on some flights is to maintain the cleanroom environment for precision instruments. Once outside the atmosphere the fairing is jettisoned, exposing the payload to outer space.

The standard payload fairing is typically a cone-cylinder combination, due to aerodynamic considerations, although other specialized fairings are in use. The type of fairing which separates into two halves upon jettisoning is called a clamshell fairing by way of analogy to the bifurcating shell of a clam.