That’s why the final approach takes so long. They don’t like anything they can’t account for in the neighborhood — and that goes for stray electrons and molecules, as well as atomic converters.”

“What is their objection to rocket blasts, provided they’re not fired directly at the station?” asked Wren. “What influence could a jet of gas even one mile away possibly have on their machinery?”

“None, directly; but gases diffuse, and some of the elements in rocket fuel are easily ionized in sunlight. The boys in there claim that the firing of a rocket blast five miles from the outer sphere will disturb some of their circuits, when the molecules which happen to leak inside their screen are ionized there. It sounds a little farfetched to me, but that’s not my line. I do know that that machine is inoperative nearly half the time from causes which are not precisely known, but which must be of the same order of magnitude as the one I mentioned. I’m careful of my jets around here, because they’d have my job if I caused them trouble more than once; and the board would slap a ‘lack of proficiency’ on my dismissal papers, so I’d have a nasty time finding a new one.”

“If you make this trip regularly, I don’t suppose you have much difficulty with this rather tricky glide.”

“I’m used to it. I’ve been making this supply run every week for nearly three years, with special flights between times. This ship carries everything they need at the station, and also the bright boys from home who have special problems to work, and don’t believe the machine can handle them without their personal presence.” The pilot looked sideways at Wren. “Most of those fellows were able to tell me things I didn’t know about the computer. You’re the first sightseer I’ve ever carried. I didn’t think the universities encouraged them. Are you a journalist?”

Wren smiled. “I don’t blame you for getting some such idea. I’ll admit I don’t know the first thing about electronic computers; the station out here is only a name to me. But I have a problem. I don’t know whether it can be stated in terms that can be treated here or now; I know very little math; but I decided to come out for a conference with the operators, to find out whether or not I could be helped.”