The Spheres of Heaven

rear. All of them presented problems. The forward one faced vertically upward, while the other two might have been damaged on impact with the seabed. He would have to make an inspection, but before that he wanted to know if they could be used as sea-locks, even in principle.

He called up detailed schematics. It must be nice to be rich. Friday Indigo had bought a ship equipped with the best of everything, hardware and software. On the other hand, most of the test equipment had never been taken from its protective covers, and he could see from their access history that he was the first person to use these data routines.

Bony studied the airlock geometry and mechanics and gradually lost himself in his task. The first part would be easy. You put on an ordinary space-suit and moved into an airlock. You closed the inner hatch, exactly as usual. Then you opened the outer hatch. Instead of air gushing out into vacuum, water came in. Depending on the airlock position and your own density, you either floated into the sea or you walked out onto the seabed.

And then did what? Bony examined the characteristics of the suits. The air supply and air circulation were self-contained and would operate exactly as in space. The main question was thermal balance. The suit had to lose the heat generated internally by its occupant. That ought to be easier in water than in space, because you could lose heat by conduction and convection as well as by radiation.

Easier in water. In spite of anything that Friday Indigo might say, it was not ordinary water. So what was it? Bony became aware of an idea that had been wandering around the fringes of his consciousness. He called for access to a completely different data base, and for on-line assistance. The next ten minutes flashed by as he and the ship’s computer looked up basic physical constants and did calculations.

At the end of that time Bony smacked his hand on the desktop. Yes! He still had to perform a couple of tests, but the ship carried a small mass spectrograph for use in calibrating the fusion drive, and that should be all he needed.

He had been right; and so, oddly enough, had Friday Indigo. Bony decided he didn’t want to think about Friday. He helped himself to another candy bar and forced himself back to his main task.

So you were in your suit, wandering around in the sea outside the ship. You were making engineering modifications designed to allow you to use the auxiliary thrustors underwater — another design task to be solved — but you couldn’t stay outside too long. You had to come back in through the airlock to replenish your suit supplies. Normally, that was straightforward. You simply entered the lock, closed the outer hatch, and flooded the lock with air to replace the hard vacuum of space.

But it would not be a vacuum in the lock. It would be at least partly water, the water that entered when you opened the hatch to go outside. Therefore, you could not close the outer hatch when you flooded the lock with air. You had to leave the hatch open . The hatch could not be at the top of the lock, either, otherwise the air would just bubble up toward the surface and be lost. The hatch must be at the bottom of the lock, so new-pumped air would force water out. When all the water had gone, you could at last remove your suit, open the inner hatch, and enter the ship.

Bony turned to the lock configurations. Given the present orientation of the Mood Indigo … forward lock, outer hatch faced upward, no good … aft lock Number One, outer hatch facing upward, no good. Aft lock Number Two, outer hatch facing downward — and it was slightly higher, which ought to mean it was clear of the seabed.

Bony leaned back in triumph and was shocked to see Liddy Morse standing in front of him. He had been so engrossed in his work that he hadn’t heard her come in.

If she was here, it meant that she and Indigo … “Liddy. Are you all right?”

“Of course I’m all right. Why wouldn’t I be?”

“You and Indigo. I thought — did he — did the two of you—”

“He’s asleep. Stop worrying. He’s not my favorite person, but I owe him something. He did buy out my contract, you know. You’re not from Earth, so you can’t imagine what life is like in the Gallimaufries. Believe me, I’ve had to put up with a lot worse than Friday Indigo.” She was studying him. “You don’t like to hear about him, do you?”

“Not especially.”

“Then let’s not talk about him. Tell me what you were doing before you knew I was here. You looked so happy and pleased with yourself.”

“I was working. Deciding how to get outside and come back inside. Liddy, I’ve figured out what’s outside! What the liquid is.”

“Who was right, you or Indigo?”

“Both of us.”

“You can’t both be right.”

“We are. That’s what’s so strange. Do you know what hydrogen is?”

“Of course I do.”

“But did you know that it can come in two forms? One of them is an atom where the nucleus is a proton, and there’s one electron in orbit around it. That’s the common form. But you can also have a form called deuterium , which has a nucleus, a deuteron , with one proton and one neutron. You still have one electron, so the chemical properties of deuterium are the same as hydrogen.”

“So?”

“So you can make a molecule, a water molecule, with two atoms of hydrogen and one atom of oxygen. Or you can, just as well, make a kind of water molecule with two atoms of deuterium and one atom of oxygen. It’s been known for centuries, it’s called deuterium oxide, or heavy water — and it’s about eleven percent more dense than ordinary water. It can be used just like ordinary water. You can bathe in it, you can cook with it. I’m pretty sure you can drink it, at least some, and not notice a difference. That’s what we have outside the ship. We are sitting at the bottom of an ocean, but it’s a heavy-water ocean.”

“Are you sure of this?”

“Sure as I can be until I do the final tests of molecular weight. But assuming I’m right, it’s good news. We can wander around outside in our suits and be quite safe. If we run low on water, we can even drink some. I suspect there are differences in diffusivity rates from ordinary water, and that could have long-term fatal effects, but …”

She was laughing at him. Bony stopped talking. “I’m sorry. I get carried away. I’m boring you, aren’t I?”

“Of course you’re not. I get such a kick out of watching you when an idea catches fire. You light up like a little kid.”

“Sure. Thanks.”

“Oh, stop that.” Liddy pulled out the little chair on the other side of the desk and squeezed onto it. “Can’t you recognize a compliment when you hear one? Now what are you doing?”

What Bony was doing, not very successfully, was crumpling up candy wrappers and trying to count them at the same time. He was amazed at their number. “I tend to eat when I’m working.”

“Then you must have been absolutely slaving. And I interrupted you. I’ll go away.”

“No. You can help me. If you don’t mind.”

“I can’t do that stuff to save my life.” Liddy’s wave took in the display of schematics, the computer dialog, and Bony’s random notes on pressures and volumes.

“I don’t mean calculations. I need practical help. Now we know what’s out there, I’m ready to consider an EVA — a trip outside the ship. To do that, we have to make one of the airlocks work, underwater. I think I know how, but it’s a two-person job. Are you free?”

“I think so.” Liddy caught Bony’s unconscious glance upward. “Don’t worry, he’ll snore for at least another hour. He always does afterwards.”

“I don’t believe it.”

“Indigo sleeps a lot.”

“I mean, I don’t understand how he’s able to sleep now . We’re lost on the seabed of an unknown planet when we ought to be in open space. We’re in a ship never designed for anything but space operations. We have no idea how we came here, or if we’ll ever be able to get away. And he’s asleep. How can anybody sleep at a time like this?”