Sci-Fi short story possibly from a “Best of” anthology from the 1950s-60s about a space voyage with a secret engine activated via sex

Question

I read it in the 1980s. I'm pretty sure it was from an annual science fiction short story anthology compilation, probably from sometime in the mid 50s to mid 60s. It was written in English and nothing about the story read as though it was translated from another language.

The story was about a group of astronauts and/or possibly various types of scientists (male and female) on a spaceship with a special engine that they didn't know how to activate. Mission Control wouldn't tell them, either. The voyage was going to take a very long time. Finally, after some time several of the crew paired off and had sex and they noticed the ship seemed to travel faster when they did, taking years off their expected travel time.

Mission Control hadn't wanted to tell them that that was how to trigger the engine because they didn't want to make the astronauts uncomfortable or feel obligated to have sex or something like that. They all got very busy after that and the voyage went by very quickly.

Answer 1

Is there any chance this is Frederik Pohl's The Gold at the Starbow's End?

Pros

• Mixed male/female crew on a mission where Mission Control hides the purpose of the mission
• Sex plays a big role
• In an annual Best of collection
• they improved the drive significantly and got to the destination a lot faster

Cons

• Sex doesn't exactly run the drive, it just makes them smarter
• the Best of collection was in 1973, not the 50s or 60s

Answer 2

While it wasn't my intent to corner the market on answers to questions about sexually powered interstellar drives, I just read a story that is very likely to actually be the answer that was sought.

Namely, "Thrust" by Alan Dean Foster.

In this story, humanity's first interstellar ship is expected to reach its destination in just over 16 years. But there's a device aboard, the Molenon Multiplier, that is "somehow supposed to react to mental output and translate that into space-time leaps along our line of flight." The device was created by aliens, but that back-story isn't explained.

After the ship's automation starts introducing aphrodisiacs and pheromones into the ship's air, the crew starts having a lot of sex, the Multiplier kicks in, and they arrive at the destination sixteen years early.

Undistorted mental output engages the space-time distortion functioning of the Molenon Multiplier. That output peaks during the act of sex. Score one for the brain boys back home, but I'm still not entirely sure I like being tricked into it. How do we measure velocity from now on? In light-years per orgasm?