“They’ll get their return. We’re mining more iron every year.”
“And most of it goes right back into Mars. If you can believe his figures, Earth has invested two hundred billion dollars in Mars and received back about five billion dollars’ worth of iron. It’s put five hundred billion dollars into the Moon and gotten back a little over twenty-five billion dollars of magnesium, titanium, and assorted light metals. It’s put fifty billion dollars into Venus and gotten back nothing. And that’s what the taxpayers of Earth are really interested in— tax money out; nothing in.”
The screen was filled, as he spoke, with diagrams of the Scavengers on the route to Mars; little, grinning caricatures of ships, reaching out wiry, tenuous arms that groped for the tumbling, empty shells, seizing and snaking them in, branding them MARS PROPERTY in glowing letters, then scaling them down to Phobos.
Then it was Hilder again. “They tell us eventually they will return it all to us. Eventually! Once they are a going concern! We don’t know when that will be. A century from now? A thousand years? A million? ‘Eventually.’ Let’s take them at their word. Someday they will give us back all our metals. Someday they will grow their own food, use their own power, live their own lives.
“But one thing they can never return. Not in a hundred million years. Water!
“Mars has only a trickle of water because it is too small. Venus has no water at all because it is too hot. The Moon has none because it is too hot and too small. So Earth must supply not only drinking water and washing water for the Spacers, water to run their industries, water for the hydroponic factories they claim to be setting up—but even water to throw away by the millions of tons.
“What is the propulsive force that spaceships use? What is it they throw out behind so that they can accelerate forward? Once it was the gases generated from explosives. That was very expensive. Then the proton micropile was invented—a cheap power source that could heat up any liquid until it was a gas under tremendous pressure. What is the cheapest and most plentiful liquid available? Why, water, of course.
“Each spaceship leaves Earth carrying nearly a million tons—not pounds, tons— of water, for the sole purpose of driving it into space so that it may speed up or slow down.
“Our ancestors burned the oil of Earth madly and wilfully. They destroyed its coal recklessly. We despise and condemn them for that, but at least they had this excuse—they thought that when the need arose, substitutes would be found. And they were right. We have our plankton farms and our proton micropiles.
“But there is no substitute for water. None! There never can be. And when our descendants view the desert we will have made of Earth, what excuse will they find for us? When the droughts come and grow—”