Bow shock protons in the lunar environment

Protons from the Earth's bow shock are observed by the Suprathermal Ion detector Experiment (SIDE) in two regions of the lunar orbit. The dawn region begins at the dawn side bow shock crossing and ends ç 5 days later and the dusk region begins at ç 2 days prior to entering the dusk side magnetosheath and ends at the inbound bow shock crossing. Dusk and dawn refer to a terrestrial coordinate system. The dominant contribution to the ion spectra observed by the SIDE in these regions is from particles with energies between ç 750 eV q^–1 and 3500 eV q^–1. 3500 eVq^–1 is the upper limit of the energy range of the detector. Analysis of simultaneous data from the Explorer 35 magnetometer and the SIDE indicates that the observability of bow shock protons at the lunar distance is dependent on the configuration of the interplanetary magnetic field.Paper presented at the Conference on Interactions of the Interplanetary Plasma with the Modern and Ancient Moon, sponsored by the Lunar Science Institute, Houston, Texas and held at the Lake Geneva Campus of George Williams College, Wisconsin, between September 30 and October 4, 1974.