Unflown neutral mass spectrometer tube of the type flown on Aerobee sounding rockets by the Aeronomy group at the Naval Research Laboratory (NRL) in the 1950s and 1960s. Normally would be enclosed in a protective metal cylinder housing. Transferred to NASM by NRL in March 1986.

During the early 1950s the NRL carried out studies of the upper atmosphere by sending specialized instruments to extreme altitudes on Aerobee sounding rockets. Maximum altitude for these rockets was close to 230 kilometers. This radio frequency mass spectrometer, which was designed by Willard H. Bennett when he was at the National Bureau of Standards, was used to determine the identity of the neutral gases present in the near vacuum at extreme altitudes. The compact size and light weight of this mass spectrometer made it suitable for use in sounding rockets. It incorporates an element that ionizes gases it encounters so that they can be analyzed, leading to the term, neutral mass spectrometer. This instrument is the same as those that NRL sent aloft in the late 1950's in connection with the International Geophysical Year.