John Whiteside “Jack” Parsons (born Marvel Whiteside Parsons;[nb 1] October 2, 1914 – June 17, 1952) was an American rocket engineer and rocket propulsion researcher, chemist, and Thelemite occultist. Associated with the California Institute of Technology (Caltech), Parsons was one of the principal founders of both the Jet Propulsion Laboratory (JPL) and the Aerojet Engineering Corporation. He invented the first rocket engine to use a castable, composite rocket propellant, and pioneered the advancement of both liquid-fuel and solid-fuel rockets.
Born in Los Angeles, Parsons was raised by a wealthy family on Orange Grove Avenue in Pasadena. Inspired by science fiction literature, he developed an interest in rocketry in his childhood and in 1928 began amateur rocket experiments with school friend Ed Forman. He dropped out of Pasadena Junior College and Stanford University due to financial difficulties during the Great Depression, and in 1934 he united with Forman and graduate student Frank Malina to form the Caltech-affiliated Guggenheim Aeronautical Laboratory (GALCIT) Rocket Research Group, supported by GALCIT chairman Theodore von Kármán. In 1939 the GALCIT Group gained funding from the National Academy of Sciences (NAS) to work on Jet-Assisted Take Off (JATO) for the U.S. military. Following American entry into World War II, in 1942 they founded Aerojet to develop and sell their JATO technology; the GALCIT Group became JPL in 1943.
After a brief involvement with Marxism in 1939, Parsons converted to Thelema, the English occultist Aleister Crowley‘s new religious movement. In 1941, alongside his first wife Helen Northrup, Parsons joined the Agape Lodge, the Californian branch of the Thelemite Ordo Templi Orientis (O.T.O.). At Crowley’s bidding, he replaced Wilfred Talbot Smith as its leader in 1942 and ran the Lodge from his mansion on Orange Grove Avenue. Parsons was expelled from JPL and Aerojet in 1944 due to the Lodge’s infamous reputation, along with his hazardous workplace conduct.
In 1945 Parsons separated from Helen after having an affair with her sister Sara; when Sara left him for L. Ron Hubbard, he conducted the Babalon Working, a series of rituals designed to invoke the Thelemic goddess Babalon to Earth. He and Hubbard continued the procedure with Marjorie Cameron, whom Parsons married in 1946. After Hubbard and Sara defrauded him of his life savings, Parsons resigned from the O.T.O. and went through various jobs while acting as a consultant for the Israeli rocket program. Amid the climate of McCarthyism, he was accused of espionage and left unable to work in rocketry. In 1952 Parsons died at the age of 37 in a home laboratory explosion that attracted national media attention; the police ruled it an accident, but many associates suspected suicide or murder.
Parsons’ occult and libertarian writings were published posthumously, with Western esoteric and countercultural circles citing him as one of the most significant figures in propagating Thelema across North America. Although academic interest in his scientific career was negligible, historians came to recognize Parsons’ contributions to rocket engineering. For these innovations, his advocacy of space exploration and human spaceflight, and his role in the founding of JPL and Aerojet, Parsons is regarded as among the most important figures in the history of the U.S. space program. He has been the subject of several biographies and fictionalized portrayals, including the television drama Strange Angel.