Analytical model of the Van Allen radiation proton flux for applications in low-thrust trajectory optimization
Citation
Foster, Alexander. Analytical Model of the Van Allen Radiation Proton Flux for Applications in Low-Thrust Trajectory Optimization. --In Proceedings: 11th Annual Symposium on Graduate Research and Scholarly Projects. Wichita, KS: Wichita State University, p. 44
Abstract
As electronic propulsion systems such as ion thrusters, arc jets, and Hall thrusters become more
powerful and able to produce more thrust, they become a much more enticing mechanism to
transfer a spacecraft from an initial injection orbit to its final orbit. This means that designers and
operators will be able to utilize electric propulsion in order to drastically improve fuel efficiency
and by extension make lighter payloads. However, with this increased fuel efficiency there is
also a few drawbacks, mainly in that the lower thrust generated by the electric systems require a
much longer time-of-flight to move from the lower initial orbit to the higher goal orbit. This
longer time spent in the transit introduces a new wrinkle when it comes to calculating the optimal
transfer trajectory and is due to the presence of the Van Allen radiation belts. As the spacecraft
moves through these regions that surround Earth, it is impacted by thousands of particles which
can damage the exposed solar arrays, limiting the amount of power that is able to be generated
and therefore decreasing the amount of thrust produced. Chemical propulsion fueled transfers
minimize the effects of solar array degradation due to the particles within the Van Allen belts by
firstly utilizing a very quick transfer time and secondly by keeping the solar arrays stowed and
shielded during the transfer. Lowering of power output capacity and therefore lowering of
maximum available thrust will also lead to longer transfer times which lead to more damage and
so on. In order to more accurately account for this in an all-inclusive optimization scheme,
numerical data is taken from the latest available source, the newly released Ap9/Ae9
measurements, and is then used to determine a simple analytical expression for use within the
optimizer that will allow for quicker computation and more accurate trajectory designs.
Communications satellites, due to their large power requirements to perform their mission, can
possibly support the use of multiple thrusters during the transfer when power generation for its
mission is not necessary, making them ideal candidates for all-electric orbit raising. Due to this,
the application for this method will be limited to transfers ranging from Low Earth Orbit (LEO)
to Geosynchronous Orbit (GEO).
Description
Presented to the 11th Annual Symposium on Graduate Research and Scholarly Projects (GRASP) held at the Heskett Center, Wichita State University, April 24, 2015.
Research completed at Department of Aerospace Engineering, College of Engineering