The sign accompanying the Descent Propulsion System mockup (actually, the DPS
engine's sign is located on the Ascent Propulsion System (APS)
mockup across the room). It reads
For a successful manned lunar landing, the lunar module had to have a descent
engine that could be restarted easily and could be controlled with a throttle.
The astronauts needed the ability to fully control their descent and to hover
over [the lunar surface].