Space environment simulation for radiation tests of materials: third version of an international standard

In the framework of the International Organization for Standardization (ISO ) activity of 1996 we started development of an international standard seri es for a space environment simulation of on-ground tests of materials. A dr aft of the first international standard 'Space environment simulation for r adiation tests of materials' (first version) was presented at the 7th Int. Symp. on Materials in Space Environment by Briskman et al (1997). The secon d version of the standard was limited to nonmetallic materials and was pres ented at the 20th Space Simulation Conf The Changing Testing Paradigm by Br iskman et al (1998). The third version of the standard was discussed at the last ISO TC20/SC14 meeting (Torino, Italy, 1999); in essence it was comple tely revised. A new standard orbit for the International Space Station is introduced in t he recommended list of such orbits. The values of energy fluences for elect rons and protons at all six orbits are calculated just as the absorbed dose s on the 1 mg cm(-2) depth in aluminum. Values of the depth distribution cr iterion of the absorbed dose for two exponents are also calculated for four standard orbits. Now the list of radiation includes the near ultraviolet r egion. The spectral solar irradiances for far and near ultraviolet radiatio n based on ASTM E 490 data are introduced into the document. Accordingly, t he 'Radiation sources for simulation' issue is enlarged and the section 'Te rms and definitions' is replaced with a new version, the list being enlarge d from seven to 32 terms. For the section 'Requirements for simulation of s pace radiation' a fixed procedure is recommended for space environment simu lation of the radiation tests. For the section 'Simulation of radiation dos e rate' extra sections are introduced that correspond to induced factors li miting the conduct of radiation tests conduction: radiation heating, residu al atmosphere impact, vacuum requirements and electrical charging, Special attention is focused on dose rate effects in nonmetallic material, irradiat ed in vacuum.