“Once humans get space travel,” said Ram Odin, “this ship is the first thing they’ll visit, long before they have the technology to build anything like it. Leaving the ship in space will change everything.”
“It may already have changed things,” said the expendable, “and every minute spent debating about it creates new folklore about this strange star in the sky.”
“At least we’re not geosynchronous over Bethlehem,” said Ram Odin.
“Palestine is too far north of the equator for that,” said the expendable. “And the ship now has a tentative date, based on settlement patterns and existing technology. No railroads, no significant canals. But Constantinople’s new buildings are Turkish and there are European settlements in the Americas. For all we know, Galileo is studying us on each orbital pass. We don’t want Copernicus to try to work us into his heliocentric model.”
“Take us farther back,” said Ram Odin.
“I still can’t find anybody’s path from this far out,” said Noxon.
“Just fling us back again,” said Ram Odin. “Only farther. A lot farther.”
Noxon gripped a handhold on the wall, and reached out to Ram Odin.
“Do we have to do that every time?” asked Ram Odin.
“I don’t know,” said Noxon. “What if we don’t do it, and it turns out we should have?”
Ram Odin took Noxon’s hand. “Are the mice all still attached to you?”
“Their little footprints are all over my body,” said Noxon. Then he sliced rapidly into the past.
Again, there was nothing to see—inside the starship, there were no observation windows. After a little while, though, the ship’s computers put up a display of the huge swath of Earth that was visible from their orbit about three hundred kilometers above the surface.
“It’s very white,” said Noxon. “Is it an unusually cloudy day?”
“We’re over the northern hemisphere,” said the expendable, “and we appear to be in a glacial maximum.”
“An ice age,” said Ram Odin. “Any idea which one?”
“There would be humans all over the place,” said the expendable. “Sapiens and Neanderthal, during the most recent one, but it was nearly a hundred thousand years long and so it’ll take a few passes to get a clear fix. And if it’s an earlier glacial maximum we’ll still have Homo erectus, and they got control of fire about half a million years ago.”
“The last ice age ended more than ten thousand years ago,” said Ram Odin to Noxon. “So you definitely took us a long way back.”
“I was aiming for at least eleven thousand years,” said Noxon. “Like when I followed a barbfeather’s path before you crashed nineteen starships into Garden.”
“Not me,” said Ram Odin. “It was a copy of me did all that.”
“What matters is that astronomical observations from this era aren’t going to be remembered and written down,” said the expendable. “But we still have to deal with the problem of concealment.”
Because the Moon was so large and strange to Noxon, and because it showed only one face to Earth, his first thought was to put the starship on the back side of it. But Ram Odin laughed out loud. “Humans had satellites going behind the Moon taking pictures long before this ship was built. And then there’s the little matter of half the moon getting sucked away.”
“So we can’t leave it anywhere in space,” said Noxon. “But it’s not as if we can lay it down on Earth, either. By the time this ship gets built, the surface of Earth will have been fully explored, won’t it?”
“Satellite photography even finds buried civilizations after thousands of years, by the traces of their irrigation ditches and house foundations,” said the expendable.
“So we can’t even bury the ship,” said Noxon.
“And the hull can’t withstand underwater pressures,” said Ram Odin. “So we can’t drop it into the ocean without risk of debris washing up on shore and getting discovered.”
“Even with the fields that protected it from impact with the surface of Garden?” asked Noxon.
“The energy cost of maintaining that strong a field can only be paid once, using the heat gathered during reentry. In the ocean, it would have to last thousands of years under relentless pressure. And it still might be found.”
“It might be found because of the fields,” said the expendable. “Don’t forget that it’s technology from Earth that creates those fields. There is no chance that such a field anywhere on or under the planet’s surface will go undetected once we get close to the time when the ship was built.”
Again, the mice were full of suggestions. Noxon sorted them out and relayed the most cogent one. “The mice keep saying to put it under the ice.”
“We can go back in time before the top hundred meters of Antarctic ice formed,” agreed the expendable. “But either the ice will crush the ship, or the fields that prevent the ice from doing so will give away our location years before this starship was built.”
Noxon and Ram Odin looked at each other in glum silence.
Inside Noxon’s clothing, the mice gathered and murmured to each other and then settled into a chant: “Stupid stupid stupid.”
“The mice are saying that we’re stupid,” said Noxon. To the mice he said, “Do you include yourselves in that? Or do you have some obvious solution that we’ve overlooked?”
The explanation, when Noxon understood it, was charmingly simple. “Oh, of course,” he said, and then relayed it to Ram Odin. “The mice suggest that the ship doesn’t have to survive intact. Park it a hundred thousand years back, at the beginning of the last glacial period, and then let the ice crush it and grind it. We aren’t going to use it at the end of that period, we just need it not to be found, and not to give off detectable signals or heat or fields of any kind.”
Ram Odin nodded. “We’re going to go back in time and pick it up right after we left it there. When it’s still virtually brand-new. So what happens to the ship a week after we park it there is irrelevant.”
“Not completely,” said Noxon. “For instance, if we left the mice on the ship and they took it over, they could lift it off the surface long before the ice formed any kind of impediment. Then they could destroy the human race before it became numerous, and have the planet to themselves.”
The howls of protest from the mice were loud enough that Ram Odin could hear them, though he couldn’t distinguish any of their words.
“They’re saying,” said Noxon, “that they would never do that and it didn’t even cross their minds and shame on you for thinking them capable of such treachery.”
“You believe them?” said Ram Odin.
“I’m quite sure that’s exactly what they were planning,” said Noxon. “Their only goal all along has been to get to Earth and prevent the destruction of Garden. Keeping the human race from evolving in the first place would do the job.”
Again, the howls from the mice. But they were both angrier and briefer in their protests. Which Noxon took as a sign that his guess was dead on.
“Still, their point is valid,” said Noxon. “We don’t have to leave a living ship to be picked up in the high-technology future. We’re going to come back to the beginning of the ice age to pick it up. So whatever happens between the time we leave the ship and the far future, when we find out why the Visitors attack Garden, doesn’t matter.”
“You’re suggesting that we kill everybody aboard?” said Ram Odin.
“Without stasis fields, all the colonists will rot away within a few decades, no matter how strong the seal on their sleep chambers is,” said the expendable.
“So the kindest thing,” said Ram Odin to the expendable, “would be to park the ship where we know the ice will form, kill everybody aboard, leave you awake long enough to make sure it’s fully covered with ice, and then you shut everything down permanently.”