 Why was the fuel drained out of Hennessy's ship's tank?
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. One, at the front, was stuttering into life, and Gwayne dashed for it as the exit port slid back.
 Hennessy drained it so they couldn't leave
 Gwayne doesn't know  Hennessy drained it so they couldn't leave  it was destroyed by creatures from the planet  the blobs used it for energy