Murgatroyd said "_Chee!_" in a subdued voice.

"But where the devil did they put them?" demanded Calhoun. "A polar
orbit would be ridiculous! They--" Then he grunted in disgust. "Oh! Of
course! Now, where's the landing-grid?"

He worked busily for minutes, checking the position of the Wealdian
landing-grid, which was mapped in the Sector Directory, against the
look of continents and seas on the half-disk so plainly visible
outside. He found what he wanted. He put on the ship's solar system
drive.

"I wish," he complained to Maril, "I wish I could think straight the
first time! And it's so obvious! If you want to put something out in
space, and not have it interfere with traffic, in what sort of orbit
and at what distance will you put it?"

Maril did not answer.

"Obviously," said Calhoun, "you'll put it as far as possible from the
landing-pattern of ships coming in to the spaceport. You'll put it on
the opposite side of the planet. And you'll want it to stay out of the
way, where anybody can know it is at any time of the day or night
without having to calculate anything.

"So you'll put it out in orbit so it will revolve around Weald in
exactly one day, neither more nor less, and you'll put it above the
equator. And then it will remain quite stationary above one spot on
the planet, a hundred and eighty degrees longitude away from the