ung it around your head?" asked Connel.

"Sure, sorta like a slingshot," said Astro.

"That's right, Astro," said Connel, "and if you released the rope, the
rock would fly in the direction it was headed, _when you let go_!"

"I get it," cried Tom excitedly. "The gravity of Tara is the rope
holding Junior--ah"--he fumbled--"making it swing around!"

"And the reactant power of the _Space Devil_ placed in the right spot
would be the trigger to make it let go!" commented Roger.

"It's as simple as that, boys!" said Connel with a smile.

"But how in the blazing beams of the sun are you going to _stop_ that
blasted thing when you get it rolling?" asked Shinny.

"The chances of Junior hitting anything on the way home are so small it
doesn't present a problem. So we just aim Junior for our solar system!
Later on, arrangements can be made to steer it into an orbit around our
sun."

"You know," wheezed Shinny, his merry eyes twinkling, "that sounds
pretty neat!"

"It is," replied Connel. He leaned against the control-board desk top
and folded his arms across his massive chest. He looked at each of the
cadets and Shinny a long time before speaking. Finally he stepped
forward and stood among them, turning now and then to speak directly to
each of them.

"We have only four days, five hours, and some few minutes to pull Junior
out of Tara's grip, and later, the grip of Alpha Centauri. You boys will
have to work as you've never worked before. You'll do things you never
dreamed you could do. You'll work until your brains ache and your bodies
scream. But when you're finished, you will have accomplished one of
man's greatest challenges. You're going to do all this because I know
you can--and I'm going to see that you do! Is that clear?"

There was a barely audible "Yes, sir" from the cadets.

"The six of us, working together, are going to send a hunk of copper
fifteen miles in diameter hurtling through twenty-three million million
miles of space, so let's get that ball rolling. _Right now!_"

With Major Connel roaring, pleading, and blasting, four young cadets and
a derelict spaceman began the monumental task of assembling the mass of
information necessary for the satellite's big push through space. During
the three days that their project had been under way, Tom, Roger,
Astro, Alfie, and Mr. Shinny worked, as Major Connel promised, as they
had never worked before.

Late in the afternoon of the third day Connel stepped th