Solar Ultraviolet and Space Radiation Effects on Inflatable Materials

Abstract

Public reporting burden tor this collection of information is estimated to average 1 hour per response, including the time for reviewing Instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Inflatable structures are being developed for use in space to take advantage of the potential for lower packaging volumes and lighter weights. These structures may consist of thin polymer membranes as well as more robust inflatable, then rigidizable, structural elements. For space applications, it must be shown that the materials can tolerate the orbital environment. This includes the effects of solar radiation and electron/proton radiation on the optical properties and mechanical response of the materials, as well as atomic oxygen effects for possible LEO applications. The highest radiation concern is with the thin-film materials, e.g., the canopy and reflector of an antenna or components of a sun shade or solar sail. All materials used in an inflatable structure need to be capable of tolerating the orbital environment and maintaining properties within the mission requirements.The approach to assessing the effects of space environment on materials begins with consideration of the orbital environment. The solar radiation spectrum is not orbital dependent, but the radiation from electrons and protons varies by orders of magnitude, depending on the particular orbit. The atomic oxygen environment is strongly dependent on altitude and solar activity. Once an orbit has been defined, the atmospheric models are available to calculate the flux and energy of the particle radiation. The orbital lifetime then is used to calculate dose levels and solar exposures that the materials must tolerate. With the environment specified, the expected dose in the materials can then be calculated. If damage thresholds are available for the particular materials involved, possible degradation can be predicted; if not, a ground or orbital test is needed. For a ground test to assess the durability of a material in orbit, the methodology is to predict the dose levels in the materials, which then drive the test parameters.The orbital environment of solar, electron and proton radiation are discussed. Typical levels for a LEO, MEO, and GEO orbit are presented, and examples of test conditions to simulate the space environment in a ground test on materials properties are discussed. Available results on materials for inflatables are presented.

Photodegradation of PEEK sheets under tensile stress

“…Polymeric sheets are also essential for inflatable structures, which is state-of-the-art in the construction of space facilities [20][21]. There are many severe factors on polymers in low earth orbit (LEO) altitudes from 100 to 1000 km where the International Space Station (ISS) orbits.…”

Effect of proton irradiation on structure and optical property of PTFE film

“…The concentration of the spins could be determined by comparing with the standard specimen according to the following formula [18]: In which, N is the spin quantity, H m the modulation, P the microwave power, and the G the gain of the spectrometer, and AE the areas of the absorbance spectra which usually called as spectral intensity. Usually spectral intensity is in direct proportion to the product of peak-to-peak amplitude Y and the line width square (ÁH PP ) [2]. The subscript ''s'' denotes standard specimen, and the ''x'' denotes the test experiment.…”

“…Polytetrafluoroethylene (PTFE) film is commonly used on exterior surfaces of spacecrafts for heat insulation and surface protection [1,2]. Under space conditions, the PTFE film would be subjected to damage caused by irradiation of protons, which exist in the earth radiation belts [3,4], leading to a degradation of optical properties.…”

Effects of vacuum ultraviolet on the structure and optical properties of poly(tetrafluoroethylene) films

“…Polymeric materials have widely been used in spacecraft for parabolic antennas, solar battery base plates, and thermal control systems 1–7. Their service behavior in space will directly influence the reliability and lifetime of spacecraft.…”