“Obviously.” She smiled again, a bit too broadly, and sneaked a look at her watch. “But think about that supply side. We’d like to increase the planted acreage, of course. But how? We’re using every spare inch, unless we can move the lunar agricultural experiments to massive production — and nobody feels optimistic about that. Plant yields are as high as they will go — we’re seeing bad effects of plant overbreeding already. No hope there. So what’s left?”

Before we could chance an answer or she could provide one, the door behind us opened. A skinny man with plastered-down grey hair entered and stood deferentially at the threshold.

“Come in, Bayes.” Anna Lisa Griss looked again at her watch. “You’re late.”

“Sorry.” He remained at the door, hesitating.

“I began without you. Come in and sit down.” She turned to face us without offering introductions. “There was one area still to be examined: alternative supplies of organic materials that might easily be converted to food. Six years ago, everyone thought that was a hopeless avenue. Now, with the Griss-Lanhoff Theory” — I could hear the capital letters in her voice as she proclaimed the name — “we have new hope.”

I was watching Bayes’ face as she spoke. His lips tightened when Anna Lisa Griss pronounced the name of the theory, but he remained silent.

McAndrew cleared his throat.

“I’m afraid that I’m not as well up on the literature of food production as I ought to be,” he said. “Lanhoff’s a familiar name. If it’s the same person, I knew him fairly well ten years ago, when he was working on porphyrin syntheses. What’s he doing now?”

“We don’t know. Maybe you can help us to find out.” She leaned forward and looked at us intently. “Lanhoff has disappeared — out in the Halo, testing our theory. Two weeks ago I learned that you have available a high-acceleration ship with an inertia-less drive.” (I saw McAndrew wince and mutter “not inertia-less” to himself.) “We need the use of that, for a mission of the highest priority. We have to find out what happened to Lanhoff’s project. Three days from now we must be on our way to the Halo.”

It said something for the lack of efficiency of the Food Department that they would drag McAndrew and me all the way to Earth for a meeting, then shuttle us back to the Penrose Institute and the Hoatzin on a Government-owned ship less than four hours after we arrived. Anna Lisa Griss would follow to the Institute in another and even fancier vessel, but Bayes went with us to continue the briefing on the way. Without his boss around he lost his intimidated look and became a much cheerier person.

“Let’s start with Lanhoff’s ideas,” he said. “Though after listening to Anna back in her office it’s apparently going to be called the Griss-Lanhoff Theory, at least while Lanhoff’s not on the scene. I’ll keep it short, but I’m not sure where to begin. In the Halo, I guess. Professor McAndrew, do you know anything about the Halo?” He cackled with laughter at his joke.

Griss had asked McAndrew that same question when she was giving us our first briefing. I had watched Bayes’ eyes bulge with astonishment. I felt the same way myself. McAndrew probably knew more about the Halo and the outer parts of the extended Solar System than anyone, living or dead — he had developed the entire theory that predicted the existence of the kernel ring, the broad belt of Kerr-Newman black holes that girdles the ecliptic at four hundred AU, ten times the distance of Pluto. And of course he had travelled out there himself, in the first test of the McAndrew balanced drive. I assumed that any scientist worth the name would know all about McAndrew and his work, but apparently Anna Lisa Griss proved me wrong.

McAndrew laughed. He and Will Bayes had needed only ten minutes alone together to discover a mutual fascination with bad jokes, and they were getting along famously. I thought ahead to a long trip with the two of them and shuddered at the prospect.

“Lanhoff wandered into our offices six or seven years back,” went on Bayes after he had had a good giggle at his own wit. “He’d been analyzing the results of Halo remote chemistry probes. Didn’t you do some of that yourself, a few years ago?”

McAndrew rubbed at his sandy, receding hairline. “Och, just a little bit. I wanted to find power kernels, not low-density fragments, but as part of the survey we sneaked in a look at some other stuff as well. Most of the Oort cloud’s so poorly surveyed, you know, it’s a crime not to explore it whenever you have the chance. But I never looked out more than a few hundred AU — it was before we had the drive, and probes were too expensive. I’m sure Lanhoff had all my results to work with when he started.”

“He certainly knew your work,” said Bayes. “And he remembered you well. You made quite an impression on him. He’s an organic chemist, and he had been looking at all the data on the Halo, and plotting body chemical composition as a function of distance from the Sun. He has a special algorithm that allows him to look at the fractional composition of each object — I think it came from Minga’s team. You probably don’t remember Minga, he never published much himself. I met him once or twice, way back… no, maybe I’m thinking of Rooney. You know, he was the one who did the high-energy work, I think it was for the Emerald Project, wasn’t it? Yes, I think so…”

It’s probably a kindness if I edit Will Bayes’ briefing of McAndrew and me. He tried hard enough, but everything he said reminded him of something else, and that something else had to be explained, too, and all the people involved in it reminded him or other people, and what they had done. Regression, ad infinitum.

We didn’t mind too much, with a two-day journey before we were back at the Institute, but I must say I thought a bit more kindly of Anna Griss before the trip was over. Staff meetings with Bayes must be hell.

Boiling Will’s verbiage down to a minimum, it was a simple story: Lanhoff had done a systematic chemical analysis of the cometary Halo, from its beginnings beyond the Edgeworth-Kuiper Belt, all the way to the fading outer edge nearly half a light-year away, where the Sun’s gravitational hold is so weak that the frozen bodies drift around in orbits with periods of millions of years.

That’s the Oort cloud, a great ball of loosely-held matter centered on the Sun. There are several hundred billion comets out there, ranging from near-planet-sized monsters a few hundred kilometers across to snowballs no bigger than your fist. Chapman’s Rule applies as well to the cometary Halo as it does to the asteroid belt: for every object of given diameter, there are ten objects with one-third of that diameter.

The Halo has been described and studied since the middle of the twentieth century, but Lanhoff’s interests were different. He divided the solar vicinity into regions of different distances and inclinations to the plane of the ecliptic, and he looked at the percentage of different organic materials within each orbital regime. Naturally, with a trillion objects to work with he could only look at a tiny sample of the total, but even so the analysis took him eight years. And he found something new and surprising. In a part of the Halo about 3200 AU from the Sun, running out to maybe 4,000 AU, the complexity of chemical compounds increases enormously. Instead of simple organic molecules like cyanogen, formaldehyde, and methane, his program told him he was finding higher compounds and complex polymers — macromolecules like polysaccharide chains.

“Like what?” At that point in the discussion I had interrupted Will Bayes’ rambling. Organic chemistry is low on the list of educational priorities for controlling a spacecraft.

“Organic polymers,” said McAndrew thoughtfully. He had been frowning hard as Bayes talked of the chemical composition. “Chains of glucose molecules, to make starches and cellulose.” He turned back to Bayes. “Did Lanhoff find any evidence of porphyrins, or nitrogen compounds like purines and pyrimidines?”