Number Five engine had started having problems. The diagnostics pinpointed one of the valves involved in feeding reaction mass to the chamber. Fortunately, it was in a well-shielded area, because both she and Gupta wanted to replace the valve immediately and examine the old one to see what had gone wrong. If it was simply a defective part, fine. What they didn't want was to discover at the end of the trip that there was some underlying problem that had caused it to malfunction. By then, it might be too late to fix—and they'd need that engine for the braking maneuver.
"All bolts off, Jackie."
"Good." She forced her eyes to focus on the scene in front of her. "Okay, that panel was designed to swing up and out. It's on hinges, and there's a clip on the wall behind it which should keep it out of the way. Open her up."
Tim complied, slowly opening the access panel and locking it to the clip on the wall. "Got it."
"You should be seeing . . ." She trailed off, fighting to focus her memory. "There'll be three pipes in there. One has a bright red stripe on it, one a bright yellow, and one bright white."
"Yeah, you got it. Red, yellow, white."
"There should be two shutoff valve handles on each pipe. In between these shutoff valves are the control valve units."
"The shutoff valve handles are sort of like door handles, not like round spigot things, right?"
"Yes, that's right. They're open if they're in line with the pipe and closed if they're at right angles to the pipe. All of them should be open right now."
"They are," Tim verified, after a short pause. "You want me to close them?"
"Just the ones for the feeder line. That's the white-painted pipe."
"Gotcha." A few seconds went by. "Damn, this bugger is— whoa!"
Tim Edwards flailed a bit on the screen and started floating away from Nike. Jackie reflexively gasped before common sense caught up with her reaction. Just at that point, Edwards' safety line brought him to a mostly-cushioned halt and he began a very slow drift back.
"I'm okay, I'm okay! Don't worry. The one valve was sticky and I had to push pretty hard. When it gave I overcompensated."
Jackie's heart was pounding and her stomach roiled. "Ugh. Don't do that again, please. When I worry I get sicker."
"I'll try. Okay, both of these are now at right angles to the pipe. You're sure I'm not going to end up glowing in the dark?"
"You've got a rad meter on you now. Your major danger is from space radiation, not from our engines. The quicker we get this done, the better off we'll be."
"Roger that. I have the valves shut off on the white-painted pipe. What do I do next?"
"Now we have to remove—"
She stopped, appalled. "Did you say white-painted?"
"Yes. That was the one you told me to shut off."
"Jesus, I'm completely out of it. Please reopen those valves. That's not the feeder for the reaction mass, it's the coolant."
"That's bad, isn't it?"
"Not under these circumstances, actually. We've already got it shut down. But it would have been in other circumstances, and in this case it would've meant you'd have wasted your trip out there. The one you want is the yellow pipe. I did say 'yellow' this time, didn't I?"
"Yellow, as in yellow-bellied. Um. Perhaps a poor choice of words, given the way I'm feeling right now. That's the one we want. Are you sure this time?"
"Yes. I'm sure. Yellow. Put the ones on the white pipe back in line, then turn off the ones on the yellow pipe."
"Roger." A few seconds passed. "All right, Jackie, the yellow pipe now has both valves in shutoff position, at right angles to the pipe. The white pipe's valves are both in line with the pipe."
"Very good." She focused on the situation at hand. "All right. That boxy-looking affair between the two shutoff valves is the control valve we're interested in. Please do a visual verification that the two units—the one you have with you, and the one we are about to remove—look the same."
"Confirmed," Tim's voice said shortly. "Allowing for the fact that I can't see all of the one that's currently in there."
"Don't worry. We'll have a couple of other checkpoints along the way. How are you holding up?"
"It's a little warm, but I can always duck a bit down to cool off. There's shade handy, and the suits are pretty good at keeping us cool."
"Just let me know if you start feeling even a little bit off. I don't want you getting sick out there in the middle of this. We can always leave Number Five shut down for a while, if we have to. It's not like we really need nuclear drive right now anyway."