Would a satellite positioned at Earth Moon L2 be stable enough?
It would also need a relay to communicate with earth…
A circular Moon orbit can last years with no fuel use if you pick your inclination correctly. Look up "frozen orbits" (the Moon is lumpy)
Usually sats like those (there have been several dozen) aren't at the L2 point, but are in a Lissajous orbit around it. This avoids the worst stability issues, although they are still dynamically unstable so they'll require minor station keeping adjustments from time to time.
Did I miss it or did they fail to explain how that would work? Does it just slowly move around the moon so it gets its 1000 hours of observation, then eventually comes out of the EM shadow?
Or is there some final boost that pushes it?
Will it crash into the moon eventually?
The other half it would have line-of-sight with Earth and be able to communicate, but also exposed to radio pollution. Presumably the mission designers would hibernate the experiment for this period.
It will almost certainly hit the moon one day. The moon has many mascons (mass concentrations, a.k.a. lumps) and destabilizes anything orbiting it over a long period of time. Or even a short period of time: https://en.wikipedia.org/wiki/Apollo_16#Particles_and_Fields... But an orbit can be chosen to give at least a couple years, which is the mission goal.