Spacecraft Orbit and the Space Environment

As prescribed by the project directive, the satellite will be operating in geostationary earth orbit (GEO) over the continental United States at a longitude of approximately 100o west. Like all other GEO satellites, the latitude will be at the equator (0o) and the altitude will be at approximately 36,000 km. Satellites that operate at GEO experience extreme temperature dynamics, and the harsh temperatures of space are potentially harmful to nominal satellite operation if not accounted for properly. Temperatures at GEO can easily drop below -120oC which is well outside the desired operation for many electronic components. Thankfully the host spacecraft for the system will offer thermal control to help set a nominal operating temperature. Although that nominal value is not specified, it is reasonable to assume for basic calculations that the satellite will be operating at room temperature (27oC), which would allow for simplistic integration of terrestrial components (as long as they fulfill other space requirements as well). It is important to note that the thermal control system of the host spacecraft will have to provide the power for the heating components, so it could be advantageous to operate at a lower temperature to help conserve power for other flight systems.


The photo to the left shows how “thermal multilayer insulation” may be used to help maintain temperature on a satellite. Photo from Kennedy Space Center: and the photo to the right shows where GEO Orbit exists in reference to the electromagnetic and radiation effects around the Earth:

In addition to providing thermal control for the system, the host spacecraft will also be a source of radiation protection. As shown in the figure above to the right, the satellite will be operating in the outer Van Allen belt (the outer Van Allen belt extends to an altitude of 60,000 km), which means that radiation protection is a concern for the electronic system design. The radiation protection provided by the host spacecraft may not be enough by itself and should be aided by radiation hardened by design techniques to ensure that the electronic components used in the system are protected from the possible system-killing effects of radiation damage.