Possible Clues:

• Traveler in 1957 news
• It was launched the same day that 'Leave It to Beaver' premiered
• First man-made satellite to orbit the earth
• Subject of the 2001 book subtitled 'The Shock of the Century'
• A 9's unusual input into cover for schoolbook
• Soviet space orbiter
• It means "traveling companion" in Russian
• Soviet revolutionary family has sex in a revolutionary way
• One of a series of ten artificial Earth-orbiting satellites launched by the former Soviet Union
• Early Soviet satellite