Editing Retrorocket (section)

====Apollo program====
For lunar flights, the [[Apollo command and service module]] did not require retrorockets to return the command module to Earth, as the flight path took the module [[atmospheric entry|through the atmosphere]], using atmospheric drag to reduce velocity. The test flights in Earth orbit required retrograde propulsion, which was provided by the large [[Service propulsion system|Service Propulsion Engine]] on the service module. The same engine was used as a retrorocket to slow the spacecraft for [[lunar orbit insertion]]. The [[Apollo Lunar Module]] used its [[descent propulsion system|descent stage engine]] to drop from orbit and land on the Moon.