by Rick Cook
The captain punched more buttons and Ludenemeyer blinked up in a corner of his screen. “Mr. Ludenemeyer, is that heading for us?”
The engineer shrugged. “We don’t know the mass of the object, but, yes, it is possible that an object launched on that trajectory might intercept us.
“Of course, I really can’t tell much with what I’ve got down here,” he added hopefully.
“All right Mr. Ludenemeyer. Come forward to the bridge. You might as well join the party too. But keep the drive hot!” he commanded as the engineering officer grinned and broke contact.
For the next several hours, there was nothing for the group to do but watch the unwavering green point of light and do makework extrapolations as new data arrived. Jenkins moodily sucked coffee bulbs until he knew his stomach was going to pay for it tomorrow and watched as the lines and projections grew on his screen.
Sharon drifted over to look over his shoulder. Normally that would have irritated Jenkins, but he found her presence comforting instead.
“Dr. Dolan,” he said as she made a move to drift back to Carlotti’s station, “could you explain to me why this system isn’t supposed to have life?”
“Because that’s an M2 star,” Sharon said, surprised.
“Yes, but why does that preclude life?” Jenkins looked apologetic. “Forgive me, but I am not very well versed on planetology.”
“Well, there are several things. M2s put out a lot less energy than our sun. Their surface temperature is around half that of the sun, you know, and that means the life zone—the area where water can exist as a liquid—is considerably closer to the star and much smaller than it is on a G-type like our sun.
“That introduces two problems. First, it’s much less likely that a planet’s orbit will fall within the life zone and in fact none of the planets in this system do, really.
“The second problem is that the drag from the star’s gravity will have slowed the rotations of the inner planets considerably. The outermost Mars-type has a rotation period several times that of Earth and the ones further in probably barely rotate at all. A very slow rotation usually makes conditions on a planet unsuitable for life.”
She paused. “At least that’s the pattern we’ve found so far.”
“And we’ve seen a lot of planets,” Jenkins added.
Oh yes, thought Sharon, we’ve seen lots of planets. But none you’d care to live on. None that could be like Earth again.
When the star drive had been developed, man had gone looking for real estate. The first expeditions had gone out to the nearest stars that might have Earthlike planets.
The results had been scientifically fascinating and uniformly disappointing. The expeditions had found planets, but none of them Earthlike. Every single star in this neck of the galaxy seemed to have its quota of Jovian gas giants, small desolate Mars-types and a few hot hellish Venerian worlds. But no Earthlike planets at all. No oxygen worlds, no seas of liquid water and no life.
“They’ve cut off their lasers,” DeRosa announced, scanning her console quickly.
“Yes, but there’s something else there now,” Carlotti said. “There’s a rocket exhaust of some kind.”
“What kind?” Jenkins demanded.
“Tell you in a minute.” He turned back to his instruments.
No one was terribly surprised. Although you could propel a ship all the way to its destination on lasers alone, it made more sense to use them just for the initial launch. Their projections of the object’s course had made allowances for a shift to a reaction engine at some point.
“We got a reading on their exhaust, Captain,” Carlotti said. “It’s hydrox.”
“What?”
“Hydrox,” the astronomer repeated. “You know, hydrogen-oxygen.”
Jenkins turned that over in his mind. An H2-02 rocket had considerably less specific impulse than the fusion torch the Maxwell used. A culture capable of building advanced laser launchers ought to be able to do better than that.
“If that’s the best they can do, then what the hell are they using to power those lasers?” DeLorenzo asked.
“That’s another very good question, Major,” Jenkins put in. “I hope we can get some answers before we have too many more of them.”
The mission had been hasty and ill-prepared. It was driven by a single imperative—reach the strangers quickly! Hence the laser launch.
But even in haste there are rules that must be obeyed and constraints to be considered. As the ship hurtled out, driven first by the bank of lasers and then by the thrust of its rockets, frantic negotiations continued in its wake. Decisions were reached, exceptions made and conventions set aside. At last the permission the ship’s captain had awaited since launch came blasting through on a tight beam of laser light.
“Captain, their rockets just went out.”
With a flip of his arms and a flick of his leg, Jenkins scooted over to look at the readout. “Where are they headed?”
Iron Alice punched in a few commands and scowled. “It doesn’t look like they’re headed anywhere,” she said. “Maybe it’s a rendezvous, but it doesn’t make a lot of sense.”
“Wait a minute,” the astronomer called out. “I think I’m still getting something.”
“Cooling engines?” Jenkins suggested.
“I don’t know. I don’t think . . . hold it.” He fiddled frantically with his display and patterns of lines danced across the screen.
“Ion drive,” he said, looking up. “They just switched to an ion drive using cesium as the reaction mass.”
“Al, what’s their acceleration?”
“Take time to be sure. Right now just under one hundredth of a G. It may go higher.” She called up another display on her screen. “Then again it may not. If they hold their acceleration about where they have it now they’ll be on an intercept course with us.” She scowled at the screen. “It will have to go a little higher since presumably they are going to do a turn-around and start breaking at mid-course, but yeah, in about six weeks were gonna have company.”
