Mercury or Saturn vehicles?

• Extraterrestrials' fleet
• Phenomena of interest to the U.S.A.F.
• Mysterious Roswell sightings: Abbr
• 1999 Richard Belzer book, "___, JFK, and Elvis"
• Topic of the USAF's Project Blue Book
• Saucers in the sky: Abbr
• ET transporters
• Space saucers, briefly
• Crafts from another planet

Wiktionary Word definitions in Wiktionary
n. (plural of ufo English)