Solar Radiation and Spacecraft Shielding

Abstract

The space environment in the vicinity of spacecraft orbits is replete with a variety of natural and manmade threats from impact of high-speed objects. Setting aside the massive objects such as meteorites and orbital debris, it is apparent that the seeming serenity left behind is still punctuated with a boiling assortment of invisible hazards in the form of high-energy charged particles, plasmas, and electromagnetic radiation. Effects from such threats can reach down into the atmosphere to high-altitude aircraft, ground technologies, and into the DNA of living systems. Here, focus is made on the spacecraft material itself including effects on the associated subsystems. The fundamental nature, source, and temporal-spatial variation of the radiation environment affecting present and future spacecraft traffic is the subject of much in-depth research but is described broadly in order to conceptualize the hazard. Spacecraft material damage is described as either localized material damage at the atomic level or damage to the overall satellite from charge accumulation and surface erosion. The localized hazards apply mostly to susceptible spacecraft sub-components at the particle level, particularly in solid-state microelectronics composed of miniaturized circuitry. The macro hazards have a broad effect over entire surfaces or can be an accumulation of localized damage over the mission of the spacecraft. Surface erosion and contamination is of less immediate consequence but can be eventually disruptive to mission objectives. The environmental sources and distribution of ionizing radiation are addressed including how they couple to the magnetic fields influencing their trajectories and flux concentrations. Given this background, the topic is concluded by addressing the established methods for radiation hazard avoidance and shielding.