Just after dawn they caught sight of a white column of smoke, obscuring the stars over a whole quadrant of the sky. For a while this dense cloud was the only anomaly they could see in the landscape. Then, as they flew on and the terminator of the planet rolled under them, a broad swath of bright ground appeared on the eastern horizon ahead— an orange strip, or trough, running roughly northeast to southwest across the land, obscured by smoke that poured out of one section of it. The trough under the smoke was white and turbulent, as if a small volcanic eruption were confined to that one spot. Above it stood a beam of light— a beam of illuminated smoke, rather, so tight and solid that it was like a physical pillar, extending straight up and becoming less distinct as the cloud smoke thinned, and disappearing where the smoke reached its maximum height of around ten thousand meters.

At first there was no sign of the origin of this beam in the sky— the aerial lens was some four hundred kilometers overhead, after all. Then Sax thought he saw something like the ghost of a cloud, soaring very far above. Maybe that was it, maybe it wasn’t. Desmond wasn’t sure.

At the foot of the pillar of light, however, there was no question of visibility— the pillar of light had a kind of biblical presence, and the melted rock under it was truly incandescent, a very brilliant white. That was what 5000Âdeg;K looked like, exposed to the open air. “We have to be careful,” Desmond said. “We fly into that beam and it would be like a moth in a flame.”

“I’m sure the smoke is very turbulent as well.”

“Yes. I plan to stay windward of it.”

Down where the pillar of lit smoke met the orange channel, new smoke was spewing out in violent billows, weirdly lit from underneath. To the north of the white spot, where the rock had had a chance to cool, the melted channel reminded Sax of film of the eruptions of the Hawaiian volcanoes. Bright yellow-orange waves surged north in the channel of fluid rock, occasionally meeting resistances and splashing up onto the dark banks of the molten channel. The channel was about two kilometers wide, and ran over the horizon in both directions; they could see perhaps two hundred kilometers of it. South of the pillar of light, the channel bed was almost covered with cooling black rock, webbed by dark orange cracks. The straightness of the channel, and the pillar of light itself, were the only obvious signs that it was not some kind of natural lava channel; but these signs were more than enough. Besides, there hadn’t been any volcanic activity on the surface of Mars for many thousands of years.