Hot Planet

The voice droned on until about two dozen readings had been taped. Then, “I’m going closer now. The sampler is just a ladle on a twelve-foot handle we improvised, so I’ll have to get that close. The stuff is moving slowly; there should be no trouble. I’m in reach now. The lava is very liquid; there’s no trouble getting the sampler in — or out again — it’s not very dense, either. I’m heading back toward the tractor now. No, Ren, don’t come to meet me.”

There was a minute of silence, while Zaino pictured the space-suited figure with its awkwardly long burden, walking away from the creeping menace to the relative safety of the tractor. “It’s frozen solid already; we needn’t worry about spilling. The temperature is about — five eighty. Give me the markers, please.”

Another pause, shorter this time. Zaino wondered how much of that could be laid to a faster walk without the ladle and how much to the lessening distance between flow and tractor. “I’m tossing the first marker close to the edge — it’s landed less than a foot from the lava. They’re all on a light cord at ten-foot intervals; I’m paying out the cord as I go back to the tractor. Now we’ll stand by and time the arrival at each marker as well as we can.”

“How close are you to the main cone?” asked Zaino. “Not close enough to see its base, I’m afraid. Or to get a sample of it, which is worse. We — goodness, what was that?’

Zaino had just time to ask, “What was what?” when he found out.

For a moment, he thought that the Albireo had been flung bodily into the air. Then he decided that the great metal pillar had merely fallen over. Finally he realized that the ship was still erect, but the ground under it had just tried to leave.

Everyone in the group had become so used to the almost perpetual ground tremors that they had ceased to notice them; but this one demanded attention. Rowson, using language which suggested that his career might not have been completely free of adventure after all, flashed through the communication level on his way down to the power section. Schlossberg and Babineau followed, the medic pausing to ask Zaino if he were all right. The radioman merely nodded affirmatively; his attention was already back at his job. Burkett was speaking a good deal faster than before.

•“Never mind if the sample isn’t lashed tight yet — if it fails off there’ll be plenty more. There isn’t time! Arnie, get in touch with Dr. Mardikian and Dr. Marini. Tell them that this volcano is explosive, that all estimates of what the flow may do are off until we can make more measures, and in any case the whole situation is unpredictable. Everyone should get back as soon as possible. Remember, we decided that those big craters Eileen checked were not meteor pits. I don’t know whether this thing will go in the next hour, the next year, or at all. Maybe what’s happening now will act as a safety valve — but let’s get out. Ren, that flow is speeding up and getting higher, and the ash rain is getting a lot worse. Can you see to drive?”

She fell silent, Zaino, in spite of her orders, left his set long enough to leap to the nearest port for a look at the volcano.

He never regretted it.

Across the riven plain, whose cracks were now nearly hidden under the new ash, the black cone towered above the nearer elevations. It was visibly taller than it had been only a few hours before. The fountain from its top was thicker, now jetting straight up as though wind no longer meant a thing to the fiercely driven column of gas and dust. The darkness was not so complete; patches of red and yellow incandescence showed briefly in the pillar, and glowing sparks rather than black cinders rained back on the steep slopes. Far above, a ring of smoke rolled and spread about the column, forming an ever-broadening blanket of opaque cloud above a landscape which had never before been shaded from the sun. Streamers of lightning leaped between cloud and pillar, pillar and mountain, even cloud and ground. Any thunder there might have been was drowned in the howl of the escaping gas, a roar which seemed to combine every possible note from the shrillest possible whistle to a bass felt by the chest rather than heard by the ears. Rowson’s language had become inaudible almost before he had disappeared down the hatch.

For long moments the radioman watched the spreading cloud, and wondered whether the Albireo could escape being struck by the flickering, ceaseless lightning. Far above the widening ring of cloud the smoke fountain drove, spreading slowly in the thinning atmosphere and beyond it. Zaino had had enough space experience to tell at a glance whether a smoke or dust cloud was in air or not. This wasn’t, at least at the upper extremity. . And then, quite calmly, he turned back to his desk, aimed the antenna straight up, and called Eileen Harmon. She answered promptly.

The stratigrapher listened without interruption to his report and the order to return. She conferred briefly with her companion, replied “We’ll be back in twelve hours,” and signed off. And that was that.

Zaino settled back with a sigh, and wondered whether it would be tactful to remind Rowson of his offer of a year’s pay.

All four vehicles were now homeward bound; all one had to worry about was whether any of them would make it. Hargedon and Burkett were fighting their way through an ever-increasing ash rain a scant two miles away — ash which not only cut visibility but threatened to block the way with drifts too deep to negotiate. The wind, now blowing fiercely toward the volcano, blasted the gritty stuff against their front window as though it would erode through; and the lava flow, moving far faster than the gentle ooze they had never quite measured, surged — and glowed — grimly behind.

A hundred miles or more to the east, the tractors containing Mardikian, Marini and their drivers headed southwest along the alternate route their maps had suggested; but Mardikian, some three hours in the lead, reported that he could see four other smoke columns in that general direction.

Mercury seemed to be entering a new phase. The maps might well be out of date.

Harmon and Trackman were having no trouble at the moment, but they would have to pass the great chasm. This had been shooting out daughter cracks when Zaino and Hargedon passed it hours before. No one could say what it might be like now, and no one was going out to make sure.

“We can see you!” Burkett’s voice came through suddenly. “Half a mile to go, and we’re way ahead of the flow.”

“But it’s coming?” Rawson asked tensely. He had returned from the power level at Zaino’s phoned report of success.

“It’s coming.”

“How fast? When will it get here? Do you know whether the ship can stand contact with it?”

“I don’t know the speed exactly. There may be two hour, maybe five or six. The ship can’t take it. Even the temperature measures I got were above the softening point of the alloys, and it’s hotter and much deeper now. Anyway, if the others aren’t back before the flow reaches the ship they won’t get through. The tractor wheels would char away, and I doubt that the bodies would float. You certainly can’t wade through the stuff in a space suit, either.”

“And you think there can’t be more than five or six hours before the flow arrives?”

“I’d say that was a very optimistic guess. I’ll stop and get a better speed estimate if you want, but won’t swear to it.”

Rowson thought for a moment.

“No,” he said finally, “don’t bother. Get back here as soon as you can. We need the tractor and human muscles more than we need even expert guesses.” He turned to the operator.

“Zaino, tell all the tractors there’ll be no answer from the ship for a while, because no one will be aboard. Then suit up and come outside.” He was gone.

Ten minutes later, six human beings and a tractor were assembled in the flame-lit near-darkness outside the ship. The cloud had spread to the horizon, and the sun was gone. Burkett and Hargedon had arrived, but Rowson wasted no time on congratulations.

“We have work to do. It will be easy enough to keep the lava from the ship, since there seems to be a foot or more of ash on the ground and a touch of main drive would push it into a ringwall around us; but that’s not the main problem. We have to keep it from reaching the chasm anywhere south of us, since that’s the way the others will be coming. If they’re cut off, they’re dead. It will be brute work. We’ll use the tractor any way we can think of. Unfortunately it has no plow attachment, and I can’t think of anything aboard which could be turned into one. You have shovels, such as they are. The ash is light, especially here, but there’s a mile and a half of dam to be built. I don’t see how it can possibly be done. . but it’s going to be.”

“Come on, Arnie! You’re young and strong,” came the voice of the mineralogist. “You should be able to lift as much of this stuff as I can. I understand you were lucky enough to get hold of Eileen — have you asked for the