Yes and no. The airlocks would limit an accident all right, if there was one which there won't be this place is safe. Primarily they let us work on a section of the tunnel at no pressure without disturbing the rest of it. But they are more than that; each one is a temporary expansion joint. You can tie a compact structure together and let it ride out a quake, but a thing as long as this tunnel has to give, or it will spring a leak. A flexible seal is hard to accomplish in the Moon.
What's wrong with rubber? I demanded. I was feeling jumpy enough to be argumentative. I've got a ground-car back home with two hundred thousand miles on it, yet I've never touched the tires since they were sealed up in Detroit.
Knowles sighed. I should have brought one of the engineers along, Jack. The volatiles that keep rubbers soft tend to boil away in vacuum and the stuff gets stiff. Same for the flexible plastics. When you expose them to low temperature as well they get brittle as eggshells.
The scooter stopped as Knowles was speaking and we got off just in time to meet half a dozen men coming out of the next airlock. They were wearing spacesuits, or, more properly, pressure suits, for they had hose connections instead of oxygen bottles, and no sun visors. Their helmets were thrown back and each man had his head pushed through the opened zipper in the front of his suit, giving him a curiously two-headed look. Knowles called out, Hey, Konski!
One of the men turned around. He must have been six feet two and fat for his size. I guessed him at three hundred pounds, earthside. It's Mr. Knowles, he said happily. Don't tell me I've gotten a raise.
You're making too much money now, Fatso. Shake hands with Jack Arnold. Jack, this is Fatso Konski the best sandhog in four planets.
Only four? inquired Konski. He slid his right arm out of his suit and stuck his bare hand into mine. I said I was glad to meet him and tried to get my hand back before he mangled it.
Jack Arnold wants to see how you seal these tunnels, Knowles went on. Come along with us.
Konski stared at the overhead. Well, now that you mention it, Mr. Knowles, I've just finished my shift.
Knowles said, Fatso, you're a money grubber and inhospitable as well. Okay time-and-a-half. Konski turned and started unsealing the airlock.
The tunnel beyond looked much the same as the section we had left except that there were no scooter tracks and the lights were temporary, rigged on extensions. A couple of hundred feet away the tunnel was blocked by a bulkhead with a circular door in it. The fat man followed my glance. That's the movable lock, he explained. No air beyond it. We excavate just ahead of it.
Can I see where you've been digging?
Not without we go back and get you a suit.
I shook my head. There were perhaps a dozen bladder-like objects in the tunnel, the size and shape of toy balloons. They seemed to displace exactly their own weight of air; they floated without displaying much tendency to rise or settle. Konski batted one out of his way and answered me before I could ask. This piece of tunnel was pressurized today, he told me. These tag-alongs search out stray leaks. They're sticky inside. They get sucked up against a leak, break, and the goo gets sucked in, freezes and seals the leak.
Is that a permanent repair? I wanted to know.
Are you kidding? It just shows the follow-up man where to weld.
Show him a flexible joint, Knowles directed.
Coming up. We paused half-way down the tunnel and Konski pointed to a ring segment that ran completely around the tubular tunnel. We put in a flex joint every hundred feet. It's glass cloth, gasketed onto the two steel sections it joins. Gives the tunnel a certain amount of springiness.
Glass cloth? To make an airtight seal? I objected.
The cloth doesn't seal; it's for strength. You got ten layers of cloth, with a silicone grease spread between the layers. It gradually goes bad, from the outside in, but it'll hold five years or more before you have to put on another coat.
I asked Konski how he liked his job, thinking I might get some story. He shrugged. It's all right. Nothing to it. Only one atmosphere of pressure. Now you take when I was working under the Hudson
And getting paid a tenth of what you get here, put in Knowles. Mr. Knowles, you grieve me, Konski protested. It ain't the money; it's the art of the matter. Take Venus. They pay as well on Venus and a man has to be on his toes. The muck is so loose you have to freeze it. It takes real caisson men to work there. Half of these punks here are just miners; a case of the bends would scare 'em silly.
Tell him why you left Venus, Fatso.
Konski expressed dignity. Shall we examine the movable shield, gentlemen? he asked.
We puttered around a while longer and I was ready to go back. There wasn't much to see, and the more I saw of the place the less I liked it. Konski was undogging the door of the airlock leading back when something happened.
I was down on my hands and knees and the place was pitch dark. Maybe I screamed I don't know. There was a ringing in my ears. I tried to get up and then stayed where I was. It was the darkest dark I ever saw, complete blackness. I thought I was blind.
A torchlight beam cut through it, picked me out, and then moved on. What was it? I shouted. What happened? Was it a quake?
Stop yelling, Konski's voice answered me casually. That was no quake, it was some sort of explosion. Mr. Knowles you all right?
I guess so. He gasped for breath. What happened?
Dunno. Let's look around a bit. Konski stood up and poked his beam around the tunnel, whistling softly. His light was the sort that has to be pumped; it flickered.
Looks tight, but I hear Oh, oh! sister! His beam was focused on a part of the flexible joint, near the floor.
The tag-along balloons were gathering at this spot. Three were already there; others were drifting in slowly. As we watched, one of them burst and collapsed in a sticky mass that marked the leak.
The hole sucked up the burst balloon and began to hiss. Another rolled onto the spot, joggled about a bit, then it, too, burst. It took a little longer this time for the leak to absorb and swallow the gummy mass.
Konski passed me the light. Keep pumping it, kid. He shrugged his right arm out of the suit and placed his bare hand over the spot where, at that moment, a third bladder burst.
How about it, Fats? Mr. Knowles demanded.
Couldn't say. Feels like a hole as big as my thumb. Sucks like the devil.
How could you get a hole like that?
Search me. Poked through from the outside, maybe.
You got the leak checked?
I think so. Go back and check the gauge. Jack, give him the light.
Knowles trotted back to the airlock. Presently he sang out, Pressure steady!
Can you read the vernier? Konski called to him.
Sure. Steady by the vernier.
How much we lose?
Not more than a pound or two. What was the pressure before?
Earth-normal.
Lost a pound four tenths, then.
Not bad. Keep on going, Mr. Knowles. There's a tool kit just beyond the lock in the next section. Bring me back a number three patch, or bigger.
Right. We heard the door open and clang shut, and we were again in total darkness. I must have made some sound for Konski told me to keep my chin up.
Presently we heard the door, and the blessed light shone out again. Got it? said Konski.
No, Fatso. No... Knowles' voice was shaking. There's no air on the other side. The other door wouldn't open.
Jammed, maybe?
No. I checked the manometer. There's no pressure in the next section.
Konski whistled again. Looks like we'll wait till they come for us. In that case Keep the light on me, Mr. Knowles. Jack, help me out of this suit.