interference that
would have been occasioned by the vast flood of electrons encircling
Earth in the outer Van Allen belt. These electrons, trapped by Earth's
magnetic field from the solar wind of charged particles escaping the
sun, unfortunately occupied the twenty-four hour orbit, and, as their
orbit expanded and contracted under the influence of the shifting
magnetic field and solar flares, could produce tremendous havoc even
in automatic equipment, so that it had been deemed economically
impractical to set up the originally-postulated three satellites in
stationary twenty-four orbits as communications terminals.

As the next best choice, the thirty-six-hour orbit had been selected.
It gave a slow rate of angular displacement, since the satellite
itself moved ten degrees an hour, while Earth moved 15 deg., for a
differential rate of only five degrees an hour, making fairly easy
tracking for the various Earth terminals of the communications net;
and making possible a leisurely view of more than ninety per cent of
Earth's surface every seventy-two hours.

The other two power and communications stations which led and lagged
Space Lab One by 120 deg. each, would combine to command a complete view
of Earth, lacking only a circle within the arctic regions, so that
they could provide power and communications for the entire world--a
fact which had been the political carrot which had united Earth in the
effort to create the labs with their combined technologies.

The danger of such powerful instruments as Hot Rod, concentrating
megawatt beams of solar energy for relay to earth, and which could
also be one of man's greatest weapons if it fell into unscrupulous
hands, had been carefully played down, and also carefully countered in
the screening by the Security Forces of U.N. of the personnel board.

* * * * *

T minus three and counting.

On the zero signal Mike in the engineer's quarters would change the
now idly-bubbling air jets in the rim-rivers over to the
fully-directional drive jets necessary to spin the fluid in
counter-rotation through the rim tanks.

The suiting-up and strapping down were probably unnecessary, Mike
thought, but in space you don't take chances.

"T minus two and counting." Bessie's voice rang over the com circuit
in officially clipped clarity.

From the physics lab came a rather oddly pitched echo. "Allee allee in
free fallee! Hold it, please, as Confusion woul