Each month in “Slice of History” we’ll be featuring a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.
It was 1943 and JPL was at the beginning stages of rocket motor research and development. Over the next decades, JPL would design and test rocket motors with a variety of sizes and propellants. This small (50 pound thrust) liquid propellant jet unit was immersed in a bath of ice and salt in order to test the ignition properties of the propellants at temperatures near 0°F.