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.’
(1)_______________________. 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. (2)_______________________. 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.