Lunar and Planetary Institute






Apollo 15 Mission


Science Experiments - Orbital Mass Spectrometer

The Orbital Mass Spectrometer Experiment measured the composition of the lunar atmosphere.

The Orbital Mass Spectrometer Experiment was performed on Apollo 15 and 16, with the objective of measuring the composition and distribution of gases in the lunar atmosphere. On Apollo 17, a mass spectrometer was deployed on the lunar surface for the same purpose.

The Orbital Mass Spectrometer was deployed from the Scientific Instrument Module on the Service Module on a 7.3-meter boom. Most of the gases detected by this instrument are believed to be associated with the Apollo spacecraft itself. However, Neon-20 was detected that is believed to be from external sources. The amount of neon detected was about one-third of that expected to be found at the Moon due to capture of gases from the solar wind.