Energetic neutral atom imaging mass spectroscopy of the Moon and Mercury environments Original Research Article

Low-energy neutral atom (LENA) imaging is an important technique for doing planetary sciences at magnetized and unmagnetized planets. In the case of the Moon, the precipitating solar-wind causes sputtering, which releases surface atoms as LENAs into space. Moreover, the solar-wind ions may be back-scattered from the surface into space as neutral atoms. At Mercury, in addition to the above processes, LENAs are also generated by the charge-exchange of energetic ions with the exospheric gasses. Global LENA mass spectroscopic imagery at the Moon and at Mercury provides us information on their surfaces and the interaction processes between energetic particles and the surfaces via remote-sensing using LENAs. We are developing a state-of-the-art LENA instrument for the Indian lunar exploration mission Chandrayaan-1 and the Mercury exploration mission BepiColombo. The instrument is light-weight and capable of mass discrimination, including heavy components such as iron, and has high sensitivity to fulfill various scientific objectives in the area of planetary sciences.