The Moon is likely to become the industrial hub of the Solar System, supplying
the rocket fuels for its ships, easily obtainable from the lunar rocks in the
form 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.&