a case," he said at length. "But there's
one thing I do know. I've got no proof, not a shred of it, but I'm sure
of one thing just as sure as I'm on Mars." He looked at the twins
thoughtfully. "Your dad wasn't just prospecting, out in the Belt. He'd
run onto something out there, something big."

The twins looked at him. "Run onto something?" Greg said. "You mean...."

"I mean I think your dad hit a Big Strike out there, rich metal, a real
bonanza lode. Maybe the biggest strike that's ever been made," the miner
said slowly. "And then somebody got to him before he could bring it in."

3. Too Many Warnings

For a moment, neither of the boys could say anything at all.

From the time they had learned to talk, they had heard stories and tales
that the miners and prospectors told about the Big Strike, the pot of
gold at the end of the rainbow, the wonderful, elusive goal of every man
who had ever taken a ship into the Asteroid Belt.

For almost a hundred and fifty years ... since the earliest days of
space exploration ... there had been miners prospecting in the
Asteroids. Out there, beyond the orbit of Mars and inside the orbit of
Jupiter, were a hundred thousand ... maybe a hundred million, for all
anybody knew ... chunks of rock, metal and debris, spinning in silent
orbit around the sun. Some few of the Asteroids were big enough to be
called planets ... Ceres, five hundred miles in diameter; Juno, Vesta,
Pallas, half a dozen more. A few hundred others, ranging in size from
ten to a hundred miles in diameter, had been charted and followed in
their orbits by the observatories, first from Earth's airless Moon, then
from Mars. There were tens of thousands more that had never been
charted. Together they made up the Asteroid Belt, spread out in space
like a broad road around the sun, echoing the age-old call of the
bonanza.

For there was wealth in the Asteroids ... wealth beyond a man's wildest
dreams ... if only he could find it.

Earth, with its depleted iron ranges, its exhausted tin and copper
mines, and its burgeoning population, was hungry for metal. Earth needed
steel, tin, nickel, and zinc; more than anything, Earth needed
ruthenium, the rare-earth catalyst that made the huge solar energy
converters possible.

Mars was rich in the ores of these metals ... but the ores were buried
deep in the ground. The cost of mining them, and of lifting the heavy
ore from Mars' gravitational field and carrying it to E