Modeling of the Space Environment
an abstract by Yue Fei

The effects of radiation belt particles on spacecraft are well known. Electrons can produce charging which can induce electrostatic discharges; protons can produce Single Event Effects in electronics. These two effects are well correlated to the immediate environment, so they are also called space weather effects. Moreover, electrons and protons induce total dose effects which modify the characteristics of electronics, coatings and optics onboard satellites. Therefore, the development of reliable radiation belt models, either long-term or short-term, is essential in preventing these effects.
Existing long-term models have to be updated because they were developed at the beginning of the space age, when radiation belt dynamics was not well understood. Updating these models is a complex process which involves:

  1. Good measurements, taken from different orbits.
  2. A physical understanding of the dynamics of the radiation belt, and a physical
    model to interpolate between measurements.
  3. Scientific satellites, with well-chosen orbits, to deliver absolute calibration and
    to make possible inter-calibration between measurements from different satellites.
  4. Technology satellites, to make a relation between the environment and its
    effects. These satellites are essential for trying new technologies and new
    materials.
  5. Operational satellites, to measure long-term variations in the environment, and for inter-calibration between scientific and technology satellites.
A physical model of the radiation belt is very useful because it can provide a better understanding of the variation in the environment on both a short-term and a long-term basis; it can interpolate between measurements to give global now casting of the radiation belt, and; it increases the representativity of the data set. For example, a 3-D radiation belt model might use geosynchronous measurements to build the entire electron radiation belt and compare it with orbital measurements obtained by other satellites.