reader, and they stared eagerly at the last few
entries.

A series of calculations, covering several pages, but with no notes to
indicate what, exactly, Roger Hunter had been calculating. "Looks like
he was plotting an orbit," Greg said. "But what orbit? And why? Nothing
here to tell."

"It must have been important, though, or Dad wouldn't have filmed the
pages," Tom said. "Anything else?"

Another sheet with more calculations. Then a short paragraph written in
Roger Hunter's hurried scrawl. "No doubt now what it is," the words
said. "Wish Johnny were here, show him a _real_ bonanza, but he'll know
soon enough if...."

They stared at the scribbled, uncompleted sentence. Then Johnny Coombs
let out a whoop. "I told you he found something! And he found it _here_,
not somewhere else."

"Hold it," Greg said, peering at the film reader. "There's something
more on the last page, but I can't read it."

Tom blinked at the entry. "'Inter Jovem et Martem planetam interposui,'"
he read. He scratched his head. "That's Latin, and it's famous, too.
Kepler wrote it, back before the asteroids were discovered. 'Between
Jupiter and Mars I will put a planet.'"

Greg and Johnny looked at each other. "I don't get it," Greg said.

"Dad told me about that once," Tom said. "Kepler couldn't understand
the long jump between Mars and Jupiter, when Venus and Earth and Mars
were so close together. He figured there ought to be a planet out
here ... and he was right, in a way. There wasn't any one planet, unless
you'd call Ceres a planet, but it wasn't just empty space between Mars
and Jupiter either. The asteroids were here."

"But why would Dad be writing that down?" Greg asked. "And what has it
got to do with what he found out here?" He snapped off the reader switch
angrily. "I don't understand any of this, and I don't like it. If Dad
found something out here, where is it? And who tore this ship apart
after the Patrol ship left?"

"Probably the same ones that caused the 'accident' in the first place,"
Johnny said.

"But why did they come back?" Greg protested. "If they killed Dad, they
must have known what he'd found before they killed him."

"You'd think so," Johnny conceded.

"Then why take the risk of coming back here again?"

"Maybe they _didn't_ know," Tom said thoughtfully.

"What do you mean?"

"I mean maybe they killed him too soon. Maybe they thought they knew
what he'd found and where it was ... and then found out tha