Marrying asteroid defense and asteroid mining

cygonaut wrote
> I've been reluctant to support moving asteroids around for mining, but,
>if
>there's anything to this idea, it could be a side thing to the mining.. a
>complement of sorts.

>http://www.space.com/scienceastronomy/060620_science_tuesday.html

Just for curiosity, What's your objection to moving them around for mining?

That article seems tabloid shallow, hollywood fake, and puerile as anything
else about this topic in the mainstream media. A variant of "just send up a
nuke to blow it up". Never mind that there's a billion and one problems with
stating it that simply.

I may be completely wrong, but it seems like the two goals (mining and
planetary defense) go together well. We need to have a large space-based
observation capability to see them a lot better than we do today, and to
really do anything about an incoming threat, we ned to have a manned space
transportation infrastructure that lets people go to the threat like it was
any other mining target and completely survey it.
Various plans to deflect a threat all fall short because we won't know the
thing's internal consistency. Any plan requires us to know how it will
react, and the best way to affect this particular asteroid in the desired
way, and that means people moving around it for a long time. This isn't
something that can be done via telescope from a few AU away or even rovers
being teleoperated from a few AU away.
So mining and deflecting it start the same, and up until you've changed its
speed or direction a bit, they're the same. Deflecting it stops there,
because changing it a bit to avoid the Earth is all you need, while mining
it requires keeping the rockets firing a lot longer.
Very little difference in a mission sent to one to mine it or to deflect it.
You need everything the same, and actually the most fool-proof deflection
scenario is a slow rocket burn using the asteroid's mass as reaction mass
(ices or rock dust), and that's identical to a mining/retrieval. It works
equally for any type. Some might use different ISRU "rockets" depending on
whether you want to throw ices or rock dust, but rock dust through a mass
driver is always a safe bet.

The best thing we can do for planetary defense is to get out there and mine
the NEAs / Earth crossers. These are the most likely to hit us, and also the
easiest to reach for mining and the easiest to bring back either the entire
thing (what survives the particular "ISRU rocket" we're using) or packages
of mined materials.
The two aims are identical, except for mining/retrieval, we want to bring it
or bits of it controllably back to HEEO (or where the space manufacturing
facility is).

OK, I probably am wrong, but it seems to this ignorant person that if you're
going to the effort to deflect it from hitting the Earth, you might as well
send the extra equipment to make it a retrieval, which brings it back to eat
it up for resources.