l I--"

"Astro!" Tom interrupted sharply.

"O.K., O.K.," groaned the big cadet.

Glancing over the panel once more and satisfying himself that the ship
was functioning smoothly, Tom sighed and settled back in his seat,
enjoying the temporary peace and solitude. It had been a tough year,
filled with intensive study in the quest for an officer's commission in
the Solar Guard. Space Academy was the finest school in the world, but
it was also the toughest. The young cadet shook his head, remembering a
six-weeks' grind he, Roger, and Astro had gone through on a nuclear
project. Knowing how to operate an atomic rocket motor was one thing,
but understanding what went on inside the reactant pile was something
else entirely. Never had the three cadets worked harder, or more closely
together. But Astro's thorough, practical knowledge of basic nucleonics,
combined with Roger's native wizardry at higher mathematics, and his own
understanding of the theory, had enabled them to pull through with a
grade of seventy-two, the highest average ever made by a cadet unit not
specializing in physics.

As the ship rocketed smoothly through the airless void of space toward
the misty planet of Venus, Tom made another quick but thorough check of
the panel, and then returned to his reflections on the past term. It had
been particularly difficult since they had missed many valuable hours of
classroom work and study because of their adventure on the new colony of
Roald (as described in _The Space Pioneers_), but they had come through
somehow. He shook his head wondering how they had made it. Forty-two
units had washed out during the term. Instead of getting easier, the
courses of study were getting more difficult all the time, and in his
speech on the parade grounds, Commander Walters had promised--

"Emergency!"

Roger's voice over the intercom brought Tom out of his reverie sharply.

"All hands," continued the cadet on the radar bridge hurriedly, "secure
your stations and get to the jet-boat deck on the double! Emergency!"

As the sharp clang of the emergency alarm rang out, Tom did not stop to
question Roger's sudden order. Neutralizing all controls, he leaped for
the hatch leading below. Taking the ladder four steps at a time, Tom saw
Major Connel tear out of his quarters. The elder spaceman dived for the
ladder himself, not stopping to ask questions. He was automatic in his
reliance on the judgment of others. The few seconds spent in t