Commander Brown was waiting for them with an out-stretched hand. "Glad to have you aboard." And there was a genuine smile creeping across his face.

Joe talked with careful distinctness into a microphone. His voice took a little over a second to reach its destination. Then there was a pause of the same length before the first syllable of Sally's reply came to him from Earth.

"I've reported to your father," said Joe carefully, "and the Moonship has reported to the Navy. In a couple of hours Haney and the Chief and Mike and I will be taking off to go back to the Platform. We got rockets from the stores of the Moonship."

Sally's voice was surprisingly clear. It wavered a little, but there was no sound of static to mar reception.

"Then what, Joe?"

"I'm bringing written reports and photographs and first specimens of geology from the Moon," Joe told her. "I'm a mailman. It'll probably be sixty hours back to the Platform--free fall most of the way--and then we'll refuel and I'll come down to Earth to deliver the reports and such."

Pause. One second and a little for his voice to go. Another second and something over for her voice to return.

"And then?"

"That's what I'm trying to find out," said Joe. "What day is today?"

"Tuesday," said Sally after the inevitable pause. "It's ten o'clock Tuesday morning at the Shed."

Joe made calculations in his mind. Then he said:

"I ought to land on Earth some time next Monday."

Pause.

"Yes?" said Sally.

"I wondered," said Joe. "How about a date that night?" Another pause.

Then Sally's voice. She sounded glad.

"It's a date, Joe. And--do you know, I must be the first girl in the world to make a date with the Man in the Moon?"

COMBAT MISSION!

_Joe Kenmore's mission was as dangerous as it sounded simple:_

"DELIVER SUPPLIES AND ATOMIC WEAPONS TO THE s.p.a.cE PLATFORM.

THEN PREPARE FOR MAN'S FIRST EXPEDITION TO THE MOON."

Joe had helped launch the first s.p.a.ce Platform--that initial rung in man's ladder to the stars. But the enemies who had ruthlessly tried to destroy the s.p.a.ce station before it left Earth were still at work. They were plotting to stop Joe's mission!

Cover painting by Robert Schulz