Human Expansion into Space

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[This page was begun Fri Oct 13 01:52:39 1995].

As I argue in the other pages on sustainability of progress, there are adequate resources on earth to support a large human population for the next few billion years. However, some people will surely want to colonize interplanetary space, venture out into the galaxy and eventually beyond our own galaxy - up to the point where we have to share the universe with other intelligent entities.

The amount of motivation for colonization depends on several things, none of which are easy to predict.

At present the world is in a very stingy epoch, and the amount of resources governments and taxpayers are willing to put into space is tiny - tiny compared to what has been going into military activities. Moreover, the decline of military expenditures in the present state of mind will not make really large resources available for expansion into space.

The cause of the stinginess in the U.S. is the burgeoning of social expenditures. I will comment on the cause of this burgeoning elsewhere, but it will not last very long, and new money for space expansion on a large scale - say $100 billion per year will probably be available within the next 50 to 100 years. What might we do with it?


  1. Technology for exploring space.
  2. What is out there?
  3. In the short term.
  4. Initial human settlement.
  5. Beyond the solar system.
  6. The very long term.
  7. Non-governmental space colonization.

What is out there?

The parts of our solar system that have been considered for human settlement include
  1. The planets and their satellites. The surfaces of the planets are rather inhospitable to human life. They are too hot or too cold or too massive or too small and none has a suitable atmosphere. The best of them are our own moon and Mars.

    Our own moon is conveniently close and has on the average a suitable temperature. The low surface gravity (1/6 that of earth) is an advantage, but the moon lacks an atmosphere. It also seems to have only traces of some elements important to human life and technology - namely hydrogen, nitrogen and carbon. The moon is also quite undifferentiated, because it didn't undergo plate tectonics. This means that mining the moon is like mining random rock on earth. A moon colony would need to get certain elements from elsewhere and would need a high technology for those elements that it did get from the moon. The days and nights each correspond to 14 days on earth, so the colonists' lives would have to be adapted to extremes of temperature. When they are outside, they will have to wear space suits.

    In spite of all those problems, I think some people will want to live on the moon. Here are some reasons.

    There will be interesting and demanding jobs on the moon, e.g. those connected with astronomy. The low gravity will be attractive. Colonies on the moon may welcome the isolation from the earth and have social structures different from those on earth. The moon is unlikely to get crowded, because these attractions will attract only a few.

    Mars is better in the long run.

  2. The asteroids.
  3. Interplanetary space.