Introduction
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INTRODUCTION
APPROACH
RESULTS
CONCLUSION
REFERENCES/CODE
https://publicintelligence.net/nasa-solar-flare-photos-2010-2012/
Solar Radiation Pressure
Solar-Radiation pressure is a non-conservative perturbation experienced by Earth orbiting
satellites. The extent to which an orbiting satellite is effected by this force is dependent upon the
satellites geometry, mass, attitude and reflectivity as well as the intensity of the solar cycle.
Incorporating these factors the force due to solar-radiation pressure is found to be:
𝐹⃑𝑠𝑟𝑝 = −𝑝𝑠𝑟𝑝 𝑐𝑅 𝐴
𝑟⃑𝑠𝑎𝑡−𝑠𝑢𝑛
|𝑟⃑𝑠𝑎𝑡−𝑠𝑢𝑛 |
CR: Reflectivity, can vary from 0.0 and 2.0 dependent on material of satellite:
0 - No radiation is absorbed or reflected
1 - All radiation is absorbed
2 - All radiation is reflected.
Psrp: Solar Radiation Pressure, solar-radiation constant SF by speed of light:
𝑃𝑠𝑟𝑝
𝑆𝐹 1367
=
= 4.57𝐸6 𝑁/𝑚2
𝑐
3𝐸8
A: Area of the satellite exposed to the Sun
Rsat-sun: Vector from the Sun to the satellite position
Coupled with Newton’s Second Law, the acceleration due to solar radiation can be derived:
𝑎⃑𝑠𝑟𝑝 = −
𝑝𝑠𝑟𝑝 𝑐𝑅 𝐴 𝑟⃑𝑠𝑎𝑡−𝑠𝑢𝑛
𝑚𝑠𝑎𝑡 |𝑟⃑𝑠𝑎𝑡−𝑠𝑢𝑛 |
The size of exposed reflective area and altitude of orbit are principal determining factors for the
extent of solar radiation pressure felt by an Earth orbiting satellite. [1] In order to investigate the
solar perturbations on large area and high altitude orbit scenarios the satellites chosen were the
International Space Station and a generic Molniya communication satellite.
Satellites of Interest – ISS & Molniya
http://forum.kerbalspaceprogram.com/index.php?/topic/22749-022x-bobcat-ind-historical-spacecraft-thread/
https://upload.wikimedia.org/wikipedia/commons/f/fd/ISS_as_of_Nov_2010.jpg
International Space Station – Large Reflective Area:
The solar panels on the ISS provide enough power to power all station operations, and when they
are in direct sunlight 60% of the electricity is stored. The panels make up a total of 2,500 square
meters and are 20% efficient. [3]
https://www.heavens-above.com/orbit.aspx?satid=25544&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET
Figure 1: ISS Ground Track and Orbit – Generated by Heavens Above
Molniya – High Altitude Orbit:
Molniya satellites have high eccentricity orbits (e~0.7) with inclinations of 63.4°. These orbits award
these satellites the ability to spend long periods of time over the Northern Hemisphere, which makes
them ideal for communication applications. [2] Inherent to the parameters of this orbit is a high
altitude reached and therefore are more susceptible to solar radiation pressure.
http://heavens-above.com/orbit.aspx?satid=24960&lat=-35.32&lng=149.008&loc=Mt.+Stromlo%2C+Australia&alt=0&tz=AEST&cul=en
Figure 2: Molniya-14 Ground Track and Orbit – Generated by Heavens Above