In galactic space a sun is a mote, a planet well-nigh infinitesimal. How then to find a spacecraft felling through light-years?
“Ve haff our met’ods,” boasted Saxtorph. Begin by reasoning. The kzinti would not stay longer at the black hole than it took to learn everything they were able; and they were doubtless not extremely well chosen or well outfitted for scientific research. Having shot a beam at Alpha Centauri, describing what they had done and recommending a proper expedition, they’d start after it. Presently they’d receive word that the system was felling to an armada from Sol. Consider the dates of events, assume they’d been some months at work before they set forth, figure in acceleration time, and you conclude that they got the news about a third of the way along their course. What would they then plausibly do? Why, make for 61 Ursae Majoris, the star that Kzin itself orbits, the world that spawned their breed. Just as likely, they’d spend their engine reserve boosting to a full half c, and now be moving at approximately that speed. Calculate the trajectory.
Your answer will reflect the uncertainties in your guesstimates. What you get is not a curve but a cone. The ship is somewhere near the top, which leaves you with a volume still so enormous that random search is a fool’s errand.
However, space is not empty. The interstellar medium, mostly hydrogen with some helium and pinches of higher elements, has a mean density equivalent to about one proton per cubic centimeter. An object passing through it at 150,000 klicks per second hits a lot of stuff. The X-rays given off at these encounters would quickly fry the crew and their electronics, save that the screen fields keep the gas at a distance from the hull and guide it into a fairly smooth flow. Nevertheless, the perturbation is considerable. Atoms are excited and emit softer quanta. The tunnel of near-total vacuum left behind the vessel will take years to fill: which means it is correspondingly long. All this shows in the radio spectrum from that part of the sky. Sensitive instruments can detect it across quite a few parsecs.
The technique was not original with Saxtorph. The UN Navy had developed and employed it during the war. Since Rover was not specially equipped for it, he did have to devise modifications. In essence, he went via hyperspace from point to precalculated point. At each, his gang took readings. Dorcas had written a program that interpreted them. In due course, the seekers should get an identification. On that basis they could measure a parallax and obtain a fix.
Saxtorph and Tyra sat by themselves over beers in the saloon. Talk ransacked the past, for the future seemed like a wire drawn so taut that at any moment it would snap and the sharp ends recoil. “Oh, yes,” she said, “I have been on Silvereyes. It is fascinating. A hundred lifetimes were too little for to understand those ecologies.”
“You were writing about it?” he inquired.
“What else? One must pay for one’s travel somehow. Of course, I knew better than to try squeezing a whole world into a book. I looked me around, but that which I made my subject was the Cyclops island.”
“Really? I’ve got to read your book when we get back. You see, I was there myself once. A tourniquet vine damn near did for a shipmate, but we chopped her free in time, and otherwise it was, as you say, fascinating. I begrudged every minute I was on duty and couldn’t explore.”
“You have been everywhere, have you not?” she murmured.
“No, no, much though I’d like to. Besides, this wasn’t my idea. Navy, tail end of the war, establishing a just-incase base. Satellite, but initial supplies of air and water and such would come from the ground.”
Reminiscence went on. “ boats, to check out the surrounding shoals. A simple mooring is a timber tethered to a rock. What I could’ve told those clowns, because I’d been in Hawaii, was that they’d picked a chunk of volcanic pumice. But I wouldn’t‘ve known either that the log was stonewood. So they took the ensemble to the mooring place and heaved it overboard, and the rock floated while the log sank.”
He always liked the heartiness of Tyra’s laughter.
“Here I’ve gone again, blathering on about me,” he said. “You’re a good listener no, a great, a vintage listener but honest, I set out to hear about you. And I really can listen too.”
She sobered. “I know. Not many men can, or will. You act very everyday, Robert, but in truth you are a deep and complicated person.”
“Wrong, wrong. Never mind. I said we should talk about you. Uh, on Silvereyes, did you visit the Amanda Lakes region?”
“Of course.” Tyra sighed. “Beauty that high comes near to hurt, no? At least when there is no one to share it with.”
“You had nobody? You should have.”
Her smile was rueful. “Well, I roomed with another woman. Although she was pleasant, finally we agreed what a shame that one of us was of the wrong sex.”
“Yah, I daresay it’ll become a favorite honeymoon resort.” Saxtorph stared into his beer stein. “Tyra, none of my business, except we’re friends. But you rate better than going through life alone the way you’re doing.”
She reached across the table and laid her hand on his. “You are kind.” Her voice lowered. “On this journey I have discovered my father was not the only man who is a fine creature.”
“Aw, hey ”
They turned their heads. Tyra pulled her hand back. Dorcas had entered. Her slenderness reared over them. “We have a decision to make about the next jump point,” she said calmly. “It depends on what weight we give the last set of data. Will you come and consult, Bob?”
Saxtorph’s chair scraped. “ ‘Scuse me, Tyra.”
The Wunderlander smiled. “Why should I?” she replied. “What need? You go in my cause.”
He tossed off his drink and left with his wife. When they were several meters down the corridor, she told him, “I lied, you realize. Not to make a scene.”
“For Christ’s sake!” he exclaimed. “Nothing was going on.”
“I’d prefer to keep it that way.”
“You, jealous?” He forced a chuckle. “Honey, you flatter me.”
“Not exactly. I’ve watched where things are headed. No bad intentions on anybody’s part. I continue to like her myself. But, Bob, I’d hate to see you hurt. And I’ve no reason so far to wish it on her. As for this team of ours ” She clutched his forearm. Had the muscle been less thick underneath, her fingers would have left marks.