Booster stage

A booster rocket (or engine) is either the first stage of a multistage launch vehicle, or else a shorter-burning rocket used in parallel with longer-burning sustainer rockets to augment the space vehicle's takeoff thrust and payload capability. (Boosters used in this way are frequently designated "zero stages".) Boosters are traditionally necessary to launch spacecraft into low Earth orbit (absent a single-stage-to-orbit design), and are certainly necessary for a space vehicle to go beyond Earth orbit. The booster is dropped to fall back to Earth once its fuel is expended, a point known as booster engine cut-off (BECO). The rest of the launch vehicle continues flight with its core or upper-stage engines. The booster may be recovered and reused, as was the case of the Space Shuttle.

A booster rocket or engine is either the first stage of a multistage rocket or launch vehicle, or else a shorter-burning rocket used in parallel with longer-burning sustainer rockets to augment a space vehicle's takeoff thrust and payload capability. The latter are frequently designated "zero stages".

Boosters are traditionally necessary to launch spacecraft into low Earth orbit absent a single-stage-to-orbit design, and are necessary to go beyond Earth orbit. When the booster´s fuel is empty it is dropped to fall back to Earth, a point known as booster engine cut-off (BECO). The rest of the launch vehicle continues to fly with its core or upper-stage engines. The booster may be recovered and reused, as in the case of the Space Shuttle.

An illustration and description in the 14th century Chinese military treatise Huolongjing by the Ming dynasty military writer and philosopher Jiao Yu shows the oldest known multistage rocket with rocket boosters. The Huolongjing describes and illustrates the oldest known multistage rocket. It was a two-stage rocket that had carrier or booster rockets that would automatically ignite a number of smaller rocket arrows that were shot out of the front end of the missile, which was shaped like a dragon's head with an open mouth, before eventually burning out. This multi-stage rocket may be considered the ancestor to the modern YingJi-62 ASCM. The British scientist, sinologist, and historian Joseph Needham points out that the written material and depicted illustration of this rocket come from the oldest stratum of the Huolongjing, which can be dated roughly from 1300–1350 AD.

...
Wikipedia