Digest Number 61

Humans on asteroids are a pretty lethal mix - even large asteroids like 1
Ceres have a gravity well which is a pretty good approximation of microG for
work purposes. It's also two far away for human visits with current
technology & spectrums suggest that its unlikely to be of much value as a
shorterm research (unlike metal mountains like 16 Psyche or 216 Kleopatra);
but we'll know more about this soon if the Dawn 2 Vesta/1 Ceres orbiter gets
approved from Discovery AofO 2000.

Tunnelling beneath the surface of medium-small (at least 1km radius
asteroids to reduce Coriolis effects) & using the asteroid's spin to create
an artificial gravity within these asteroids is a different kettle of
Newton; & strategies can be designed for any of the larger Earthgrazers with
orbits resonant on Earth (ie, whose orbital paths cut regularly through
terrestrial space, like 4179 Toutatis). Allows you to establish in situ
processing to avoid the extended debt servicing costs of transferring then
processing (if you're selling energy from an asteroid platform - quite
feasible with near term derivatives of the automated solar cell factories
being designed for Lunar use - transportation isn't much of an issue of
course; & an asteroid base can be used to power a constellation of other
solar system craft); & eases the throw of processed material considerably.

If you have to transfer whole lumps to another location, Lunar orbit is a
better compromise than Mars orbit... close enough to the Earth to allow easy
transfer; but not so close that it freaks everyone out about the would be
impactors hanging in space.

Bear in mind: just establishing the best targets for mining &/or
colonisation will cost a conservative couple of billions [USAmerican count -
thousand millions, British count]... you need at least three unit
terrestrial arrays of 2m+ telescopes (for detection) & 70+m radars (imaging)
to do prelininary surveying of large numbers of potential targets; at least
one space telescope in the 1m+ range optimised for remote sensing & a
smaller 'scope for Aten detection; & a work fleet of small drone craft
capable of doing in situ & flyby sensing of the most promising choices. Even
though these costs can be mitigated as part of the campaign against the
impactor threat - & indeed is much less (both in cash & operational terms)
than indulgences like manned Mars missions - that's still a lot of debt to
assimilate....

All the best,
Robert Clements