Don't Waste Your Eggs on a Broken Basket
Mars exploration and colonization advocates frequently repeat the slogan Don't Put All Your Eggs In One Basket. The implication is that Mars is a "second basket", just needing a little touchup to become a permanent, comfortable second home for Earthlife, and for human beings in particular.
Slogans are the opposite of knowledge.
Instead of putting all our eggs in one basket, we can:
- Fry some eggs in hard radiation
- Explode some eggs in near-vacuum
- Freeze and bake some eggs with extreme temperature variations
- Poison some eggs with perchlorates
- Smash some eggs launching to a 10.6 km/s interplanetary Hohmann, smash more in a 5.7 km/s landing on Mars
- Rot some eggs on a 9 month journey
- Attempt to preserve the remainder where refrigerators can't be manufactured or repaired
- Hope we discover egg-laying Martian chickens
The few eggs that survive will cost millions of dollars each.
Humans are not eggs, and cost far more to keep alive. We require one-gee gravity - Mars is 62% gravity-deficient; centrifuge habitat wheels will be difficult to arrange in the remaining 38% gravity. We must breath non-poisonous air; keeping the perchlorates and other poisons out of a human habitat requires perfect isolation and cleanup.
It is much easier to put human habitats on Deimos (a small asteroid) and control exploration robots on the surface. Humans are isolated from Martian poisons; Mars is isolated from human contamination. The Earth is 10 km/s closer to Deimos than it is to the surface; that is a cost scale ratio as vast as the ratio of the Apollo Command/Service module to the entire Saturn V launch vehicle, a factor of 100.
What's Wrong With Mars?
- Human travel to and landing on Mars is "kilo-Apollo" difficult. Trip times are 60 times longer, the Tsiolkovsky multiple is 10 times larger.
- Mars is small and interplanetary arrival velocities high; aerobraking involves huge gee forces and narrow entry windows.
- Mars gravity is double the Moon's, vehicles (and structures) must be heavier than Apollo's LEM.
- Mars gravity is insufficient for long term survival.
- Mars is actively poisonous, worse than lunar vacuum.
- Mars has no radiation-deflecting magnetic field. Making one requires ultra-high-tech structures vastly larger than all human construction combined.
- Mars does not have hydro- or bio- or plate-tectonics- generated ore bodies.
- Mars requires vastly more technology to survive, and has vastly less.
Terraforming is handwaving nonsense. No conceivable nuclear/biological war could make the Earth as uninhabitable as Mars is now. The worst Earth wars cannot not destroy the deep resources available for restoring the Earth to habitability. The survivability of a war-ravaged Earth far exceeds anything we can create on Mars with the tools we can afford to deliver, and the raw materials we can expect to find.
No, lets use our limited egg supply for more productive goals. Near-earth asteroids (NEA) are smaller but more numerous; they are more differentiated and mine-able than Mars. A centrifugal habitat can create one-gee acceleration without high pivot loading and slanted floors. NEA gravity is very small, so a meters-thick regolith radiation shield can be supported over the centrifuge with a tiny fraction of the structural material. Mission delta-V to an NEA can be smaller than the Delta-V to a Moon landing, and far less than landing on Mars (mission cost is a steep exponential function of delta V). NEAs are in permanent sunshine, and in permanent darkness, you can point mirrors in all directions; ideal for processing solar energy.
And why go there? A second basket is nice, but protecting the basket we have from NEA impacts is vastly more important. That protection will require vastly more knowledge of NEAs, and on-the-spot resources to manage them. A milligram of preparation a century early is more effective than a megagram of frantic response a year before impact.
NEAs are not the Barsoom of 1930s pulp science fiction; they are a new opportunity. All may prove as difficult as Mars, but there are many more opportunities for useful surprises. Let's find the best place to invest our eggs, not just throw them at a wall that we once believed was a window.