While you may be well versed in the spiel of having to clean up our rubbish, what you may not be so well versed in, is how to clean up space rubbish. Space junk, the offcuts of our satellite technologies, is increasingly filling the space orbiting around the earth. But what exactly does this mean?
In our modern digital age, we rely on satellites for almost everything. As a means of communication; it provides us with information, entertainment and connections to every aspect of the world around us. Satellites however are not invincible. They too are subject to breakdowns or a limited life in the same way our computers and electronics at home do. However, what exactly happens to a satellite once it is decommissioned? It is certainly not worth the money and effort to go retrieve it, and so instead it floats in limbo. An endless orbit around the earth. Effectively, it has now become just another piece of space debris – one of the estimated 17,852 earth made objects that are stuck in orbit around our Earth, according to the United States Strategic Command. On top of this you have even smaller pieces of debris also trapped in orbit, small enough that they cannot be tracked, yet big enough that they can cause harm to delicate spacecraft. The more objects we send into the orbit, the higher the chance of a collision, and the more debris we produce. An unsustainable way of utilising a finite space.
Most of this debris is found in two layers of debris – the low Earth orbit (LEO), which acts like a cloud around the Earth and the geosynchronous Earth orbit (GEO), which is found in a ring around the earth
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Satellites in LEO constantly battle against Earths atmosphere and so will experience orbital decay that will cause them to “burn up” within a decade or two. This is the zone in which we use satellite for things such as topographical mapping. Satellites in the GEO however tend to be the satellites used for industries such as communication or television. These satellites could remain for centuries as the air drag is less significant meaning that orbital decay takes longer. Since the late 1950s, we have released almost 7000 satellites, only about 1,400 of which are still operational. So where do all these satellites go?
Some satellites are moved into what is called the “graveyard orbit”, a disposal orbit in which to move satellites when they are coming to the end of the life, as a means of protecting the operational satellites from a collision. It is also essential for spacecraft as large bits of debris can be tracked and avoided, but the small debris (a result of collisions) cannot be tracked. It can cause damage along the same lines of sandblasting which is far from ideal considering the delicate optics these satellites are often equipped with. To combat these collisions, the International Telecommunication Union now require evidence that a satellite can be moved out of orbit when it is no longer operational, however with no international space law to enforce this, it often falls on deaf ears. Collisions however still occur, such as the European Space Agency’s telecom satellite Olympus-1 which was struck by a meteoroid in 1993 and then moved to the graveyard orbit. This movement to the graveyard orbit however, is only a short term solution, as the orbital space is a finite resource and the more junk littering it, the less effective operational satellites will become and the less successful space missions will become.
There is no one answer about what to do to deal with the impending threat of space debris. Increasing congestion of these earth orbits is a detrimental cycle that has to be addressed. It is not effective to retrieve the space junk and it is not effective to only implement proactive legislation as the level of debris is already huge. How exactly to handle this issue is one of the biggest facing science today.
Katherine Huet
References:
https://en.wikipedia.org/wiki/Space_debris
https://www.space.com/19445-space-junk-threat-orbital-debris-cleanup.html
Science Scholars 2017 