If you go up on your roof on a dear night, the stars look so plentiful you would think that planets very much like Earth must he as common as eggs in a hen yard. Well, they are: Harry estimates that there arc between a hundred thousand and a hundred million of them in our own Milky Way-and you can multiply that figure by anything you like for the whole universe.
The hitch is that they aren't conveniently at hand. Tau Ceti was only eleven light-years from Earth; most stars in our own Galaxy average more like fifty thousand light-years from Earth. Even the Long Range Foundation did not think in those terms; unless a star was within a hundred light-years or so it was silly to think of colonizing it even with torchships. Sure, a torchship can go as far as necessary, even across the Galaxy—but who is going to he interested in receiving its real estate reports after a couple of ice ages have come and gone? The population problem would he solved one way or another long before then... maybe the way the Kilkenny cats solved theirs.
But there are only fifteen-hundred-odd stars within a hundred light-years of Earth and only about a hundred and sixty of these are of the same general spectral type as the Sun. Project Lebensraum hoped to check not more than half of these, say seventy-five at the outside—less since we had lost the Vasco da Gama.
If even one real Earth-type planet was turned up in the search, the project would pay off. But there was no certainty that it would. A Sol-type star might not have an Earth-type planet; a planet might be too close to the fire, or too far, or too small to hold an atmosphere, or too heavy for humanity's fallen arches, or just too short on the H20 that figures into everything we do.
Or it might be populated by some rough characters with notions about finders-keepers.
The Vasco da Gama had had the best chance to find the first Earth-type planet as the star she had been beading for, Alpha Centauri Able, is the only star in this part of the world which really is a twin of the Sun. (Able's companion, Alpha Centauri Baker, is a different sort, spectral type K.) We had the next best chance, even though Tan Ceti is less like the Sun than is Alpha Centauri-B, for the next closest G-type is about thirteen light years from Earth... which gave us a two-year edge over the Magellan and nearly four over the Nautilus.
Provided we found anything, that is. You can imagine how jubilant we were when Tau Ceti turned out to have pay dirt.
Harry was jubilant, too, but fur the wrong reasons. I had wandered into the observatory, hoping to get a sight of the sky—one of the Elsie's shortcomings was that it was almost impossible to see out—when he grabbed me and said, "Look at this, pal!"
I looked at it. It was a sheet of paper with figures on it; it could have been Mama O'Toole's crop-rotation schedule.
"What is it?"
"Can't you read? It's Bodes Law, that's what it is!"
I thought back. Let me see.., no, that was Ohm's Law—then I remembered; Bode's Law was a simple geometrical progression that described the distances of the Solar planets from the Sun. Nobody had ever been able to find a reason for it and it didn't work well in some cases, though I seemed to remember that Neptune, or maybe Pluto, had been discovered by calculations that made use of it. It looked like an accidental relationship.
"What of it?" I asked.
"'What of it?' the man says! Good grief! This is the most important thing since Newton got conked with the apple."
"Maybe so, Harry, but I m a little slow today. I thought Bode's Law was just an accident. Why couldn't it be an accident here, too?"
Accident! Look, Tom, if you roll a seven once, that's an accident. When you roll a seven eight hundred times in a row, somebody has loaded the dice."
"But this is only twice."
"It's not the same thing. Get me a big enough sheet of paper and I'll write down the number of zeros it takes to describe how unlikely this 'accident' is." He looked thoughtful. "Tommie, old friend, this is going to be the key that unlocks how planets are made. They'll bury us right alongside Galileo for this. Mmm... Tom, we can't afford to spend much time in this neighborhood; we've got to get out and take a look at the Beta Hydri system and make sure it checks the same way—just to convince the mossbacks back Earthside, for it will, it will! I gotta go tell the Captain we'll have to change the schedule." He stuffed the paper in a pocket and hurried away. I looked around but the anti- radiation shutters were over the observatory ports; I didn't get to see out.
Naturally the Captain did not change the schedule; we were out there looking for farm land, not trying to unscrew the inscrutable. A few weeks later we were in orbit around Constance. It put us into free-fall for the first time during the trip, for we had not even been so during acceleration- deceleration change-over but had done it in a skew path instead; chief engineers don't like to shut a torch down unless there is time for an overhaul before starting up again—there was the case of the Peter the Great who shut hers off, couldn't light up again; and fell into the Sun. '
I didn't like free-fall. But it's all right if you don't overload your stomach.
Harry did not seem disappointed. He had a whole new planet to play with, so he tabled Bode's Law and got busy. We stayed in orbit, a thousand miles up, while research found out everything possible about Connie without actually touching it: direct visual search, radiation survey, absorption-spectra of her atmosphere. She had two moons, one a nice size, though smaller than Luna, so they were able to measure her surface gravity exactly.
She certainly looked like a home away from home. Commander Frick had his boys and girls set up a relay tank in the mess room, with color and exaggerated stereo, so that we all could see. Connie looked like the pictures they show of Earth from space stations, green and blue and brown and half covered with clouds and wearing polar ice like skullcaps. Her air pressure was lower than ours but her oxygen ratio was higher; we could breathe it. Absorption spectra showed higher carbon dioxide but not as high as Earth had during the Coal Age.
She was smaller but had a little more land area than Earth; her oceans were smaller. Every dispatch back to Earth carried good news and I even managed to get Pat's mind off his profit-and-loss for a while... he had incorporated us as "Bartlett Brothers, Inc." and seemed to expect me to be interested in the bookkeeping simply because my accumulated LRF salary had gone into the capitalization. Shucks, I hadn't touched money for so long I had forgotten anybody used the stuff.
Naturally our first effort was to find out if anybody was already in occupation... intelligent animal life I mean, capable of using tools, building things, and organizing. If there was, we were under orders to scoot out of there without landing, find fuel somewhere else in that system, and let a later party attempt to set up friendly relations; the LRF did not want to repeat the horrible mistake that had been made with Mars.
But the electro-magnetic spectrum showed nothing at all, from gamma radiation right up to the longest radio wavelengths. If there were people down there, they didn't use radio and they didn't show city lights and they didn't have atomic power. Nor did they have aircraft, nor roads, nor traffic on the surface of their oceans, nor anything that looked like cities. So we moved down just outside the atmosphere in an "orange slice" pole-to-pole orbit that let us patrol the whole surface, a new sector each half turn.