A reason to go to Mars

From: Marcel

> True. But its much easier and cheaper to set up a colony on Mars than
> to build one from scratch.

Again, "easier and cheaper", even if we accept this point (and I think there's considerable room for argument here), might not be the determining factor. The determining factor might be which locations provide economic opportunities with a product or service marketable to an existing customer. Nobody can give a straight answer when asked what product Martians will sell to Earth to balance their trade.

Also, I see no reason to conceptualize a Mars colony as being a mere "set up" while same in orbit would represent "building one from scratch". (I think building a settlement on Mars is going to be just as much "from scratch" as same in orbit of the Earth.) I think this perception derives from the idea of Mars as "meeting us halfway". But I think this is fallacious thinking, and that Mars by no means meets us half-way. The presence of a 1% atmosphere in no significant way reduces the difficulties in setting up large, pressurized environments. 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.

I think there's a fallacious notion that if setting up a settlement in space we have a checklist of items we must provide, but that on Mars we can strike a significant number of those items off the checklist since they're already provided by Mars. But I think this is wrong. I think we can legitimately only strike off two items: providing gravity, and providing a day/night cycle. And I think in comparison to so many other highly-difficult things needed in both places, these will be relatively easier and cheaper things to provide.

As just one example, some people mistakenly think that building your settlement on the surface of Mars means you don't need a radiation shield. You might could get by with a radiation shield only 1/3 as thick, but you cannot strike this requirement from the list.

> The cost of delt-V would be insignificant if we're using the free
> energy from the sun via light sails.

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.

> Again, the cost of transporting material from the tiny gravitational
> wells of the moons of Mars would be insignificant since once they were
> easily transported off they surface they could be cheaply transported
> almost anywhere in the solar system via light sails.

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.

> So materials
> from the deep gravity well of the Earth's moon would never be
> competitive with material from the tiny gravitational wells of the
> Martian moons.

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.

Regards,

Mike Combs