I followed and sealed the outer port of the crawl-through behind me. The reason for that is simple enough. As long as the tunnel isn't breached, it doesn't matter what you do. But the interior of a Heechee tunnel that has remained inviolate is at a pressure only slightly above Earth-normal. Without the sealed dome of the igloo, the minute you crack the casing you let the whole ninety-thousandmillibar atmosphere of Venus pour in, heat and ablation and corrosive chemicals and all. If the tunnel is empty, or if what's in it is simple, sturdy stuff, there might not be any harm. But there are a couple of dozen mysterious chunks of scrap in the museums that might have been interesting machines-if whoever found them hadn't let the atmosphere in to squeeze them into junk. If you hit the jackpot, you can destroy in a second what has waited hundreds of thousands of years to be discovered.
We gathered around the shaft, and I pointed down. The augers had left a clean shaft, about seventy centimeters by a little over a hundred, with rounded edges. At the bottom you could see the cold blue glow of the outside of the tunnel, only pocked by the augers and blotched by the loose castings I hadn't bothered to get out.
"Now what?" Cochenour demanded. His voice was hoarse with excitement-natural enough, I guessed.
"Now we burn our way in."
I backed my clients as far away as they could get inside the igloo, pressed against the remaining heap of castings. Then I unlimbered the firejets. I'd already hung shear-legs over the shaft. The jets slipped right down on their cable until they were just a few centimeters above the round of the tunnel.
Then I fired them up.
You wouldn't think that anything a human being might do would make anything hotter than Venus does already, but the firejets were something special. In the small space of the igloo the heat
flamed up and around us. Our heatsuit cooling systems were overwhelmed in a moment.
Dorrie gasped, "Oh! I-I think I'm going to-"
Cochenour grabbed her arm. "Faint if you want to," he said fiercely, "but don't get sick inside your suit. Waithers! How bug does this go on?"
It was as hard for me as it was for them. Practice doesn't get you used to something like standing in front of a blast furnace with the doors off the hinges. "Maybe a minute," I gasped. "Hold on-it's all right."
It actually took a little more than that, maybe ninety seconds. My suit telltales were shouting overload alarm for more than half of that time. But the suits were built for these temporary overloads. As long as we didn't cook inside them, the suits themselves would survive.
Then we were through. A half-meter circular section of the tunnel roof sagged, fell at one side, and hung there, swaying.
I turned off the jets. We all breathed hard for a couple of minutes, while the Suit coolers gradually caught up with the load.
"Wow," said Dorotha. "That was pretty rough."
In the light that splashed up out of the shaft I could see that Cochenour was frowning. I didn't say anything. I just gave the jets another five-second burn to cut away the rest of the circular section. It fell free to the tunnel floor, with a smack like rock.
Then I turned on my helmet radio.
"There's no pressure differential," I said.
Cochenour's frown didn't change, nor did he speak.
"That means this one has been breached," I went on. "Somebody found it, opened it up-probably cleaned it out, if there ever was anything here-and just didn't report it. Let's go back to the airbody and get cleaned up."
Dorotha shrieked, "Audee, what's the matter with you? I want to go down there and see what's inside!"
"Shut up, Dorrie," Cochenour said bitterly. "Don't you hear what he's saying? This one's a washout."
Well, there's always the chance that a breached tunnel might have been opened by some seismological event, not a maze-rat with a cutting torch. If so, there might possibly be something in it worth having anyway. And I didn't have the heart to kill all Dorotha's enthusiasm with one blow.
So we did swing down the cable, one by one, into the Heechee dig. We looked around. It was wholly bare, as most of them are, as far as we could see. That wasn't actually very far. The other thing wrong with a breached tunnel is that you need special equipment to explore it. With the overloads they'd already had, our suits were all right for another few hours but not much more than that.
So we tramped down the tunnel about a kilometer and found bare walls, chopped-off struts on the glowing blue walls that might once have held something-and nothing movable. Not even junk.
Then they were both willing to tramp back and climb up the cable to the airbody. Cochenour made it on his own. So did Dorrie, though I was standing by to help her; she did it all hand over hand, using the stirrups spaced along the cable.
We cleaned up and made ourselves a meal. We had to eat, but Cochenour was not in a mood for his gourmet exhibition. Silently, Dorotha threw tablets into the cooker and we fed gloomily on prefabs.
