ked Walters sharply.

Brett smiled. "The same as everyone else, Commander."

"What about your feeders?" asked Strong. "With ordinary reactant, and no
new cooling units aboard your ship, you must have oversized feeders to
make such fantastic speeds."

Brett shrugged and held out his hands in a gesture of innocence. "I
don't even know myself, Captain Strong," he said blandly. "It's one
reason why I have Quent Miles piloting for me. He has a few tricks that
apparently are quite effective."

"I hope they are legitimate tricks, Mr. Brett," said Walters. "Let's go,
Steve."

The three officers turned away and left Brett sitting there, smiling
triumphantly.

"I think we'd better start from the beginning in our inspection of the
screens, Captain Howard," said Walters, as the three officers left the
control tower and walked across the spaceport. "First of all, I want a
twenty-four-hour watch placed on all operational centers, pump houses,
and generator plants. I cannot discount the idea of sabotage. Why anyone
would want to wreck the screens is beyond me, but we cannot ignore the
possibility."

"I already have men stationed at the main operational centers, sir,"
replied Howard. "Your Space Marines will help me cover the rest."

"Steve," said Walters, turning to the Solar Guard officer, "if this is a
natural phenomenon--some new element in Titan's atmosphere breaking down
the force screens--the problem is bad enough. But if this is caused by
man--if it really is sabotage--we'll have a doubly hard time. We can
find the reason eventually, if it is natural, but man can conceal his
reasons. And until we find out the motives behind this we must count on
the situation getting worse. I want you to pursue _that_ line of
investigation. Find out if anyone has a good reason to force the
abandonment of Titan."

"It's a big order, sir," said Strong. "I'll do the best I can."

"That's good enough for me," replied the commander, nodding his
satisfaction.

* * * * *

"Any word, sir?" asked Astro eagerly as the white-clad medical officer
emerged from the room.

The man smiled. "Thanks to you, Cadet Astro," he replied, "your friend
will be able to leave as soon as he gets his pants on."

"Yeow!" bawled Astro in his famous bull-like bellow. "Thanks, sir.
Thanks a million!" He turned and wrenched open the sick-bay door, almost
splintering it in his enthusiasm. Tom was just sitting up on the side of
th