"What's that?" asked Tom.
"Collision!" said Roger. "Some of these space-happy cadets might get excited, and I for one don't want to wind up as a flash in Earth's atmosphere!"
"Why, you have radar, to see anything that goes on."
"Oh, sure," said Roger, "I can keep this wagon outa their way, but will they stay outa mine? Why my father told me once—" Roger choked on his food and turned away to the radar screen.
"Well," said Tom after a moment, "what did your father tell you?"
"Ah—nothing—not important. But I've got to get a cross-fix on Regulus before we start our little games."
Tom looked puzzled. Here was another of Roger's quick changes of attitude. What was it all about? But there was work to do, so Tom shrugged his shoulders and returned to the control deck. He couldn't forget what Roger had said about a collision, though.
"Excuse me, Captain," said Tom, "but have there been any serious collisions in space between ships?"
"Sure have, Tom," replied Strong. "About twenty years ago, maybe less, there was a whole wave of them. That was before we developed superrebound pulse radar. The ships were faster than the radar at close range."
Strong paused. "Why do you ask?"