The Sentinel - Arthur C. Clarke [62]
And the Professor appeared to be rigidly attached to the eyepiece of the teleperiscope. Suddenly he gave a start and we heard a whistle of indrawn breath. After a minute, without a word, he beckoned to Searle, who took his place at the eyepiece. Exactly the same thing happened, and then Searle handed over to Fulton. It got a bit monotonous by the time Groves had reacted identically, so we wormed our way in and took over after a bit of opposition.
I don’t know quite what I’d expected to see, so that’s probably why I was disappointed. Hanging there in space was a tiny gibbous moon, its “night” sector lit up faintly by the reflected glory of Jupiter. And that seemed to be all.
Then I began to make out additional markings, in the way that you do if you look through a telescope for long enough. There were faint crisscrossing lines on the surface of the satellite, and suddenly my eye grasped their full pattern. For it was a pattern: those lines covered Five with the same geometrical accuracy as the lines of latitude and longitude divide up a globe of the Earth. I suppose I gave my whistle of amazement, for then Bill pushed me out of the way and had his turn to look.
The next thing I remember is Professor Forster looking very smug while we bombarded him with questions.
“Of course,” he explained, “this isn’t as much a surprise to me as it is to you. Besides the evidence I’d found on Mercury, there were other clues. I’ve a friend at the Ganymede Observatory whom I’ve sworn to secrecy and who’s been under quite a strain this last few weeks. It’s rather surprising to anyone who’s not an astronomer that the Observatory has never bothered much about the satellites. The big instruments are all used on extra-galactic nebulae, and the little ones spend all their time looking at Jupiter.
“The only thing the Observatory had ever done to Five was to measure its diameter and take a few photographs. They weren’t quite good enough to show the markings we’ve just observed, otherwise there would have been an investigation before. But my friend Lawton detected them through the hundred-centimeter reflector when I asked him to look, and he also noticed something else that should have been spotted before. Five is only thirty kilometers in diameter, but it’s much brighter than it should be for its size. When you compare its reflecting power—its aldeb—its—”
“Its albedo.”
“Thanks, Tony—it’s albedo with that of the other Moons, you find that it’s a much better reflector than it should be. In fact, it behaves more like polished metal than rock.”
“So that explains it!” I said. “The people of Culture X must have covered Five with an outer shell—like the domes they built on Mercury, but on a bigger scale.”
The Professor looked at me rather pityingly.
“So you still haven’t guessed!” he said.
I don’t think this was quite fair. Frankly, would you have done any better in the same circumstances?
We landed three hours later on an enormous metal plain. As I looked through the portholes, I felt completely dwarfed by my surroundings. An ant crawling on the top of an oil-storage tank might have had much the same feelings—and the looming bulk of Jupiter up there in the sky didn’t help. Even the Professor’s usual cockiness now seemed to be overlaid by a kind of reverent awe.
The plain wasn’t quite devoid of features. Running across it in various directions were broad bands where the stupendous metal plates had been joined together. These bands, or the crisscross pattern they formed, were what we had seen from space.
About a quarter of a kilometer away was a low hill—at least, what would have been a hill on a natural world. We had spotted it on our way in after making a careful survey of the little satellite from space. It was one of six such projections, four arranged equidistantly around the equator and the other two