King of the Hill by James Blish - A madman can be prevented from bomb-throwing—but a mad world?

It did Col. Hal Gascoigne no good whatsoever to know that he was the only man aboard Satellite Vehicle 1. No good at all. He had stopped reminding himself of the fact some time back.

And now, as he sat sweating in the perfectly balanced air in front of the bombardier board, one of the men spoke to him again:

"Colonel, sir—"

Gascoigne swung around in the seat, and the sergeant—Gascoigne could almost remember the man's name—threw him a snappy Air Force salute.

"Well?"

"Bomb one is primed, sir. Your orders?"

"My orders?" Gascoigne said wonderingly. But the man was already gone. Gascoigne couldn't actually see the sergeant leave the control cabin, but he was no longer in it.

While he tried to remember, another voice rang in the cabin, as flat and razzy as all voices sound on an intercom.

"Radar room. On target."

A regular, meaningless peeping. The timing circuit had cut in.

Or had it? There was nobody in the radar room. There was nobody in the bomb hold, either. There had never been anybody on board SV-1 but Gascoigne, not since he had relieved Grinnell—and Grinnell had flown the station up here in the first place.

Then who had that sergeant been? His name was—It was—