A listening post on Morska
Morska was a Klingon planet on which a grounded subspace monitoring outpost was located.
The USS Enterprise-A passed near Morska when on course to Rura Penthe to rescue Kirk and McCoy in 2293. Fortunately, Communications Officer Uhura was able to convince the two Klingon officers at Morska that the Enterprise was a legitimate Klingon ship. (Star Trek VI: The Undiscovered Country)
Through the windows in the background of the scenes the matte paintings are visible. They make the section the outpost was located look like a desert with mountains.