"Well, you never know," she answered. "If there's ever any reason for it, oxide-reducing germs will be needed."

"As well as a nuclear heating system for the whole world, and—What do your life forms use for energy, though? Hardly enough sunlight, I should think."

"Oh, but there is, for the right biochemistry with the right catalysts—analogous to our own enzymes. It makes a pretty feeble type of life, of course, but I hope to get bacteria which can live off the local ores and frozen gases by exothermic reactions. Don't forget, when it's really cold a thermal engine can have a very high efficiency; and all living organisms are thermal engines of a sort."

They took the stairs leading up into the main dome: apartments, refectories, social centers, and offices. Another stair led downward to the central heating plant in the body of the Hill. Gilchrist saw an engineer going that way with a metering kit and a worried look.

The bar was crowded, this was cocktail hour for the swing shift and—popular opinion to the contrary—a scientist likes his meals regular and only lives off sandwiches brought to the lab when he must. They found a table and sat down. Nobody had installed dial units, so junior technicians earned extra money as waiters. One of them took their orders and chits.

The ventilators struggled gallantly with the smoke. It hazed the murals with which some homesick soul had tried to remember the green Earth. A couple of astronomers at the next table were noisily disputing theories.

"—Dammit, Pluto's got to be an escaped satellite of Neptune. Look at their orbits ... and Pluto is where Neptune should be according to Bode's Law."

"I know. I've heard that song before. I suppose you favor the Invader theory?"

"What else will account for the facts? A big planet comes wandering in, yanks Neptune sunward and frees Pluto; but Neptune captures a satellite of the Invader. Triton's got to be a captured body, with this screwy retrograde orbit. And Nereid—"

"Have you ever analyzed the mechanics of that implausible proposition? Look here—" A pencil came out and began scribbling on the long-suffering table top.

Catherine chuckled. "I wonder if we'll ever find out," she murmured.

Gilchrist rubbed chilled fingers together. Blast it, the air was still cooling off! 

 Prev. P 6/20 next