External stowage platform

External stowage platforms (ESPs) are key components of the International Space Station (ISS).

Each platform is made from steel[citation needed] and serves as an external pallet that can hold spare parts, also known as orbital replacement units (ORUs), for the space station.

The first of the external stowage platforms, called ESP-1, was installed on the port side trunnion pin on the outer hull of the Destiny Laboratory Module on March 13, 2001 during the second EVA of the STS-102 Space Shuttle mission.

ESP-1 holds the following ORUs:[3] ESP-2 was detached from its Keel Yoke Assembly (which remained in the Orbiter) and installed with the assistance of Space Shuttle Discovery's robotic arm and two spacewalkers during the STS-114 mission.

The ORUs on ESP-2 are: Notes: ESP-3 was detached from its Keel Yoke Assembly (which remained in the Orbiter) and installed on the P3 Truss at UCCAS-1 on August 14, 2007 during the Space Shuttle STS-118 mission.

It has seven attachment sites for ISS spare parts and assemblies, called Orbital Replacement Units (ORUs).