Andrew J. Stofan

Andrew John Stofan (January 26, 1935 – October 26, 2025) was an American engineer. He worked for the National Aeronautics and Space Administration (NASA) at the Lewis Research Center (now Glenn Research Center). In the 1960s he played an important role in the development of the Centaur upper stage rocket, which pioneered the use of liquid hydrogen as a propellant. In the 1970s he managed the Atlas-Centaur and Titan-Centaur Project Offices, and oversaw the launch of the Pioneer 10 and Pioneer 11 probes to Jupiter and Saturn, the Viking missions to Mars, Helios probes to the Sun, and the Voyager probes to Jupiter and the outer planets. He was director of the Lewis Research Center from 1982 to 1986.

Early life Andrew J. Stofan was born on January 26, 1935, He received his Bachelor of Arts degree in mathematics from Hiram College in 1957, and the following year earned a Bachelor of Science degree in mechanical engineering from Carnegie Mellon University in Pittsburgh, Pennsylvania. He subsequently studied mathematics and engineering as a graduate student at Case-Western Reserve University in Cleveland, Ohio.

NASA career Stofan joined the Lewis Flight Propulsion Laboratory in 1958, shortly before it became part of the newly formed National Aeronautics and Space Administration (NASA) as the Lewis Research Center. He became a research engineer in the Propulsion Aerodynamics Division, where he researched the use of ejector nozzles in supersonic aircraft. These nozzles subsequently found use in the Lockheed SR-71 Blackbird. As NASA switched its focus from aviation to space-related technologies, he joined the Chemical Rocket Systems Branch in the new Rocket and Aerodynamics Division, where he studied slosh dynamics, the manner in which fuel sloshed about in the propellant tanks of liquid-fuel rockets. Fuel could slosh for many different reasons, and understanding these and their effects was crucial to mitigating them in order to ensure that the fuel could be pumped into the engine.

Stofan's expertise with sloshing was called upon in 1962 when Lewis took on the development of the Centaur upper-stage vehicle, which was fueled with liquid hydrogen and liquid oxygen. Liquid hydrogen was a cryogenic fuel about which there was little empirical knowledge at the time. He played a key role in understanding its behavior: he helped develop internal baffles to control propellant sloshing, gauges to measure the boiling of cryogenic propellants, and a propellant utilization system that ensured that the liquid hydrogen and liquid oxygen would run out at precisely the same time, thereby ensuring that neither was wasted. Centaur upper stages were used atop Atlas-Centaur rockets by the Surveyor program, which sent robotic spacecraft to the Moon. He went back to NASA headquarters in 1986 to head the Space Station Office, directing the design of the Space Station Freedom. He retired from NASA on April 1, 1988. For his services, he had received the NASA Exceptional Service Medal in 1975 and the NASA Distinguished Service Medal in 1981. He also received the Presidential Rank Awards of Meritorious Executive in 1982 and Distinguished Executive in 1985. His daughter, Ellen Stofan, served as Chief Scientist at NASA, director of the National Air and Space Museum, and Under Secretary for Science and Research at the Smithsonian Institution.

Stofan died in Fair Oaks, Virginia, on October 26, 2025, at the age of 90.