“This is the place, all right,” he acknowledged. “That little plate near the edge is the control panel. We'll use the manhole; no need to open the main hatch as we do when it's a matter of cargo.”
He bent over — slowly enough to keep his feet on the metal — and punched one of the buttons on the panel he had pointed out. A tiny light promptly flashed green, and he punched a second button.
A yard-square trap opened inward, revealing the top of a ladder. Silbert seized the highest rung and pulled himself through the opening head first — when a man weighs less than an ounce in full space panoply it makes little real difference when he elects to traverse a ladder head downward. Bresnahan followed and found himself in a cylindrical chamber which took up most of the inside of the lock structure. It could now be seen that this must extend some forty feet into the body of Raindrop.
At the inner end of the compartment, where curved and flat walls met, a smaller chamber was partitioned off. Silbert dove in this direction.
“This is a personnel lock,” he remarked. “We'll use it; it saves flooding the whole chamber.”
“We can use ordinary spacesuits?”
“Might as well. If we were going to stay long enough for real work, we'd change — there is local equipment in those cabinets along the wall. Spacesuits are safe enough, but pretty clumsy when it comes to fine manipulation.”
“For me, they're clumsy for anything at all.”
“Well, we can change if you want; but I understood that this was to be a fairly quick visit, and that you were to get a report back pronto. Or did I misread the tone your friend Weisanen was using?”
“I guess you didn't, at that. We'll go as we are. It still sounds queer to go swimming in a spacesuit.”
“No queerer than walking on water. Come on, the little lock will hold both of us.”
The spaceman opened the door manually — there seemed to be no power controls involved — and the two entered a room some five feet square and seven high. Operation of the lock seemed simple; Silbert closed the door they had just used and turned a latch to secure it, then opened another manual valve on the other side of the chamber. A jet of water squirted in and filled the space in half a minute. Then he simply opened a door in the same wall with the valve, and the spacesuited figures swam out.
This was not as bad as walking on what had seemed like nothingness. Bresnahan was a good swimmer and experienced free diver, and was used to being suspended in a medium where one couldn't see very far.
The water was clear, though not as clear as that sometimes found in Earth's tropical seas. There was no easy way to tell just how far vision could reach, since nothing familiar and of known size was in view except for the lock they had just quitted. There were no fishes — Raindrop's owners were still debating the advisability of establishing them there — and none of the plant life was familiar, at least to Bresnahan. He knew that the big sphere of water had been seeded by “artificial” life forms — algae and bacteria whose genetic patterns had been altered to let them live in a “sea” so different from Earth's.
2
Raindrop was composed of the nuclei of several small comets, or rather what was left of those nuclei after some of their mass had been used in reaction motors to put them into orbit about the Earth. They had been encased in a polymer film sprayed on to form a pressure seal, and then melted by solar energy, concentrated by giant foil mirrors.
Traces of the original wrapping were still around, but its function had been replaced by one of the first tailored life forms to be established after the mass was liquid. This was a modification of one of the gelatin-capsule algae, which now encased all of Raindrop in a microscopically thin film able to heal itself after small meteoroid punctures, and strong enough to maintain about a quarter of an atmosphere's pressure on the contents. The biological engineer who had done that tailoring job still regarded it as his professional masterpiece.
The methane present in the original comet material had been oxidized by other bacteria to water and carbon dioxide, the oxygen of course coming from normal photosynthesis. A good deal of the ammonia was still present, and furnished the principal reason why genetic tailoring was still necessary on life forms being transplanted to the weightless aquarium.
The men were drifting very slowly away from the lock, though they had stopped swimming, and the younger one asked, “How do we find our way back here if we get out of sight?”
“The best trick is not to get out of sight. Unless you want to examine the core, which I've never done, you'll see everything there is to see right here. There is sonic and magnetic gear — homing equipment — in your suit if you need it, though I haven't checked you out on its use. You'd better stay with me. I can probably show you what's needed. Just what points do you think Weisanen wants covered?”
“Well, he knows the general physical setup — temperature, rotation, general current pattern, the nature of the skin. He knows what's been planted here at various times; but it's hard to keep up to date on what's evolved since. These tailored life forms aren't very stable toward mutation influences, and a new-stocked aquarium isn't a very stable ecological environment. He'll want to know what's here now in the way of usable plants, I suppose. You know the Agency sold Raindrop to a private concern after the last election. The new owners seem willing to grant the importance of basic research, but they would sort of like a profit to report to the stockholders as well.”
“Amen. I'm a stockholder.”
“Oh? Well, it does cost something to keep supply ships coming up here, and…"
“True enough. Then this Weisanen character represents the new owners? I wonder if I should think of him as my boss or my employee.”
“I think he is one of them.”
“Hmph. No wonder.”
“No wonder what?”
“He and his wife are the first people I ever knew to treat a space flight like a run in a private yacht. I suppose that someone who could buy Raindrop wouldn't be bothered by a little expense like a private Phoenix rocket.”
“I suppose not. Of course, it isn't as bad as it was in the days of chemical motors, when it took a big commercial concern or a fair-sized government to launch a manned spaceship.”
“Maybe not; but with fourteen billion people living on Earth, it's a little unusual to find a really rich individual, in the old Ford-Carnegie tradition. Most big concerns are owned by several million people like me.”
“Well, I guess Weisanen owns a bigger piece of Raindrop than you do. Anyway, he's my boss, whether he's yours or not, and he wants a report from me, and I can't see much to report on. What life is there in this place besides the stuff forming the surface skin?”
“Oh, lots. You just aren't looking carefully enough. A lot of it is microscopic, of course; there are fairly ordinary varieties of pond-scum drifting all around us. They're the main reason we can see only a couple of hundred yards, and they carry on most of the photosynthesis. There are lots of non-photosynthetic organisms — bacteria — producing carbon dioxide just as in any balanced ecology on Earth, though this place is a long way from being balanced. Sometimes the algae get so thick you can't see twenty feet, sometimes the bacteria get the upper hand. The balance keeps hunting around even when no new forms are appearing or being introduced. We probably brought a few new bacteria in with us on our suits just now; whether any of them can survive with the ammonia content of Raindrop this high I don't know, but if so the ecology will get another nudge.