Lem is perhaps best known for his novel "Solaris". This novel was published in 1961. It is set into the future. Humans have discovered what they think is intelligent life in space. They want to talk to the alien life form. The only problem they have is that the life form is the size of a planet. It is an ocean. This book has also been made into a film by Andrei Tarkowski in 1972. Steven Soderbergh made another film of the book in 2002.