Something to space-out to on the plane, one of those very silly sci-fi movies from the 60’s that gradually becomes a Godzilla knock-off. Movieishness is high, reasonable human behavior low, with some really cool miniatures, but the zero-gravity effect of “dangling stuff on strings” is lame. A mission to Mars (to discover why all other missions to Mars have disappeared) is led by Captain Sano with White Biologist Lisa. They stop for a shower on the moon base, where radio operator Michiko is jealous of the white girl, leaving behind their doctor who wasn’t feeling well, and picking up the whiny, dubbed, panic-prone Dr. Stein. Their ship loses power after they collect a Luminous Object near Mars, and they get a tow home. Of course the object grows into a giant monster that threatens Tokyo, but at least the massive-scale destruction and countless deaths resolve the astronaut love triangle. The cast is mostly nobodies, but the comic relief guy was in an Imamura film, and the guy in charge of ground control is Eiji Okada, star of Hiroshima Mon Amour and Woman in the Dunes.
The X has a name: Guilala
The flying saucer is a Monty Python fan: