Measurement of Cosmic Ray and Trapped Proton LET Spectra on the STS-95 HOST Mission

This paper reports on in situ measurements of the linear energy transfer spectra of galactic cosmic rays and their progeny and of trapped Van Allen belt protons as recorded by a pulse height analyzer (PHA) radiation spectrometer which flew on the STS-95 DISCOVERY mission on the Hubble Orbital Systems Test cradle. The shuttle was launched on October 29, 1998 and had a mission duration of 8.5 days during the minimum phase of the solar activity cycle. The orbit of the STS-95 was about 550 km altitude and 28.5° inclination. Close agreement was seen between radiation environment model predictions and the measurements of the PHA. Agreement is obtained by considering the directionality of the radiation interacting with the shuttle structure.