Maintaining orbit around the moon

In summary, maintaining orbit around the moon is a complex and critical task for space missions. It requires precise calculations and constant monitoring to ensure the spacecraft stays in a stable orbit. Factors such as the moon's gravity, orbital velocity, and potential debris must be taken into account. Engineers also use various techniques, such as thrusting and gravitational assist, to adjust the spacecraft's trajectory and maintain its desired orbit. Accurate orbit maintenance is essential for successful moon exploration and any potential future lunar missions.
  • #1
vjk2
90
0
http://news.discovery.com/space/ast...s-put-an-asteroid-into-lunar-orbit-130111.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?
 
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  • #2
vjk2 said:
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?
Why do you expect this?

Low orbit times are proportional to ##\sqrt{\rho}## with the average density ρ only. This gives ~105 minutes for very low lunar orbits.
 
  • #3
mfb said:
Why do you expect this?

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

Earth gravity should gradually affect any object orbiting. I wonder for how long thought.

It takes 90 minutes for the space shuttle to orbit the Earth.
 
  • #4
vjk2 said:
Earth gravity should gradually affect any object orbiting. I wonder for how long thought.

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

I think the spacecraft is well within the distance that the effect of the moon's gravity dominates over the effect of the Earth's. But another way to think about it is that the object is in a stable orbit around Earth just like the moon is.
 
  • #5
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 earth-moon-system 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
cepheid said:
I think the spacecraft is well within the distance that the effect of the moon's gravity dominates over the effect of the Earth's. But another way to think about it is that the object is in a stable orbit around Earth just like the moon is.

It should be akin to how the moon affects tides on the earth. As a thought experiment...if the moon had oceans, and if it rotated instead of being tidally locked, would the "tides" be greater than the Earth's tides, due to the mass of the Earth being so great compared to the mass of the moon vs the earth?
 
  • #7
With an earth-like ocean and 24-hours rotation period, moon would have larger tides.
This has nothing to do with an orbit, however.
 
  • #8
mfb said:
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.

The maximum altitude seems to be much lower for circular orbits

http://science.nasa.gov/science-news/science-at-nasa/2006/30nov_highorbit/

And low orbits can also be unstable, because of mass concentrations in the moon

http://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/
 
  • #9
Inclination is the problem here:
NASA said:
Stable circular lunar orbits do exist below an inclination of 39.6º, says Ely, but they spend so much time near the equator that "they are terrible orbits for covering the poles."
[...]
The instability of polar orbits poses a real problem for exploration.
 

Related to Maintaining orbit around the moon

1. How do spacecraft maintain orbit around the moon?

To maintain orbit around the moon, spacecraft use a combination of their engines and gravity. They adjust their speed and direction to match the moon's gravitational pull, allowing them to stay in a stable orbit.

2. What factors affect the stability of a spacecraft's orbit around the moon?

The stability of a spacecraft's orbit around the moon is affected by its speed, altitude, and the mass of the spacecraft. The gravitational pull of other celestial bodies, such as the sun and Earth, can also influence the orbit.

3. How often do spacecraft need to adjust their orbit around the moon?

The frequency of orbit adjustments varies depending on the specific mission and spacecraft. Some spacecraft may need to adjust their orbit more frequently to maintain stability, while others may be able to maintain their orbit for longer periods of time.

4. What happens if a spacecraft loses orbit around the moon?

If a spacecraft loses orbit around the moon, it can either crash onto the surface or drift off into space. In either case, the mission would likely be considered a failure.

5. How do scientists and engineers plan for maintaining orbit around the moon?

Maintaining orbit around the moon requires precise calculations and careful planning. Scientists and engineers use computer simulations and mathematical models to predict the spacecraft's trajectory and determine the necessary adjustments to maintain orbit.

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