University of Notre Dame Department of Aerospace and Mechanical Engineering AME 30381 – Orbital and Space Dynamics
Date: Feb. 14, 2012 To: John Goetz, Instructor From: Charles Hunter, Student Subject: Satellite Mission Project
Introduction I am currently working for a major satellite design firm. The company has 6 different satellites to design. Since a typical rocket launch can be very expensive, $50 million or more, the company wants to know if it can launch them all from the same rocket together. We will assume the following for the project:
The satellites are small enough that they theoretically could all fit on one rocket Previous mission profiles may be used as justification
What we need to determine is:
For each mission, list whether you expect the orbit type to be LEO, MEO, HEO, or GEO. Based on the orbit types and any other information, group the satellites together by which can be launched on the same rocket
Outside information necessary for problem solution:
Information pertaining to the 6 satellites missions Details about the LEO, MEO, HEO, and GEO orbit types
Procedure Task 1: Determine the orbit types for the satellites The cartography satellite will be used to map the surface of the Earth. A similar satellite to the one that will be sent is the TerraSAR-X. The TerraSAR-X is a German Earth observation satellite. This satellite has an inclination of 44o. This satellite is used to acquire high-quality radar images of the Earth while circling in a polar Low Earth Orbit. Since the planned cartography satellite is carrying out a similar mission to map the Earth, I believe this satellite should be placed in Low Earth Orbit and at a similar inclination to TerraSAR-X. This also allows the retrieval of the images from the satellite to be cheaper since the satellite will be
relatively close to the Earth. This will be cheaper because it will require a less powerful satellite dish on the Earth to send and receive signals to the satellite if it is closer to the Earth. The reconnaissance satellite is to be used by the NSA for an unknown mission, but carry a suite of high resolution cameras. Previous reconnaissance and communication satellites are often placed into the Low Earth Orbit. The Lacrosse Radar Imaging satellites were sent into orbit with inclinations that ranged from 57o to 68o in orbits around 700 km. This allows the satellite to orbit the Earth at the same rate, easily allowing the NSA to have the satellite placed above a point above the Earth and capture data. Based upon earlier reconnaissance satellite examples the new satellite will be placed in a Low Earth Orbit at an inclination near 60o. The DIRECTV communication satellite will be used to replace an older generation satellite which is currently in orbit. TV communication satellites are often placed in a Geostationary Earth Orbit because the satellite will orbit the Earth at the same rate. This allows satellite dishes on Earth to only need to be in one stationary position to receive a signal from the satellite orbiting the Earth. Current DirecTV satellites range from orbital inclinations of 72oW to 109.8oW. The DirecTV satellite will be placed in a similar inclination and orbit to the previous satellites in Geostationary Earth Orbit. The navigation satellite will be used by the US government as a next generation GPS. Compass, GPS, and GLONASS are navigation systems which are currently in operation. The current GPS system consists of 32 Medium Earth Orbit satellites. These current satellites are currently inclined at a 55o of the plane towards the equator. The satellites are placed in the medium orbit range because the orbital period in this region can vary from 2-24 hours depending on the distance from Earth. The current GPS system is placed to complete one full orbit of the Earth in 12 hours. The next generation of GPS satellites should also be placed in the Medium
Earth Orbit with a similar 55o inclination as well. The set of atmospheric sensing satellites will be used by the NOAA to study weather patterns and improve weather prediction. Current weather satellites are often placed in a Geosynchronous Earth Orbit so the satellite orbits at the same rotation as the Earth. This allows them to gather weather data for certain areas over time without the satellite losing the position on Earth. The NOAA currently has satellites in geostationary and polar orbits. The GOES set of satellites are used to monitor weather and are placed at inclination angles such as 60oW, 75oW, 105oW, and 135oW. The satellite should be placed in a Geosynchronous Earth Orbit at a similar inclination to the GOES satellites. The solar observatory is requested by NASA and will have a similar mission to that of SOHO, however it will stay in orbit around the Earth rather than be moved to the L1 position. The solar observatory should be placed in Low Earth Orbit. This placement requires less energy and lower powered amplifiers to allow communication to the observatory. I would also recommend that a solar observatory be placed in a sun-synchronous orbit between 600 km - 800 km so the observatory can always study the sun. The inclination is difficult to compare to SOHO at eh L1 point so this observatory will be placed in a Low Earth Orbit at a similar inclination to the other satellites sent to that orbit in order for them to be on the same rocket. Task 2: Group the satellites together The satellites are going to be placed per rocket depending on the selection of orbit placement and inclination angle. The first rocket will head to Low Earth Orbit and carry the cartography, reconnaissance, and solar observatory satellites. The second rocket will head to Medium Earth Orbit and carry the navigation satellite into orbit. The third rocket will carry the TV communication and atmospheric sensing satellites to the Geosynchronous Earth Orbit.
These satellites are able to be grouped into three rockets because the inclination they will achieve in orbit will be very similar to one another dependent upon their mission to LEO, MEO, or GEO.
Results
Cartography Satellite – LEO Reconnaissance Satellite – LEO TV Communication Satellite – GEO Navigation Satellite – MEO Atmospheric Sensing Satellite – GEO Solar Observatory - LEO
Discussion The 6 satellites have been placed into the orbit level which will aid each of their respective missions. The satellites will be placed on a total of 3 rockets to be sent out into orbit at LEO, MEO, and GEO. The combined cost for the companies to launch these rockets should be on the order of $150 million. The orbit selection for these satellites highlights the importance to the mission of the type of orbit the satellite is in, as well as the angle of inclination of the satellite.
Appendix
TerraSAR-X satellite and mission data -http://en.wikipedia.org/wiki/TerraSAR-X Medium Earth Orbit information and example satellites http://en.wikipedia.org/wiki/Medium_Earth_orbit Low Earth Orbit Information and example satellites http://en.wikipedia.org/wiki/Low_Earth_orbit Geosynchronous Earth Orbit information and example satellites http://en.wikipedia.org/wiki/Geosynchronous_orbit High Earth Orbit information and example satellites http://en.wikipedia.org/wiki/High_Earth_orbit SOHO satellite mission and data - http://sohowww.nascom.nasa.gov/ DIRECTV satellite fleet information - http://en.wikipedia.org/wiki/DirecTV_satellite_fleet Weather satellite information and examples - http://en.wikipedia.org/wiki/Weather_satellite Reconnaissance satellite information and examples - http://en.wikipedia.org/wiki/Spy_satellite GPS satellite information - http://en.wikipedia.org/wiki/GPS_(satellite) GPS Orbit inclinations - http://www.kowoma.de/en/gps/orbits.htm NOAA Information - http://www.noaa.gov/satellites.html
 
GOES satellite information - http://en.wikipedia.org/wiki/GOES Lacrosse satellite information - http://en.wikipedia.org/wiki/Lacrosse_(satellite)