They got off the track at Valve Two and stepped through into the rocket's
interior. Two seats just ahead of the fins were vacant, and they slid
into them. Rip looked through the thick port beside him and saw the
distinctive blue glow of a nuclear drive cruiser sliding toward the
platform.

"Wave your eye stalks at that job," Flip said admiringly. "Wonder what
it's doing here."

The space platform was a refueling depot, where conventional chemical
fuel rockets topped off their tanks before flaming for space. The newer
nuclear drive cruisers had no need to stop. Their atomic piles needed new
neutron sources only once every few years, and they carried thousands of
tons of methane, compressed into solid form, for their reaction mass.

The voice horn in the rocket cabin sounded. "The SCN _Scorpius_ is
passing Valve Two, landing at Valve Eight."

"I thought that ship was with Squadron One on Mercury," Rip recalled.
"Wonder why they pulled it back here."

Flip had no chance to reply, because the chief rocket officer took up his
station at the valve and began to call the roll. Rip answered to his
name.

The rocket officer finished the roll, then announced: "Buttoning up in
twenty seconds. Blast off in forty-five. Don't bother with acceleration
harness. We'll fall free, with just enough flame going for control, after
ten seconds of retrothrust to de-orbit."