ntrol deck on the way to the radar bridge,
he glanced at the clock. It was ten minutes to eight.

"Only one thing I'm worried about, Corbett," said Roger through a
mouthful of sandwich.

"What's that?" asked Tom.

"Collision!" said Roger. "Some of these space-happy cadets might get
excited, and I for one don't want to wind up as a flash in Earth's
atmosphere!"

"Why, you have radar, to see anything that goes on."

"Oh, sure," said Roger, "I can keep this wagon outa their way, but will
they stay outa mine? Why my father told me once--" Roger choked on his
food and turned away to the radar screen.

"Well," said Tom after a moment, "what _did_ your father tell you?"

"Ah--nothing--not important. But I've got to get a cross-fix on Regulus
before we start our little games."

Tom looked puzzled. Here was another of Roger's quick changes of
attitude. What was it all about? But there was work to do, so Tom
shrugged his shoulders and returned to the control deck. He couldn't
forget what Roger had said about a collision, though.

"Excuse me, Captain," said Tom, "but have there been any serious
collisions in space between ships?"

"Sure have, Tom," replied Strong. "About twenty years ago, maybe less,
there was a whole wave of them. That was before we developed
superrebound pulse radar. The ships were faster than the radar at close
range."

Strong paused. "Why do you ask?"

Before Tom could answer, there was a sharp warning from the captain.

"Eight o'clock, Corbett!"

Tom ripped open the envelope containing the sealed orders.
"Congratulations," he read. "You are in command of the defenders. You
have under your command, Squadrons A--B--C--D--E--F. Squadrons G and H
are your enemies, and at this moment are on their way to attack Luna
City. It is your job to protect it and destroy the enemy fleet.
Spaceman's luck! Walters, Commander Space Academy, Senior Officer Solar
Guard."

"Roger," yelled Tom, "we've been selected as flagship for the defenders!
Get me a course to Luna City!"

"Good for us, spaceboy. I'll give you that course in a jiffy!"

" ... _Capella_ to _Polaris_--am standing by for your orders...." Tony
Richards' voice crackled over the teleceiver. One by one the
twenty-three ships that made up the defender's fleet checked in for
orders.

"Astro," shouted Tom, "stand by for maneuver--and be prepared to give me
every ounce of thrust you can get!"

"Ready, willing and able, Tom," replied Astro. "Just