UK design to 'harpoon' old satellites

Firing range This is early stage research to prove the concept

UK engineers are developing a system to harpoon rogue or redundant satellites and pull them out of the sky.

It is a response to the ever growing problem of orbital junk - old pieces of hardware that continue to circle the Earth and which now pose a collision threat to operational spacecraft.

The harpoon would be fired at the hapless satellite from close range.

A propulsion pack tethered to the projectile would then pull the junk downwards, to burn up in the atmosphere.

"Space has become a critical part of our infrastructure - from weather forecasting and Earth observation, to GPS and telecommunications," said the harpoon's designer, Dr Jaime Reed, from Astrium UK.

"Space junk poses a real threat to these vital services if we do nothing about it, and so it's very important we develop capture technologies to remove some of this material. Studies have shown that taking out just a few large items each year can help us get on top of the problem."

Dr Reed's proposal is for a barbed spear about 30cm in length. It would be mounted on a "chaser satellite" that would edge to within 100m of a junk object.

Pictures sent to the ground would then be used to assess the target, before the chaser was moved to within perhaps 20m to take a shot.

Once the harpoon is hooked through the skin of the rogue satellite or rocket stage, the chaser could either pull on a trailing polymer cord itself or deploy a separate thruster unit to do the job of dragging the aimless drifter towards Earth.

Explosive concern

This is research in its very early stages. The BBC has filmed firing tests of a prototype harpoon at Astrium UK's Stevenage base.

David Shukman sees the experimental harpoon being tested

The company, the largest space manufacturer in Europe, is also pursuing other ideas at its centres in France and Germany. These concepts involve nets and robotic grappling devices. All systems have their pros and cons.

Harpoons could deal well with a satellite that is tumbling, for example, but the approach has its critics because of the fear it could actually add to our problems in space.

"Historically, one of the great sources of debris has been the explosion of fuel tanks in spent rocket stages," explained Dr Reed.

"We obviously don't want to be the cause of that, so our harpoon has a crushable cylinder. It's like a piston, and as soon as the harpoon hits the satellite wall, it rapidly decelerates, ensuring we don't travel right through the spacecraft, puncturing the tanks."

More than 50 years of space activity have left a huge quantity of redundant hardware in orbit.

This includes not just whole satellites and the upper-stages of the rockets used to put them there, but also that debris from fuel tank explosions.

Orbital objects

Today, it is said there are more than 22,000 objects actively being tracked.

These are just the big, easy-to-see items, however. Moving around unseen are an estimated 500,000 particles ranging in size between 1-10cm across, and perhaps tens of millions of other particles smaller than 1cm.

All of it is travelling at several kilometres per second - sufficient velocity for even the smallest fragment to do a lot of damage if it strikes an operational space mission.

Two events have really focussed the mind on this issue. The first was China's deliberate destruction of a decommissioned weather satellite using a missile in 2007. The second was the accidental collision in 2009 of the Cosmos 2251 and Iridium 33 satellites.

These two incidents produced hundreds of thousands of new fragments, negating all the mitigation gains that had been made over the previous decades.

Prof Richard Crowther is the UK Space Agency's chief engineer. He says there is a short window of opportunity to get on top of the issue before the number of collisions starts to increase and the problems associated with junk and debris begin to cascade. But he warns that any proposal for satellite removal requires international agreement because these systems could also be viewed as aggressive developments - as space weapons.

"If you've watched James Bond films over the years, you know that anything with a harpoon, with a laser, with a net in space has the potential to grab another spacecraft and destroy it," he told BBC News.

"So, we need to build reassurance within the space community and demonstrate that the systems being proposed are peaceful in their nature but also peaceful in the intent and the way in which they are going to be used."

The Astrium UK harpoon concept is being presented to the 63rd International Astronautical Congress in Naples on Wednesday.

Harpoon diagram The on-the-ground test harpoon is about 60cm in total length. A space harpoon would not need the winged stabilizer
Jonathan Amos, Science correspondent Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this

    Comment number 34.

    The space shuttle was used to repair Satellites - seems to me an easy to maneuver space only vehicle could be used to retrieve the small space junk - and haul it to the space station - for later return to earth. The space version of a trash collector.

  • rate this

    Comment number 33.

