The sign read: “IN CASE OF ELECTRICAL FAILURE BREAK GLASS”.
Johnson broke the glass.
“The hell is this?”
“It’s a slide rule. And it’s going to save our asses.”
“Lotta fancy numbers. What’s it do?”
“It multiplies, divides, square roots, all the usual things ‘cept addition. This one does trig and exponents too. It’s more precise than your brain, but less so than a computer. That EMP means we don’t have a computer, though. Both backups are dead too.”
“Well, we had no way of knowing that that particular CME would hit us way out here at Jupiter. The chances of that must be pretty absurd.”
“Not really. Happens all the time. But our electrical shielding clearly wasn’t up to par, and this was a particularly big one. Right now, we’re dead fish in a very big sea. See if the emergency sparkgap is working. Tell Ganymede we’re scrubbing the mission–and we’ll use this thing to figure out how to burn for home.”
Ed. note: Idea from Atomic Rockets. I myself restored a K&E for work, and have another at home. They’re useful for one-off calculations that would be too slow to do in my head and too unimportant to boot a shell.