The spacecraft that slowed itself with heat

For decades, astrophysicists were sweating because the Pioneer probes were mysteriously slowing down at the edge of the solar system, making them think Newton's laws were broken. Nope. It was just the spacecraft 'farting' thermal radiation. The heat coming off their plutonium power sources was bouncing off their massive dish antennae, creating enough photon recoil to act like tiny, unwanted brakes.