Paraterraforming vs. terraforming the Moon and Mars

On Tue, Jun 29, 2010 at 2:28 PM, William wrote:
(...)
> 4. (eventually) metals and rare earth elements mined from asteroids,
> or more likely captured metal-rich micro-sized asteroids sent down
> to earth.
(...)

I suspect that we can do (4) with nowadays technology. We can land
probes on asteroids and IIRC we can detect asteroids a few meters
across - aka "meteoroids". Maybe we can land a probe in a meteoroid
and gently nudge it into a path that, many years later (and probably
with gravitational assists and the like) will make it hit Earth. Of
course, I don't know if the ammount of platinum in a single meteoroid
would justify the costs of such operation...