Adapter (rocketry)

In rocketry, an adapter is a hollow cylindrical^[1] or conical segment^[2] which provides a sound aerodynamic and structural connection, either between rocket stages (oftern referred to as an interstage) or between a spacecraft and the top rocket stage (referred to as a payload adapter). It may shroud and protect vulnerable systems such as electrics or machinery of rocket engines/spacecraft from weather or noise caused by running engines.^[3] It is discarded during staging.

Interstage of the UGM-73 Poseidon missile. First stage is on the right, separated second stage - on the left

Examples of rocket stages featuring an interstage adapter:

• Centaur (second stage of several Atlas-based launch vehicles, from Atlas-Centaur to Atlas V)^[4][5][6]
• S-II and S-IVB (second and third stage of the Saturn V)^[7][8]
• The Interim Cryogenic Propulsion Stage (ICPS) of SLS Block 1 is connected to the Core Stage with the Launch Vehicle Stage Adapter (LVSA)^[9][10]

Examples of rocket stages featuring a payload adapter:

• (Planned) The Exploration Upper Stage (EUS) is expected to connect large secondary co-manifested payloads SLS Block 1B/2 using the Universal Stage Adapter (USA).^[11]