Existing Commercial Potential for Helium-3 from Luna

>
> > --- In ssi_list@... Frank
> > >
> > > >
> > > Wouldn't it be a lot more economical to get this
> > material from a
> > Near
> > > Earth Asteroid located at about 0.25 AU from
> > Earth?
> > >
> Apologies, I can't keep track of who wrote what now.
>
> To my knowledge, there has not yet been an asteroid
> discovered whose entire orbit is within the orbit of
> Mercury.
>
> There are however several near-earth asteroids for
> which the delta vee is less than that of the moon.
>
> Ed
>

Ed you are correct. You were quoting Frank BTW.

Frank did not mention NEO asteroids. The delta-vee to NEO can be
less than landing on the Moon.

But there are other logisticial problems with NEOs, e.g. the multi-
year round-trip mission time, lack of launch windows, and long
communications path. All those tend to increase the cost of NEO
missions.

Each NEO only approaches Earth once every few years, so once you have
sent a probe there, it will be years before you get anything back
from it.

Lunar missions can be done at short ntoice, and can be short duration.
Furthermore, it is easy to resupply the Moon and send spare parts to
repair equipment. On asteroid missions, it is so far away from
Earth for most of the time (years) that the hardware has to be very
reliable and expensive. Once you have a hardware failure on an
asteroid you are dead. Period.