They depict the planned Skylab B international space station, a follow up to the historical US Skylab program.
In reality the Skylab B hardware exists and is on museum display. It was identical to the flown Skylab, since it was its flight spare.
For this add-on, an alternate reality is considered, based in several proposals by NASA made in the 1970's.
The main changes are the lack of the Solar Observatory, the additional docking ports for Soviet spacecraft, and the alternate solar panel positions. This configuration would allow the station to accommodate extended docking or servicing by Apollo, Soyuz, Progress, Salyut and eventually the Space Shuttle.
There's a basic “virtual cockpit” with the "Wardroom Window", that faces sideways from the station, so you will have to turn the viewing direction to look outside.
Besides the initial Skylab B add-on (http://www.orbithangar.com/searchid.php?ID=6394), there are two missions packs available:
Skylab B missions (SL5 & SL6) and AMU v2
Skylab B missions 2 (SL7) and ATM B
The mission use both AMSO and AAPO Apollo spacecraft, along with the correct launch pads for the Saturn V and Saturn Ib.
The AMU (Autonomous Maneuvering Unit) is an early EVA backpack, that allows the astronaut to move away from the station, without being tethered. I'm following some references from the Gemini AMU, but with the spacesuit being more in line with the Apollo era.
The ATM (Apollo Telescope Mount) B is a space observatory based on the Apollo Lunar Module. Again based on a Nasa proposal, I have it setup so that both the ascent and descent stages can perform autonomous observations. When docked to Skylab B, the cabin serves as an manned observation station.