Fireball XL5 (1962)

S1E2 The Doomed Planet

The Fireball XL5 narrowly avoids a rogue planet that has drifted off its orbit, only to discover it is heading straight for Membrono. After determining that both planets are uninhabited, Steve recalls seeing a flying saucer. When the saucer lands at Venus' home, it draws the XL5 back into action to prevent Membrono from facing imminent destruction.