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Maintaining orbit around the moon 
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#1
Jan1313, 03:28 AM

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http://news.discovery.com/space/aste...bit130111.htm
Basically, wouldn't any object that orbited around the moon gradually see its orbit be made more and more eliptical until it crashed into the moon itself? Also, it actually takes longer for a satellite to orbit around the moon than the Earth itself, due to the Earth being more dense despite having a much larger diameter, correct? 


#2
Jan1313, 08:36 AM

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Low orbit times are proportional to ##\sqrt{\rho}## with the average density ρ only. This gives ~105 minutes for very low lunar orbits. 


#3
Jan1313, 11:44 AM

P: 74

It takes 90 minutes for the space shuttle to orbit the Earth. 


#4
Jan1313, 01:29 PM

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Maintaining orbit around the moon



#5
Jan1313, 01:30 PM

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I took 82 minutes, which would correspond to a height of 0 km (not possible as earth has an atmosphere, of course).
Earth affects the orbit, but orbits which are not too high can be stable for a long time  a satellite around the moon should be closer than 20 000 to 30 000km. Consider the earthmoonsystem as interesting example: The gravitational force between moon and sun exceeds the gravitational force between moon and earth! But still, the lunar orbit has been stable for some billion years. 


#6
Jan1313, 02:24 PM

P: 74




#7
Jan1313, 02:53 PM

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With an earthlike ocean and 24hours rotation period, moon would have larger tides.
This has nothing to do with an orbit, however. 


#8
Jan1413, 12:19 AM

P: 1,397

http://science.nasa.gov/sciencenews...nov_highorbit/ And low orbits can also be unstable, because of mass concentrations in the moon http://science.nasa.gov/sciencenews...6nov_loworbit/ 


#9
Jan1513, 03:55 PM

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Inclination is the problem here:



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