Long-Term Measurements of Solar Particle Events and Inner Belt Protons by GOSAT

The Light Particle Telescope (LPT) onboard the Greenhouse gases observing satellite (GOSAT, 2009 to present) measured almost the entire 24-cycle period of solar activity (December 2008 to February 2019) with the same sensor, acquiring trapped protons (400 keV to 37 MeV) and the impact on low Earth orbit (LEO) of all solar energetic protons generated during the 24 cycle period.The 4 MeV protons affect solar paddle degradation, and the impact of solar high-energy particles and trapped protons on LEO satellites may be comparable or several times different, depending on the activity of each solar cycle. We observed clear variations that correlate inversely with the solar radio wave strength (F10.7), as well as a clear range of variation in flux per energy. These observations provide important data for the design and operation of low Earth orbit spacecraft and instruments.