 Why were they getting the jeeps out?
They were something more—and something less—they were, in short, humanity's hopes for survival! Earth couldn't turn out enough starmen in the schools, so promising kids were being shipped out for training as cadets on their twelfth birthday. The two he'd drawn, Kaufman and Pinelli, seemed to be totally devoid of any sense of caution. But something had happened to the exploration party fifteen years back, and to the more recent ship under Hennessy that was sent to check up. The Sol-type sun must be rising, since there was a dim light. Even the deep gorge where they'd found Hennessy's carefully buried ship was completely hidden by the fog. Earth had ordered him to detour here, after leaving his load of deep-sleep stored colonists on Official World 71, to check on any sign of Hennessy. Now the three were streaking at fantastic speed to a spot near the ship, to hover excitedly above something that moved there. One, at the front, was stuttering into life, and Gwayne dashed for it as the exit port slid back. At a gesture, the jeep rolled down the ramp, grinding its gears into second as it picked up speed. The jeep was doing twenty miles an hour now, but the horde began to increase the distance, in spite of the load of the two struggling boys! The creatures dived downward into lower ground, beginning to disappear into the mists. Then it cleared to show the mob of creatures doubling back on their own trail to confuse the pursuers.
 to go on an urgent rescue mission
 to tour the planet  to attack the natives  to find the lost crew  to go on an urgent rescue mission