"What's that?" cried Tom.
A bell began to ring. Then another—and then three more. Finally the entire ship was vibrating with the clanging of emergency bells.
Astro made a diving leap for the ladder leading down to the power deck, with Tom lunging for the control board.
Quickly Tom glanced about the huge board with its many different gauges and dials, searching for the one that would indicate the trouble. His eye spotted a huge gauge. A small light beside it flashed off and on. "By the moons of Jupiter, we've run out of reactant fuel!"
"Tom!—Tom!" shouted Astro from the power deck. "We're smack out of reactant feed!"
"Isn't there any left at all?" asked Tom. "Not even enough to get us into Marsopolis?"
"We haven't enough left to keep the generator going!" said Astro. "Everything, including the lights and the teleceiver, will go any minute!"
"Then we can't change course!"
"Right," drawled Roger. "And if we can't change course, the one we're on now will take us straight into Mars's gravity and we crash!"
"Send out an emergency call right away, Roger," said Tom.