A reason to go to Mars

"Combs, Mike"Nobody can give a straight answer when asked what product
Martians will sell to Earth to balance their trade.

MW: Mars has two captured asteroids (Phobos and Deimos) with tiny
gravity wells. Mars orbit can also be a central location for the
import and processing of small asteroids (100 to 1000 tonnes). And the
cost of transporting Martian moon materials out of Mars orbit would be
insignificant if you used huge 'Drexler type' light sails since the
cost of solar energy would be zero. Only the capital cost of the
material and construction of these multi-kilometer in diameter
aluminum kites would factor into the cost of transporting materials
out of Mars orbit.

So setting up a facility on Mars allows large numbers of people to
remotely operate mining facilities on the Martian moons.

"Combs, Mike"The gravity of Mars may be insufficient for our health,
and in fact only complicates obtaining a full 1-G in the same way we
can in orbit.

MW: That may turn out to be true. But I'm not advocating any mass
migration of humanity to Mars. I'm advocating setting up a simple
industrial community for the exploitation of the moons of Mars and to
see if humans can survive off the natural resources of an
extraterrestrial world. These are things we need to know.

"Combs, Mike" You might could get by with a radiation shield only 1/3
as thick, but you cannot strike this requirement from the list.

MW: You need as much radiation shielding on Mars as you would on the
Moon or in space. And again, this is much easier to provide on the
surface of a large Moon or planet than it would be for a large
rotating structure in space.

"Combs, Mike"Solar sail are a potential game-changer, I must say. But
in that case, the savings of avoiding steep gravity wells may relate
more to time than to fuel requirements (and time is money). Solar
sails must spend many months executing tight spiral paths to both
ascend and descend planetary gravity wells. In fact, I would say that
a solar sail enthusiast has more reason than most to prefer avoiding
steep planetary gravity wells.

MW: Huge space manufactured light sails would be extremely fast:
faster than any chemical or nuclear rocket over interplanetary
distances and could rapidly transfer several hundred tonnes of payload
within the inner part of the solar system within just a few months for
20 to 50 tonnes sails. Much more massive sails (200 to 500 tonnes)
could transport thousands of tonnes of payload rapidly.

"Combs, Mike"> Any proposed space transportation system which improves
the prospects for resource retrieval from the gravity well of Mars
would improve the prospects for a lower-delta-V target to an even
greater extent. If solar sails are good for the moons of Mars, then
they're several times better for NEAs.

MW: Exploiting NEAs is a lot more difficult since you actually have to
find people willing to live in isolated communities near one for at
least several years in probably very cramped quarters. On Mars, your
labor force can live under large transparent water shielded biodomes
amongst a continuously growing American community and possibly
international communities not just there to exploit the Martian moons
or to import small asteroids from the asteroid belt, but also to
explore Mars.

"Combs, Mike"> What you don't seem to be grasping is that the tiny
gravity wells of the Martian moons are themselves embedded inside the
enormous gravity well of Mars itself. You have to include that in the
calculations. When you do, you see that the delta-V from the lunar
surface to HEO is much smaller than that from even Deimos to HEO.
Then if you add the fact that the transit time for resources from a
moon of Mars is probably many months (and if we go with your solar
sail plan, perhaps years) while the transit time for lunar resources
is a few days, and it becomes no contest at all.

MW: Again, the gravity wells in-- Mars orbit-- are insignificant since
light sails utilize free solar energy. And space manufactured light
sails are much faster than rockets over interplanetary distances.
Lunar resources require either expensive rockets or huge capital
intensive investments in lunar mass driver technology which will also
require electricity from large nuclear power facilities on the lunar
surface in order to power them.

Good discussion Mr. Combs:-)

Marcel F. Williams
http://newpapyrusmagazine.blogspot.com/