<h3>Low lunar orbits</h3>
<p>For low lunar orbits it's a challenge because the Moon as a lot of mass concentrations or <a href="https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons" rel="noreferrer">mascons</a> near the surface, and these will continue to perturb a low orbit and ultimately bring it down to impact the surface after months or at best years.</p>
<p>There are certain sets of orbital parameters, basically certain combinations of inclination and semi-major axes... these are called <a href="https://en.wikipedia.org/wiki/Frozen_orbit" rel="noreferrer">frozen orbits</a> because while perturbations affect them they tend to remain somewhere near the same orbital elements rather than veer into surface impact.</p>
<blockquote>
<p><strong>Lunar frozen orbits</strong></p>
<p>Through a study of many lunar orbiting satellites, scientists have discovered that most low lunar orbits (LLO) are unstable.<sup>3</sup> Four frozen lunar orbits have been identified at 27°, 50°, 76°, and 86° inclination. NASA expounded on this in 2006:</p>
<blockquote>
<p><a href="https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons" rel="noreferrer">Lunar mascons</a> make most low lunar orbits unstable ... As a satellite passes 50 or 60 miles overhead, the mascons pull it forward, back, left, right, or down, the exact direction and magnitude of the tugging depends on the satellite's trajectory. Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. ... [There are] a number of 'frozen orbits' where a spacecraft can stay in a low lunar orbit indefinitely. They occur at four inclinations: 27°, 50°, 76°, and 86°&quot;—the last one being nearly over the lunar poles. The orbit of the relatively long-lived Apollo 15 subsatellite PFS-1 had an inclination of 28°, which turned out to be close to the inclination of one of the frozen orbits—but less fortunate PFS-2 had an orbital inclination of only 11°.<sup>4</sup></p>
</blockquote>
<ul>
<li><sup>3</sup>https://arc.aiaa.org/doi/abs/10.2514/2.5064?journalCode=jgcd</li>
<li><sup>4</sup>Bell, Trudy E. (November 6, 2006). Phillips, Tony (ed.). &quot;<a href="https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/" rel="noreferrer">Bizarre Lunar Orbits</a>&quot;. Science@NASA.</li>
</ul>
</blockquote>
<p>Another problem with low lunar orbits is that any particular spot on the surface is only visible for a few minutes every pass, and you may pass over a given site for about one day a month - the moon will slowly rotate around it's axis each month while the orbit will mostly remain fixed.</p>
<p>See also:</p>
<ul>
<li><a href="https://space.stackexchange.com/q/20582/12102">Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?</a> relatively long-lived relatively low lunar orbit</li>
<li><a href="https://space.stackexchange.com/q/55782/12102">Was Chandrayaan-1 recovered (tracked) only that one time in 2016, or is someone still keeping an eye on it from time to time?</a></li>
</ul>
<h3>Higher lunar orbits</h3>
<p>For earth, we get 24/7 access to a big chunk of one hemisphere by going to geostationary orbits (or at least geosynchronous). However luna-stationary orbits don't really exist because the moon rotates only once a month, and by the time you would get high enough to orbit that slowly you're interacting with the gravity of the Earth and Sun too much. Not an option for the Moon.</p>
<p><strong>However</strong> there is the <a href="https://en.wikipedia.org/wiki/Distant_retrograde_orbit" rel="noreferrer">distant_retrograde_orbit</a> meaning far from the Moon but moving the <s>wrong</s>  opposite direction - counterclockwise if looking down from above (north of) the Earth-Moon system. <a href="https://en.wikipedia.org/wiki/Distant_retrograde_orbit#List_of_objects_in_distant_retrograde_orbit" rel="noreferrer">At least two spacecraft have used this</a>:</p>
<ul>
<li><a href="https://en.wikipedia.org/wiki/Chang%27e_5" rel="noreferrer">Chang'e 5</a></li>
<li><a href="https://en.wikipedia.org/wiki/Orion_(spacecraft)" rel="noreferrer">Orion spacecraft</a> on the <a href="https://en.wikipedia.org/wiki/Artemis_1" rel="noreferrer">Artemis 1</a> mission.</li>
<li><a href="https://space.stackexchange.com/q/48746/12102">What will happen to Chang’e 5 orbiter?</a></li>
</ul>
<h3>Halo and other 3-body Lagrange point-associated orbits</h3>
<p>There are a whole host of 3-body orbits associated with the Earth-Moon Lagrange points, primarily L1, L2, that will rotate together with the Moon and stay on one side of it.</p>
<p>The most famous right now (but not necessarily the most suitable for you) is the <a href="https://en.wikipedia.org/wiki/Near-rectilinear_halo_orbit" rel="noreferrer">near-rectilinear halo orbit</a> planned for the <a href="https://en.wikipedia.org/wiki/Lunar_Gateway" rel="noreferrer">Lunar Gateway</a>.</p>
<ul>
<li><a href="https://space.stackexchange.com/q/24019/12102">What is a near rectilinear halo orbit?</a></li>
<li><a href="https://space.stackexchange.com/q/23992/12102">Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)</a></li>
<li><a href="https://space.stackexchange.com/q/58273/12102">Where is Artemis on this Earth-Moon three-body bifurcation plot? Where's the near-rectilinear halo orbit for example?</a> covers (and illustrates) some of the huge variety of 3-body orbits associated with the Earth-Moon Lagrange points</li>
<li><a href="https://space.stackexchange.com/q/41870/12102">How does a butterfly orbit move in 3D? Way to generate or visualize?</a></li>
<li><a href="https://space.stackexchange.com/q/30153/12102">How will the Lunar Gateway go to L2 and L1; how much delta-v is needed?</a> in case you want to see the mining activities on the other side of the Moon</li>
<li><a href="https://space.stackexchange.com/q/36671/12102">Is the Gateway's halo orbit bound to Earth? Would the Gateway remain in Earth orbit if the Moon disappeared?</a></li>
<li><a href="https://space.stackexchange.com/q/54633/12102">Can mascons have Lagrange-like points? In principle? At the Moon?</a> (probably not)</li>
<li><a href="https://space.stackexchange.com/q/58427/12102">Where do the butterflies land on this bifurcation plot? (Earth-Moon three-body butterfly orbits)</a></li>
<li><a href="https://space.stackexchange.com/q/49015/12102">Station-keeping delta-v per year for an Earth-Moon vanilla halo orbit?</a></li>
<li><a href="https://space.stackexchange.com/q/58445/12102">What are &quot;transcritical, pitchfork, period-doubling, torus, and subharmonic bifurcations&quot; in the context of three-body orbits? (e.g. butterflies)</a></li>
</ul>

