Solid Rocket Booster

A solid rocket booster is a solid propellant rocket motor used to provide additional thrust for a launch vehicle from liftoff through the early part of its ascent, typically strapped alongside a vehicle's main liquid fueled stage. The Space Shuttle flew with two four segment solid rocket boosters that were, at the time, the largest solid propellant motors ever built and the first designed to be recovered from the ocean and reused across multiple missions, each carrying roughly 500,000 kilograms of propellant. The same approach carries the Space Launch System, which uses two five segment boosters, and appears in variable count on the Atlas V and in multiples on the Ariane 5 and Ariane 6, among other vehicles including the Delta II and India's PSLV. Compared with liquid propellant boosters, solid rocket boosters deliver substantial thrust from a mechanically simpler design that needs no refrigeration or insulation for cryogenic propellant, though once ignited a solid motor cannot be throttled or shut down.