The National Aeronautics and Space Administration (NASA) plans to create a program for the human exploration of Mars that will rely heavily on nuclear technologies. NASA has an established nuclear technology program that recently became the focus of public protest over the risk from the technologies. Focusing on the Cassini mission to Saturn, the citizens protesting the mission claimed that the risk was environmental, global and moral. This protest is the first coherent international protest ever faced by the U.S. space program. The language and ideas espoused by the anti-nuclear groups protesting the use of plutonium-238 to power the Cassini spacecraft shows a clear linkage between anti-nuclear power and environmental protests and nuclear war protests. The analysis focuses on the use messages and meanings that underlie the protestor's use of three acronyms: Not in My Backyard (NIMBY), Not on Planet Earth (NOPE), and Not [in] Outer Space Either (NOSE). The anti-space nuclear power protest is predicted to have significant consequences for NASA's planned human missions to Mars because of NASA's reliance on nuclear technologies such as radioisotope thermoelectric generators and nuclear reactors. / Master of Science