Re: What planets and moons in our solar system can colonized and habitated?

If people try hard enough and have enough technology, it seems to me that
they could live on almost any planet in our solar system. But some places
would certainly be easier to colonize than others.

The first thing that you have to understand about our cosmic backyard is
that there are two kinds of planets in the solar system: terrestrial or
Earthlike planets (Mercury, Venus, Mars, Earth, Pluto) and Jovian or gas
giants (Jupiter, Saturn, Uranus, and Neptune). The many moons in are solar
system are like terrestrial planets, but smaller still.

Terrestrial planets are made up of rock. You could land a spaceship on one
and stand on its surface. Jovian planets weigh tens to hundreds of times as
much as the Earth and are made up mostly of gas. You can't stand on them.
It would be like trying to stand on top of a cloud. They may have a small,
rocky core, but we don't know because we've never sent any space probes
down that far. 

So the first rule would be that terrestrial planets would be more easy to
inhabit than Jovian planets. To live on a Jovian world, you'd have to build
some kind of giant flying city. 

Next you have to consider things like how hot or cold the planet (or moon)
is and whether it has an atmosphere. It would be more difficult to live on
Mercury or Pluto than it would be to live on Mars, for example. Both
Mercury and Pluto have extremely hot and cold temperatures at their
surfaces and no atmosphere. Mars, on the other hand, has relatively mild
temperatures and a thin atmosphere. You could walk around on Mars with the
help of an insulated pressure suit. 

The easiest places to inhabit are the ones that are most like Earth. Mars
is a favorite because it is nearby, has a thin atmosphere, and has gravity
and temperatures similar to the Earth's. Venus is also nearby, but has an a
thick, corrosive atmosphere that would bake and crush almost any satellite
we sent to its surface. We'd have to be pretty inventive if we wanted to
live on Venus. 

Another favorite are the moons of Jovian planets. Europa is a moon of
Jupiter. It's interesting because it's thought to have a crust made
entirely of water ice. Some writers and scientists have envisioned
colonists landing on Europa and melting the ice to make water and rocket
fuel. Water is critical to Earth-based life, but it's hard to find in its
liquid form. Ice is usually the closest we can get.

Saturn's moon Titan has also caught the attention of a great many people.
Titan is big enough to have an atmosphere of its own (it's the biggest moon
in the solar system, in fact). Some speculate that there may even be liquid
water on its surface. But it's difficult to tell because the atmosphere
hides the moon's surface. We will have to wait for more space probes or
better telescopes to find out more about this little world. 

But naturally our own moon would be a great starting point. Even though the
Moon has no atmosphere and low gravity, it is very, very close. It takes
only a day or so to travel to the moon in a spaceship, instead of years or
decades it would take to get to other planets. Also, new data indicate that
there is water on the moon, although whether there is enough to be useful
to humans is another question. But if we sent many supplies up from Earth,
we could certainly establish a moon base. 

[Moderator's note: a listing of resources available on the various planets
seems to be very hard to come by. To find this information, it looks like
you'll need to research each planet individually.]