Summary of:
Putting the ‘P’ in ‘JPL’: The Past, Present, and Future of Propulsion at the Jet Propulsion
Laboratory
By Todd J. Barber
For the development of propulsion methods in both rockets and satellites, NASA’s JPL
provides a history of innovative excellence that dates back to Halloween of 1936. Originating in
a dry river bed named Arroyo Seco near JPL’s current location, the organization’s innovations
began with a group of graduate students under their advisor Theodore von Kármán from the
California Institute of Technology experimenting with liquid propellant rockets. An early
challenge associated with solid propellant motors that JPL overcame in 1940 was explosions
resulting from rapid increases in pressure during the combustion process. These instabilities were
traced back to variances in the burning area of the propellant grain. In solving this issue and
achieving a constant burning area, the star-shaped cross section still used today in propellant
grains was developed (Barber, 2024).
Further advancing propulsion with liquid propellants, JPL first saw their innovations used
for military applications during WWII. Pairing Red Fuming Nitric Acid (RFNA) with gasoline,
JPL developed Jet-Assisted Take-Off (JATO) units first used in 1942 to drastically reduce the
take-off time of aircraft. JPL also developed solid propellant JATO units initially with black
powder. However, since these early units proved to be intolerant of changes in temperature and
humidity (leading to explosions), the black powder was later replaced with an asphalt and
perchlorate mixture, also making the propellant castable. Further improving, the asphalt was
eventually replaced with a polymer binder, which is still in use today. Additional to these
Putting the ‘P’ in ‘JPL’: The Past, Present, and Future of Propulsion at the Jet Propulsion
Laboratory
By Todd J. Barber
For the development of propulsion methods in both rockets and satellites, NASA’s JPL
provides a history of innovative excellence that dates back to Halloween of 1936. Originating in
a dry river bed named Arroyo Seco near JPL’s current location, the organization’s innovations
began with a group of graduate students under their advisor Theodore von Kármán from the
California Institute of Technology experimenting with liquid propellant rockets. An early
challenge associated with solid propellant motors that JPL overcame in 1940 was explosions
resulting from rapid increases in pressure during the combustion process. These instabilities were
traced back to variances in the burning area of the propellant grain. In solving this issue and
achieving a constant burning area, the star-shaped cross section still used today in propellant
grains was developed (Barber, 2024).
Further advancing propulsion with liquid propellants, JPL first saw their innovations used
for military applications during WWII. Pairing Red Fuming Nitric Acid (RFNA) with gasoline,
JPL developed Jet-Assisted Take-Off (JATO) units first used in 1942 to drastically reduce the
take-off time of aircraft. JPL also developed solid propellant JATO units initially with black
powder. However, since these early units proved to be intolerant of changes in temperature and
humidity (leading to explosions), the black powder was later replaced with an asphalt and
perchlorate mixture, also making the propellant castable. Further improving, the asphalt was
eventually replaced with a polymer binder, which is still in use today. Additional to these
