Then the Orionad sped into the sky above Sahara Base on the way to Pluto.
Guy Maynard was on his way to the top. Ertene was a dim remembrance by now, and though he could almost pick out the spot of the nomad planet's present position, it occurred to him only at odd intervals. Ertene was gone. But the strength of Ertene's knowledge was serving both him and Terra, and her brief visit was not wasted.
Maynard lost himself in reverie for a half hour, relaxing in the luxury of the master's office aboard the mighty Orionad. Then Guy's active mind asserted itself, and he called the chief technician for a conference.
Senior Executive Martin Carrington entered the office and stood at attention, and Guy recalled briefly that on his first command, he had been of the same rank as his chief technician now. Then he asked Carrington to be seated.
"Carrington, I've been worrying."
"Worrying, sir?"
"Suppose we are attacked by a sub-ship? How may we detect him?"
"You are supposing that the Martians gain the secret."
"I fear they will, some day. We haven't all the brains, you know."
"But a Martie, sir?"