I take back my earlier comment. You “could” have a lunar synchronous orbit that held over the far side from about 88,500 km radius from the moon. That’s about twice the orbit radius of an Earth Geosynchronous satellite.
It would take some propellant to maintain but that’s probably not some unreasonable amount.
I used to some orbit analysis. Intuition isn’t always right so I should have run the numbers first. If you’re interested, the formula for determining the synchronous orbit radius for a single body system is:
(mu/(omega^2.0))^(1.0/3.0)
“mu” is the gravitational constant of the planet. “omega” is the planets rotational rate. The symbol “^” is raising to the power of.
For Earth, mu = 3.9860e+05 km^3/sec^2 and omega = 7.2921151467e-5 radians/sec, resulting in synchronous radius of approximately 42,164 km
For the moon, mu = 4.9028e+03 km^3/sec^2 and omega = 2.6617e-06 radians/sec, resulting in synchronous radius of approximately 88,452 km
I am not sure if this is the same as the L2 Lagrange libration point or not. I believe the L2 Lagrange point is always in relation to the any two body system, so there may be separate Earth/sun and Earth/moon Lagrange points. I studied briefly but never really used Lagrange points in my work. So off the top of my head, I am not sure if the Lagrange point is farther still from the Earth/moon system.
This is probably enough heavy thought for now...For the Chinese and the article, this is still a very challenging problem.
I’ll take your word for it. I barely squeaked by in advanced math.
It seems to me that a lunar synchronous orbit would actually be not only around the moon, but around the Earth-moon system and be a real headache to maintain, but maybe not.