    A harpoon to catch space junk? Who will they get to pilot the spacecraft - Dan Dare? Buck Rogers? Steve Zodiac?
    What a load of twaddle!

  • rate this

    Comment number 32.

    The idea has merit; after all we need to clear space of our debris, however a more practical solution for the future would be to equip all new satellites with a suicide device!

    Basically a small separate motor that once a satellite’s job is done, it forces the satellite towards earth, include a few small nitrogen / Co2 cylinders that explode with the heat of re-entry, this should do the job?

  • rate this

    Comment number 31.

    @29 The energy required to raise the objects to higher orbits would be enormous and wasteful. It's more efficient to drag them down and burn up in the atmosphere. Actually if we left it long enough most of the rubbish would come down anyway due to atmospheric effects.

  • rate this

    Comment number 30.

    While they ponder on a solution maybe we/they should be thinking about adding systems to future satellites so when they reach the end of their useful life they bring themselves into an orbit where they burn up safely.
    I cannot believe with all the knowledge & expertise used to design & get them up there nobody thought of what happens when we are done with them.

    hardly rocket science.. or is it?

  • rate this

    Comment number 29.

    Why not fling the satellites into the path of the moon? Its gravity will pick them up but with no atmosphere they'll be crushed upon impact but not incinerated, allowing their components to be recycled at a later date and possibly assist the construction of any lunar abode. Most the money's spent getting stuff up there, may as well put it to use.

  • Comment number 28.

    All this user's posts have been removed.Why?

  • rate this

    Comment number 27.

    #19 random alias

    Obviously we cant do it with todays technology. - It will require the design and construction of a whole new class of laser and aiming system, but it should be well within our technical capabilities to do. Aiming could be achieved by scanning with the beam at low power and shooting the target as you highlight it. The power rating required could be achieved by building big & ..400

  • rate this

    Comment number 26.

    Uh, hasn't anyone heard of delta-V.
    You have the costs of launching the killer satellite, the costs of the additional fuel to move from debris to debris and the expendables that get dragged out of orbit.

    Fuel requirements for delta-V can be mitigated by increasing the orbit transfer time from target to target, but you still use up fuel.

    Time versus debris accumulation?

  • Comment number 25.

    All this user's posts have been removed.Why?

  • rate this

    Comment number 24.

    What, give the public a voice on important issues? Which planet are you living on?

  • rate this

    Comment number 23.

    Why has the BBC given a comments section for this story?

    I can pretty safely say that people don't know much or have an opinion about this issue.

    Maybe it's just our opportunity to make sci-fi references/jokes so lets just klingon to this!

    On another point could we just have comments for every news story

  • rate this

    Comment number 22.

    Come on, i was born at night but not last night. What hogwash! Looks like another Glomar Explorer to me!

  • rate this

    Comment number 21.

    I guess, eventually, we may be able to identify planets that may host intelligent life by the faint rings of metallic debris orbiting them (but not, of course, those hosting life that's intelligent enough to remove it).

  • Comment number 20.

    All this user's posts have been removed.Why?

  • rate this

    Comment number 19.

    #16 Ground-based lasers cannot (in the foreseeable future) deliver enough intensity in space to vaporise something as small as a satellite or space junk. This is due to atmospheric density fluctuations associated with air currents and turbulence). But file this away for later, perhaps for deflecting an incoming comet. Vaporising ice on the comet's surface would create a small but steady thrust.

  • rate this

    Comment number 18.

    1945: Arthur C Clarke publicised (but didn't discover - that was 1928) the geostationary orbit. 1963, it happened. 1979, the same guy anticipated the need for this problem to be solved. 2012, we're catching up with him...

  • rate this

    Comment number 17.

    How about a strong adhesive or glue? Fly paper in space!

  • rate this

    Comment number 16.

    #14 For me though a much better cheaper solution (though more Dr Evil than James Bond) is to build a few very large laser canons that vaporise the debris from the ground. The big advantage of lasers is that they can shoot the real debris, from flecks of paint to whole structures or the debris wakes of explosions. Of course the tiny danger with such lasers is their amazing military capability .. :)

  • rate this

    Comment number 15.

    Insert 20p and zap that space junk

    Asteroids! that was it


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