This is the classic model of solar proton fluence expected on space missions. Based on the work of King and Burrell at NASA, it has been coded by Stassinopoulos and used widely since.¹

The JPL1991 model (Space Radiation Standard Edition) is mathematically similar to SOLPRO but utilizes a database covering approximately two additional solar cycles.

¹ E.G. Stassinopoulos, SOLPRO: A Computer Code to Calculate Probabilisitc Energetic Solar Proton Fluences, NSSDC 75-11, Greenbelt, Maryland (1975)

The image on this page was taken from the NASA Solar Flare Theory Web Pages. Please see that site for more information and pictures of solar flares.