. but nobody else knew that, not even the
captain waiting at the control board on the satellite, and in spite of
the fear Greg Hunter would not have traded places at this moment with
anyone else in the universe.

He had worked too hard and waited too long for this moment.

He heard the count-down monitor clicking in his ears, and his hands
clenched into fists. How far from Mars would he be ten minutes from now?
He didn't know. Farther than any man had ever traveled before in the
space of ten minutes, he knew, and faster. How far and how fast would
depend on him alone.

"All set, Greg?" It was the captain's voice in the earphones.

"All set, Captain."

"You understand the program?"

Greg nodded. "Twenty-four hours out, twenty-four hours back, ninety
degrees to the ecliptic, and all the accelleration I can stand both
ways."

Greg grinned to himself. He thought of the months of conditioning he had
gone through to prepare for this run ... the hours in the centrifuge to
build up his tolerance to accelleration, the careful diet, the rigorous
hours of physical conditioning. It was only one experiment, one tiny
step in the work that could someday give men the stars, but to Gregory
Hunter at this moment it was everything.

"Good luck, then." The captain cut off, and the blastoff buzzer sounded.

He was off. His heart hammered in his throat, and his eyes ached
fiercely, but he paid no attention. His finger crept to the air-speed
indicator, then to the cut-off switch. When the pressure became too
great, when he began to black out, he would press it.

But not yet. It was speed they wanted; they had to know how much
accelleration a man could take for how long and still survive, and now
it was up to him to show them.

Fleetingly, he thought of Tom ... poor old stick-in-the-mud Tom, working
away in his grubby little Mars-bound laboratory, watching bacteria grow.
Tom could never have qualified for a job like this. Tom couldn't even go
into free-fall for ten minutes without getting sick all over the place.
Greg felt a surge of pity for his brother, and then a twinge of
malicious anticipation. Wait until Tom heard the reports on _this_ run!
It was all right to spend your time poking around with bottles and test
tubes if you couldn't do anything else, but it took something special to
pilot an XP ship for Project Star-Jump. And after this run was over,
even Tom would have to admit it....

There was a lurch, and quite suddenl