In any case, in the north they were; and spring had arrived.  The days got longer by a little bit every day, and the work went on.  The area around the base got more cluttered, more criss-crossed with tracks; they had laid a cement road to Chernobyl, and the base itself was now so big that from the trailer park it extended over the horizon in all directions:  the alchemists' quarter and the Chernobyl road to the east, the permanent habitat to the north, the storage area and the farm to the west, and the bio-med center to the south.

Eventually everyone moved into the finished chambers of the permanent habitat.  The nightly conferences there were shorter and more routinized than they had been in the trailer park, and days went by when Nadia got no calls for help.  There were some people she saw only once in a while; the biomed crew in its labs, Phyllis's prospecting unit, even Ann.  One night Ann flopped on her bed next to Nadia's, and invited her to go along on an exploration to Hebes Chasma, some 130 kilometers to the southwest.  Obviously Ann wanted to show her something outside the base area; but Nadia declined.  "I've got too much work to do, you know."  And seeing Ann's disappointment:  "Maybe next trip."

And then it was back to work on the interiors of the chambers, and the exteriors of a new wing.  Arkady had suggested making the line of chambers the first of four, arranged in a square, and Nadia was going to do it; as Arkady pointed out, it would then be possible to roof the area enclosed by the square.  "That's where those magnesium beams will come in handy," Nadia said.  "If only we could make stronger glass panes. . . ."

They had finished two sides of the square, twelve chambers entirely done, when Ann and her team returned from Hebes.  Everyone spent that evening looking at their videotapes.  These showed the expedition's rovers rolling over rocky plains; then ahead there appeared a break extending all the way across the screen, as if they were approaching the edge of the world.   Strange little meter-high cliffs finally stopped the rovers, and the pictures bounced as one explorer got out and walked with helmet camera turned on.

Then abruptly the shot was from the rim, a one-eighty pan shot of a canyon that was so much bigger than the sinkholes of Ganges Catena that it was hard to grasp.  The walls of the far side of the chasm were just visible on the distant horizon.  In fact they could see walls all the way around, for Hebes was an almost-enclosed chasm, an sunken ellipse about two hundred kilometers long and a hundred across.  Ann's party had come to the north rim in late afternoon, and the eastern curve of the wall was clearly visible, flooded by sunset light; out to the west the wall was just a low dark mark.  The floor of the chasm was generally flat, with a central dip.  "If you could float a dome over the chasma," Ann said, "you'd have a nice big enclosure."