to happen a lot oftener," Blades said enthusiastically.
"The Belt's going to grow!" He aimed his words at Ellen. "This is the
real frontier. The planets will never amount to much. It's actually
harder to maintain human-type conditions on so big a mass, with a
useless atmosphere around you, than on a lump in space like this. And
the gravity wells are so deep. Even given nuclear power, the energy
cost of really exploiting a planet is prohibitive. Besides which, the
choice minerals are buried under kilometers of rock. On a metallic
asteroid, you can find almost everything you want directly under your
feet. No limit to what you can do."

"But your own energy expenditure--" Gilbertson objected.

"That's no problem." As if on cue, the worldlet's spin brought the sun
into sight. Tiny but intolerably brilliant, it flooded the dome with
harsh radiance. Blades lowered the blinds on that side. He pointed in
the opposite direction, toward several sparks of equal brightness that
had manifested themselves.

"Hundred-meter parabolic mirrors," he said. "Easy to make; you spray a
thin metallic coat on a plastic backing. They're in orbit around us,
each with a small geegee unit to control drift and keep it aimed
directly at the sun. The focused radiation charges heavy-duty
accumulators, which we then collect and use for our power source in
all our mobile work."

"Do you mean you haven't any nuclear generator?" asked Warburton.

He seemed curiously intent about it. Blades wondered why, but nodded.
"That's correct. We don't want one. Too dangerous for us. Nor is it
necessary. Even at this distance from the sun, and allowing for
assorted inefficiencies, a mirror supplies better than five hundred
kilowatts, twenty-four hours a day, year after year, absolutely free."

"Hm-m-m. Yes." Warburton's lean head turned slowly about, to rake
Blades with a look of calculation. "I understand that's the normal
power system in Stations of this type. But we didn't know if it was
used in your case, too."

_Why should you care?_ Blades thought.

He shoved aside his faint unease and urged Ellen toward the dome
railing. "Maybe we can spot your ship, Lieutenant, uh, Miss Ziska.
Here's a telescope. Let me see, her orbit ought to run about so...."

* * * * *

He hunted until the _Altair_ swam into the viewfield. At this distance
the spheroid looked like a tiny crescent moon, dully painted; but he
could make out the sini