Seveneves. Neal Stephenson

the walls, and suddenly Arklet 3 rotated into view, a few hundred meters away. It too was flying under MAP, coming about until its front door was aimed their way. Dinah stifled the impulse to wave at Markus and Fuhua. It was unprofessional, and anyway they wouldn’t be able to see her through the tiny porthole.

      A spindly white arm swung outward from the side of Arklet 3 and locked into position, extended off to one side. A few moments later they heard and felt their own arm actuating likewise, and watched an animation of it on a flat screen.

      “Bringing up the Paw camera,” Dinah muttered, and tapped a control that flooded a screen with high-resolution video from a telephoto lens mounted at the end of the arm. This showed nothing, at first, but the blue limb of the Earth’s atmosphere down in one corner. Then a targetlike pattern veered across the screen, slowed, and veered back. All of this was accompanied by more fidgety percussion from the thrusters. The feed was remarkably close, and clear. Comparing it to the direct view out the porthole, Dinah could see the target on the end of Arklet 3’s extended arm, looking tiny from this distance. But the machine vision system now in control of their little spacecraft had found it, and recognized it, and …

      “We have a lock,” Ivy said. “We see you, Three.”

      “We see you, Two,” Markus answered. “It proceeds.”

      It proceeded with a longer firing of the aft thrusters that nudged them forward enough that Dinah could feel the pressure on her bottom, sense the straps of the harness tightening. The target flailed around some, but a few moments later, the lock was reestablished. Dinah could see Arklet 3 growing larger. Numbers on a screen, gauging the distance between the ships—or, to be precise, between the two ships’ outstretched Paws—were counting down.

      “It is all nominal,” Ivy said, but the last word was drowned out by a digital voice making an announcement over the arklet’s rudimentary PA system: “Bolo Coupling Operation entering its terminal phase. Prepare for acceleration.” And then in classic NASA style it counted down: “Five, four, three, two, one, grapple initiated.”

      At “one” the test pattern on the screen disappeared in shadow, for it was too close now for the camera to even see it. The Paws of Arklet 2 and Arklet 3 slapped together, like runners exchanging a high five as they passed each other going opposite ways. Strange whiny noises propagated down the arm into the hard shell of the arklet.

      “Grappling achieved,” said the voice.

      Dinah’s ears finally identified the whiny noise as the sound of cable unwinding from a spool. She felt a lurch in her stomach as the arklet did a half somersault, reversing its direction so that it was pointed back at its bolo partner.

      As she knew, having studied this maneuver for weeks, the two arklets were now joined together by a cable. They had flown right past each other, but the tension in that cable had spun them around so that they were pointing toward each other again—she verified this with a glance out the window, which gave her a view of the nose of Arklet 3 slowly receding as it “backed away” from them. The spool of cable mounted next to its docking port was in motion, unwinding as the two craft gained distance from each other. In the exact center, the cables of Arklets 2 and 3 were clasped together by a coupling device that could be remotely disengaged whenever they made the decision to go their separate ways.