The Mercurian Planeteer base was in the twilight zone, but the Planeteers did all their work on the sun side, using special alloy suits to mine the precious nuclite that only the hot planet provided.
At some time during its first years, Mercury had been so close to the sun that its temperature was driven high enough to permit a subatomic thermo-nuclear reaction. The reaction had shorn some elements of their electrons and left a thin coating of material composed almost entirely of neutrons. The[pg 165] nuclite was incredibly dense. It could be handled only in low gravity because of its weight. But nothing else provided the shielding against radiation and meteors half so well and it was in great demand for spaceship skins.
"Things aren't so bad," Go told Rip. "The base is comfortable and we only work a two hour shift out of each ten. We've had a plague of silly dillies recently. They got into one man's suit while we were working, but mostly they're just a nuisance."
Rip had heard of the creatures. They were like earth armadillos, except that they were silicon animals and not carbon like those of earth. They were drawn to oxygen like iron to a magnet, and their diamond hard tongues, used for drilling rock in order to get the minerals on which they lived, could drive right through a space suit. Or, if they could work undetected for a short while, they could drill through the shell of a space station.
Scralabus primus was the scientific name of the creature, but the fact that it looked like a silicon armadillo had given it the popular name of "silly dilly." Apart from its desire for oxygen it was harmless.
Koa reported, "Sir, the block of thorium is ready. We've hung it on a line behind the landing boat. The blast won't hurt it, and it's too big to get inside the boat."
"Fine, Koa. Well, Captain, that does it."
The Mercurian Planeteers got into their craft and blasted off, trailing the block of thorium in their exhaust. Rip watched the cruiser take the craft and thorium aboard, then drive toward Mercury, brilliant sunlight reflecting from its sleek sides. The planet was only a short distance away by spaceship. It was the largest thing in space, except for the sun, as seen from the asteroid. To Rip it looked about three times the size of the moon as seen from earth.
Past the orbit of Mercury, the sun side of the asteroid grew dangerously hot for men in space suits. Rip and the Planeteers stayed in the bitter cold of the dark side, which ceased to be entirely dark. Even the temperature rose somewhat. They were close enough to the sun so that the prominences, great flaming tongues of hydrogen that sped many thousands of miles into space, gave them light and enough heat to register on Rip's instruments.
Mercury was left far behind, and earth could not be seen because of the sun. There was nothing to do now but ride out the rest of the trip as comfortably as possible until it was time to throw the asteroid into an ever-tightening series of elliptical orbits around earth, known as braking ellipses. The method would use earth's gravity to slow them down to the proper speed. A single atomic bomb and a half dozen tubes of rocket fuel remained.