ESA sets its sights on harpooning space debris


June 25, 2014

Artist's concept of a derelict satellite being reeled in after being harpooned by the e.DeOrbit satellite (Image: Airbus Defence and Space)

Artist's concept of a derelict satellite being reeled in after being harpooned by the e.DeOrbit satellite (Image: Airbus Defence and Space)

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In 2021, as part of its Clean Space Initiative, ESA plans to launch the e.DeOrbit mission. The aim of this mission is to clean up the important polar orbits between altitudes of 800 to 1,000 km (500 to 625 mil) that face the prospect of becoming unusable due to the increasing buildup of space debris. The ESA has now announced plans to examine the potential for the mission to use space harpoons to capture large items, such as derelict satellites and the upper stages of rockets.

The ESA has previously revealed it is considering a number of approaches to meet the challenge of capturing and securing space debris. These include snaring the debris in a net, securing it with clamping mechanisms, or grabbing hold of it using robotic arms. Another option is a tethered harpoon, which would pierce the debris with a high-energy impact before reeling it in.

Such an approach wouldn't be applicable for smaller debris, but is aimed at reeling in uncontrolled multitonne objects that threaten to fragment when colliding with other objects, resulting in debris clouds that would steadily increase in density due to the Kessler syndrome.

The ESA says the space harpoon concept has already undergone initial investigations by Airbus Defense and Space in Stevenage, UK, whose preliminary design incorporates a penetrating tip, crushable cartridge to help embed it in the target satellite structure and barbs to keep it sticking in so the satellite can then be reeled in.

The initial tests involved shooting a prototype harpoon into a satellite-like material to assess its penetration, the strength of the harpoon and tether as the target is reeled in, and the potential for the target to fragment, which would result in more debris that could threaten the e.DeOrbit satellite.

The ESA now plans to follow up these initial tests by building and testing a prototype "breadboard" version of the harpoon and its ejection system in the hope of adopting it for the e.DeOrbit mission. The project will examine the harpoon impact, target piercing and the reeling in of objects using computer models and experiments, ultimately leading up to a full hardware demonstration.

The space agency has put out the call for bidders to compete for the project contract.

Source: ESA

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Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

In theory once you harpoon a satellite and bring it to a much lower altitude you could use the tether to finish deorbiting the prey and fling the hunter back up to use an additional harpoon on further prey.


And what happens after the satellite is captured?


The article doesn't say. I suspect that the capture craft would then have to deorbit itself and the captured sat which makes it a multi-billion dollar waste. If it can at least capture several large objects prior to deorbiting it might not be such a terrible waste.


I expect the targets will be tumbling. What happens when you spear a big object tumbling? The deOrbit vehicle winds up (literally!) spinning on the end of its tether like the rock in David's sling. Now what? Maybe it's still possible to apply thrust, but I like to know how the developers intend to deal with the problem.


Instead of harpooning it, punch it out of orbit down toward the earth, let the denser air disintegrate them. If you miss, the shot would still direct earthward and also have to disintegrate.

Or maybe just the orbital tugboat approach, and nudge it towards a burn.

Either way your clean-up machine still needs to get up, and be able to move around, and maybe it can even feed off of the scrap.

Bob Flint

How about micro-sats with a thick, sticky pad that can conform to the target? Give the micro-sats a control system with enough RCS fuel to aim and hold the target to point a small solid rocket motor retrograde.

Once the thing reaches the right point in orbit so it'll splash instead of crash, fire the rocket then wait.

Sticking it onto a point of balance so the rocket won't set it spinning would be a ahem sticking point.

An alternate method would be to have the sticky part on the end of a tether then unreel it prograde from the target so that when the rocket fires any twist of the target being pulled off center won't have much effect. A possible problem there would be ripping pieces off the target.

What has to be done is to just lower the perigee enough so that the atmosphere will finish the job of bringing the debris down.

Gregg Eshelman

All that debris has kinetic energy. E= 0.5 m v^2 Why not harvest that too? Could speed up the catcher (higher orbit?)

Rob Tillaart

@ Rob Tillaart Too avoid generating more pieces of debris you have to match the velocity of the piece you are capturing pretty closely so there won't be the energy differential to work with.


Rather than sending stuff out of orbit piecemeal, keep the pieces together in a relatively more manageable aggregated unit that could then be de-orbited to a preassigned surface area. Should such an area be the Russian steppes, the Australian outback or USA desert, the salvage value would go considerably far in recouping the expense of the harvest. Incorporate a retro-rocket module with parachutes on a tether, and the hazard below would be diminished, not to mention how the debris could be inspected. The effort should pay off in research, that said debris would reveal the failures (or success) of the past. Beyond answering open questions about past performance, the salvaged hi-tech material would contribute to future missions.


@ anthodyd With the exception of titanium spheres most of the stuff will burn up during reentry.


@ Paul Anthony I think multiple harpoons would work better. Too many things to go wrong trying to reuse one.


Can the harpoon be reusable? perhaps use retractable barbs

Paul Anthony
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