To stop the foolish waste of life, the Earth Government stepped in. It was decreed that no space ship might be owned or built privately. It was further decreed that those who felt an urge to explore must join the regular service and do so under efficient supervision. And there was created the Government bureau designated as the Planetary Exploration Control Board, which was headed by Commander Stone. * * * * * Under this Board the exploration of the planets was undertaken methodically and efficiently, with a minimum of lives sacrificed. Mercury was charted, tested for essential minerals, and found to be a valueless rock heap too near the sun to support life. Venus was visited and explored segment by segment; and friendly relations were established with the rather stupid but peaceable people found there. Mars was mapped. Here the explorers had lingered a long time: and all over this planet's surface were found remnants of a vast and intricate civilization--from the canals that laced its surface, to great cities with mighty buildings still standing. But of life there was none. The atmosphere was too rare to support it; and the theory was that it had constantly thinned through thousands of years till the last Martian had gasped and died in air too attenuated to support life even in creatures that must have grown greater and greater chested in eons of adaptation. Then Jupiter had been reached: and here the methodical planet by planet work promised to be checked for a long time to come. Jupiter, with its mighty surface area, was going to take some exploring! It would be years before it could be plotted even superficially. * * * * * Brand had been to Jupiter on four different trips; and, as he walked toward his quarters from Stone's office, he reviewed what he had learned on those trips. Jupiter, as he knew it, was a vast globe of vague horror and sharp contrasts. Distant from the sun as it was, it received little solar heat. But, with so great a mass, it had cooled off much more slowly than any of the other planets known, and had immense internal heat. This meant that the air--which closely approximated Earth's air in density--was cool a few hundred yards up from the surface of the planet, and dankly hot close to the ground. The result, as the cold air constantly sank into the warm, was a thick steamy blanket of fog that covered everything perpetually.