Imperial Earth

He glanced frantically around the audience; then, to his horror, saw that there was a perfectly enormous woman halfway back on the far left. She was the fattest person Duncan had ever seen-and the entire audience seemed to be carefully not looking in her direction.

Well, thought Duncan, I’ve got nothing more to lose. It can only go uphill from here. He plunged into his prepared speech.

“The history of my world goes back little more than halfway to the event we are all celebrating next month. The first manned ship touched down on Titan in 2015-but the first permanent base wasn’t established there until considerably later-2046. Even then, it was only a scientific observation post, with the crews rotating back to Earth every few years. There was no thought, in those days, of a selfcontained colony that might eventually develop its own culture, just as happened on this continent. In any case, the twenty-first century was too busy dealing with Mars and the Moon to have the energy, or the resources, for activities farther afield.”

Could that have been a yawn he spotted there, near the back of the hall?

Surely not so soon! He was being morbidly sensitive; that sea of hats

was getting 138 him down. Most of the faces beneath them seemed to be reasonably attentive…. But how to make these sleek and elegant matrons -not one of whom, probably, had ever been farther than the Moon-understand the harsh realities of his distant world? It was a challenge, and that was something that no Makenzie could ever resist.

“You may wonder why anyone would want to settle down in a place where the temperature never rises above a hundred below zero, where the atmosphere is poisoned by methane and ammonia, and the sun’s so feeble that you can’t detect its heat when it shines full on your face. Well, I won’t pretend that Titan is an atractive tourist resort-though we have some tourists, believe it or not. But it does have certain unique advantages, which is why it’s become important in human affairs.

“First of all, it’s the only place, outside the Earth, where a man can move around on the surface without a full spacesuit. That may surprise your after what I’ve just said about the conditions there! I don’t deny that we need protection, but it’s much less than required on the Moon, or even on

Mars. The atmosphere is so dense it allows us to breathe with simple oxygen masks, though we have to be extremely careful to avoid any leaks. If you’ve ever smelled ammonia, you’ll know why. And lightweight thermosuits can cope with the temperature, except in very bad weather.

“Having an atmosphere-even a poisonous one! makes life easier in dozens of ways. It means that we can use aircraft for long-distance transportation.

It protects us from meteorites-not that there are many out there-and from the temperature extremes that a completely airless world would have. And, most important of all-we’ve got an atmosphere we can burn, and use as a source of energy. “It,s just the opposite of the way things are on Earth. Here, you burn hydrogen compounds, and -the atmosphere supplies the oxygen. On Titan, we have to provide the oxygen, and we burn that in the hydrogen atmosphere. But the final

result is the same-heat and energy, to warm ourselves and drive our vehicles “That hydrogen-rich atmosphere is Titan’s greatest asset, and the reason men settled there in the first place. For without hydrogen, our spaceships cannot operate. Our chemical rockets burn it, and our fusion rockets—er-fuse it. Hydrogen is the key to the Solar System.

“And there are only two places where it’s easily obtainable. One is right here—in the oceans of Earth. But it’s expensive, lifting it out into space against the huge gravity field of your world-the one that’s keeping me pinned to this chair right now.”

Duncan paused hopefully, and got a few encouraging smiles.

“The other place is Titan. It’s a filling station, if you like, halfway to the stars. And because of its low gravity, we can export hydrogen cheaply, to anywhere in the Solar System, using robot tankers carrying up to ten thousand tons. Without us, space travel would be at least four times as expensive as it is now, and interplanetary commerce would be crippled.

“And how we get that hydrogen is interesting. We’ve been called ‘sky miners’ because of the way we take it out of the atmosphere. Specialized aircraft’ramscoops’-fly at high altitude and ever-increasing velocity, collecting hydrogen and liquefying it, then jumping up to orbit when they have a full load. There they rendezvous with the space tankers, deliver the goods, and go back into the atmosphere for more. They stay up for weeks on end, and land only when it’s time for servicing, or a change of crew.”