Fifty Years in Space, Part III

In my two previous pieces about human space exploration, I discussed the fundamental problem:  why send humans into space at all? I looked at profit (financial and intellectual) as a motive. Now I'm going to consider fear.

Fear

When people fear harm to themselves, their property, or their way of living, they become willing to spend large sums and take great risks in the cause of self-defense. Could fear get people into space? Well, let's think about things to be afraid of.

Inanimate Threats:  There's only two threats which could plausibly motivate large-scale human operations in space. The first is the menace of Giant Rocks From Space. If the peoples of Earth ever get sufficiently worried about being smacked by falling asteroids, one can imagine a permanent outfit like Clarke's SPACEGUARD patrolling the Solar System, adjusting the orbits of dangerous objects. But sadly for would-be rock jockeys, I'm afraid unmanned vehicles would be far better for that purpose. An unmanned probe could spend years or decades in space, visiting multiple objects and dropping off landers equipped with thrusters or powerful bombs to divert or destroy menacing planetoids. Humans doing the same would be much more expensive, and quite likely go bonkers.

The second inanimate threat is more topical:  global warming. How can we fight global warming by sending people into space? Simple. Build sunshades. It sounds absurd at first, but think about it:  if the Earth's heat balance gets out of whack, why not just turn down the furnace a little? Reducing the sunlight reaching the Earth could be done with an orbiting sunshade. Given that it's a question of small percentage changes over decades, an object capable of blocking only 1 percent of the energy reaching Earth could have a dramatic effect. Of course, we're still talking about something more than 700 miles on a side, but it would be little more than a vast sheet of mirror-coated Mylar.

The chief appeal of the brute-force space engineering method is that it may well be the only one that has even the slightest chance of working. Sure, America and Europe may reduce their carbon emissions in the name of Saving The Earth -- but Russia seems to be against the whole idea, and current treaties don't even try to rein in China's mushrooming growth in (coal-based) energy production. Social engineering is hard. Building a giant sunshade in orbit is just a question of putting enough stuff on boosters. And so far, space construction has proved startlingly difficult for machines to master, so the Big Parasol would require humans to build and maintain it.

Enemies:  What about war in space? It's certainly a popular subject for films. Would conflict result in a permanent human presence off Earth, just as World War II and the Cold War led to permanent presence in the polar regions? It's worth remembering that the whole first generation of the Space Age was driven entirely by Soviet-American fear and rivalry.
    But an actual shooting war might not have the same effect. If a conflict were waged in Earth orbit, for instance, the first thing any sensible spacefaring power would do would be to get its astronauts safely down on the ground. Humans are fragile things, as are spacecraft which keep humans alive in space. The first thing any space warship designer would eliminate would be the crew.
    A conflict in the outer Solar System (say, over the helium mines of Saturn) would involve humans if humans are out there. However, any humans would quickly become hostages to the other side's unmanned weapon platforms. I'm afraid a war in space would tend to end human presence in space rather than encourage it.

Of course, a war in space doesn't have to be against humans. What if alien beings turn up and decide to act like the Martians in The War of the Worlds? Wouldn't we have to go out into space to fight them?
    Alas, probably not. Consider three possible alien invaders. First, the "Angry Space Gods" scenario. Aliens far more advanced than humans arrive and beat on us. Sending people to battle such a foe would be suicidal. Stick to robots and missiles.
    Second, aliens turn up who are about equal to ourselves in technology -- possibly ahead in some areas but behind in others. Call it the "Even Match" scenario. Would it make sense to send out human space warriors? Again, no. Just as in an inter-human conflict described above, humans in a space war are vulnerable and not cost-effective. Battle these aliens using unmanned weapons.
    Finally, the rather sad case of less advanced aliens trying to conquer us. The "Papuans Invade Singapore" scenario. This is the only scenario in which it might make sense to send out humans, in order to try to persuade these low-tech starfarers to give up before being annihilated by unmanned weapon platforms. Of course, since we ourselves can't cross interstellar distances with current or near-future technology, it's difficult to see how this situation could ever arise. (Except perhaps for the scenario presented in Harry Turtledove's short story "The Road Not Travelled.")

So it appears that the only fear which could motivate us to invest in permanent off-world human presence might be the need to build something protect the planet from sunlight. Anything involving blowing stuff up should be left to machines.