The Moon is likely to become the industrial hub of the Solar System, supplying the rocket
fuels fro its ships, easily obtainable from the lunar rocks in the from of liquid oxygen. The
reason lies in its gravity. Because the Moon has only an eightieth of the Earth's mass, it
requires 97 per cent less energy to travel the quarter of a million miles from the Moon
to Earth-orbit than the 200 mile-journey from Earth's surface into orbit!
This may sound fantastic, but it is easily calculated. To escape from the Earth in a rocket,
one must travel at seven miles per second. The comparable speed from the Moon is
only 1.5 miles per second. Because the gravity on the Moon's surface is only a sixth of
Earth's (remember how easily the Apollo astronauts bounded along), it takes much less
energy to accelerate to that 1.5 miles per second than it does on Earth. Moon-dwellers
will be able to fly in space at only three per cent of the cost of similar journeys by their
terrestrial dwellers will be able to fly in space at only three per cent of the cost of similar
journeys by their terrestrial cousins.
Arthur C. Clark once suggested a revolutionary idea passes through three phases:
1 'It's impossible -- don't waste my time.'
2 'It's possible, but not worth doing.'
3 'I said it was a good idea all along.'
The idea of colonising Mars -- a world 160 times more distant time the Moon -- will
move decisively from the second phase to the third, when a significant number of people
are living permanently in space. Mars has an extraordinary fascination for would-be voyagers.
America, Russia and Europe are filled with enthusiasts -- many of them serious and senior
scientists -- who dream of sending people to it. Their aim is understandable. It is the one
world in the Solar System that is most like the Earth. It is a world of red sandy deserts
(hence its name -- the Red Planet), cloudless skies, savage sandstorms, chasms wider than the
Grand Canyon and at least one mountain more than twice as tall as Everest. It seems ideal for
settlement.