Caption: Artist’s impression of debris in low earth orbit Credit: ESA
Space may be big — vastly, hugely, mind-bogglingly big — but the space around Earth is beginning to get cluttered with space junk. This poses a threat, not only to other satellites, space stations and missions, but to us here on Earth as well. While we wrestle with environmental issues posed by human activity on our planet, ESA’s new ‘Clean Space’ initiative aims to address the same issues for its missions, making them greener by using more eco-friendly materials and finding ways to cut down levels of space debris.
Last month ESA and Eurospace organized the Clean Space Eco-design and Green Technologies Workshop 2012 held in the Netherlands. Clean Space is a major objective of Agenda 2015, the Agency’s upcoming action plan. The aim was outlined by ESA Director General Jean-Jacques Dordain: “If we are convinced that space infrastructure will become more and more essential, then we must transmit the space environment to future generations as we found it, that is, pristine.”
The workshop looked at all aspects of space missions, their total environment impact, from concept development to end of life. The impact of regulations regarding substances such as hydrazine, which is used widely as a propellant in space programs and the development of Green Propulsion with propellants that have a reduced toxicity. Environmental friendliness and sustainability often mean increased efficiency, which ESA hopes will give the industry a competitive advantage, so they are looking at technologies which will consume less energy and produce less waste, therefore cutting costs.
Finally they looked at debris mitigation to minimize the impact to the space environment as well as the debris footprint on Earth using controlled and uncontrolled re-entry events and passive de-orbiting systems along with active de-orbiting and re-orbiting systems. They are even considering tethers or sails to help drag abandoned satellites out of low orbit within 25 years. New ‘design for demise’ concepts hope to prevent chunks of satellites surviving re-entry and hitting the ground intact. Active removal of existing debris is also needed, including robotic missions to repair or de-orbit satellites.
6,000 satellites have been launched during the Space Age; less than 1000 of these are still in operation. The rest are derelict and liable to fragment as leftover fuel or batteries explode. Traveling at around 7.5 km/s, a 2 cm screw has a ‘lethal diameter’ sufficient to take out a satellite. Taking the recent loss of the Envisat satellite as an example, this satellite now poses a considerable threat as space junk. An analysis of space debris at Envisat’s orbit suggests there is a 15% to 30% chance of collision with another piece of junk during the 150 years it is thought Envisat could remain in orbit. The satellite’s complexity and size means even a small piece of debris could cause a “fragmentation event” producing its own population of space garbage. Envisat is also too big to be allowed to drift back into the Earth’s atmosphere. The choices seem to be to raise the satellite to a higher, unused orbit, or guide it back in over the Pacific Ocean.
As ESA Director General Jean-Jacques Dordain says “We will not succeed alone; we will need everyone’s help. The entire space sector has to be with us.”
Find out more about ESA’s Clean Space initiative here
Planetes! http://www.nihonreview.com/anime/planetes/
Apparently Envisat is in a polar orbit. Could it not be ditched into Antarctica? Not that there’s any advantage to this over the Pacific, but I do wonder why Antarctica is never mentioned as an option.
Can they recover anything from the satellites if they crash them in the Pacific? Cause if they can, that’s maybe the advantage.
The private sector is already gazing at asteroids for mining potential.
Surely there is a niche here for one of them to “mine” dead satellites so much closer to home.
Precious metals and still-viable technology recovered are the two most obvious profit inspirations – I’m sure there are a lot more.
Wonder what the legal complications of that idea entails..
Space pirates! Wouldn’t that be fun with a whole new set of shanties and a revised pirate code of conduct? I, for one, will be encouraging this sort of thing. Mind you, back in the 18th Century, the British navy were unofficially encouraged to pirate enemy commercial vessels. Whose military might become the modern-day pirates? Could the X-37 be a reconnaissance vessel before the pirate fleet is launched? 🙂
Solar Maximum approaches. It is well known that an increase in solar wind energy alters satellite orbitals.. here’s hoping we get a few gusts to ‘clear the air’~
Um, sorry, but how is this good? Uncontrolled deorbits are exactly what we don’t want!
Yeah.. for the big stuff uncontrolled deorbits may be a problem. Fortunately, it’s the smaller stuff that gets shoved around the most by the solar wind. Still, as above… “Traveling at around 7.5 km/s, a 2 cm screw has a ‘lethal diameter’ sufficient to take out a satellite.” Here’s hoping nobody gets ‘screwed’…
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While we wrestle with environmental issues posed by human activity on our planet, ESA’s new ‘Clean Space’ initiative aims to address the same issues for its missions, making them greener by using more eco-friendly materials and finding ways to cut down levels of space debris.”
Regarding this first paragraph, can I point out that the issue of Space junk is about the ‘safety’ of space travel, not about the mess we’re causing in space. It’s nothing to do with being ‘green’ or ‘environmentalism’. Also, there is a huge difference between true environmentalism (which actually has visible results) and this phony green movement hijacking the title of ‘science’
And don’t accuse me of trolling, because it’s a legitimate point, and i’m sure there are others who agree.
To clean up debris in low-Earth orbit will need lots of energy and several maneuvers that can be easily performed by a spacecraft with fusion-powered plasma turbines. http://www.youtube.com/watch?v=ro5-QYqqxzM
Sadly not – the debris would begin sinking to the deep immediately and it would take far too long a time to pinpoint the exact crash site and get a boat there. Besides, hitting water at such a high speed is likely to be just as damaging to a satellite’s equipment as hitting rock. There’s not much hope for recovery of anything useful (but the pieces would make good museum exhibits!)