Carl Sagan is one of the most adored scientists to have walked the Earth. Thanks in large part to his ability to communicate complex concepts to an amateur audience through many media, from documentaries to novels, Sagan inspired a generation to take up science, pioneered the United States space program, curated NASA’s Pioneer Plaque, and helped legitimize the search for extraterrestrial life.

For a few years in the 1970s and 1980s, one of Sagan’s assistants at Cornell University, Shirley Arden, collected documents that passed through the scientist’s office, including notes, letters, and books bearing his signature. Now, those documents are being auctioned off by RR Auction with an estimated sale price of $3,000.

Among Arden’s collection are 20 letters, cards, and notes signed by the scientist, many also signed by his wife, Ann Druyan, a novelist who co-wrote many of Sagan’s most well-known works. For example, the couple collaborated on Contact, a novel that was later adapted into a film staring Jodie Foster, which helped shed light on the search for extraterrestrial intelligent life.

One of Sagan’s autographed letters reads, “This has been quite an extraordinary year! Without your help and support, initiative, intelligence and general commitment to excellence it might have been much less successful for me … My own senses of your remarkable abilities and dedication are confirmed every time I visit [the Jet Propulsion Laboratory] or give a lecture at some university or corporation where you played some role in making the arrangements.”

Three books signed by Sagan are also in the collection, including first editions of Cosmos and Comet, also co-written by Druyan. Sagan and Druyan actually dedicated Comet to Arden.

There are hundreds of pages of typed notes dating from 1975 to 1981, which give some details on Sagan’s day-to-day activities.

The collection also includes a couple candid photos of Sagan, over 200 photos from the Voyager and Viking programs he worked on, and 40 color slides with audio.