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Geosynchronous Orbit

  • Thread starter KillerZ
  • Start date
  • #1
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Homework Statement



NASA would like to place a satellite in orbit around the moon such that the satellite always remains in the same position over the lunar surface. What is the satellite's altitude?

Homework Equations



[tex]T^{2} = \left(\frac{4\pi^{2}}{GM}\right)r^{3}[/tex]

The Attempt at a Solution



I think I have this right:

[tex]r_{geo} = R_{e} + h_{geo} = \left[\left(\frac{GM}{4\pi^{2}}\right)T^{2}\right]^{1/3}[/tex]

[tex]r_{geo} = R_{e} + h_{geo} = \left[\left(\frac{(6.67x10^{-11})(5.98x10^{24})}{4\pi^{2}}\right)(2358720)^{2}\right]^{1/3}[/tex]

[tex]= 383065776.5m[/tex]

[tex]h_{geo} = r_{geo} - R_{e} = 383065776.5m - 6.67x10^{6}m[/tex]

[tex]= 376695776.5m[/tex] from earth.

[tex]=>3.84x10^{8}m - 376695776.5m[/tex]

[tex]= 7304223.492m[/tex]

[tex]= 7.30x10^{6}m[/tex] from moon

I calculated it from the earth then subtracted that from the distance between the earth and the moon to get the distance from moon. I used the earth because the moon is in synchronous orbit with the earth and for T I used the moons period around the earth to keep the satellite with it.
 

Answers and Replies

  • #2
gneill
Mentor
20,793
2,773
You want the satellite to be in orbit around the Moon. I don't understand why you're involving the Earth. I don't see the Moon's mass used anywhere.
 
  • #3
4,239
1
You would want your satellite at any of the Earth-Moon Lagrange points.
 

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