By Edward Ayrapetian | Jan 14, 2014
In this ongoing series we’ll cover some considerations for engineers when creating designs for space applications. Read up on the types of radiation we posted about last week if you missed it!
The earth’s atmosphere protects humans and electronics from most of the harmful radiation that is present in space. Though some radiation that can affect electronics does get through the atmosphere, for most applications, the probability of such a particle affecting a system is small enough that it can be disregarded. (Exceptions could be in nuclear reactors, particle accelerators, and a few other applications we mentioned in the last post.)
The radiation environment of outer space is highly dynamic and is composed of both electromagnetic radiation and particle radiation of varying energy. The radiation environment of concern to most space vehicles can be broken down into two main parts: the Van Allen Radiation Belt, and the Transient Environment.
Van Allen Radiation Belt
The Van Allen Radiation Belt refers to layers of charged particles trapped around the earth by the earth’s magnetic field. The particles include protons, electrons, heavy ions that come from solar wind (charged particles released from the sun) and cosmic rays (high energy particles from outside the Solar System). A depiction of the radiation belt is shown in the image below.
The radiation belt contains many highly energetic particles that present a significant risk to humans and electronics operating in or passing through the belt. The level of risk depends heavily on the specific spacecraft orbit, solar activity, and the magneto-static conditions. The radiation in the belts presents such a hazard to humans and electronics and is so expensive to shield against that there is in fact a project that proposes to remove this radiation.
The transient environment of space refers to the radiation that varies dynamically as a function of various cosmic processes and events. The transient environment can be thought of as a combination of space weather and particle radiation. Space weather is a term used to describe the changing conditions in the flows of matter and energy in the space between the earth and the Sun. Space weather is affected by events on the sun such as solar flares and coronal mass ejections that produce varying amounts of radiation. Solar events can be severe enough to deliver deadly doses of radiation to astronauts and space based electronics. Several agencies and efforts around the world are aimed at monitoring and predicting space weather in order to prevent catastrophic damage to space-based equipment and personnel.
Next we’ll discuss the effect of radiation and the space environment on electronics.