to do with the crash. I think the whole trouble was caused
on the ship. I have nothing to back up my opinion, except my feelings.
But feelings can go a long way in making a man innocent until proved
guilty. Unit dis-missed!"

Alfie Higgins listened attentively to the story of the crash and Roger's
disappearance as Tom, and then Astro, described the situation in detail.

"It is a pity, of course, but Manning was always the impulsive type. Not
very definite in his attitude and emotionally unstable," commented Alfie
when the story was finished.

"Lay off that talk, you overstuffed brain!" growled Astro. "In this
outfit, Roger is just away on vacation!"

"Yes--yes, of course!" said Alfie quickly. It wasn't wise to get off on
the wrong foot in a new unit, especially when one was trying to fill the
shoes of a cadet, who, Alfie had to admit, had everything. Alfie
Higgins' mother didn't raise any stupid children, he said to himself. He
was too happy being a member of the _Polaris_ unit, the hottest crew at
the Academy, to allow anything to interfere with his success.

"I've heard a great deal about hyperdrive," he said quickly, changing
the subject. "I would appreciate it if you could describe the basis of
this new feature in space travel so that I may have at least a surface
familiarity with its operation and application."

Astro gulped and looked at Tom. "Might as well get used to that kind of
chatter, Astro," said Tom, smiling. "Alfie can't talk any other way."

"Is there something wrong with the way I speak?" asked Alfie, wrinkling
up his nose a little to see through the thick lenses of his glasses.

"You wanta know about hyperdrive?" growled Astro.

"To be sure, if you'd be so kind," said Alfie.

"Well, if you'll close your trap long enough, I'll tell you about it!"

Alfie sat back and waited, hands clasped around one knee.

"In the first place," began Astro, "hyperdrive was developed by Joan
Dale back at the Academy. And it's so blasted simple, I get mad at
myself for not thinking of it first!"

"Uhhh," snorted Alfie. "I respect your great talent on the power deck,
Astro, but I would hardly compare myself with Dale!"

"Shut up!" barked Astro. "You'll see how simple it is! Hyperdrive is
based on the idea that the thrust of the rockets acts in the exact same
way on _all_ the atoms inside the spaceship. So you can have as much
thrust as you want and no one will feel a thing. Even if the ship were
to accelera