"Yeah… yeah. Enough bore holes and shafts have been sunk all over Farside to tell us pretty closely where the old surface was. I’ll show you something over here…" A major section of the far wall comprised nothing but rows of small metal drawers, each with its own neatly lettered label, extending from floor to ceiling. Steinfield walked across the room, and stooped to scan the labels, at the same time mumbling to himself semi-intelligibly. With a sudden "That’s it!" he pounced on one of the drawers, opened it, and returned bearing a closed glass container about the size of a small pickle jar. It contained a coarse piece of a light gray rocky substance that glittered faintly in places, mounted on a wire support.

"This is a fairly common KREEP basalt from Farside. It-"

"‘Creep’?"

"Rich in potassium-that is, K-rare earth elements, and phosphorus: KREEP."

"Oh-I see."

"Compounds like this," Steinfield continued, "make up a lot of the highlands. This one solidified around 4.1 billion years ago. Now, by analyzing the isotope products produced by cosmic-ray exposure, we can tell how long it’s been lying on the surface. Again, the figure for this one comes out at about 4,100 million years."

Hunt looked slightly puzzled. "But that’s normal. It’s what you’d expect, isn’t it?"

"If it had been lying on the surface, yes. But this came from the bottom of a shaft over seven hundred feet deep! In other words, it was on the surface for all that time-then suddenly it’s seven hundred feet down." Steinfleld gestured toward the wall chart again. "As I said, we find the same thing all over Farside. We can estimate how far down the old surface used to be. Below it we find old rocks and structures that go way back, just like on Nearside; above it everything’s a mess-the rock all got pounded up and lots of melting took place when the garbage came down, all the way up to what’s now the surface. It’s what you’d expect."

Hunt nodded his agreement. The energy released by that amount of mass being stopped dead in its tracks would have been phenomenal.

"And nobody knows where it came from?" he asked.

Steinfield repeated his head-shaking act. "Some people say that a big meteorite shower must have got in the way of the Moon. That may be true-it’s never been argued conclusively one way or the other. The composition of the garbage isn’t really like a lot of meteorites, though-it’s closer to the Moon itself. It’s as if they were made out of the same stuff-that’s why it looks the same from higher up. You have to look at the microstructure to see the things I’ve been talking about."

Hunt examined the specimen curiously for a while in silence. At length he laid it carefully on the top of one of the benches. Steinfield picked it up and returned it to its drawer.

"Okay," Hunt said as Steinfield rejoined him. "Now, what about the Farside surface?"

"Kronski and company."

"Yes-as we discussed yesterday."

"The Farside surface craters were made by the tail end of the garbage-dumping process, unlike the Nearside craters, which came from meteorite impacts oh… a few billion years back. In rock samples from around the rims of Farside craters we find that things like the activity levels of long half-life elements are very low-for instance, aluminum twenty-six and chlorine thirty-six; also the rates of absorption of hydrogen, helium, and inert gases from the Solar wind. Things like that tell us that those rocks haven’t been lying there very long; and since they got where they were by being thrown out of the craters, the craters haven’t been there very long, either." Steinfield made an exaggerated empty-handed gesture. "The rest you know. People like Kronski have done all the figuring and put them at around fifty thousand years old-yesterday!" He waited for a few seconds. "There must be a Lunarian connection somewhere. The number sounds like too much of a coincidence to me."

Hunt frowned for a while and studied the detail of the Farside hemisphere of the model. "And yet, you must have known about all this for years," he said, looking up. "Why the devil did you wait for us to call you?"

Steinfield showed his hands again and held the pose for a second or two. "Well, you UNSA people are pretty smart cookies. I figured you already knew about all this."

"We should have picked it up sooner, I admit," Hunt agreed. "But we’ve been rather busy."

"Guess so," Steinfield murmured. "Anyhow, there’s even more to it. I’ve told you all the consistent things. Now I’ll tell you some of the funny things…" He broke off as if just struck by a new thought. "I’ll tell you about the funny things in a second. How about a cup of coffee?"

"Great."

Steinfield lit a Bunsen burner, filled a large laboratory beaker from the nearest tap, and positioned it on a tripod over the flame. Then he squatted down to rummage in the cupboard beneath the bench and at last emerged triumphantly with two battered enamel mugs.

"First funny thing: The distribution of samples that we dig up on Farside that have a history of recent radioactive exposure doesn’t match the distribution or strength of the activity sources. There ought to be sources clustered in places where there aren’t."

"How about the meteorite storm including some, highly active meteorites?" Hunt suggested.

"No, won’t wash," Steinfield answered, looking along a shelf of glass jars and eventually selecting one that contained a reddish-brown powder and was labeled "Ferric Oxide." "If there were meteorites like that, bits of them should still be around. But the distribution of active elements in the garbage is pretty even-about normal for most rocks." He began spooning the powder into the mugs. Hunt inclined his head apprehensively in the direction of the jar.

"Coffee doesn’t seem to last long around here if you leave it lying around in coffee jars," Steinfield explained. He nodded toward a door that led into the room next-door and bore the sign "RESEARCH STUDENTS." Hunt nodded understandingly.

"Vaporized?" Hunt tried.

Again Steinfield shook his head.

"In that case they wouldn’t have been in proximity to the rock long enough to produce the effects observed." He opened another jar marked "Disodium Hydrogen Phosphate." "Sugar?"

"Second funny thing," Steinfield continued. "Heat balance. We know how much mass came down, and from the way it fell, we can figure its kinetic energy. We also know from statistical sampling how much energy needed to be dissipated to account for the melting and structural deformations; also, we know how much energy gets produced by underground radioactivity and where. Problem: The equations don’t balance; you’d need more energy to make what happened happen than there was available. So, where did the extra come from? The computer models of this are very complex and there could be errors in them, but that’s the way it looks right now."

Steinfield allowed Hunt to digest this while he picked up the beaker with a pair of tongs and proceeded to fill the mugs. Having safely completed this operation, he began filling his pipe, still silent.

"Any more?" Hunt asked at last, reaching for his own cigarette case.

Steinfield nodded affirmatively. "Nearside exceptions. Most of the Nearside craters fit with the classic model: old. However, there are some scattered around that don’t fit the pattern; cosmic-ray dating puts them at approximately the same age as those on Farside. The usual explanation is that some strays from the recent Farside bombardment overshot around to the Nearside…" He shrugged. "But there are peculiarities in some instances that don’t really support that."

"Like?"

"Like some of the glasses and breccia formations show heating patterns that aren’t consistent with recent impact… I’ll show you what I mean later."

Hunt turned this new information over in his mind as he lit a cigarette and sipped his drink. It tasted like coffee, anyway.