'Tina glanced at the sky, surprised. "So soon? I didn't know it had taken us so long. It seems as if only a few hours ago it was noon."
"It was," grinned Greg. "Titan's days are shorter than Earth's. Its diameter is only about 3,000 miles. By Earth measurements you'd say Titan had a sixteen hour day."
"And the 'day,'" grumbled Sparks, "ain't none too bright at that. On account of we're so far from the Sun."
"You haven't seen the worst of it. Right now we're on the Sun side of Saturn. We revolve about our primary once every 500-odd hours. Since Saturn is so large, when we are to the lee of it, it eclipses us entirely. So for about five days every Titan 'month' we suffer a complete blackout.
"And that—" Greg sobered. "That is another reason the others should dig into a good warm cave. It gets plenty cold during that eclipse period. An open camp on an exposed plain—" He shook his head.
Maud Andrews said, "I can't understand why this satellite is habitable at all. I was under the impression that Saturn is a frozen planet."
"It is. Its surface temperature is approximately 300° below zero, Fahrenheit. But the warmth of its numerous satellites is one of the astonishing discoveries made by the early space explorers, fifty or sixty years ago. Scientists have not yet explained the matter satisfactorily. Some say the tremendous mass of Saturn, the waves of atmospherics set up by its swirling motion and the 'grindstone' of its ring, form an electronic barrier-shield for the satellites. Still others believe that frigid Saturn acts as a gigantic mirror or solar reflector for its children."
"But Greg—" That was Tommy O'Doul. "Why ain't there any colonies here if the climate's O.Q.? Men live on Venus, where it's hot as billy-be-hanged, and on Uranus, which is nothing but a ball of ice, and on a bunch of cold, airless asteroids—"
"Economics, Tommy. The simple, single dictator of mankind's every venture. Venus has valuable vegetation, Uranus and the asteroids have important metals that can't be duplicated in Earth's laboratories, the asteroids have rare ore deposits. There is not—or at least there has not as yet been discovered—anything native to Titan that cannot be mined or made elsewhere more cheaply, more easily. Some day man's ever-expanding frontiers will claim this satellite as a colony, too. But now that the entire universe is open to man, the human race can increase a millionfold and still allow every soul more lebensraum than he can possibly use."
Sparks Hannigan gazed at him admiringly.