Most of artificial satellites of the Moon has depleted their batteries, lost communication, been deorbited or impacted the surface after orbital decay. The list doesn't exactly make it clear which ones are still functional and active. Could you provide the current, complete list of active lunar orbiters and what functions they fulfill?
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1$\begingroup$ If you click on the links for each satellite, you will see exactly what you are asking for. $\endgroup$– BurkhardJul 17, 2013 at 11:02
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1$\begingroup$ Inactive, inactive, inactive, inactive, inactive, inactive... hardly what I'm asking for. $\endgroup$– SF.Mar 19, 2017 at 17:40
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Orbiting the moon is notoriously difficult for long periods of time. The lunar gravity field varies by as much as 1%. There has been some work to maximize the lifetime, but it hasn't been particularly successful to date. For a complete technical explanation, see this paper. The bottom line is, there are 4 orbits which one could orbit to stay for an extended period of time, namely 27º, 50º, 76º, and 86º (See also Wikipedia, Science@NASA). Given this, there aren't many satellites that are even orbiting the moon, let alone functioning. It is difficult to tell which satellites have crashed into the moon, but it is safe to say that any spacecraft orbiting from more than 20 years ago will have crashed in to the moon already.
The only known spacecraft currently orbiting the moon arethe Lunar Reconnaissance Orbiter (LRO), as well as the two ARTEMIS probes, which are functioning. Beyond that, it is unlikely that any spacecraft is still orbiting, let alone functioning. There are plans for a few more launches in the next few years, but for now, it is only these 3.
answered Jul 17, 2013 at 11:23
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4$\begingroup$ @gerrit: It just lost communications, but as I mentioned, orbiting the Moon is quite difficult. It was placed in a polar orbit, which most likely means it wasn't perfectly stable, meaning it has probably impacted the moon even without further encouragement. $\endgroup$– PearsonArtPhoto ♦Jul 17, 2013 at 13:03
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5$\begingroup$ Wow - another spaceflight gotcha easily overlooked! In the 22 years following the NASA Technical Paper 3394, supercomputer speed has grown six orders of magnitude, complex orbital mechanic theory has blossomed, and computing orbits around even crazy things (cubes {1} and {2}, massive line segments(many)) has recently become popular. Maybe long-lived orbit solutions near the moon deserves a fresh look! $\endgroup$– uhohMay 24, 2016 at 4:08
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$\begingroup$ What about a very high orbit around moon, will it be stable for a long time? But a very high orbit is not useful to get good pictures of the moon surface with a lot of small details. $\endgroup$– UweOct 26, 2016 at 8:34
