What's the best way to land on a spinning asteroid?

I think the first phase of using asteroid material will be to bring
it to near-earth space, not to develop it in its original orbit. I
envision minimal processing with robots, so in that case it's
definitely a simple tether rather than a pressurized tube.

The role of spin is twofold: to provide pseudogravity for the
processing, and to store energy that can readily be used for the
final maneuvers near earth by simply releasing material from the end
of the tether. It would be spun up by using a mass driver at the end
of the tether. The initial spin of the asteroid just provides a head
start.

I suspect that small asteroids held together by their structure would
include a fair number with markedly faster spin than large asteroids
have. Over the eons, collisions have happened. Since there's more
off-center than center, most of the collisions would involve
significant change of spin. In roughly half the collisions, it would
add to the previous spin; in about an eighth of cases it would add
three times in a row, and so on. So we ought to be able to find a
small asteroid where the spin is enough to provide a fair amount of
ready-supplied angular momentum that we wouldn't have to build up
with the mass driver. But I don't know whether that imposes too much
of a restriction along with finding a good orbit.

--- In spacesettlers@yahoogroups.com, "Combs, Mike"
>
> From: Michael Persohn-Costa
>
> > Probably the asteroids structure, if it is a single piece of
> material.
>
> OK, as long as we have a firm understanding that although some
asteroids
> may be, most are probably a mix of different materials.
>
> But even given that, of how much use is such spin gravity going to
be?
> I'd be surprised if it was more than a very few percent of a G, and
> we're already concerned that the moon's 1/6th G is probably not
enough
> to maintain health.
>
> I can think of only one way that the angular momentum of the
asteroid
> might be of some use in this regard. If we had a very long set of
> cables and/or a long pressurized tunnel (I'd prefer the latter)
going
> out to a habitat sphere at the end, the sphere would be describing a
> much wider circle with the same period than any point on or beneath
the
> surface of the asteroid. This might be a way to have useful
amounts of
> spin gravity while maintaining a convenient, non-rotating
connection to