<p>The Moon has a "Roche lobe", where the Moon's gravity dominates, and all you need for the situation you describe is that the Roche lobe lies physically outside the Moon.  That will be true, because the Lagrange points are on the outside edge of that Roche lobe, and it's outside the Moon.  The Moon's Roche lobe is shown here: <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/lagpt.html" rel="noreferrer">http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/lagpt.html</a></p>

CC BY-SA 3.0
2017-01-06T04:50:33.987Z
I don't understand, why does an object need to be sustained in Earth's orbit?  Earth's gravity can do that all by itself.   Basically, the Roche lobe geometry explains everything, how the Moon alters the orbits near the Earth, and how the Moon can sustain its own orbits near the Moon.
Ken G
CC BY-SA 3.0
2017-01-18T02:47:26.527Z
I'm not following, an orbit is already eternal, in any of these idealizations.
Ken G
CC BY-SA 3.0
2017-01-06T03:35:31.370Z
2017-01-06T03:35:31.370Z
Ken G
<p>Can a satellite maintain an equatorial orbit around Earth near the Moon's orbit to receive partial gravitational boosts by gaining momentum as the satellite passes though the Moon's gravity well? </p>

<p>I'm not asking about hanging out in the Lagrange points, but passing between the L2 point and the Moon or the Moon and Earth aligned, in a Moon assisted orbit.</p>

CC BY-SA 3.0
2017-01-06T05:34:16.383Z
What are some of these "many" types or orbit around the Earth?
userLTK
CC BY-SA 3.0
2017-01-06T11:35:09.970Z
Muze - "an orbit...in parallel with the moon's orbit...pulled along by the moon's gravity..." Yes, you are talking about Lagrange points.
Rory Alsop
CC BY-SA 3.0
2017-01-06T15:04:45.620Z
Agree with @RoryAlsop. Also, you seem to make the implicit assumption that there are no stable orbits around Earth outside the Moon's. (the "providing the force needed..." part).
Alex
CC BY-SA 4.0
2018-12-18T21:59:37.280Z
This has come up in the Reopen Queue *again*, after an utterly superficial edit on Nov 14 that has failed to address the issues identified. Muze, you've already accepted an answer, so I'm going to edit the question to remove the elements that create the problem, and we can rightly consider reopening. If you're not satisfied with that and you roll back the edit (as is your right), the only remaining option would be for me to flag the post for moderator intervention, since you forcing this question back to review yet again would in my view be vexatious behaviour.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2018-12-18T22:00:11.173Z
Noting also [this meta post](https://astronomy.meta.stackexchange.com/q/456/14094). And of course, noting my edit will have to be approved, as I don't yet have rep for automatic approval.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2018-11-04T02:54:15.413Z
@uhoh is this better?
Muze
CC BY-SA 4.0
2018-11-04T04:40:14.523Z
I'm voting *not* to reopen, as the edits haven't changed your incorrect premise (that a satellite in orbit "needs propellant" to stay in that orbit), and you've introduced other unclear elements like "changing the artificial satellite center gravity" (what does that mean?). Ken G's answer and subsequent comments remain correct and should be sufficient for you.
Chappo Hasn't Forgotten
<the-moon><natural-satellites><orbital-mechanics><satellite><eccentric-orbit>
Can the Moon provide momentum to an object in Earth's orbit? Gravity Assisted Boost
Muze
# Can the Moon provide momentum to an object in Earth's orbit? Gravity Assisted Boost

(Asked by: username_0 on 2017-01-06)

Can a satellite maintain an equatorial orbit around Earth near the Moon's orbit to receive partial gravitational boosts by gaining momentum as the satellite passes though the Moon's gravity well?

I'm not asking about hanging out in the Lagrange points, but passing between the L2 point and the Moon or the Moon and Earth aligned, in a Moon assisted orbit.

**Tags:** the-moon, natural-satellites, orbital-mechanics, satellite, eccentric-orbit

> **Comments:**
> **username_1**: What are some of these "many" types or orbit around the Earth?  
> **username_2**: username_0 - "an orbit...in parallel with the moon's orbit...pulled along by the moon's gravity..." Yes, you are talking about Lagrange points.  
> **username_3**: Agree with @username_2. Also, you seem to make the implicit assumption that there are no stable orbits around Earth outside the Moon's. (the "providing the force needed..." part).  
> **username_0**: @uhoh is this better?  
> **username_4**: I'm voting *not* to reopen, as the edits haven't changed your incorrect premise (that a satellite in orbit "needs propellant" to stay in that orbit), and you've introduced other unclear elements like "changing the artificial satellite center gravity" (what does that mean?). username_5's answer and subsequent comments remain correct and should be sufficient for you.  
> **username_4**: This has come up in the Reopen Queue *again*, after an utterly superficial edit on Nov 14 that has failed to address the issues identified. username_0, you've already accepted an answer, so I'm going to edit the question to remove the elements that create the problem, and we can rightly consider reopening. If you're not satisfied with that and you roll back the edit (as is your right), the only remaining option would be for me to flag the post for moderator intervention, since you forcing this question back to review yet again would in my view be vexatious behaviour.  
> **username_4**: Noting also [this meta post](https://astronomy.meta.stackexchange.com/q/456/14094). And of course, noting my edit will have to be approved, as I don't yet have rep for automatic approval.  

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## 1 answers

### Answer by username_5 on 2017-01-06. Score: 5 | Accepted answer

The Moon has a "Roche lobe", where the Moon's gravity dominates, and all you need for the situation you describe is that the Roche lobe lies physically outside the Moon. That will be true, because the Lagrange points are on the outside edge of that Roche lobe, and it's outside the Moon. The Moon's Roche lobe is shown here: <http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/lagpt.html>

> **Comments:**
> **username_5**: I don't understand, why does an object need to be sustained in Earth's orbit?  Earth's gravity can do that all by itself.   Basically, the Roche lobe geometry explains everything, how the Moon alters the orbits near the Earth, and how the Moon can sustain its own orbits near the Moon.  
> **username_5**: I'm not following, an orbit is already eternal, in any of these idealizations.  

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