He helped found Bulletin of the Atomic Scientists, and his wife Martyl Langsdorf designed the 1947 cover of the publication which debuted the Doomsday Clock.
Its first representation was in 1947, when bulletin co-founder Hyman Goldsmith asked artist Martyl Langsdorf (wife of Manhattan Project research associate and Szilárd petition signatory Alexander Langsdorf, Jr.) to design a cover for the magazine's June 1947 issue.
Martyl Suzanne Schweig Langsdorf (March 16, 1917 – March 26, 2013) was an American artist who created the Doomsday Clock image for the June 1947 cover of the Bulletin of the Atomic Scientists.