It may have happened silently, and it may have happened 930,000 miles above our heads, but two months ago the Herschel Space Observatory became part of a problem that is becoming very hard to ignore. On the 29th April 2013, Herschel finally ran out of coolant leaving it dead in orbit around our planet. Unfortunately it is not alone up there.
From fragments of rocket fuel tanks, spy satellites someone forgot about, to entire observatories like Herschel, the Earth is being orbited by a cocoon of space debris that is likely to make space travel hazardous. Scientists at the 6th European Conference on Space Debris warn that we are heading dangerously close to a ‘cascade of collisions’ which will see an explosion in the number of hazardous particles in space.
In a single band around our planet’s equator, it is possible to launch a satellite, allow its speed to match Earth’s orbit, and it will remain fixed above one point of the planet. This is the favoured position for communications satellites and leads to a high concentration of debris in one region. The sheer volume of space junk leads to collisions. Collisions lead to a larger number of fragments, making further collisions more and more likely.
These fragments cause corrosive damage to satellites – satellites that are being used for: government surveillance, monitoring the deepest regions of space, communication and media. Danger of collisions also increases the cost and risk of launch of space missions.
As the problem of space junk has become more apparent several methods of reducing the danger have been proposed or attempted each having varying degrees of success. However, there appear to be two main options for space debris: move them to a high, unused orbit, or bring them down into an ocean.
Some satellites will fall of their own accord; the Hubble Space Telescope is in a decaying orbit which will lead to it burning up on the way back to Earth in 2019-2020. Space junk can cause a problem even as it returns to Earth – with the risk of a person being hit and the pollution of oceans with potentially toxic satellite materials.
Whilst Herschel and many other satellites may be gone for good hope remains for the Kepler Observatory which has been in a dormant state to conserve fuel since May 15th 2013 after the second of its four reaction wheels jammed. The Kepler mission to hunt for planets orbiting other stars with particular emphasis on those capable of supporting life had been extended for another four years. It is still possible to communicate with the satellite but no new data has been collected since mid May. In mid July attempts to spin the seized reaction wheels will begin. In the meantime work will be done to analyse the data already collected by Kepler.
Of course all these measures are only a temporary reprieve. Whatever wonderful new planets Kepler may have and still might show us it is destined to one day become another useless piece of debris. And unless we can work something out soon it will be a danger to the next satellites that will be launched.