Tales of the Heliosphere

Spacedaily has this story about Astrobiology magazine's publication of their latest thought experiment. (Here.) In this one, scientist Bernard Foing proposes putting a "Noah's Ark" on the Moon to preserve humanity and life as we know it in the event disaster befalls the Earth.

The lifeboat theory of space settlement is a fairly common justification for human colonization of other planets. That theory holds that other worlds could be a refuge for humanity in the event the Earth is destroyed by war or environmental destruction or a big giant asteroid or comet striking our world.

Not a bad idea but you've got to wonder how practical it is. If it's war that destroys the Earth the conflict is likely to sweep the colonies in space. As a refuge in case of environmental disaster, well that's a better idea, although if we can't save our own planet from ecological catastrophe, one wonders how we'll do making other planets habitable for humanity.

But as havens against asteroid or comet collision, Earth is at least as safe as anywhere else. With apologies to the followers of Gerard K. O'Neill, the two most commonly suggested homes for humanity in space are the Moon and Mars. The common characteristic of those two worlds is how heavily cratered they are.

Unlike the Moon, the Earth has an atmosphere to protect it from collisions. It's true that Earth's atmosphere won't protect us from a large asteroid but there is even less protection on the Moon. On the Moon, even the tiniest of meteors has a clear shot at the surface because of the lack of a true Lunar atmosphere.

As for Mars, one look at all the craters tells the story about that planet's history with asteroid collisions. Its two moons are asteroids for that matter. And just look at its location in the Solar System: one orbital position in from the Asteroid Belt.

We've always been a bit depressed at the lifeboat theory of space settlement. We prefer more glorious reasons for settling space. Spreading life to other planets, preparing other worlds for new branches of human civilization, opening frontiers, fulfilling American manifest destiny --- humanity's too, and making tons of money. O yeah, and learning things about the universe we live in. That's also important. But settling other planets so we can preserve humans in case Earth is destroyed; that's just depressing.

On the other hand, we have to admit that humans are a sorry lot who, although they learn from their mistakes, can really make a mess of things before they get it right. We also have to admit that we subscribe to a tragic view of humanity in which human nature is fixed throughout time and in which the future is likely to see the same sort of problems as the past and the present, just played out in different ways and magnified, thanks to how advanced our science and technology have become. In other words, with humans, what you see is what you get, and the best we can hope for is to preserve civilization to keep our worst instincts in check.

So, by all means lets put lifeboats on other planets. Humanity will certainly be better off when we spread our eggs among many baskets. Yet one could describe space settlement as the easy way out. The hard way would be learning to get along with each other, learning how our ecology can be protected, tracking the solar bodies that can do our planet in, and learning how to divert or destroy them before they do. Given human nature, however, our best bet for long-term survival is to do settlement and the rest. There's no good reason why we shouldn't.

-tdr

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