Next the impellers. They were simple enough—a motor, a battery, and a pair of counter-rotating propellers. You held on to a handle on the top and controlled your speed with a thumb switch. They were supposedly quiet, though in Rob’s experience they weren’t any more stealthy than the ones you could rent at any dive shop back on Earth. Some contractor in Japan had made a bundle on them. Rob found two with full batteries and hooked them on the edge of the pool for easy access.
Now for the hard part: suiting up without any help. Rob took off his frayed and slightly smelly insulated jumpsuit and stripped to the skin. First the diaper—he and Henri were going to be out for eight hours, and getting the inside of his suit wet would invite death from hypothermia. Then a set of thick fleece longjohns, like a child’s pajamas. The water outside was well below freezing; only the pressure and salinity kept it liquid. He’d need all the insulation he could get.
Then the drysuit, double-layered and also insulated. In the freezing air of the changing room he was getting red-faced and hot with all this protection on. The hood was next, a snug fleece balaclava with built-in earphones. Then the helmet, a plastic fishbowl more like a space helmet than most diving gear, which zipped onto the suit to make a watertight seal. The back of the helmet was packed with electronics—biomonitors, microphones, sonar unit, and an elaborate heads-up display which could project text and data on the inside of the faceplate. There was also a little self-sealing valve to let him eat with the helmet on, and a freshwater tube, which he sipped before going on to the next stage.
Panting with the exertion, Rob struggled into the heavy APOS backpack, carefully starting it up before attaching the hoses to his helmet, and took a few breaths to make sure it was really working. The APOS gear made the whole Ilmatar expedition possible. It made oxygen out of seawater by electrolysis, supplying it at ambient pressure. Little sensors and a pretty sophisticated computer adjusted the supply to the wearer’s demand.
The oxygen mixed with a closed-loop argon supply; at the colossal pressures of Ilmatar’s ocean bottom, the proper air mix was about 1,000 parts argon to 1 part oxygen. Hitode Station and the subs each had bigger versions, which was how humans could live under six kilometers of water and ice. The tons of argon needed to supply the expedition had been gathered locally, by a robot spaceplane skimming the atmosphere of Ilmatar’s giant primary world.
The APOS units made it possible to live and work on the bottom of Ilmatar’s ocean. The price, of course, was that it took six days to go up to the surface. The pressure difference between the 300 atmospheres at the bottom of the sea and the half standard at the surface station meant a human wouldn’t just get the bends if he went up quickly—he’d literally burst. There were other dangers, too. All the crew at Hitode took a regimen of drugs to ward off the scary side effects of high pressure. Every day spent at Hitode knocked about a week off Rob’s estimated life span.
With his APOS running (though for now its little computer was sensible enough to simply feed him air from the room outside), Rob pulled on his three layers of gloves, buckled on his fins, put on his weight belt, switched on his shoulder lamp, and then crouched on the edge of the moon pool to let himself tumble backward into the water. It felt pleasantly cool, rather than lethally cold, and he bled a little extra gas into his suit to keep him afloat until Henri could join him.
He gave the drones instructions to follow at a distance of four meters, and created a little window on his faceplate to let him watch through their eyes. He checked over the camera clamped to his shoulder to make sure it was working. Everything nominal. It was 1920 now. Where was Henri?
Kerlerec lumbered into view ten minutes later. In the bulky stealth suit he looked like a big black toad. The foam cover of his faceplate was hanging down over his chest, and Rob could see that he was red and sweating. Henri waddled to the edge of the pool and fell back into the water with an enormous splash. After a moment he bobbed up next to Rob.
“God, it is hot in this thing. You would not believe how hot it is. For once I am glad to be in the water. Do you have everything?”
“Yep. So how are you going to use the camera in that thing? Won’t it spoil the whole stealth effect?”
“I will not use the big camera. That is for you to take pictures of me at long range. I have a couple of little cameras inside my helmet. One points forward to see what I see, the other is for my face. Link up.”
They got the laser link established and Rob opened two new windows at the bottom of his faceplate. One showed him as Henri saw him—a pale, stubbly face inside a bubble helmet—and the other showed Henri in extreme close-up. The huge green-lit face beaded with sweat looked a bit like the Great and Powerful Oz after a three-day drunk.
“Now we will get away from the station and try out your sonar on my suit. You will not be able to detect me at all.”
Personally Rob doubted it. Some Russian had probably made a few million Swiss francs selling Henri and his sponsors at ScienceMonde a failed prototype or just a fake.
The two of them sank down until they were underneath Hab One, only a couple of meters above the seafloor. The light shining down from the moon pool made a pale cone in the silty water, with solid blackness beyond.
Henri led the way away from the station, swimming with his headlamp and his safety strobe on until they were a few hundred meters out. “This is good,” he said. “Start recording.”
Rob got the camera locked in on Henri’s image. “You’re on.”
Henri’s voice instantly became the calm, friendly but all-knowing voice of Henri Kerlerec, scientific media star. “I am here in the dark ocean of Ilmatar, preparing to test the high-tech stealth diving suit which will enable me to get close to the Ilmatarans without being detected. I am covering up the faceplate with the special stealth coating now. My cameraman will try to locate me by sonar. Because the Ilmatarans live in a completely dark environment, they are entirely blind to visible light, so I will leave my safety strobe and headlamp on.”
Rob opened up a window to display sonar images and began recording. First on passive—his computer could build up a vague image of the surroundings just from ambient noise and interference patterns. No sign of Henri, even though Rob could see his bobbing headlamp as he swam back and forth ten meters away.
Not bad, Rob had to admit. Those Russians know a few things about sonar baffling. He tried the active sonar and sent out a couple of pings. The sea bottom and the rocks flickered into clear relief, an eerie false-color landscape where green meant soft and yellow meant hard surfaces. The ocean itself was completely black on active. Henri was a green-black shadow against a black background. Even with the computer synthesizing both the active and passive signals, he was almost impossible to see.
“Wonderful!” said Henri when Rob sent him the images. “I told you: completely invisible! We will edit this part down, of course—just the sonar images with me explaining it in voiceover. Now come along. We have a long trip ahead of us.”
The Bitterwater Company are waking up. Longpincer’s servants scuttle along the halls of his house, listening carefully at the entrance to each guest chamber and informing the ones already awake that a meal is ready in the main hall.
Broadtail savors the elegance of having someone to come wake him when the food is ready. At his own house, all would starve if he waited for his apprentices to prepare the meals. He wonders briefly how they are getting along without him. The three of them are reasonably competent, and can certainly tend his pipes and crops without him. Broadtail does worry about how well they can handle an emergency—what if a pipe breaks or one of his nets is snagged? He imagines returning home to find chaos and ruin.