the
longer light-waves of red and orange which were absent, so that things
looked much as they would have under the light of a G0-type star like
Sol. The air was faintly yellow, the sky was yellow with a greenish
cast, and the clouds were green-gray.

A thousand feet below, the local equivalent of a forest grew, the
trees, topped with huge ragged leaves, looking like hundred-foot
stalks of celery. There would be animal life down there, too--little
round things, four inches across, like eight-legged crabs, gnawing at
the vegetation, and bigger things, two feet long, with articulated
shell-armor and sixteen legs, which fed on the smaller herbivores.
Beyond, in the middleground, was open grassland, if one could so call
a mat of wormlike colorless or pastel-tinted sprouts, and a river
meandered through it. On the skyline, fifty miles away, was a range of
low dunes and hills, none more than a thousand feet high.

No human had ever set foot on the surface, or breathed the air, of
Niflheim. To have done so would have been instant death; the air was a
mixture of free fluorine and fluoride gasses, the soil was metallic
fluorides, damp with acid rains, and the river was pure hydrofluoric
acid. Even the ordinary spacesuit would have been no protection; the
glass and rubber and plastic would have disintegrated in a matter of
minutes. People came to Niflheim, and worked the mines and uranium
refineries and chemical plants, but they did so inside power-driven
and contragravity-lifted armor, and they lived on artificial
satellites two thousand miles off-planet. This vehicle, for instance,
was built and protected as no spaceship ever had to be, completely
insulated and entered only through a triple airlock--an outer lock,
which would be evacuated outward after it was closed, a middle lock
kept evacuated at all times, and an inner lock, evacuated into the
interior of the vehicle before the middle lock could be opened.
Niflheim was worse than airless, much worse.

The chief engineer sat at his controls, making the minor lateral
adjustments in the vehicle's position which were not possible to the
automatic controls. One of the radiomen was receiving from the orbital
base; the other was saying, over and over, in an exasperatedly
patient voice: "Dr. Murillo. Dr. Murillo. Please come in, Dr.
Murillo." At his own panel of instruments, a small man with grizzled
black hair around a bald crown, and a grizzled beard, chewed nervously
at the