Fifteen minutes later Captain Strong and Governor Hardy climbed aboard
and Tom received the order to raise ship.

The young curly-haired cadet turned to the control board and flipped on
the teleceiver. "Rocket cruiser _Polaris_ to spaceport control tower,"
he called. "Request blast-off orbit and clearance!"

The traffic-control officer in the spaceport tower answered immediately.
"Control tower to _Polaris_. You are cleared for blast-off at 1405
hours, orbital tangent 867."

Tom repeated the instructions and turned to the intercom and began
snapping out orders. "Power deck, energize the cooling pumps!"

"Power deck, aye!" replied Astro. The slow whine of the powerful pumps
began to scream through the ship. Tom watched the pressure indicator and
when it reached the blast-off mark called to Roger for clearance.

"All clear, forward and up!" declared Roger.

"Feed reactant at D-9 rate!" ordered Tom. And far below on the power
deck, Astro began to feed the reactant energy into the firing chambers.

Hardy looked at Strong and nodded in appreciation of the cadets' smooth
efficient work. They strapped themselves into acceleration cushions and
watched the red second hand of the astral chronometer sweep around, and
then heard Tom counting off the seconds.

"Blast off--" bawled Tom, "minus five--four--three--two--one--_zeroooo!_"