The Hermes Manipulation System (HERA) will be an important part of the Hermes space plane system. The HERA is a sophisticated space manipulator system, which has to perform tasks ranging from capture and berthing to tool operation in various operational modes from fully automatic to purely manual. The HERA system main contractor is Fokker Space & System B.V. Since early 1985, NLR is involved in the development of the so-called HERA Simulation Facility (HSF) . Presently, the HSF consists of three distinct facilities: - the HSF Pilot (HSFP); - the Non-Real-Time HSF (NRT HSF), and - the Real-Time HSF (RT HSF). The HSFP is a limited real-time simulation facility, which includes a simple Hermes cockpit mockup, a simulation computer and a real-time computer image generation system. The NRT HSF will be the main HERA simulation tool for detailed design, analysis and verification. It will feature the highest model fidelity of all three facilities. The RT HSF prime function is to provide high fidelity real-time "man-in-the-loop" and "hardware-in-theloop" simulation. The paper will give an in-depth description of the specifications of the three facilities and the present HSFP development. This paper has been presented on the first European In-orbit Operation Technology Symposium, Darmstadt, 7-9 September 1987