be addressed on a much larger scale.
Sweep the sky
The larger solution that future spacecraft and satellites need isn’t all that obvious though. The ideal scenario is that all spacecraft be designed to safely remove themselves from orbit at the end of their missions to control the fallout. Even if that kind of self-destruction is part of some missions, it can’t be retrofit onto older debris, or future craft that just fail along the way. In those cases, engineers are considering everything from nets to sweep up debris to robotic spacecraft that can grab derelict satellites and pull them out of orbit. Neither option is close to realization, but the demand for space-based technology growing, we really need an orbital clean-up crew before things get too messy overhead.
Source: The race to destroy space garbage by Jane O'Brien, BBC News
