Tom, Astro, and Jeff looked at each other. Finally Tom asked, "Well,
what do you think it is?"

"There's only one thing I know really well, Tom," replied Roger. "Just
one thing, and that's electronics. I may be a jerk about a lot of
things, but I know electronics."

"O.K.," said Astro. "You know electronics. But what has that got to do
with the instruments going out of whack?"

"The only natural element that would cause such disturbance is uranium."

"Uranium!" breathed Tom. "You mean uranium pitchblende?"

"I mean uranium!" snapped Roger. "Uranium pitchblende isn't concentrated
enough to cause a reaction like that on the instruments. It would take a
big chunk of pure uranium to do the job."

"But if that were so," Astro protested, "wouldn't the instruments still
be acting up? In fact, wouldn't we start feeling the effects of the
radiation?"

"Not necessarily, Astro," said Tom. "I understand what Roger's getting
at. The uranium could be located in another sector of the satellite, on
the other side, maybe. It could be throwing radiation out into space
without affecting us here."

"You mean we're _under_ the effects?" asked Astro.