ets!" ordered Tom, his eyes glued to the altimeter.

The _Polaris_ shuddered under the sudden reverse in power, then began an
upward curve, nose pointing back toward space. Tom barked another
command. "Braking rockets full! Stand by main drive rockets!"

The sleek ship began to settle tailfirst toward its destination--Space
Academy, U.S.A.

In the heart of a great expanse of cleared land in the western part of
the North American continent, the cluster of buildings that marked Space
Academy gleamed brightly in the noon sun. Towering over the green grassy
quadrangle of the Academy was the magnificent Tower of Galileo, built of
pure Titan crystal which gleamed like a gigantic diamond. With smaller
buildings, including the study halls, the nucleonics laboratory, the
cadet dormitories, mess halls, recreation halls, all connected by
rolling slidewalks--and to the north, the vast area of the spaceport
with its blast-pitted ramps--the Academy was the goal of every boy in
the year A.D. 2353, the age of the conquest of space.

Founded over a hundred years before, Space Academy trained the youth of
the Solar Alliance for service in the Solar Guard, the powerful force
created to protect the liberties of the planets. But from the beginning,
Academy standards were so high, requirements so strict, that not many
made it. Of the one thousand boys enrolled every year, it was expected
that only twenty-one of them would become officers, and of this group,
only seven would be command pilots. The great Solar Guard fleet that
patrolled the space lanes across the millions of miles between the
satellites and planets possessed the finest, yet most complicated,
equipment in the Alliance. To be an officer in the fleet required a
combination of skills and technical knowledge so demanding that eighty
per cent of the Solar Guard officers retired at the age of forty.

High over the spaceport, the three cadets of the _Polaris_ unit, happy
over the prospect of a full month of freedom, concentrated on the task
of landing the great ship on the Academy spaceport. Watching the
teleceiver screen that gave him a view of the spaceport astern of the
ship, Tom called into the intercom, "One thousand feet to touchdown. Cut
braking rockets. Main drive full!"

The thunderous blast of the rockets was his answer, building up into
roaring violence. Shuddering, the great cruiser eased to the ground foot
by foot, perfectly balanced on the fiery exhaust from her mai