Satellite salvaging: safely de-orbit and retrieve spacecraft or other objects

(This question is not about getting scrap metal out of orbit and recycling it: please see the second and third sections of the question text.)

Consider an object which was not designed for, or has lost its capacity to perform, atmospheric reentry (for instance: a space station or part of it, a spacecraft with failed propulsion), in orbit around a planet. Suppose now that the residents of the planet's surface decide that it is desirable to have the object be brought, (mostly) intact, to the surface.

What would seem like a reasonable way to achieve this?

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The relevant setting is near-future-ish, but post-cataclysm: the predecessors of the surface dwellers had the capability to deploy extensive infrastructure in space, and performed interplanetary travel. The technology presently available to the recovering civilisation on the surface is recognisable as modern day, maybe plus a couple of pieces of handwavium gadgetry. The surface dwellers are not capable of reproducing the Magical Space Drive™ that enabled commonplace spaceflight for the predecessors, but they would know enough, for instance, to repurpose a spacecraft engine retrieved from orbit to be used as a power source.

The constraint on technology level is important, since it would not make sense if the surface dwellers could, at a lower cost, instead manufacture things on the surface that serve the same purpose as the salvage. This rules out sending a re-entry-capable cargo ship up, loading the stuff in, then flying it back down. However, it is also required that they be able to send things to a sufficient altitude at least momentarily, for them to be able to carry out the salvage operation in the first place.

The closest thing I could come up with was for someone to launch themselves into orbit, bringing with them thruster modules (perhaps plain chemical rockets) that would then be attached to the target, and be used to decelerate it and commit it to deorbit. However, I know of no robust way of modifying arbitrary satellites to enable them to survive re-entry.

Additional information that might be relevant:

• The operation is routine, but does not need to be indefinitely sustainable. If necessary, the surface dwellers might make use of technological relics found on the surface: for example, they expend one Magical Space Drive to send a crew up, expecting them being able to bring back at least two Magical Space Drives. Alternatively, they might make use of any infrastructure put in place by the predecessors that has survived the cataclysm and the subsequent lack of maintenance and remains sufficiently operable.

• It is preferred for the planet itself to be as similar to Earth as possible, but if the bottleneck to this question turns out to be planetary mass, atmospheric composition, or something along those lines, those parameters may be changed.

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I'm aware of several questions dealing with related subjects, but have been unable to piece from this information a complete solution to the present question. Links are left here for reference, and for the purpose of highlighting the differences of this question from similar ones.

• How to efficiently deorbit space junk has some creative solutions for de-orbiting without requiring much futuristic technology; however, the question deals only with the matter of removing space junk from orbit, allowing it to burn in the descent. The present question requires that the de-orbited object to be returned to the surface mostly intact.

• Would ablation be an effective way to redirect objects in space? examines an alternative way to impart delta-V, but similarly does not treat the issue of re-entry.

• How can I catch an asteroid asks the same question, except aiming to capture asteroids instead of artificial satellites. Several solutions involve destroying the asteroid beforehand for ease of transport, which is undesirable here where the objects of interest might be delicate technological artifacts. Other answers suggest use of a space elevator, which would be unavailable to the technology level required by this question. The option of using an elevator built by the predecessors leaves the questions of maintenance and operation of a space elevator without the capability of building one.

• How to Effectively Collect and Recycle Space Junk deals with the collection and recycling of objects in orbit, but is performed near a body without an atmosphere and explicitly forbids de-orbiting. The level of technology considered is also far beyond the constraints of this question.

There is also an xkcd post that I'm sure is bound to be brought up at some point.

posted almost 7 years ago

Lok‭

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