“I’ve thought about that,” Moon said. “There’s still a lot we don’t know about the Arctic Ocean and surrounding seas. For years — decades, really — phantom shoals have appeared on some charts, but not others. One Navy sonar picks up a submerged reef that looks as though it should rip the keel off the ship, while another steams by with nothing between them and the bottom but three hundred fathoms of cold water. Some say these are caused by rising biologics — schools of fish, plankton clouds, even giant squid. Others believe there is a magnetic anomaly and the charts are simply wrong. The point is, Mr. President, the Arctic is a mysterious place. That’s why I’m there, doing what I do. There’s a good chance we’re more familiar with the surface of the moon than we are with what’s down under the ice. Subs are gathering more and more data every day, but it’s a big place, with lots of secrets. What we do know is that the area around the Chukchi Borderland is toothy. There are all sorts of ridges and ledges jutting up from the seabed. A couple of them reach within a few fathoms of the surface. I suspect that whatever… whoever… made the sounds I recorded was located on the opposite side of one of those ridges. Sound waves travel long distances through water, but they are easily attenuated by solid rock, at least as far as my hydrophones are concerned.”
Ryan nodded slowly, picturing the scene.
“So,” he said. “For the sake of illustration, whatever is making voices is on one side of a ridge, say, a hundred meters below the peak, and you lowered your hydrophone on the opposite side. The sounds would be picked up as the hydrophone descended, and then blocked by the underwater mountain when the equipment went below the top, in the rock shadow, so to speak.”
“Exactly, sir,” Moon said.
Forestall put up his hand. “If I may, sir.”
“Go ahead, Robbie.”
“Given this scenario,” Forestall said, “knowing that the sounds came from the direction of the ridge in relation to the hydrophone, we may be able to triangulate on the signal strength as the instrument descended and the known depth. In theory, that could get us a general location from which the sounds emitted.”
“He’s right,” Dr. Moon said, turning Forestall’s tablet around so Ryan had a good view. The others leaned in. The screen depicted a cross-sectional view of the seabed with the research vessel
Foley leaned closer, adjusting her reading glasses. “The hydrophone is still above the ridgetop,” she said. “Not in the shadow yet.”
“Ah,” Dr. Moon said. “But it would be in the shadow if the sounds emanated from this point.” She tapped the screen again, bringing up the red triangle, five hundred feet down, resting on a ledge on the opposite side of the ridge as the hydrophone. “Any sounds coming from here would travel upward, spreading out just enough to allow me to pick them up for a few meters. But if the sounds are coming from here, close to the wall, the shadow starts much higher, before the instrument passes the ridgetop.”
Ryan looked around the room. “Anyone else have questions for Dr. Moon?”
No one did. The matters they had to discuss would take place out of her presence.
“Very well.” Ryan got to his feet. “Thank you for dropping everything for this trip.”
Moon worked her way around the room, shaking hands.
“I wonder,” Ryan said. “Would you mind staying around D.C. for a couple of days?”
“Of course,” she said. “But I’ve already told you everything I know. My field of study is relatively narrow. I’m not sure what help I could offer.”
“You’re smart,” Ryan said, “and you stick up for what you know when peers and superiors try to wave you off. It’s only a request, mind you. If you have something pressing, I understand, but I would appreciate it if you could stay. Commander Forestall will get you set up at the Willard and see that you get a few bucks in per diem.” Ryan walked with her to the door, struck with a sudden idea. “The First Lady is accompanying me to Fairbanks day after tomorrow, where I’m hosting some meetings with the polar nations. You could fly up on Air Force One as my guest, and then I’ll get someone from Wainwright or Eielson to get you back to your ship. If this is what I think it is, things are likely to develop fast, and I’d like to have you around.”
Moon’s brow inched up again. “And what do you think it is, Mr. President?”
Ryan opened the door for her. “The same thing you do. A Chinese submarine that has gotten itself into trouble.”
It seemed a simple assignment. Pick three names, one of which would be randomly selected for a suicide mission.
