The ground track of a the first orbit of a spacecraft at PEO, or an orbital altitude of 282 km, that was launched from SA is depicted in the image below (Image A).
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| Image A: First Ground Track for a 33 Degree Orbital Inclination |
ORBITAL ALTITUDE = 282 km
ORBITAL INCLINATION = 33.0 degrees
ORBITAL INCLINATION = 33.0 degrees
PAYLOAD = –8.182 x ORBITAL ALTITUDE + 31085
PAYLOAD = –8.182 x 282 + 31085
PAYLOAD = 28,778 kg
PAYLOAD = –8.182 x 282 + 31085
PAYLOAD = 28,778 kg
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However, a closer inspection of Image A reveals an embarrassing problem about the ground track of this orbit.
THE PROBLEM
The launch vehicle overflies several states on its way into CEO. This scenario is unacceptable due to possible injury and death on the ground in the path of the launch vehicle should it suffer a major malfunction.
Specifically, the launch vehicle overflies:
- New Mexico
- Texas
- Louisiana
- Mississippi
- Alabama
- Florida
THE SOLUTION
Immediately after liftoff, the launch vehicle turns south, and is injected into a 60o orbital inclination. Now only the states of New Mexico and Texas are overflown (Image B).
Immediately after liftoff, the launch vehicle turns south, and is injected into a 60o orbital inclination. Now only the states of New Mexico and Texas are overflown (Image B).
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| Image B: First Ground Track for a 60 Degree Orbital Inclination |
ORBITAL ALTITUDE = 282 km
ORBITAL INCLINATION = 60.0 degrees
PAYLOAD = –7.727 x ORBITAL ALTITUDE + 23182
PAYLOAD = –7.727 x 282 + 23182
PAYLOAD = 21,003 kg
PAYLOAD = –7.727 x 282 + 23182
PAYLOAD = 21,003 kg
Table 1: Standard Earth Orbital Parameters
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CONLUSION
Even though the south turn results is a horrendous reduction in payload capability to orbit, it is an acceptable sacrifice since it allows for easier and smoother spaceflight launch operations, as summarized in Table 1.
It also provides a better opportunity for Earth observation for both the tourist and the scientist.
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