Tentacle-like mechanical arms that can ’embrace’ dead satellites and bring them out of orbit are among the new technologies proposed by ESA to tackle Earth’s space junk problem
- ESA will spend £348million on space safety programmes including tackling junk
- One proposal would involve a satellite with ‘tentacle-like’ mechanical arms
- Other plans would use a giant net and a harpoon to bring down a satellite
The European Space Agency has revealed a proposal to tackle space junk which involves using tentacles to catch dead satellites and pull them out of orbit.
The agency will spend nearly £350million on space safety programmes – including clearing up space – over the next five years.
One of the ESA missions would involve using tentacle-like mechanical arms to embrace a dead satellite and drag it out of orbit.
The agency are considering several different technologies to achieve their goal including using a net, a harpoon and a satellite with a robotic arm attached.
The European Space Agency is considering several different options for space debris removal technologies including one that would capture the debris and take it on board as seen in this artist impression of an Active Debris Removal satellite
At a meeting in November European space ministers agreed to spend £348million out of a £12billion budget on ‘space safety programmes’.
Some of this funding will go towards an already planned mission aimed at capturing an ESA owned satellite and pushing it out of orbit.
‘The goal is to make these removal actions happen more frequently, and therefore they need to be cheap’, said Holger Krag, the head of ESA’s Space Debris Office.
‘The technology that we will most likely use now is actually consisting of some sort of arms, like tentacles, that embrace the object.”
An artist´s impression of the ESA Environment Satellite. It is be used to monitor climate change on Earth
He added that it would be an extremely difficult exercise as it would mean trying to cooperate with an object whose state was unknown, and then get it down from space – something which has not been done before.
‘The dynamics in space are very interesting because if you touch the object on one side it will be dragged away, so you can basically embrace it.
‘So you can basically embrace it before you touch it and then you just embrace it closer as you dampen the tumbling motion.’
About two-thirds of the satellites orbiting the Earth are dead – about 3,000 of about 4,500 objects – and pose a ‘very big danger’ to the planet, European space ministers were warned at a meeting in Spain (artist’s impression)
Space junk has become a growing concern as the debris in Earth’s orbit has the potential to collide, causing damage to other satellites.
Of the almost 4,500 satellites in orbit, only 1,500 are active, according to ESA.
ESA is funding by ‘subscriptions’ from each of the member nations, including France, Germany, Italy and the UK who make up the four largest financial contributors.
HOW MANY ITEMS ARE THERE IN ORBIT?
- Rocket launches since 1957: 5450
- Number of satellites in orbit: 8950
- Number still in space: 5000
- Number still functioning: 1950
- Number of debris objects: 22300
- Break-ups, explosions etc: 500
- Mass of objects in orbit: 8400 tonnes
- Prediction of the amount of debris in orbit using statistical models
- Over 10cm: 34 000
- 1cm to 10cm: 900 000
- 1mm to 1cm: 128 million
Source: European Space Agency
The UK Space Agency has committed an investment of £374 million per year with ESA to deliver international space programmes over the next five years.
This will secure its involvement in the mission to remove space junk.
Mr Krag said ESA had a fleet of 20 spacecraft to operate, and for these spacecraft they received several hundred collision alerts a day but most are false alarms.
‘Why are they false alerts? Because there’s a limited accuracy of the data, and we are acting based on probability.
‘So whenever the collision probability is higher than one in 10,000, we manoeuvre.
‘But that means in 9,999 cases there would have not been a collision if you did not manoeuvre.’
He said that while there was an issue of manoeuvres using fuel, one of the biggest burdens was not being able to run a mission while they were carried out.
‘If you run a very expensive science mission, in particular, and you have to interrupt the data for one hour in order to fit the manoeuvre in, you have a community of 1,000 scientists waiting for the data and that’s an economic loss.’
WHAT IS SPACE JUNK?
There are an estimated 170 million pieces of so-called ‘space junk’ – left behind after missions that can be as big as spent rocket stages or as small as paint flakes – in orbit alongside some US$700 billion (£555bn) of space infrastructure.
But only 22,000 are tracked, and with the fragments able to travel at speeds above 16,777 mph (27,000kmh), even tiny pieces could seriously damage or destroy satellites.
However, traditional gripping methods don’t work in space, as suction cups do not function in a vacuum and temperatures are too cold for substances like tape and glue.
Grippers based around magnets are useless because most of the debris in orbit around Earth is not magnetic.
Around 500,000 pieces of human-made debris (artist’s impression) currently orbit our planet, made up of disused satellites, bits of spacecraft and spent rockets
Most proposed solutions, including debris harpoons, either require or cause forceful interaction with the debris, which could push those objects in unintended, unpredictable directions.
Scientists point to two events that have badly worsened the problem of space junk.
The first was in February 2009, when an Iridium telecoms satellite and Kosmos-2251, a Russian military satellite, accidentally collided.
The second was in January 2007, when China tested an anti-satellite weapon on an old Fengyun weather satellite.
Experts also pointed to two sites that have become worryingly cluttered.
One is low Earth orbit which is used by satnav satellites, the ISS, China’s manned missions and the Hubble telescope, among others.
The other is in geostationary orbit, and is used by communications, weather and surveillance satellites that must maintain a fixed position relative to Earth.
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