On May 23, 1:42*pm, Marvin the Martian wrote:
On Sat, 23 May 2009 12:34:53 -0700, Quadibloc wrote:

Mars is indeed an attractive place to consider building a space colony.
Its thin - but not virtually nonexistent - atmosphere, though,
complicates landing on it. And while it has most of the elements needed
for permanent habitation, nitrogen is in very short supply.

Mars has a 0.6 to 1.0 kPa atmosphere, 2.7% of which is nitrogen.
Certainly not earth like, but not a lot of nitrogen is needed, and it can
be "recycled" once gathered from the Martian atmosphere.

Nitrogen is one of the most basic elements of life. If obtaining it on
Mars is difficult and expensive, that will inhibit the growth of a
Martian colony.

The Martian atmosphere aids, not complicates, landing on the surface of
Mars. Aero-braking and all that.

Landing payloads like Sojourner, yes. But the kind of slow,
controlled, descent required for landing people on Mars can't be
achieved with parachutes (like on Earth) or by using rockets all the
way down (like on the Moon), because in the latter case, the
atmosphere, hitting the rocket nozzles at high speeds, creates
turbulence that interferes with their operation.

This problem may well be soluble, for example by using a structure
with many small rocket engines, but it is an issue that has to be
overcome.

One body in our Solar System that has water ice, methane, and ammonia in
abundance, as well as rock, is the former planet Pluto. Since it is no
longer called a planet, though, it will be psychologically perceived as
less important.

Of course, Pluto is so far away that we will first have to perfect
life-support in space by attaining Mars.

Please tell me this is dry humor and you're not serious.

It is not entirely serious; I know that sending people to Pluto will
be much more difficult, due to the length of the voyage, than sending
them to Mars.

But the cold on Pluto can be easily dealt with by building bigger
mirrors to collect sunlight, and it does have the needed resources.
There may be other options, like a few comets that are in circular
orbits, or the Centaurs. We have lots of time before the Sun goes off
the Main Sequence, at which time Pluto would offer definite advantages
during the red giant phase.

After all, if faster-than-light travel is really *impossible* by
physical law, we have to plan ahead somehow.

John Savard