“Even Dr. Burkett? That is — I mean—”

“Even Dr. Burkett. Here, get into your suit. And maybe you’d better take out the mike. It’ll be enough if you can listen for the next hour or two.” Zaino made no answer, suspecting with some justice that anything he said would be wrong.

Each made final checks on the other’s suit; then they descended one more level to the airlock. This occupied part of the same deck as the fusion plants, below the wings and reaction mass tanks but above the main engine. Its outer door was just barely big enough to admit a space-suited person. Even with the low air pressure carried by spaceships, a large door area meant large total force on jamb, hinges and locks. It opened onto a small balcony from which a ladder led to the ground. The two men paused on the balcony to look over the landscape.

This, hadn’t changed noticeably since the last time either had been out, though there might have been some small difference in the volcanic cones a couple of miles away to the northeast. The furrows down the sides of these, which looked as though they had been cut by water but were actually bone-dry ash slides, were always undergoing alteration as gas from below kept blowing fresh scoria fragments out of the craters.

The spines — steep, jagged fragments of rock which thrust upward from the plain beyond and to both sides of the cones — seemed dead as ever.

The level surface between the Albireo and the cones was more interesting. Mardikian and Schlossberg believed it to be a lava sheet dating from early in Mercury’s history, when more volatile substances still existed in the surface rocks to cut down their viscosity when molten. They supposed that much — perhaps most — of the surface around the “twilight” belt had been flooded by this very liquid lava, which had cooled to a smoother surface than most Earthly lava flows.