The European Space Agency is warning about the potential disaster of space junk —hundreds of thousands of manmade bits and pieces travelling at an average speed of 40,000 km/h. And is calling for a worldwide effort to combat the problem.
Next week, the ESA will hold its 7th European Conference on Space Debris, bringing together the best and brightest to tackle the growing concern and discuss new ideas for space junk removal. The agency has released a video documenting the urgency of the issue, one that since the inception of human space operations some 60 years ago has only gotten worse.
Over 21,000 objects larger than ten centimetres, at least 750,000 coin-sized fragments and literally millions of smaller pieces are all circling the Earth right now, causing huge worries for space and telecommunications operations about a potential collision. “It is not comparable to a gunshot,” says Holger Krag, head of the ESA’s Space Debris Office. “The energy contained in a one-cm particle hitting a satellite at that velocity roughly corresponds to an exploding grenade.”
And while space agencies like the ESA and NASA regularly track the larger of the space bits with radar and even optical telescopes, altering launches and diverting orbits in order to avoid big collisions, the serious threat from space debris comes in the form of a potential chain reaction. “These collisions generate more fragments and these fragments are candidates for new fragments to come,” says Krag. “The largest fear that we have is that we enter into some sort of cascading effect where one collision triggers the next one … and this is unstoppable.”
The source of the debris is for the most part accidentally exploding spacecraft, yet in 2007 China’s space program intentionally blew up a weather satellite in space, and in 2009, a defunct Russian military satellite hit an operational satellite owned by American company, Iridium Communications.
In 1993, during the first servicing of the Hubble Space Telescope, astronauts removed a solar array and brought it back to Earth where it showed the obvious effects of being peppered with space debris.
This past January, the ESA had to perform an avoidance manoeuvre with one of its Swarm satellites to avoid collision with a 15-cm chunk of debris from the former Cosmos 375 Soviet satellite.
Various methods have been imagined for space junk removal using nets or sails to pull objects out of their orbit and push them either towards Earth where they would burn up in the atmosphere or out further into the so-called graveyard orbit above the area normally used for satellites and space operations around the Earth.
The Japan Aerospace Exploration Agency (JAXA) recently attempted to test an electrodynamic tether designed to use electricity generated as it swung through the Earth’s magnetic field to nudge space debris out of its orbit. The 700-metre tether was sent up with a cargo ship headed to the International Space Station in December 2016 but problems reportedly arose ahead of the planned deployment and the tether could not be released.
In 2013, the Canadian Space Agency launched its first military satellite, Sapphire, which is dedicated to monitoring space debris.