to, sir?" asked Strong.

"No, let them decide," replied Walters. "But it would be best if you
could keep Manning away from Miles. That's like putting a rocket into a
fire and asking it not to explode."

The two men grinned at each other and then settled down to working out
the details of Strong's trip. Before the evening was over, Walters had
decided, if necessary, he would follow Strong out to Titan.

In the distance, they could hear the muffled roar of rocket motors as
the three finalists tuned up their ships, preparing for the greatest
space race in history. And it seemed to Strong that with each blast
there was a vaguely ominous echo.

* * * * *

"I've strained that fuel four times and come up with the same answer,"
said Astro. The giant Venusian held up the oil-smeared test tube for Kit
Barnard's inspection. "Impure reactant. And so impure that it couldn't
possibly have come from the Academy supply depot. It would have been
noticed."

"Then how did it get in my feeders?" asked Kit, half to himself.

"Whoever was messing around on the power deck just before you blasted
off for the trials must have dumped it in," said Tom.

"Obviously." Kit nodded. "But who is that? Who would want to do a dirty
thing like that?"

"Who indeed?" said a voice in back of them. They all spun around to
face Quent Miles. He lounged against the stabilizer fin and grinned at
them.

"What do you want, Miles?" asked Kit.

"Just stopped by to give you the proverbial handshake of good luck
before we blast off," replied the spaceman with a mocking wink.

"Kit doesn't need your good wishes," snapped Sid.

"Well, now, that's too bad," said Quent. "I have a feeling that he's
going to need a lot more than luck."

"Listen, Miles," snapped Kit, "did you come aboard my ship and tamper
with the fuel?"

Quent's eyes clouded. "Careful of your accusations, Barnard."

"I'm not accusing you, I'm asking you."

"See you in space." Quent laughed, turning to leave, not answering the
question. "But then, again, maybe I won't see you." He disappeared into
the darkness of the night.

"The nerve of that guy," growled Tom.

"Yes," Kit agreed, shrugging his shoulders. "But I'm more concerned
about this unit than I am about Quent Miles and his threats. Let's get
back to work."

Renewing their efforts, Tom, Roger, Astro, Sid, and Kit Barnard turned
to the reactor unit and began the laborious job of putting it back