Gordon Lee took to his feet as well. There was a strange sparkle in his eyes as he began to get caught up in Nathan’s speculations. “Yes. All right, we send out probes and we use the most powerful, most capable telescopes we can. What next?”
“Next depends on the recon. Everything depends upon what we know or don’t know about the aliens. It’s impossible to say much now, without any observational data, but there are a few assumptions we can make about the enemy just because of the way it moves.”
“Go on.”
“They’re traveling here in a rocket—a magic rocket with an inexhaustible source of fuel, but a rocket nonetheless. That would seem to indicate that they don’t have any sort of warp drive or wormhole jumps or reactionless, inertialess, Roswell alien sort of spaceships. Right?”
Lee tipped back his beer and fetched another pair of bottles as he actually seemed to consider Nathan’s supposition. Nathan finished his own beer and took the fresh bottle the other man held out to him. Eventually, Lee nodded. “I think you may have over-extended your assumptions, but I’ll go along with it.”
“Okay. They have high technology but not supernatural, magical technology. They are bound by inertia the same as we are, so the simplest way to attack them would be to put something in their way. A kinetic missile strike would ruin their day, and given the velocities involved, it would be fairly simple to achieve. On the same mission that sends out the recon probe, you can seed the outer solar system with mines. When the big bad aliens show up, the mines rocket toward them and no more invasion.”
Lee sat down, looking vaguely disappointed. “Mr. Kelley, these aliens have come here from nearly twenty light-years away and have traveled at nearly half the speed of light. Given the amount of damage a single grain of sand could do at those velocities, not to mention the radiation involved, don’t you think the aliens would have come up with some method of clearing their path? I doubt simply throwing a rock in their way to trip them up would be the best defense for the planet.”
Nathan nodded slowly and grinned in a way that was more adversarial than friendly. He would either confirm or end his chances at this mysterious job, depending upon how he responded to Lee’s criticism. Agree or disagree with the boss, both choices were dangerous. “Sir, I said that was the simplest method of attack, not the best. And while they probably do have some sort of deflector shield or clearance beam or relativistic dust-buster, it’s a completely different proposition to deflect a coordinated strike with hardened, militarized weapons than it is to annihilate some micrometeors.”
Lee’s eyes had narrowed and his mouth was set in a grim line. “Very well.”
“The best ways to defeat any defensive system is with depth, diversity, mass, and maneuver. Depth is layers upon layers of weapons. Diversity is in types of weapons. You hit them with every type of attack that might even remotely be effective: lasers, nukes, bomb-pumped lasers, particle beams, kinetic strikes, logic bombs, and more. Hell, if you can put a rocket underneath the kitchen sink, you use that too.
“Mass is the density of attacks in each layer. Every defense has a threshold, a limit to what it can take. You give me enough of the right kind of weapons, I can storm the gates of heaven. And maneuver, well, we’ve already said they’re bound by inertia. If you make your weapons agile enough, set them up on just the right bearing, at just the right offset and velocity, throw in some countermeasures perhaps, then you can slip past almost any defense short of a force field. And defeating a force field just brings us back to mass. You want to defeat an alien invasion, that’s how you do it.”
“And what is the most important part of our defensive plan?” Lee’s voice was quiet, almost too quiet to hear, and absolutely too quiet to determine if his hush was in disappointment or admiration.
“Time and distance. The most important thing, sir, is to keep the aliens from reaching Earth. If they make it to the planet, it’s all over. All they have to do is turn the exhaust of their magic space drive toward us and the planet would be roasted like a marshmallow. Or, if they favor things up close and personal, put them in orbit at the top of our deep gravity well so the energy balance is on their side. They can just rain down strike after strike until not even the cockroaches are left.”
Lee just stared at him. Nathan took a long drink, nervously finishing most of the bottle. When he looked back down, Gordon Lee was walking away. Nathan grimaced and said under his breath, “Damn it.”
Lee came back with a tablet computer in his hand and gave it over to Nathan. It automatically scrolled through a series of astronomy slides. The first picture was of a particular night sky. An unfamiliar constellation drew itself around a set of stars, and a number of Greek symbols popped up next to the most prominent stars.
“Mr. Kelley, what you are looking at is the constellation Pavo, the Peacock. It’s only visible in the southern hemisphere. The fourth brightest star in Pavo is Delta Pavonis, and it’s a G-type star much like our own. In fact, of all the nearby stars capable of supporting life as we know it, Delta Pavonis has long been considered one of the best candidates for an alien intelligence, even though it is a bit old and in its declining years. All the other G-type yellow suns in our vicinity are binary pairs, and it is thought that the interactions of the sister stars would interrupt the regular orbits and seasons of a terrestrial planet, making life almost impossible. But Delta Pavonis is alone in the heavens, 19.9 light-years away, and free to develop life, much as we did.”
“Why are you telling me this, sir?”
Lee tapped the tablet’s screen and another series of slides popped up. It focused in on the fuzzy yellow circle/dot of Delta Pavonis. In the next slide, a blue pinprick dominated one side of the star. In successive slides the pinprick drifted across the face of the yellow dot and back again, getting ever brighter and wider, and drifting further and further over the dot in the background.
“In the 1930’s, radio was truly born. It went from a laboratory and military oddity to a worldwide tool, a tool which would help drive empires and wars, and a tool which cast out its beacon into the night sky. Much of it was of too low a power to penetrate the ionosphere in any sort of intelligible fashion, but it is apparent that something did. Whatever the reason, nineteen point nine years later, someone around Delta Pavonis noticed us, and they sent out a magic rocket without any sort of warning or courtesy call to the people they’re coming to visit. Forty three years later, they turned around and began to slow down, because they intend on staying a while, it seems. Ten years after that, in 2023, I saw it and began my preparations. And now, here we are, with uninvited guests en route, and no way to turn them back at the door.”