The sign accompanying the Descent Propulsion System engine. It reads
Lunar Module Descent Engine
The Lunar Module (LM) was a two-stage vehicle designed for space operations
near and on the Moon, incapable of reentering the Earth's atmosphere. The
descent stage is the lower unmanned portion of the LM. The engine could be
gimballed six degrees in any direction in response to positioning commands.
||Aerozine 50/Nitrogen Tetroxide (hypergolic)
|Engine start capability:
Developed by Rocketdyne
On loan from Smithsonian Institute
While Rocketdyne did develop a DPS engine as part of Grumman's competition for
the engine, TRW's Space Technology Laboratories (STL) eventuall won the
contract and built the engines actually used by the Lunar Modules. For
additional information about the engine competition and development, see chapter
6 of Chariots
for Apollo: A History of Manned Lunar Spacecraft.