communicator," snorted Roger. "I figured once we got aboard
the scout we'd be able to use this set to contact the Academy instead of
having to monkey around with the homemade job back on the _Polaris_. But
it's no soap."

"Why not?" boomed Astro over the intercom.

"The only open circuit here is beamed to the _Polaris_. And the radar is
too complicated to change over to audio communications. We haven't got
enough time."

Tom clenched his teeth. He had had the same idea about using the
communications set on the scout to contact the Academy. Now there was
nothing to do but hope Vidac wouldn't find the one they were building.
He called into the intercom again. "Is the radar working well enough for
us to search the asteroid cluster without plowing into any space junk?"

"Yeah," growled Roger. "He left it in working condition all right, but
if we burn out a tube, we're blacked out until we get back. There isn't
a spare nut or bolt in the locker for repairs."

"But what happens if something happens to the radar when we're in the
cluster," called Astro. "We'll be sitting ducks for every asteroid!"

"That's the chance we have to take, Astro," said Tom. "If we complained,
you know what he'd do."

"I sure do," growled Astro. "He'd call us yellow again, because we'd
refused to make the trip!"

"That's the way it adds up," said Tom. "So I guess we'd better get
started. Stand by to blast!"

"All clear fore and aft," reported Roger.

"Full thrust, Astro," ordered Tom, "but stand by for emergency
maneuvers. This is going to be a tough trip, fellows. Perhaps the
toughest trip we've ever made. So keep your eyes and ears open and
spaceman's luck!"

"Spaceman's luck!" echoed his unit mates.

Under full thrust the speedy little ship shot ahead of the fleet toward
the gigantic mass of asteroids, planetoids, and millions of lesser space
bodies, whirling and churning among themselves at an incredible rate of
speed. Hardly had they left the fleet when Roger's voice crackled over
the intercom again.

"Say, you space monkeys!" he yelled. "I got an idea! How about taking
this wagon and heading back for the Academy?"

"Can't," replied Astro, "we've only got forty-eight hours of fuel,
water, and oxygen--and no reserves. We couldn't get one-tenth of the way
back before we ran out of everything, even if we wanted to go back."

"What do you mean--_if_?" snapped Roger. "Wouldn't you go back? How
about you, Tom?"

"I'd think a long