External stowage platform

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ESP-1 is the rectangular object on the Destiny module
ESP-2 is located under the Quest airlock
ESP-3 is transferred from the shuttle arm to the station arm

The External Stowage Platforms ( ESPs ) are three components of the International Space Station (ISS). Each ESP is a device that is attached to the outside of the space station and in which equipment and spare parts, so-called Orbital Replacement Units (ORUs), are housed.

ESP-1

The first External Stowage Platform, ESP-1, was transported to the ISS on the space shuttle flight STS-102 . On March 13, 2001, the installation on the outer hull of the Destiny module took place during the second external mission (EVA) .

ESP-2

ESP-2 was mounted on the Quest airlock on August 3, 2005 during the third space exit of the STS-114 mission . ESP-2 is much larger than ESP-1 and can therefore accommodate more spare parts (ORUs).

Originally four video camera mounts were also attached to the ESP-2. For outboard missions, these were attached to the P1 element on November 7, 2005 , to the S1 element on August 3, 2006 , to the S3 element on June 17, 2007 and to the P1 element on July 23, 2007.

ESP-3

ESP-3 was installed on August 14, 2007 during the space shuttle mission STS-118 . The platform has eight suspensions on which up to seven ORUs or pieces of equipment can be stored. The platform has handles and attachment points for safety lines and footrests for astronauts.

Unlike the other two ESPs, ESP-3 was only attached to the P3 lattice structure with the robotic arms of the ISS and the shuttle without a space exit .

The following ORUs are currently attached to ESP-3:

  • Battery Charge / Discharge Unit (BCDU) - A charging and discharging device for batteries that ensure a constant power supply during orbital night phases.
  • Nitrogen Tank Assembly (NTA) - A replacement nitrogen tank for either of the two tanks attached to the S1 and P1 grid structures. The NTAs ensure a constant pressure in the ammonia tanks when they release their contents into the lines of the cooling circuit system.
  • Pitch Roll Joint (P / RJ) - A replacement joint for the space station's robotic arm built by the Canadian Space Agency .

A spare gyroscope was also attached to the ESP-3 during the launch of the STS-118. This gyroscope was attached to the ISS during the second spacecraft mission and the defective gyroscope was attached to ESP-2, as the removal of ESP-3 from the space shuttle's cargo bay meant that it was no longer possible to transport the component back to Earth. As part of an EVA at STS-122 , it was attached to the Integrated Cargo Carrier of the space shuttle Atlantis and transported to Earth.

Web links

Commons : External Stowage Platforms  - Collection of images, videos and audio files