Casani was elected a member of the National Academy of Engineering in 1989 for pioneering systems engineering of planetary spacecraft and for leadership of spacecraft engineering and science teams.
From 1958 to 1959, Casani was a payload engineer working on Pioneer 3 and Pioneer 4.[3] These spacecraft were so small that he carried them in a suitcase to the University of Iowa to have their instruments calibrated.[2] He worked as a spacecraft systems engineer on Ranger 1 and Ranger 2 from 1959 to 1962, and then on the Mariner 3 and Mariner 4Mars probes from 1962 to 1965. He became the Chief Engineer of the Mariner Mars project in 1965, Deputy Spacecraft System Manager in 1966, Spacecraft System Manager in 1969, and Project Manager in 1970.[3] Early missions to Mars were dogged by failures, which a reporter attributed to the Great Galactic Ghoul.[2][4] After a hiatus, the Ghoul returned on Mariner 7, and Casani received drawing and paintings of the Ghoul.[2]
Casani served as project manager for the Voyager program from 1975 to 1977, and then the Galileo from 1977 to 1988.[3] This project was troubled by multiple delays and changes in configuration due to uncertainty as to how it should be launched on its way to Jupiter, and delays caused by the Space Shuttle Challenger disaster. It was finally launched by the Space ShuttleAtlantis in 1989, and reached Jupiter by a roundabout route in 1995.[5] It remained in orbit around Jupiter until 2003.[6] He became the Deputy Assistant Laboratory Director for Flight Projects in 1988,[7] and Assistant Laboratory Director for Flight Projects from in 1989. In 1994 he became Project Manager of the Cassini project.[3] He became Chief Engineer at JPL in 1994.[8]