When we ventured into space, we brought along our tendency to litter. Thankfully, there are a few solutions under way to depollute our local cosmic environment.
We share a cultural perception of space as a vast vacuum of nothingness, dotted by the occasional rock or asteroid. Looking up at the night sky only reinforces this idea, because all we see besides our neighboring planets are distant stars, the closest of which is still over 4 light-years away. But this pristine expanse of darkness is far from the cluttered reality.
The 2013 film Gravity most likely gave the public its first glimpse of this troubling situation. Throughout the movie, great swathes of debris formed from the destruction of a satellite threaten the safety of NASA astronaut Dr. Ryan Stone. Space travel more closely resembles a deadly obstacle course of hazardous junk than the serene drifting most of us imagine.
Space debris has been accumulating in Earth’s gravitational field since we first ventured beyond the atmosphere. While we’ve made great strides in space travel, we focus most of our energy and innovation on putting more stuff up in space than trying to bring things back down. Whenever a mission is completed and a spacecraft runs out of fuel, it is simply abandoned to drift through its orbit, tossing off chunks and fragments with every collision. Astronauts have also lost their belongings to zero-gravity — floating among the chunks of metal and plastic are cameras, a glove, various tools, and a toothbrush.
As a result, the near-Earth environment is full of space debris ranging in size from fine pebbles to large boulders weighing more than the average adult man. Obviously, the larger pieces pose considerable danger, but astronauts must also steer spacecraft out of the way of smaller particles to reduce wear and tear on equipment. While we have developed shielding technology to protect, for example, the International Space Station, there’s not much to be done for delicate instruments like solar panels and telescopes. In fact, astronauts spend most of their time on spacewalks repairing damage caused by impacts from debris.
One solution was proposed by researchers at the University of La Rioja. They have devised a method that can decommission satellites in “Highly Elliptical Orbits” (HEO) and reduce the risk of damaging our operational spacecraft: the defunct satellites are maneuvered towards Earth’s atmosphere so that they disintegrate upon re-entry.
To remove the HEOs from orbit without burning valuable fuel, researchers will advantage of the very characteristics that make HEOs so unpredictable and dangerous to space traffic. The researchers devised a simulation that will indicate the ideal times and places at which the satellites can head back towards Earth, using minimal fuel and without endangering anyone on the planet’s surface.
The method will be applied to the ESA INTEGRAL mission that was launched in 2002. Using this model, the researchers estimate that the satellite will re-enter Earth’s atmosphere between September 2028 and July 2029, experiencing a controlled disintegration.
Another potential way to deal with space debris has already shown some promise. The Clean Space One Project has developed a “Pac-Man” spacecraft that will be able to capture rogue satellites and drag them back to Earth to be disintegrated during re-entry. “Pac-Man” will employ sophisticated visual sensor technology to anticipate an approaching target, and then expand a rigid conical net to engulf it.
If all goes as planned, Clean Space One could launch as soon as 2018. For its first test run, it will pursue SwissCube, a small cubical spacecraft first launched five years ago. The cube will likely prove to be an elusive target, since it has variegated light and dark areas that will be difficult to detect. But if Clean Space One succeeds, it will collect valuable data that can help the researchers revamp its design to work on all types of space trash.
With these projects in development, we are on our way to clearing the Earth’s gravitational zone of dangerous debris and making it safe for ongoing space research.