emy Corps heading in for the evening meal. From all corners of the
quadrangle, the slidewalks carried Earthworms in their green uniforms,
upper-class cadets in deep blue, enlisted spacemen in scarlet red, and
Solar Guard officers in their striking uniforms of black and gold.
Chatting and laughing, they all were entering the great building.

The _Polaris_ unit was well known among other cadet units, and they were
greeted heartily from all sides. As Astro and Roger joked with various
cadet units, forming up in front of the slidestairs leading down to the
mess halls, Alfie turned to take a slidestairs going up. Suddenly he
stopped, grabbed Tom by the shoulders, and whispered in his ear. Just as
abruptly he turned and raced up the ascending slidestairs.

"What was that about?" asked Roger, as Tom stood staring after the
little cadet.

"Roger--he--he said our next assignment would be one of the great
experiments in space history. Something to be done that--that hasn't
ever been done before!"

"Well, blast my jets!" said Astro. "What do you suppose it is?"

"Ahhh," sneered Roger, "I'll bet it's nothing more than taking some
guinea pigs to see how they react to Jovian gravity. That's never been
done before either! Why can't we get something exciting for a change?"

Tom laughed. "Come on, you bloodthirsty adventurer, I'm starved!"

But Tom knew that Alfie Higgins didn't get excited easily, and his eyes
were wide and his voice trembled when he had whispered his secret to
Tom.

The _Polaris_ unit was due to embark on a great new adventure!

[Illustration]

CHAPTER 2

"All O.K. here on the relay circuit," yelled Astro through the intercom
from the power deck.

"O.K.," answered Tom. "Now try out the automatic blowers for the main
tubes!"

"Wanta give me a little juice for the radar antenna, Astro?" called
Roger from the radar deck.

"In a minute, Manning, in a minute," growled Astro. "Only got two hands,
you know."

"You should learn to use your feet," quipped Roger. "Any normal Venusian
can do just as much with his toes as he can with his fingers!"

Back and forth the bantering had gone for twelve hours, while the three
members of the _Polaris_ unit tested, checked, adjusted, and rechecked
the many different circuits, relays, junction boxes, and terminals in
the miles of delicate wiring woven through the ship. Now, as dawn began
to creep pink and gray over the eastern horizon, they made their
last-minu