der!" insisted Walters.

"Very well, sir. But this will have to go into my report to the senior
medical officer."

"And I'll commend you for insisting on proper care for your patients,"
Walters stated. "But in the meantime we've got to find out what
happened. And Cadet Astro is the only one who can tell us."

The corpsman turned to his emergency kit. He took out a large hypodermic
needle, filled with a clear fluid, and injected it into the big cadet's
arm.

In less than a minute Astro was sitting up and telling Walters
everything that had happened. When he told of the pipe that was sucking
off the oxygen from the main pumps, Walters dispatched an emergency crew
to the mine immediately to plug the leak. Then, when Astro revealed the
secret of the mine, the presence of the uranium pitchblende, Walters
shook his head slowly.

"Amazing!" he exclaimed. "Greed can ruin a man. He could have declared
such a discovery and still had more money than he could have spent in a
lifetime."

Walters spun around. "Steve, I want the _Polaris_ ready to blast off
within an hour. We're going after one of the dirtiest space rats that
ever hit the deep!"

[Illustration]

CHAPTER 18

Roger peered around the edge of the baffling shields. The power deck was
empty. He edged out and stood upright, eyes moving constantly for signs
of Miles.

No longer needing the cumbersome space suit, he stripped it off and
walked across the deck to the ladder. He stopped to listen again but
there was only the sound of the rockets under emergency space drive. A
quick glance at the control panel told him that the ship was hurtling
through space at a fantastic speed. Satisfied that Miles was nowhere
near, Roger gripped the rocketman's wrench tightly and began climbing
slowly and cautiously.

When he reached the next deck, he raised his head through the hatch
slowly. Then, in one quick movement, he pulled himself up on the deck
and ran for cover behind a small locker to his right. Above him, through
the open network of frames and girders, he could see the control deck,
but Miles was nowhere in sight.

Something on the opposite side of the ship caught his eye. Miles' space
suit hung on its rack, the heavy fish-bowllike space helmet beside it in
its open locker. Roger's heart skipped a beat as he noticed the holster
for a paralo-ray gun nearby. But the large flap was closed and he could
not see if it held a gun.

[Illustration: _Slowly and cau