ctly; the materialization is spontaneous. Mass somehow distorts
hyperspace, and when the projected matter has penetrated a certain
distance into such distortion, it pops back into normal space. The
penetration depends mainly upon a sort of internal energy in the
missile; you might think of it more as a voltage than as velocity.
You've made it very hard for us to get reports, but I understand we
successfully placed stuff in Sennech's crust."

"Yes; causing volcanoes. Our scientists speculated that any kind of
matter would do it."

"That's right. Actually, we were projecting weighed chunks of rock. When
one bit of matter, even a single atom, finds itself materializing where
another already is, unnatural elements may be formed, most of them
unstable. That's what blew holes in your crust and let the magma out."

Tulan considered the military implications of the weapon for a few
moments, then pulled his mind back. "I see; but what about the
radiation? It wasn't more than a trace when I left."

Kliu looked away for a while before answering. "When we learned you'd
defied your government, our own military got out of hand. They had a
couple of days before the sun cut us off completely, and they began
throwing stuff as soon as it could be dug and hauled to the projectors.
They used high energies to get it past the sun. As we realize now, a lot
of it hit the planet deeper than at first, below the crust. Under such
pressure a different set of fissionables was formed. Some of them burst
out and poisoned the atmosphere, but most of them are still there." He
leaned forward and eyed Tulan hard. "We've got to get an expedition out
there to study things. Will you help?"

There was another of the palpable silences, and when he spoke Tulan's
voice sounded unnatural. "I--yes; we'll help. Whatever you want. Is ...
Sennech finished?"

Kliu smiled tightly. "Sennech, for sure; and she may take the rest of us
with her. Nobody conceived what this might come to. A lot of those deep
materializations produced pockets of dense fissionables, and they're
converging toward the center under their own weight. When they get to a
certain point, we'll have a fine monument to Man's ingenuity. A
planet-size nova." He stood up. "I'll start organizing."

* * * * *

Tulan existed someway through the preparations, and when they were in
space again the solid familiarity of his ship helped. His staff was
carrying on wonderfull