There must be an atmosphere of some sort, or else that snow and ice wouldn't be there, and everything would be either black or white as it was on the Moon.

We may as well land, however, and get a specimen of the rocks and soil to add to the museum, though I don't expect there will be very much to see in the way of life." In another hour or so the _Astronef_ had dropped gently on to the surface of Calisto at the foot of a range of mountains crowded with jagged and splintery peaks, and a mile or two from the edge of a sea of snow and ice which stretched away in a vast expanse of rugged frozen billows beyond the horizon.

Redgrave, as usual, went into the air-chamber and tried the atmosphere.

A second's experience of it was enough for him.

It was unbreathably thin and unbearably cold, although, when mixed with the air of the _Astronef_, it distinctly freshened it up.