Can space colonization solve Earth's over population and
environmental problems? This page provides certain facts
(numbers), followed by commentary by Gene Shiles,
author of "Tribes of the Orange Sun," "Pale Yellow Sun"
and "White Sun Chronicle."
(Descriptions of these intriguing books are given later.)

Our Solar System

Earth is the only "earthlike" planet in our solar system, but
other bodies may be considered for space colonization. The
closest, about a quarter-million miles away, is our own moon.
The moon is about 1/4 the size of Earth (diameter), so it has
roughly 1/16 the surface area. Since the moon has no ocean,
its land area is roughly 1/4 that of Earth. This is a lot of
living space, but, since the moon has no atmosphere, humans
would have to live in enclosed structures or in specially
constructed underground facilities; they would venture
outside only in space suits or with some other kind of
protection. They would also have to become accustomed to a
gravity that is only about 1/6 that of Earth. Depending on
its mineral wealth and any presence of water, the moon can
support only a few million or at best a few tens of millions
of excess "earthlings."

Venus is about the same size as Earth. Following an orbit
of the sun closer than Earth's (about .7 AU), its distance
from Earth ranges from about .3 AU to 1.7 AU (where AU,
an astronomical unit, is the average distance of Earth to
the sun, about 93 million miles). Venus has a very thick
atmosphere and the surface is much too hot for life
(hot enough to melt lead); it cannot be considered
for any human colonization.

Mars follows a larger orbit than Earth (about 1.5 AU); its
distance from Earth ranges from about .5 AU to 2.5 AU. It
is about 1/2 the size of Earth (diameter), so its surface
area is about 1/4 that of Earth. Since Mars (at present)
has no ocean, its land area is roughly equal to Earth's.
Its atmosphere is very thin and very cold, and does not
have the composition necessary to support life as we know
it. Like on the moon, colonists would have to live mostly
in enclosures and/or underground. Mars' gravity is about
1/3 that of Earth, so some "adjustment" would be necessary.
An advantage on Mars is that the day-length (rotation
period) is very close to that of Earth. But, given the lack
of a proper atmosphere, Mars could likely support no more
than a few tens of millions of people.

Other possibilities could be several of the moons of
Jupiter and Saturn. But there the conditions are less
favorable for space colonization than that of the moon
or Mars. Clearly only very small colonies might be possible.

One might consider a "closer" space colonization
by constructing a number of "space stations" of
various sizes in near or far Earth orbit. A few million
people, or even a few tens of millions, might colonize
such stations (they most likely would need some level
of continuing "support" from Earth). It is unlikely
that present and forseeable-future technology could
construct anything large enough to support many more
people than those few tens of millions. Far-future
technology might someday support larger "stations,"
and they might even be self-supporting after some
years of partial support from Earth. But such facilities
will be "expensive." Constructing them will certainly
consume resources that will be needed to support the
people remaining on Earth. Also, "far-future" means
hundreds of years into the future; Earth's human
population, at current growth rates, could become
unsustainable long before then.

So there are "places" in our solar system that may be
considered for space colonization - with present and
near-future technology - but apparently not in the large
numbers necessary to relieve Earth's over population.
We now consider "outside our solar system."

Modify Mars?

Scientists have been examining the idea that space
colonization might involve a "modified" nearby planet.

Mars is the only realistic candidate for "terraforming."
The topic will be covered only very briefly here (for a
detailed treatise, one might read the excellent article by
Christopher P. McKay in Scientific American, March, 1999).

Mars might be made "partially habitable" in about 100
years or so (a thicker carbon dioxide atmosphere may
support plant growth, and even make the enclosures
unnecessary, but humans would still have to carry oxygen
tanks); optimistically the planet might then support maybe
several hundred million people. Fully earthlike, with an
earthlike atmosphere, would take much longer, maybe
1000 years or more, if it is possible at all. Even so, a fully
earthlike Mars would support only "another Earth" full of
people (or fewer, depending on the size of newly-created
ocean(s) on the planet). Even if Earth's population
doubling-time were slowed to 100 years (as opposed to
the current 40 years), an earthlike Mars, even if it can be
accomplished sooner than 1000 years, would only be a
stop-gap measure for Earth's over population and
environmental problems.

Commentary

Earth's Growing Human Population

Is over population on Earth a serious problem? One
might look at various "symptoms." Just a few examples:
Thousands, mostly children, starve to death every day in
different places around the world. Forests everywhere
are "disappearing." The global unpolluted fresh water
supply is in danger. Illegal immigration is a big problem
for the United States.

Science and technology, and, yes, politics, may "handle"
over population problems in the short term even if human
population continues to grow. But what kind of world will
our great-great-grandchildren inherit? Eventually over
population must be controlled, but the longer society waits
the more draconian must be the method and the greater
must be the price paid in terms of human lifestyles and
environmental problems.

We revisit the question:
Is space colonization an alternative?

NOW AVAILABLE: "Colors of the Sun - A Trilogy" contains all three stories in one volume!

"Tribes of the Orange Sun," published in November, 2001, "Pale Yellow Sun," published in June, 2004, and "White Sun Chronicle," published in November, 2007, look at Earth more than two hundred years in the future. Population has grown to 24 billion. Science and technology has kept up with this over population (fed the people) and struggled with the environmental problems - but human lifestyles have changed dramatically. (Note that growth to 24 billion in 200 years requires a slowing of the current growth rate - to a doubling in 100 years instead of 40 years.)