I like the solar sail and laser ideas. The solar sail is nice because it doesn't add a lot of weight to something. And it works like a poor-man's ion thruster. Low thrust over long periods of time during part of the orbit. Well that depends on the Earth's shadow. and the laser would work, I guess, because you can hit a target at an angle. The target won't necessarily be boosted to a higher orbit at all! I'm assuming the generated/ablated micro-debris would behave like dust and eventually fall victim to other natural forces like sunlight pressure or magnetic fields or upper atmo-drag. Whatever.
What I don't like is the idea of a big shield or barrier of foam and aerogel. This has too much potential to create more debris. It can be expensive, it can create more debris. it is really limited in the area where it is effective. And with conservation of energy laws, blahh blahh. Once it absorbs enough debris, it now has momentum that needs to be controlled. It is really no better than putting retro-rockets on an existing satellite.
And one thing about HST, and I hear this through 9th-hand resources, is that Hubble is a Keyhole satellite and the NSA does not want it left up there; for fear that another enemy satellite would get close to it and start taking pictures of secret tech. So that's the reasoning behind the de-orbit, contrary to what the public is being told.
And one more thing, about money.. Money is no more than a means for smarter people to control dumber people. Once our species gets rid of that notion(and the accompanying politics) then perhaps true space exploration can get underway.
---------- Post added at 01:58 PM ---------- Previous post was at 01:53 PM ----------
The problem with this plan is that it doesn't take care of non-satellite debris like spent stages or satellites that die and lose the ability to be controlled...
Well yes, it won't do any good for existing stuff.
But, for each object you send up you attach a solar sail module, boosters included. If you mass produce the modules you can get them cheap enough. And over time they will improve and the weight cost would be on the order of a few kilograms. Each solar-sail de-orbit module could have its own independent timer and battery and activation electronics package. So it will work on a dead satellite. I can envision these little de-orbit packages to be no more the size of a potted plant! We have the materials and technology today, right now.