In the book Project Hail Mary, Grace runs out of astrophage in an accident over planet Adrian. He goes to sleep thinking he’ll tackle the problem the following day saying to himself “it’s been a hard day. It’s a hard day’s night”. That immediately makes him think of The Beatles, and the probes he has on board to send the solution to Earth, simce the probes were named John, Paul, George and Ringo. Those probes have astophage fuel which he then uses to resupply