CC BY-SA 4.0
2023-02-18T01:46:59.357Z
Are there medium orbits beyond low-lunar orbit but well below rectilinear and lagrange that might be stable?  Like in the 500 - 2000 km range?
antlersoft
CC BY-SA 4.0
2023-02-18T03:16:34.207Z
@antlersoft I don't know - I guess what is and isn't "stable" is a question - that altitude is much less susceptible to gravitational perturbations from the lunar mascons but more susceptible to gravitational perturbations from the Earth and Moon. Anyway, thanks for your comment - I added a section for the distant retrograde lunar orbit/
uhoh
CC BY-SA 4.0
2023-02-17T21:42:06.293Z
2023-02-18T03:23:14.020Z
2023-02-18T03:23:14.020Z
uhoh
<p>Let’s say I wanted to build a space habitat in orbit around the moon. Better still, let’s say I want to build a ring of habitats occupying the same orbital path, encircling Luna, to oversee the mining/exploration of this body.</p>
<p>Given that Luna is tidally locked, and most orbital paths around it decay over time, what is most stable orbit these objects could occupy?</p>

CC BY-SA 4.0
2023-02-18T09:37:13.613Z
Seems an odd idea to build orbital habitats and an office to oversee the mining operation when the ground is there waiting to be used, some ground presence is presumably needed anyway and potential building materials are on the ground.  You might also want to check out [worldbuilding.se] and [space.se]
StephenG - Help Ukraine
<the-moon><orbital-mechanics><orbital-decay>
What is the most stable orbit around the moon?
user98816
# What is the most stable orbit around the moon?

(Asked by: username_0 on 2023-02-17)

Let’s say I wanted to build a space habitat in orbit around the moon. Better still, let’s say I want to build a ring of habitats occupying the same orbital path, encircling Luna, to oversee the mining/exploration of this body.

Given that Luna is tidally locked, and most orbital paths around it decay over time, what is most stable orbit these objects could occupy?

**Tags:** the-moon, orbital-mechanics, orbital-decay

> **Comments:**
> **username_1**: Seems an odd idea to build orbital habitats and an office to oversee the mining operation when the ground is there waiting to be used, some ground presence is presumably needed anyway and potential building materials are on the ground.  You might also want to check out [worldbuilding.se] and [space.se]  

---

## 1 answers

### Answer by username_2 on 2023-02-17. Score: 14 | Accepted answer

### Low lunar orbits

For low lunar orbits it's a challenge because the Moon as a lot of mass concentrations or [mascons](https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons) near the surface, and these will continue to perturb a low orbit and ultimately bring it down to impact the surface after months or at best years.

There are certain sets of orbital parameters, basically certain combinations of inclination and semi-major axes... these are called [frozen orbits](https://en.wikipedia.org/wiki/Frozen_orbit) because while perturbations affect them they tend to remain somewhere near the same orbital elements rather than veer into surface impact.

