“You see, gentlemen, most of what we learned, we learned from putting negamatter atoms together.  We annihilated a few of them—­over there in that little concrete building, we have one of the most massive steel vaults in the world, where we do that—­but we assembled millions of them for every one we annihilated, and that chunk of nega-iron inside the magnetic bottle kept growing.  And when you have a piece of negamatter you don’t want, you can’t just throw it out on the scrap-pile.  We might have rocketed it into escape velocity and let it blow up in space, away from the Moon or any of the artificial satellites, but why waste it?  So we’re going to have the rocket eject it, and when it falls, we can see, by our telemetered instruments, just what happens.”

“Well, won’t it be annihilated by contact with atmosphere?” somebody asked.

“That’s one of the things we want to find out,” Pitov said.  “We estimate about twenty percent loss from contact with atmosphere, but the mass that actually lands on the target area should be about forty kilos.  It should be something of a spectacle, coming down.”

“You say you had to assemble it, after creating the negative protons and neutrons and the positrons.  Doesn’t any of this sort of matter exist in nature?”

The man who asked that knew better himself.  He just wanted the answer on the record.

“Oh no; not on this planet, and probably not in the Galaxy.  There may be whole galaxies composed of nothing but negamatter.  There may even be isolated stars and planetary systems inside our Galaxy composed of negamatter, though I think that very improbable.  But when negamatter and posimatter come into contact with one another, the result is immediate mutual annihilation.”

They managed to get away from the press, and returned as far as the bunkers, a mile and a half away.  Before they went inside, Richardson glanced up at the sky, fixing the location of a few of the more conspicuous stars in his mind.  There were almost a hundred men and women inside, each at his or her instruments—­view-screens, radar indicators, detection instruments of a dozen kinds.  The reporters and telecast people arrived shortly afterward, and Eugenio Galvez took them in tow.  While Richardson and Pitov were making their last-minute rounds, the countdown progressed past minus one hour, and at minus twenty minutes all the overhead lights went off and the small instrument operators’ lights came on.

Pitov turned on a couple of view-screens, one from a pickup on the roof of the bunker and another from the launching-pad.  They sat down side by side and waited.  Richardson got his pipe out and began loading it.  The loudspeaker was saying:  “Minus two minutes, one fifty nine, fifty eight, fifty seven—­”

He let his mind drift away from the test, back to the world that had been smashed around his ears in the autumn of 1969.  He was doing that so often, now, when he should be thinking about—­