Space Colonization Basics

DISCLAIMER: This web site is not a policy statement. It is intended to be an accessible introduction to the ideas developed in the Stanford/NASA Ames space settlement studies of the 1970s to support the annual NASA Ames Student Space Settlement Design Contest. You. Or at least people a lot like you. Space settlements will be a place for ordinary people.

Presently, with few exceptions, only highly trained and carefully selected astronauts go to space. Space settlement needs inexpensive, safe launch systems to deliver thousands, perhaps millions, of people into orbit. If this seems unrealistic, note that a hundred and fifty years ago nobody had ever flown in an airplane, but today nearly 500 million people fly each year.

Some special groups might find space settlement particularly attractive: The handicapped could keep a settlement at zero-g to make wheelchairs and walkers unnecessary. Penal colonies might be created in orbit as they should be fairly escape proof. People who wish to experiment with very different social and political forms could get away from restrictive social norms.

Although some colonies may follow this model, it's reasonable to expect that the vast majority of space colonists will be ordinary people. Indeed, eventually most people in space settlements will be born there, and some day they may vastly exceed Earth's population. Based on the materials available, the human population in orbit could one day exceed ten trillion living in millions of space colonies with a combined living space hundreds of times the surface of the Earth.

For an alternate view, see Robert Zubrin's powerful case for Mars exploration and colonization. Mars' biggest advantage is that all the materials necessary for life may be found on Mars. While materials for orbital colonies must be imported from the Moon or Near Earth Objects (NEO's -- asteroids and comets), there are many advantages to orbital colonies. Advantages include:

By contrast, orbital colonies can rotate to provide any g level desired, although it's not true gravity. Spinning the colony creates a force called pseudo-gravity, that feels a lot like gravity. Pseudo-gravity is much like what you feel when a car takes a sharp turn at high speed. Your body is pressed up against the door. Simillarly, as an orbital space colony turns, the inside of the colony pushes on the inhabitants forcing them to go around. The amount of this force can be controlled and for reasonable colony sizes and rotation rates the force can be about 1g. For example, a colony with an 895 meter (a bit less than 1000 yards) radius rotating at one rpm (rotations per minute) provides 1g at the hull. Children raised on orbital colonies should have no trouble visiting Earth for extended periods.

Mars and the Moon have one big advantage over most orbits: there's plenty of materials. However, this advantage is eliminated by simply building orbital settlements next to asteroids. It may even be easier to mine asteroids for materials than the Mars or the Moon as there is much less gravity. Fortunately, there are tens of thousands of suitable asteroids in orbits near that of Earth alone, and far more in the asteroid belt. Early settlements can be expected to orbit the Earth.

Later settlements can spread out across the solar system, taking advantage of the water in Jupiter's moons or exploiting the easily available materials of the asteroid belt. Eventually the solar system will become too crowded, and some settlements will head for nearby stars.

Interstellar travel seems impractical due to long travel times. But what if you lived in space settlements for fifty generations? Do you really care if your settlement is near our Sun or in transit to Alpha Centuri? So what if the trip takes a few generations? If energy and make up materials for the trip can be stored, a stable population can migrate to nearby stars. At the new star, local materials and energy can be used to build new settlements and resume population growth.

With great difficulty. Fortunately, although building space colonies will be very difficult, it's not impossible. Building cities in space will require materials, energy, transportation, communications, life support, and radiation protection.

Read more:
Space Colonization Basics