Free The Mote in God's Eye by Larry Niven, Jerry Pournelle Page B

habitable world circling the Mote.”
    “Could it have used a battery of laser cannon?”
    “Sure, why not?” Renner wheeled over. “In fact, you could launch with a small battery, then add more cannon as the vehicle got farther and farther away. You get a terrific advantage that way. If one of the cannon breaks down you’ve got it right there in your system to repair it.”
    “Like leaving your motor home,” Potter cried, “and you still able to use it.”
    “Well, there are efficiency problems. Depending on how tight the beam can be held,” Renner answered. “Pity you couldn’t use it for braking, too. Have you any reason to believe—”
    Rod left them telling the Sailing Master about the variations in the Mote. For himself, he didn’t particularly care. His problem was, what would the intruder do now?
    It was twenty hours to rendezvous when Renner came to Blaine’s post and asked to use the Captain’s screens. The man apparently could not talk without a view screen connected to a computer. He would be mute with only his voice.
    “Captain, look,” he said, and threw a plot of the local stellar region on the screen. “The intruder came from here. Whoever launched it fired a laser cannon, or a set of laser cannon—probably a whole mess of them on asteroids, with mirrors to focus them—for about forty-five years, so the intruder would have a beam to travel on. The beam and the intruder both came straight in from the Mote.”
    “But there’d be records,” Blaine said. “Somebody would have seen that the Mote was putting out coherent light.”
    Renner shrugged. “How good are New Scotland’s records?”
    “Let’s just see.” It took only moments to learn that astronomical data from New Scotland were suspect, and no such records were carried in MacArthur ’s library because of that. “Oh, well. Let’s assume you’re right.”
    “But that’s the point: it’s not right, Captain,” Renner protested. “You see, it is possible to turn in interstellar space. What they should have done—”
    The new path left the Mote at a slight angle to the first. “Again they coast most of the way. At this point”—where the intruder would have been well past New Cal—”we charge the ship up to ten million volts. The background magnetic field of the Galaxy gives the ship a half turn, and it’s coming toward the New Caledonia system from behind . Meanwhile, whoever is operating the beam has turned it off for a hundred and fifty years. Now he turns it on again. The probe uses the beam for braking.
    “You sure that magnetic effect would work?”
    “It’s high school physics! And the interstellar magnetic fields have been well mapped, Captain.”
    “Well, then, why didn’t they use it?”
    “I don’t know ,” Renner cried in frustration. “Maybe they just didn’t think of it. Maybe they were afraid the lasers wouldn’t last. Maybe they didn’t trust whoever they left behind to run them. Captain, we just don’t know enough about them.”
    “ I know that, Renner. Why get in such a sweat about it? If our luck holds, we’ll just damn well ask them.”
    A slow, reluctant smile broke across Renner’s face. “But that’s cheating.”
    “Oh, go get some sleep.”
     
    Rod woke to the sound of the speakers: “GRAVITY SHIFT IN TEN MINUTES. STAND BY FOR CHANGE TO ONE STANDARD GRAVITY IN TEN MINUTES.”
    Blaine smiled — one gravity! — and felt the smile tighten. One hour to match velocities with the intruder. He activated his watch screens, to see a blaze of light fore and aft. MacArthur was sandwiched between two suns. Now Cal was as large as Sol seen from Venus, but brighter.
    Cal was a hotter star. The intruder was a smaller disc, but brighter still. The sail was concave.
    It was effort merely to use the intercom. “Sinclair.”
    “Engineering, aye aye, Captain.”
    Rod was pleased to see that Sinclair was in a hydraulic bed. “How’s the Field holding, Sandy?”
    “Verra well, Captain.