“Constant acceleration drive,” said Jenkins. “Laser launch to give them an initial boost and then drive straight on. They can reach any place in this system in a few weeks.”
“So why wait until they were so far out to light up?” the pilot asked. “They could be here a hell of a lot sooner if they had turned on their drive as soon as the lasers shut down instead of using hydrox to start.”
“Maybe it takes time to light and they were in a hurry.”
The pilot frowned. “Maybe, but they still would have been ahead if they waited until the drive was ready instead of using those boosters.”
“I don’t think you’d want to turn on that ion drive too close to the habitat,” Carlotti said. “Between the electric field and the cesium ions it could interfere with a lot of space-based activities.”
“That explains the laser launcher, but not the hydrox rockets,” DeRosa said. “Why load yourself down with a lot of tankage and propellant when you’ve got an ion drive? You just don’t gain that much velocity.”
Sharon Dolan came up beside Jenkins. “Captain, would you explain something to me now?”
“If I can.”
“If those aliens are as advanced as we think they are, and if they’re in such a hurry to meet us, why don’t they use a fusion-powered ship?”
“I can think of several possible reasons. For one thing, a fusion torch is big. You need a separate fusion pile to drive the torch, plus whatever power source you use for your ship—in our case a second fusion pile.”
Sharon frowned, prettily, Jenkins thought. “But it is still a constant acceleration drive.”
“No, it’s a high acceleration drive, not a constant acceleration one,” Jenkins told her. “It can drive us at a steady acceleration for some weeks if it had to, but that’s not what it’s designed for.
“Basically a torch is supposed to produce a lot of thrust over a fairly short period of time. It’s not near
ly as efficient as an ion engine, but it gives a hell of a push when we need it. And we need it. A starship has to be able to shed velocity fast when we break out from KOH drive. That takes very powerful engines.
“Besides that, a fusion torch is hideously expensive to run. It took an appreciable fraction of the deuterium and tritium mined over two years to enrich the hydrogen in the Maxwell’s tanks. You couldn’t do that for every ship in the system. We can barely afford to do it for the star ships we have operating.”
Sharon was silent for a moment watching the displays. Out of the corner of his eye Jenkins watched her.
“Do you think they can build a fusion torch?”
“Probably. A torch is just a modified fusion pile and they must have something like that on the ship to power the ion drive. An ion drive is much more efficient. It makes better use of its energy than nearly any other form of propulsion and it is ideally suited to constant acceleration missions.”
“Then why don’t we have one?”
“Two reasons. First, an ion drive by its nature has a relatively low maximum acceleration. We need a high maximum acceleration because we may not have much room to slow down when we break out. The second reason is we can’t build one capable of giving high enough acceleration to a ship to make it worthwhile.”
“So they’re more advanced,” Sharon said slowly, not liking the idea.
“Let’s just say they do some things more efficiently than we do.”
“If they’re so much more efficient, why don’t they use beamed power to power their ships?” Carlotti put in from where he had been listening. “That would give them efficiency and high acceleration.”
“Maybe they don’t know how,” Sharon suggested.
“They beam power from those power stations near the star out to the Colonies. For that matter, we use the same technique with our powersats.”
“I’ll tell you why not,” DeLorenzo said. “Because our alien friends are not fools. To power a ship you would have to concentrate the beam down to a few square meters. If it jiggles even just a little you have a sword of energy reaching out across your system. Any kind of accident or failure of control and poof!” He made a throw-away motion.
“Makes sense,” Ludenemeyer said. “Living in space habitats as they do, they would be terribly vulnerable to an accident like that.”
Sharon turned back to Jenkins. “What’s going to happen when they reach us?” she asked.
“That’s a very good question. I wish I knew the answer.”
“I wonder what the hell that ship looks like,” Ludenemeyer said thoughtfully. “An ion drive needs a long, long accelerator sticking out the back and a laser-launched ship wants some kind of big sail structure to catch the light. It must be an ugly sucker.”
“Their standards of beauty may be different from ours,” Aubrey said from his couch.
Ludenemeyer shrugged. “Hybrid propulsion systems like that are damned near impossible to make pretty by any standard.”
Aubrey smiled tolerantly. “Ethnocentrism?”
“Nope, engineering.”
“Can we get a visual image of them?” Jenkins called across the bridge.
Carlotti shook his head. “We don’t have anything designed for that kind of work. We could deploy one of the large arrays, I suppose, but that would take several days.”
“Damn,” Jenkins breathed. “A starship full of astronomical equipment and we don’t have anything that will track an object right in the planetary system.”
“That was hardly one of the parameters in our planning,” Carlotti told him.
Again the Ship’s Council met in the large forward conference room; this time Captain Jenkins and Ludenemeyer were present, along with Sharon Dolan and one or two other specialists. Although the meeting had been physically closed to keep down the crowds, screens all over the ship were tuned in. Clearly, this was the most critical meeting the Ship’s Council was ever likely to have and no one wanted to miss it.
Aubrey started off by bringing the Council, and through the screens, the rest of the ship’s complement, up to date.
