on duty would walk in, seal it up, turn on the equipment, and wait until
the gauges registered sufficient air and heat, then remove their space
suits. When it was time to leave again, they would don suits, open the
door and walk out, and the next shift would enter and repeat the process.
Earlier models had permanent compartments, but they took up too much room
in craft designed for carrying as many men and as much equipment as
possible. They were strictly work boats, and hard experience had showed
the best design.

The rocket launcher was already set up near the boat. It was a simple
affair, with four adjustable legs bolted to ground spikes. The legs held a
movable cradle in which the rocket racks were placed. High-geared hand
controls enabled the gunner to swing the cradle at high speed in any
direction except straight down. A simple, illuminated optical sight was
all the gunner needed. Since there was no gravity and no atmosphere in
space, the missiles flashed out in a straight line, continuing on into
infinity if they missed their targets. Proximity fuses made this a remote
possibility. If the rocket got anywhere near the target, the shell would
explode.

Rip found his astrogation instruments set carefully to one side. He took
the data sheets from his case and examined them. Now came the work of
finding the exact spots in which to place his atomic charges. Since the
computer aboard ship had done all the mathematics necessary, he needed
only to take sights to determine the precise positions.

He took a transit-like instrument from the case, pulled out the legs of
its self-contained tripod, then carried it to a spot near where he had
estimated the first charge would be placed. The instrument was equipped
with three movable rings to be set for the celestial equator, for the zero
meridian, and for the right ascension of any convenient star. Using a
regular level would have been much simpler. The instrument had one, but
with so little gravity to activate it, the thing was useless.

The sights were specially designed for use in space and his bubble was no
obstacle in taking observations. He merely put the clear plastic against
the curved sight and looked into it much as he would have looked through a
telescope on earth.

As he did so, a hint of pale pink light caught the corner of his eye. He
backed away from the instrument and turned his head quickly, looking at
the colorimeter-type radiation detector at the side of