# Can ion propulsion system be used to maintain lunar orbit?

I am doing research on propulsion systems and it was suggested that I use an ion propulsion system for a theoretical satellite I am tasked with designing, I need to maintain orbit for three years totaling 720m/s (+ 830m/s to get there) delta v to maintain the orbits, and using a 400kg satellite. One orbit is pretty circular with another being more elliptical, both around 5000km on the semi-major axis. I am trying to figure out how much thrust the propulsion system will need to be able to produce to maintain the orbital patterns I come up with. This is made a bit trickier by the lumpiness of the moon's gravitation field, but I also know very little about guidance and propulsion to come up with any good ideas. I haven't been able to find any lunar orbiting 400kg satellites that use ion propulsion systems, so I can't tell if it is just not feasible given the low thrust of the systems or how to even best approach this.

• "720 total delta v" what units? "ESPA class satellites" What are those? Satellites can stay in lunar orbit for decades if they don't go too low, so without additional details about "the orbital patterns (you) come up with" the answer is certainly "Yes, and in some cases even without it". For example, Chandrayaan-1 was launched in 2008 and last detected in 2016 still in lunar orbit. See also.
– uhoh
Feb 17 at 5:15
• Sorry, 720m/s (+ 830m/s to get there) delta v to maintain the orbits, and using a 400kg satellite. It was mentioned by a person I'm working with on this project that one orbit is pretty circular with another being more elliptical, both around 5000km on the semi-major axis
– Sam
Feb 17 at 5:29
• Okay great, can you go ahead and click "edit" and put that into your question? Thanks!
– uhoh
Feb 17 at 5:46
• just for ref (as i think its been edited out), ESPA class of satellites <700kg: csaengineering.com/content/dam/moog/literature/Space_Defense/… Feb 17 at 7:19

Assuming you just need the 720 m/s in electric propulsion for orbital maintenance (830 m/s insertion is done chemically?), I think it's possible.

A first order analysis gives a thrust requirement on the order of milli-Newtons:

$$accel_{avg} = \frac{\Delta V}{T}=\frac{F_T}{m} \to F_T = 400kg \cdot \frac{720 m/s}{3 yr} \to F_T = \sim 3mN$$

NASA's DART, though not a lunar mission, is a similar mass (610 kg) and uses electric propulsion (NEXT-C) so that may be a good starting point for ideas.

The NEXT-C from Aerojet Rocketdyne can amply produce this amount of thrust:

(Source: NEXT-C datasheet)

Even with more realistic duty cycles (10% -> ~30mN, 1% -> ~300mN) it is still possible with NEXT-C, though other options certainly exist.

All of the papers I am seeing on "low thrust orbital maintenance" seem to ignore or leave to the reader dealing with aspherical gravity, but they may be useful regardless:

The last paper is a dissertation so it is quite verbose, though that may be useful for building up an understanding.