“The upshot is,” he paused briefly and went on, “the aliens definitely know we are here. They have launched at least one ship out to meet us. We may assume we are under observation by instruments at least as good as our own.”
That produced a ripple throughout the room. Almost everyone at the table knew just how good modern astronomical instruments were. Even an object as small as the Maxwell could have little to hide at these distances.
“If we stay where we are the aliens will be in physical contact with us in less than six weeks. The question is,” he looked up and down the table, “what do we do?”
“Aren’t there some kind of rules about alien contact?” one of the Council members asked.
“Very sketchy,” Jenkins said. “Anyone who thinks they have seen any sign of intelligent non-humans is supposed to report immediately.”
“There was a lot of discussion about fifty or sixty years ago,” Sharon Dolan said from down the table. “There were proposals to establish a very elaborate system of rules to govern first contact, but eventually they all fell through. We realized we simply didn’t know enough about possible aliens to set firm guidelines.” And besides, we lost faith that there were any aliens, she thought.
“But the standing orders are to report immediately?” DeLorenzo asked sharply.
“Well, yes,” Jenkins said.
“That settles it then,” the major said firmly. “We run for Earth. Right now.”
“Captain, I believe you have considerable latitude in how you carry out your orders?” Aubrey put in. “Those orders were hardly drawn to cover a starship a hundred light-years out. They were drawn up to cover the situation in the solar system and they were not revised when we started sending out star-ships. Besides, what can we report? We don’t know anything.”
“We know there’s someone else out there,” DeLorenzo replied. “That’s enough.”
“I beg your pardon Major, but I don’t think it’s nearly enough,” Aubrey said. “After all, what can we tell Earth? Only that there are aliens here with a space-faring civilization. We know nothing else about them, not even what they look like. How much good would that information do Earth?”
“That’s enough.”
“Be reasonable, Major,” Aubrey went on. “It will take us months to get home and months to mount another expedition. Two or three years at least before an expedition can reach here again. What harm is there in waiting a while longer until we can report more accurately?”
“Plenty if we never make it home,” DeLorenzo told him.
“I see no reason to assume we won’t,” Aubrey said.
“Captain, what is our armament like?” DeLorenzo asked.
Jenkins blinked. “I beg your pardon?”
“Armament? How are we armed?”
“Well, we aren’t. I mean there are the pistols in the provost marshal’s locker. Six or eight of them, as I recall, but that’s it.”
“And Dr. Takiuji’s samurai sword,” DeLorenzo said with a tight grin. “But we’ve got nothing bigger. No missile launchers, no fighting lasers. And a ship that’s built to commercial standards.”
“There is always the fusion torch,” Ludenemeyer said. “Makes a pretty good weapon close in.”
“With no tracking and the slew rate of an arthritic snail,” DeLorenzo said. “No thank you.”
“This is a scientific expedition, not an attack,” Aubrey said stiffly.
“I’m not concerned about attack, Dr. Aubrey, I’m worried about defense.”
“Defense against what?”
“Them,” DeLorenzo gestured sunward.
“Major, we have been over this repeatedly. There is not one single shred of evidence they intend to attack us or anyone.”
“And there’s no evidence they don’t,” DeLorenzo said. “We need to get out of here now.”
“Formally, that is the captain’s decisio
n,” Aubrey said carefully. “After all, this could be construed as a matter of ship’s safety.”
Jenkins looked up and down the table. And there’s no doubt which way you want me to decide, he thought, looking at the expectant faces. He didn’t like it, his instincts told him he was wrong. But there was no hard evidence to back him up.
“All right, we make contact,” Jenkins said firmly. “But we don’t do it here.”
“Where then?”
“In the main settlement belt. I want to get close enough to learn something and I want them to know we can come and go instantaneously.” He turned to his engineering officer.
“Ludenemeyer, how close to the center of their belt of habitation can you get us?”
“Depends on where we are positioned and what our relative energy profiles are like. I’d say pretty close.”
“Fine. We’ll jump down into the gravity well and aim for a stable position within the habitation zone. We’ll plan to undershoot rather than overshoot and try to close to our desired position on the torch.”
“Moving that close to the star will play hell with our observations,” Carlotti said gloomily.
“Doctor, I don’t think astronomy is our main mission anymore,” Aubrey said.
“Oh and Ludenemeyer . . .”
“Yessir?”
“Once we jump, the drive stays hot. I want to be able to jump out of there at a moment’s notice.”
“Yessir, but we can’t update our position often enough.”
“I’m not concerned about that. I just want to be able to jump instantly. We’ll worry about where we are later.”
He looked up and down the table.
“If that’s all then . . .” Aubrey said, and picked up his computer.
“Not quite all,” DeLorenzo said as the others made to rise.
“Major?”
DeLorenzo turned to Jenkins. “Scuttling charges.”
“I beg your pardon?”
“I want permission to rig scuttling charges in case we are in danger of capture.”
“Absurd!” someone further down the table exploded.
“Captain, your decision carries with it enormous risks for our entire race. We need to be able to destroy the ship, or at least the most important parts of it to prevent their capture.”