# Modelling of Force and Torque Due to Solar Radiation Pressure Acting on Interplanetary Spacecraft

## Abstract

In this paper Planck’s quantum theory is considered to explain the effect of SRP (Solar Radiation Pressure) on interplanetary spacecraft, which not only disturbs the orbit of spacecraft but also exerts torque (absorbed by reaction wheel), thereby creating the requirement for momentum desaturation using thrusters. The force acting on the spacecraft and hence the torque due to SRP can be computed with the knowledge of the optical properties of the material used, i.e. absorption, reflection and transmission. Further, using Newtonian mechanics and momentum conservation principle a mathematical relation is derived between the force and coefficient of the material properties. The model, thus, derived can be used to predetermine the disturbance torque acting on the spacecraft for various orientations and thus optimum orientation of the spacecraft can be chosen where disturbance on the platform is minimum. The model is already verified for Mars Orbiter Mission during cruise phase (spacecraft in heliocentric orbit).

## Keywords

Planck’s quantum theory Solar radiation pressure Torque## References

- 1.Planck constant (2017, April 10). Retrieved from https://en.wikipedia.org/wiki/ Planck_ constant.
- 2.Solar Energy Reaching the Earth’s Surface. (n.d.). Retrieved from http://www.itacanet.org/-sun-as-a-source-of-energy/part-2-solar-energy-reaching-the-earths-surface.
- 3.Diffuse Reflection. (2017, April 2). Retrieved from https://en.wikipedia.org/wiki/Diffuse_ reflection.
- 4.Lambert’s cosine law (2017, April 13). Retrieved from https://en.wikipedia.org/wiki/ Lambert%27s_cosine law.