Many ideas for harvest material form asteroids and comets have been proposed.
There is a related field of inquiry around the problem of moving a rubble pile asteroid so that it does not collide with Earth (or any other Solar System object that humans might wish to remain undisturbed).
As it happens, a member of the Knowledge community (Dave Z) has introduced a possible harvesting method I have not seen before, and this topic provides a place for Dave Z and for any other Knowledge community member to build up a set of posts to support the idea, and to guide future asteroid miners and planetary defense workers to achieve success.
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