> **Lunar frozen orbits**
>
> Through a study of many lunar orbiting satellites, scientists have discovered that most low lunar orbits (LLO) are unstable.3 Four frozen lunar orbits have been identified at 27°, 50°, 76°, and 86° inclination. NASA expounded on this in 2006:
>
> > [Lunar mascons](https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons) make most low lunar orbits unstable ... As a satellite passes 50 or 60 miles overhead, the mascons pull it forward, back, left, right, or down, the exact direction and magnitude of the tugging depends on the satellite's trajectory. Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. ... [There are] a number of 'frozen orbits' where a spacecraft can stay in a low lunar orbit indefinitely. They occur at four inclinations: 27°, 50°, 76°, and 86°"—the last one being nearly over the lunar poles. The orbit of the relatively long-lived Apollo 15 subsatellite PFS-1 had an inclination of 28°, which turned out to be close to the inclination of one of the frozen orbits—but less fortunate PFS-2 had an orbital inclination of only 11°.4
>
> * 3https://arc.aiaa.org/doi/abs/10.2514/2.5064?journalCode=jgcd
> * 4Bell, Trudy E. (November 6, 2006). Phillips, Tony (ed.). "[Bizarre Lunar Orbits](https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/)". Science@NASA.

Another problem with low lunar orbits is that any particular spot on the surface is only visible for a few minutes every pass, and you may pass over a given site for about one day a month - the moon will slowly rotate around it's axis each month while the orbit will mostly remain fixed.

See also:

* [Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?](https://space.stackexchange.com/q/20582/12102) relatively long-lived relatively low lunar orbit
* [Was Chandrayaan-1 recovered (tracked) only that one time in 2016, or is someone still keeping an eye on it from time to time?](https://space.stackexchange.com/q/55782/12102)

### Higher lunar orbits

For earth, we get 24/7 access to a big chunk of one hemisphere by going to geostationary orbits (or at least geosynchronous). However luna-stationary orbits don't really exist because the moon rotates only once a month, and by the time you would get high enough to orbit that slowly you're interacting with the gravity of the Earth and Sun too much. Not an option for the Moon.

**However** there is the [distant\_retrograde\_orbit](https://en.wikipedia.org/wiki/Distant_retrograde_orbit) meaning far from the Moon but moving the ~~wrong~~ opposite direction - counterclockwise if looking down from above (north of) the Earth-Moon system. [At least two spacecraft have used this](https://en.wikipedia.org/wiki/Distant_retrograde_orbit#List_of_objects_in_distant_retrograde_orbit):

* [Chang'e 5](https://en.wikipedia.org/wiki/Chang%27e_5)
* [Orion spacecraft](https://en.wikipedia.org/wiki/Orion_(spacecraft)) on the [Artemis 1](https://en.wikipedia.org/wiki/Artemis_1) mission.
* [What will happen to Chang’e 5 orbiter?](https://space.stackexchange.com/q/48746/12102)

### Halo and other 3-body Lagrange point-associated orbits

There are a whole host of 3-body orbits associated with the Earth-Moon Lagrange points, primarily L1, L2, that will rotate together with the Moon and stay on one side of it.

The most famous right now (but not necessarily the most suitable for you) is the [near-rectilinear halo orbit](https://en.wikipedia.org/wiki/Near-rectilinear_halo_orbit) planned for the [Lunar Gateway](https://en.wikipedia.org/wiki/Lunar_Gateway).

* [What is a near rectilinear halo orbit?](https://space.stackexchange.com/q/24019/12102)
* [Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)](https://space.stackexchange.com/q/23992/12102)
* [Where is Artemis on this Earth-Moon three-body bifurcation plot? Where's the near-rectilinear halo orbit for example?](https://space.stackexchange.com/q/58273/12102) covers (and illustrates) some of the huge variety of 3-body orbits associated with the Earth-Moon Lagrange points
* [How does a butterfly orbit move in 3D? Way to generate or visualize?](https://space.stackexchange.com/q/41870/12102)
* [How will the Lunar Gateway go to L2 and L1; how much delta-v is needed?](https://space.stackexchange.com/q/30153/12102) in case you want to see the mining activities on the other side of the Moon
* [Is the Gateway's halo orbit bound to Earth? Would the Gateway remain in Earth orbit if the Moon disappeared?](https://space.stackexchange.com/q/36671/12102)
* [Can mascons have Lagrange-like points? In principle? At the Moon?](https://space.stackexchange.com/q/54633/12102) (probably not)
* [Where do the butterflies land on this bifurcation plot? (Earth-Moon three-body butterfly orbits)](https://space.stackexchange.com/q/58427/12102)
* [Station-keeping delta-v per year for an Earth-Moon vanilla halo orbit?](https://space.stackexchange.com/q/49015/12102)
* [What are "transcritical, pitchfork, period-doubling, torus, and subharmonic bifurcations" in the context of three-body orbits? (e.g. butterflies)](https://space.stackexchange.com/q/58445/12102)

> **Comments:**
> **username_3**: Are there medium orbits beyond low-lunar orbit but well below rectilinear and lagrange that might be stable?  Like in the 500 - 2000 km range?  
> **username_2**: @username_3 I don't know - I guess what is and isn't "stable" is a question - that altitude is much less susceptible to gravitational perturbations from the lunar mascons but more susceptible to gravitational perturbations from the Earth and Moon. Anyway, thanks for your comment - I added a section for the distant retrograde lunar orbit/  

---

