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Can space debris capture be modeled on surgical grapple baskets?

Most plans for de-orbiting space debris involve orbital rendezvous and grappling the debris. Grappling an uncooperative, spinning, irregularly shaped object is challenging. Some proposals involve analyzing the object’s spin and grabbing a suitable appendage as it whizzes by. There is a sudden transfer of angular momentum between debris and spacecraft. What could go wrong?

Surgeons must grapple irregular objects like kidney stones. Fortunately, they are not spinning. They have designed a wide variety of “baskets” for this purpose. The basket is initially collapsed inside a catheter (tube). As it is pushed from the tube, elasticity opens the wires into a cage much larger than the object to be grabbed. Once the object is positioned inside the cage, the process is reversed and the object is captured.

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If this design was applied to debris capture, angular momentum would be transferred to the spacecraft to be dealt with by its attitude control system.

Is this a sound design for debris capture? Are there any real world de-orbiting design projects using this principle?

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  • $\begingroup$ "Most plans for de-orbiting space debris involve orbital rendezvous and grappling the debris". I'd argue that most plans that suggest cleaning up space debris by going there and grappling it are bad plans. An enormous amount of delta-v is required to rendezvous, and since debris is spread out over an incredible volume, a "garbage collector" style satellite is infeasible. Capturing an individual satellite basically only makes sense if you want to do something with it like recover or revitalize it. $\endgroup$
    – Dragongeek
    Nov 2, 2022 at 13:12
  • $\begingroup$ @ Dragongeek ... you make good points. Garbage collection is slow and expensive. If rendezvous and grappling is a bad plan, what is a good plan? $\endgroup$
    – Woody
    Nov 2, 2022 at 15:04
  • $\begingroup$ Personally, I find garbage removal proposals that involve shooting down space debris much more convincing, such as by using a high-powered (Earth or space-bound) laser. A sufficiently powerful laser turret would be able to vaporize or slow debris enough to make sure it deorbits faster. Beyond that, the best way to prevent space debris is to prevent weapons usage in space--most of the problematic debris clouds today come from a small collection of anti-satellite missile tests, and if we could simply not perform these tests, a large amount of space debris would clean up itself in a decade or so. $\endgroup$
    – Dragongeek
    Nov 3, 2022 at 7:12

2 Answers 2

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This is partial as I am sure someone else will come along with a project that is closer to the one OP is asking about:

The RemoveDEBRIS project

..not quite the same but the closest i have seen is the 'net' test carried out a few years ago:

An untethered test, the design would actually be tethered to a mother craft, to tow, drag, de-orbit, etc.

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Net expands to ensnare target object (footage filmed from parent satellite)

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Net captures target object (top right of net)

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Net is wrapped around and constricts the target object.

The target was initially spinning and you can see the momentum is transferred.

Mission simulation:

In the simulation you can see that it sort of matches the OP's suggestion in that:

..the net is initially collapsed inside a container. As it is ejected from the container, a mechanism opens the wires into a cage (or web) much larger than the object to be grabbed. Once the object is positioned inside the cage, the momentum will go some way to dragging the web or net around the object, but in effect capturing it.

as seen in the real test, there is still a 'sudden transfer of angular momentum between debris and...' the net or web, but with it being tethered you could conceive that the same momentum might be dissipated in some way before it gets to the mother spacecraft.

Website:

https://www.surrey.ac.uk/surrey-space-centre/missions/removedebris

Description:

Net experiment and cubesat

The experiment is designed to help mature net capture technology in space. In this experiment, the first CubeSat (produced by Surrey Space Centre), DS-1, is ejected by the platform at a low velocity. DS-1 proceeds to inflate a balloon which, as well as acting as a deorbiting technology, provides a larger target area.

A net (produced by Airbus Defence and Space) is then ejected from the platform when DS-1 is at 7m distance. Once the net hits the target, deployment masses at the end of the net wrap and entangles the target and motor driven winches reel in the neck of the net preventing re-opening of the net.

From notes:

spinning is caused by a cold gas generator onboard the target cubesat as a result of the inflatable.

For future missions the NET would be tethered to the spacecraft.

For this mission we are in a relatively low orbit and the extra drag from the NET will pull the debris down fairly quickly anyway.

Article:

https://www.thinkdefence.co.uk/2021/04/defence-applications-of-space-debris-removal-systems/

The UK, with its very strong presence in the satellite sector, has the Remove Debris project led by the Surrey Space Centre

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I think the key positive aspects of this scheme are:

a) - bulk capture rather than targeting a specific hard point

b) - potential for highly controllable bulk capture by orienting the "wires" carefully around the debris object to avoid secondary debris production.

Aspect a) isn't necessarily ideal for all capture targets but may well be the right approach for awkward mass distributions

Aspect b) is a highly desirable property of bulk capture. Its not obvious that the grapple basket approach would have this property but it might be worth a look.

Lastly, the obvious reason the grapple basket came into existence is its packaging advantage. This isn't necessarily going to transfer into the space domain and so, for example i) there isn't obviously a need for the sprung-loaded packaging into a tube and ii) it isn't obvious the closed ends of the wire basket are also an advantage in orbit.

However, all that said, it might be worth a look.

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