opic sighter. He saw the ship, but where there
had been a golden sphere there was now only a shattered fragment of
twisted metal.

The enemy ship changed before his eyes. The remaining silvery sphere
glowed brighter, and took on a golden hue. Then it seemed as if the
ship were growing smaller. He realized finally that it was retreating.

Burl gave an involuntary shout, and in his earphones he heard the same
shouts of triumph from every voice on the ship.

Although it might have been possible to pursue the battered enemy ship,
the _Magellan_ did not try. They were still on course for Saturn and
were not going to deviate.

They reached Saturn after several more days. Matching their great speed
with that of the ringed world in its orbit took time, and then they
began their survey.

As they had suspected, the Sun-tap station was on one of the moons. The
moon was called Iapetus, the third largest of Saturn's family. It was
about eight hundred miles in diameter and the next to the farthest
satellite from Saturn. Russ was disappointed that they hadn't picked
Titan, the biggest moon of all. Titan was over two thousand miles wide
and appeared to have an atmosphere of methane.

The view of Saturn was awesome, even from Iapetus' orbit two million
miles away. Burl knew it would be a sight unparalleled in the system.
The great broad rings, composed of innumerable tiny particles of metal,
stone, and possibly ice, encircled it as if held there by an invisible
hand. They were, he knew, the particles of a moon that had either come
too close to Saturn's great gravitational pull to hold its shape, or
else had never escaped far enough to congeal as one solid mass.

Iapetus was a solid world, though. A rocky body, it had a dull gleam,
and was streaked here and there with layers of white and yellow, where
veins of frozen gases lay forever upon the frigid surface. No atmosphere
veiled the surface nor softened the harsh, jagged mountains and clefts
of this forbidding little subplanet.

The Sun-tap station stood in plain sight on a high plateau near a polar
region. The _Magellan_ hovered over it while Lockhart held a council of
war.

"I don't see what's to be gained by attempting a landing party," he
said. "We've taken all the readings and pictures of the other
stations--and we've had a couple of narrow escapes. They've probably
mined this one, and they have had plenty of time to prepare a trap. I'm
in favor of simply dropping an H-b