Hi folks, it has been a while since I had anything to contribute to
the ongoing dialog, but an idea struck me and I would like some
feedback on it.
While looking at the Tethers Unlimited Inc. site, I noticed that
their plan to clean up the lower Van Allen radiation belt calls for
ejecting the ions (predominantly protons-hydrogen ions) with an
electro-magnetic field. See below:
http://www.tethers.com/HiVOLT.html
I wonder if it may be possible to collect the ions instead of
rejecting them? If so, how many tonnes of hydrogen can be collected
each year? Since most of these ions come from the solar wind, this
would be a never-ending source of hydrogen already in orbit.
I further thought of the possibility of collecting the mono-atomic
oxygen in lower earth orbit, which is a source of degrading radiation
in its current location. The source of most of it is the earths
atmosphere, and represents a significant supply resource.
By collecting both and utilizing electrons from the outer Van Allen
belt, we could make our own rocket fuel and water with resources
already in orbit and possibly self sustaining into perpetuity at the
same time as remediating a known radiation hazard to life in orbit.
If any one has thoughts on this topic, please respond.
Sincerely,
Harvey

Harvey,

--- In spacesettlers@yahoogroups.com, "Shane Brown" wrote:
>
> Harvey,
>
> The answer to your question would require summing up all protons
> in all energies in all the space of the inner Van Allen belt. Source:
>
> http://www.clavius.org/envrad.html
>
> The short answer is: probably not. There are a lot of particles there,
> but the flux is so thin (better than the highest vacuums achievable
> on Earth) that there aren't enough to justify the cost unless you built
> a very, _VERY_ large collector. Like a Bussard Ramscoop. Which we
> are _very_ far from being able to build.
>
> When you're dealing with such low numbers of particles that you can't
> assume they exist in a continuum, in fact, that you can count them
> with single digit numbers of zeroes, it's unfortunately not practical
> to collect them. You'll be collecting an awful long time.
>
> Easier (IMHO, again) to derive those materials from passing NEA's
> or from the permanently shadowed craters on the Moon. Extinct
> comets that look like carbonaceous chondrites would be perfect.
>
> Shane
>
>From my research, the 'vacuum' in LEO varies from 10^-3 to 10^-10 or
less millibarrs of pressure. This indicates something along the lines
of density ranging from 10^12 to 10^3 particles per cubic centimeter.
See below for some figures:
http://deoxy.org/vacuum.htm
Of course, the higher particle densities will be in lower orbits and
the lesser particle densities in comparatively higher orbits, varying
with particle mass and speed (temperature).
Using a collector of even one square meter area in orbit at
appropriate speed, even high altitude (hydrogen belt), particle influx
will be sufficient to collect grams per minute using electro-magnetic
funnel type collection and compression of particles into tanks. Since
the elimination of the particles itself is worth doing to clean the
radiation, why not collect the matter? Even if only a kilogram or two
is collected every orbit, it is still a kilogram or two that do not
have to be launched from earth.
Any 'cheap' collector would pay for itself in a short period of time
due to both resource collection and radiation mitigation.
I agree that other resources are better, but I like to think of using
all available resources at the same time as removing 'problem'
pollutants (another word for resources in the wrong place). I think
this could be done 'on the cheap' and would be a worthwhile project,
either private industry or a governmental agency might be interested
in doing.
Thanks for the comments.
Harvey