Pressurized Mating Adapter
Pressurized Mating Adapter (PMA ) is a set of three coupling adapters of the International Space Station ( ISS), which are used for docking of feeder vehicles and as a link between the American and Russian segments. The adapter PMA -1 used to connect the connection node to the Unity Zarya module, two additional adapters (PMA and PMA -2 -3) were used as docking sites for the Space Shuttle. The two crossed projects, Crew Return Vehicle ( CRV) and Orion spacecraft should dock to a PMA.
Technology
Each conical PMA consists of aluminum is about 2,0 m long and has a mass of between 1.6 T ( PMA -1) and 1.2 T ( PMA 3). Each adapter has at one end of a 1.3 m wide CBM - saver- American design (Common Berthing Mechanism), which is used in all other U.S. modules, the station, and a APAS - saver- laterally offset ( Androgynous Peripheral Attachment System) Russian design with 0.7 m diameter for docking of the Space Shuttle or the Zarya module.
In the construction of the PMA experience from the developed to the Mir space station Shuttle docking modules were incorporated. The Russian module crystal also used on the Mir a similar APAS - coupling unit, which was intended for the Russian Buran space shuttle. Inside the heated PMAs there is normal air pressure so that the astronauts in this tunnel-like modules without space suit between the individual sections of the ISS and a docked space shuttle can move. If the PMA is not occupied by space vehicles, the interior is mainly used as storage space for supplies and unneeded equipment. On the outer skin of the PMA various brackets are mounted, used to receive from smaller components and spare parts for spacewalks. At PMA -1 of the Russian Strela -1 crane was stored from 1999, for example, temporary.
Were made the adapter from the Boeing Company in Huntington Beach ( California).
PMA -1
PMA -1 was launched on 4 December 1998 with the mission STS -88 together with the Unity connecting node and PMA -2 to the ISS. Both PMAs were already mounted before starting the Unity module. With the robotic arm of the space shuttle Endeavour, the Zarya module was connected to the PMA -1 coupling adapter. Thus, PMA- 1, the connector between the American and the Russian part of the ISS.
PMA -2
PMA -2 was mounted before starting the Unity module on the opposite side of PMA -1 and also carried on STS -88 to the ISS. It served until 2011 as a docking site for the Space Shuttle.
With the further expansion of the station PMA -2 was implemented several times. First, it was transferred on 12 February 2001 during mission STS -98 on the bow of the U.S. Destiny laboratory, which occupied the previous docking of PMA -2. The 16 long-term ISS crew replied PMA -2 finally in November 2007 with the help of the robotic arm Canadarm2 to its final position at the bow of the delivered during the mission STS -120 Harmony connecting node.
On February 4, 2007 PMA -2 was at a spacewalk with the SSPTS lines ( Station -to- Shuttle Power Transfer System). In order for the U.S. space shuttles could be supplied with power from the space station and remain docked longer.
PMA -3
The launch of PMA -3 was carried out on 11 October 2000 together with the Z1 - grid structure with the mission STS -92. PMA 3 is installed at the bottom of the Unity module.
One and a half months later, when STS -97 brought the P6 solar cell element, docked with the Endeavour for the first time a space shuttle to PMA- 3 at. The Atlantis docked during the mission STS -98 on to PMA- 3 to allow the displacement of the PMA- 2 coupling adapter of Unity in the Destiny laboratory. This was the second and final coupling of a Space Shuttle on PMA- third
In March 2001, PMA -3 was moved during the mission STS- 102 to the port side of Unity, to make room for the MPLM. On 30 August 2007 PMA -3 was again coupled to the underside of Unity, to make room for the temporary coupling of the Harmony module during STS- 120. PMA -3 was moved to the top of Harmony, so as not to interfere with the coupling of tranquility during the mission STS -130 on January 25, 2010.
After activation of tranquility PMA -3 was moved on 16 February 2010 to its final position at the front of the Tranquility module. There it remained as a spare in case of failure of the shuttle used for couplings PMA -2 and serves as a micro- meteorite shield for tranquility.