Sunday, February 05, 2012

Cold As Ice 1-6 - Charles Sheffield

"To the colonists and explorers creeping outward past the Belt in the third decade of the twenty-first century, Ganymede was the plum of the Jovian system. The largest of Jupiter's four Galileian satellites, it was also the biggest moon in the solar system, planet-sized with its radius of 2650 kilometers. There was plenty of Ganymede real estate to explore, shape, and develop.

Ganymede's low density offered a gravity only one-seventh that of Earth's, a factor most appealing to the low-gee Belters. And, finally, Ganymede had volatiles in abundance; ammonia and methane and—most precious of all—water. Half of Ganymede was fresh water and water-ice, the latter covering almost all of the frigid, cracked surface. A human wandering in a suit could split off a chunk of ice, thaw it, and safely drink the slightly sulfurous result.

There was only one snag. Jupiter loomed in the sky, a million kilometers away. Jupiter pluvius: Jupiter, the bringer of rain. But this rain was no cooling balm from heaven. It was an endless sleet of high-energy protons, gathered from the solar wind, accelerated by the demon of Jupiter's magnetic field, and delivered as a murderous hail into Ganymede's frozen surface. A human wanderer, garbed in a suit offering ample protection on Moon or Mars, would cook and die on Ganymede in a few hours.

The colonists had taken the problem in their stride. After all, the proton rain was far worse on little watery Europa, closer to Jupiter and visible in Ganymede's sky as a disk half the size again of Earth's moon. It was worse yet on sulfur-spitting Io, innermost of the four Galileian satellites.

Ganymede would do nicely. The whole solid interior of the moon was available and safe; all it needed was a little work. A handful of Von Neumanns in the form of tunneling robots was developed, dropped off, and left to replicate and do their thing for a few years, while the humans went away and redesigned their suits."

4 out of 5