Article by Nick Zotalis
The beautiful rings of Saturn are one of the most striking planetary features in the solar system. However, zooming in on them reveals a darker secret: the rings, which appear solid from a distance, are composed of many billions of particles of ice and small meteoroids caught in Saturn’s gravity. These particles range in size from a few nanometers across to the size of mountains. They orbit at tens of thousands of miles per hour. A spacecraft passing through the rings would be entering a shooting gallery of cosmic scale.
Through humanity’s exploration of space, we are in danger of carelessly creating a similar shooting gallery around our own planet. Known as “space junk,” pieces of plastic, parts from old spacecrafts like satellites, paint, and other debris from previous space missions orbits the earth in the same way that the particles in Saturn’s rings do.
According to the European Space Agency, there are over 170 million such objects larger than 1 mm in diameter, 670,000 larger than 1 cm, and 29,000 larger than 10 cm. Even miniscule objects can cause significant damage to spacecraft systems at high speeds. Space junk orbits the earth at speeds reaching 17,500 mph. At this speed, one could travel from New York to Los Angeles in less than ten minutes. Spacecrafts in orbit are themselves travelling at similar speeds, so collisions with space junk can be very dangerous.
These particles are primarily by-products of past space missions, but some are preventable. China invoked the wrath of the space community in 2007 by deliberately destroying one of its own satellites in a test of an anti-satellite missile system, adding 3,000 large pieces of space junk to the mix.
While a significant amount of space junk falls into the atmosphere and naturally burns away, it is being thrusted into orbit at a sufficiently high rate that continues to accumulate. The Department of Defense keeps a catalogue of the objects with the most destructive potential, and the graphic shows that they are spread out and over time could become a serious threat to future space missions.
A possible end result of debris building up in orbit is the Kessler Syndrome – a theoretical scenario where the density of space junk in Low-Earth orbit (1200 miles or less from Earth) becomes so high that collisions between debris particles create more debris, which in turn causes more collisions, in a cascading effect that could eventually make space travel impossible.
In addition, the proliferation of space junk will become an immediate threat to the satellites upon which the internet, GPS, weather forecasts and so many other modern essentials depend.
Several methods have been proposed to clean up space junk, from collecting it with magnets to frying it with lasers. The lasers would be used from either the ground or from orbiting spacecraft to change the orbit of space junk and have it reach the atmosphere sooner in order to burn up.
However, all the ideas that have been suggested are tremendously expensive. Whatever the solution is, it can’t come soon enough, because space junk is the silent threat to future space missions, and we must stop polluting our cosmic backyard before it is too late.
Feature Image: 300,000 pieces of Space Junk. Image Credit: Michael Najjar/Braunschweig University