Who was Carl Sagan's second wife?

Carl Sagan's second wife was Linda Salzman.

Sagan married the artist Linda Salzman on April 6, 1968, after his first marriage to biologist Lynn Margulis ended in divorce. Salzman and Sagan had one child together, author and screenwriter Nick Sagan, and their marriage lasted until 1981.

Linda Salzman was more than Sagan's spouse. She created the artwork for the plaques placed aboard the Pioneer spacecraft and helped produce the Voyager Golden Record, two of the most famous attempts to communicate information about Earth to possible extraterrestrial observers. She also co-authored Murmurs of Earth with Sagan, documenting the ideas and cultural material behind the Voyager record.

A common mix-up is Ann Druyan, who became Sagan's third wife in 1981 and collaborated with him on Cosmos: A Personal Voyage. Sasha Sagan was their daughter, not Sagan's second wife, while Lynn Margulis was his first wife.