, down on the power deck Astro's face turned red.

"Manning," he growled into the intercom microphone, "if I didn't need
you to get me back to Mother Earth, I'd come up there and take you
apart!"

For four days the two cadets had been aboard the rocket scout, circling
in an orbit between Mars and Earth, conducting equipment tests for Dave
Barret. They had become bored with the routine work and spent most of
their time needling each other, but as Roger said, at least they were in
space.

"O.K., let's knock off the space gas!" called Roger over the intercom.
"It's time to run another test. Want to come up topside and take a
hand?"

"Be right there, Roger!" said Astro. He set the power-deck controls on
automatic, and then, with a quick look around to make sure everything
was shipshape, he climbed the ladder to the control deck.

Roger was standing at the chart table, audiophones on his ears,
listening for the automatic astral chronometer time-check broadcast on a
suprahigh-frequency audio channel from the giant electronic clock in the
Tower of Galileo. All spaceship chronometers were checked against this
huge clock regularly, in order to maintain constant uniform time so
necessary for the delicate art of astrogation between celestial bodies.

Astro started to speak to the blond-haired cadet, but Roger waved him
off, listening for the signal. Suddenly he looked up at their own
chronometer above the control board and took off the audiophones,
smiling his satisfaction.

"Right on the split second, Astro," he said.

"O.K.," replied the big Venusian. "Then let's run that test and get it
over with."

"Right," said Roger, turning back to the control panel. "Do you want to
go outside this time?"

"I might as well," replied Astro. "Give me a change of scenery."

The big Venusian turned to a locker, pulled out a bulky space suit, and
climbed into it quickly. Adjusting the space helmet, he nodded at Roger
and stepped into the air-lock chamber, pulling the hatch closed behind
him. While waiting for the oxygen in the small chamber to be pumped back
into the ship and the pressure to be equalized with the vacuum of space
outside, he checked his helmet intercom to insure a clear line of
communication with Roger.

The red hand closed on the _zero_ of the gauge over the door and Astro
moved to the outer hatch. He unlocked it, swung the door open, and
slowly climbed out into the fantastic beauty of endless space. No
sooner wa