“I didn’t think of it, any more than you would have. It was bad luck, but I’m not grousing about it. Let’s get on with this job.” Hargedon nodded with approval, and possibly with some surprise, and the tractor hummed on its way.
The darkness deepened around the patches of lava shown by the driving lights; the sky darkened toward a midnight hue, with stars showing ever brighter through it; and radio reception from the Albireo began to get spotty. Gas density at the low ion layer was high enough so that recombination of molecules with their radiation-freed electrons was rapid. Only occasional streamers of ionized gas reached far over Darkside. As these thinned out, so did radio reception. Camille Burkett’s next broadcast came through very poorly.
There was enough in it, however, to seize the attention of the two men in the tractor.
She was saying: “—real all right, and dangerous. It’s the . . . thing I ever saw . . . kinds of lava from what looks like . . . same vent. There’s high viscosity stuff building a spatter cone to end all spatter cones, and some very thin fluid from somewhere at the bottom. The flow has already blocked the valley used by the Brightside routes and is coming along it. A new return route will have to be found for the tractors that . . . was spreading fast when I saw it. I can’t tell how much will come. But unless it stops there’s nothing at all to keep the flow away from, the ship. It isn’t coming fast, but it’s coming. I’d advise all tractors to turn back. Captain Rowson reminds me that only one takeoff is possible. If we leave this site, we’re committed to leaving Mercury. Arnie and Ren, do you hear me?”
Zaino responded at once. “We got most of it, Doctor. Do you really think the ship is in danger?”
“I don’t know. I can only say that if this flow continues the ship will have to leave, because this area will sooner or later be covered. I can’t guess how likely . . . check further to get some sort of estimate. It’s different from any Earthly lava source—maybe you heard—should try to get Eileen and Eric back, too. I can’t raise them. I suppose they’re well out from under the ion layer by now. Maybe you’re close enough to them to catch them with diffracted waves. Try, anyway. Whether you can raise them or not you’d better start back yourself.”
Hargedon cut in at this point. “What does Dr. Mardikian say about that? We still have most of the seismometers on this route to visit.”
“I think Captain Rowson has the deciding word here, but if it helps your decision Dr. Mardikian has already started back. He hasn’t finished his route, either. So hop back here, Ren. And Arnie, put that technical skill you haven’t had to use yet to work raising Eileen and Eric.”
“What I can do, I will,” replied Zaino, “but you’d better tape a recall message and keep it going out on—let’s see band F.”
“All right. be ready to check the volcano as soon as you get back. How long?”
“Seven hours—maybe six and a half,” replied Hargedon. “We have to be careful.”
“Very well. Stay outside when you arrive; I’ll want to go right out in the tractor to get a closer look.” She cut off.
“And that came through clearly enough!” remarked Hargedon as he swung the tractor around. “I’ve been awake for fourteen hours, driving off and on for ten of them. I’m about to drive for another six; and then I’m to stand by for more.”
“Would you like me to do some of the driving?” asked Zaino.
“I guess you’ll have to, whether I like it or not,” was the rather lukewarm reply. “I’ll keep on for a while though—until we’re back in better light. You get at your radio job.”
Zaino tried. Hour after hour he juggled from one band to another. Once he had Hargedon stop while he went out to attach a makeshift antenna which, he hoped, would change his output from broadcast to some sort of beam; after this he kept probing the sky with the “beam,” first listening to the Albireo’s broadcast in an effort to find projecting wisps of ionosphere and then, whenever he thought he had one, switching on his transmitter and driving his own message at it.
Not once did he complain about lack of equipment or remark how much better he could do once he was back at the ship.
Hargedon’s silence began to carry an undercurrent of approval not usual in people who spent much time with Zaino. The technician made no further reference to the suggestion of switching drivers. They came in sight of the Albireo and doubled the chasm with Hargedon still at the wheel, Zaino still at his radio and both of them still uncertain whether any of the calls had gotten through.
Both had to admit, even before they could see the ship, that Burkett had had a right to be impressed.
The smoke column showed starkly against the sky, blowing back over the tractor and blocking the sunlight which would otherwise have glared into the driver’s eyes. Fine particles fell from it in a steady shower; looking back, the men could see tracks left by their vehicle in the deposit which had already fallen.
As they approached the ship the dark pillar grew denser and narrower, while the particles raining from it became coarser. In some places the ash was drifting into fairly deep piles, giving Hargedon some anxiety about possible concealed cracks. The last part of the trip, along the edge of the great chasm and around its end, was really dangerous, cracks running from its sides were definitely spreading. The two men reached the Albireo later than Hargedon had promised, and found Burkett waiting impatiently with a pile of apparatus beside her.
She didn’t wait for them to get out before starting to organize.
“There isn’t much here. We’ll take off just enough of what you’re carrying to make room for this. No—wait. I’ll have to check some of your equipment; I’m going to need one of Milt Schlossberg’s gadgets, I think, so leave that on. We’ll take—”
“Excuse me, Doctor,” cut in Hargedon. “Our suits need servicing, or at least mine will if you want me to drive you. Perhaps Arnie can help you load for a while, if you don’t think it’s too important for him to get at the radio—”
“Of course. Excuse me. I should have had someone out here to help me with this. You two go on in. Ren, please get back as soon as you can. I can do the work here; none of this stuff is very heavy.”
Zaino hesitated as he swung out of the cab. True, there wasn’t too much to be moved, and it wasn’t very heavy in Mercury’s gravity, and he really should be at the radio; but the thirty-nine-year-old mineralogist was a middle-aged lady by his standards, and shouldn’t be allowed to carry heavy packages. . . .
“Get along, Arnie!” the middle-aged lady interrupted this train of thought. “Eric and Eileen are getting farther away and harder to reach every second you dawdle!”
He got, though he couldn’t help looking northeast as he went rather than where he was going.
The towering menace in that direction would have claimed anyone’s attention. The pillar of sable ash was rising straighter, as though the wind were having less effect on it. An equally black cone had risen into sight beyond Northeast Spur—a cone that must have grown to some two thousand feet in roughly ten hours. It had far steeper sides than the cinder mounds near it; it couldn’t be made of the same loose ash. Perhaps it consisted of half-melted particles which were fusing together as they fell—that might be what Burkett had meant by “spatter-cone.” Still, if that were the case, the material fountaining from the cone’s top should be lighting the plain with its incandescence rather than casting an inky shadow for its entire height.
Well, that was a problem for the geologists; Zaino climbed aboard and settled to his task.