Pressurized Mating Adapter

The International Space Station (ISS) uses three Pressurized Mating Adapters (PMAs) to interconnect spacecraft and modules with different docking mechanisms. The first two PMAs were launched with the "Unity" module aboard STS-88. The third was launched aboard STS-92.

Uses

Each PMA on the ISS is used slightly differently, but all three perform the same basic function of connecting a Common Berthing Mechanism (CBM) port of an ISS module to the Androgynous Peripheral Attach System (APAS) docking port of another module or visiting spacecraft. [cite web
title = Human Space Flight - Space Fact
publisher = NASA
date = 04/07/2002
url = http://spaceflight.nasa.gov/dayfacts/2000/0118.html
accessdate = 2007-01-17 ] For this the PMAs carry a passive CBM port and a passive APAS port. They are pressurized and heated from the inside, and through docking rings as well as external connections allow for power and data communications transfer. [cite web
url=http://www.shuttlepresskit.com/sts-92/payload78.htm
title= STS-92 Press Release Kit: Payload section
publisher = NASA
date = 2000-10-10
accessdate = 2007-10-27 ]

PMA-1

This was one of the first components of the International Space Station and joins the Russian side of the station with the US side. On STS-88 the crew used the shuttle's robotic arm to attach the Zarya control module to PMA-1, which was already connected to the aft berthing port of "Unity". PMA-1 now permanently connects these first two station components.

PMA-2

PMA-2 is currently mounted on the forward port of the "Harmony" connecting node and used when Space Shuttle orbiters dock at the station. It is the only PMA that has been outfitted with Station-to-Shuttle Power Transfer System (SSPTS) hardware, which allows shuttles to stay docked longer to the space station. [cite web | url = http://www.nasa.gov/centers/johnson/news/station/2007/iss07-08.html | title = International Space Station Status Report #07-08 | publisher = NASA]

Due to space station assembly PMA-2 has been moved several times. It was originally connected to the forward hatch of "Unity", but when STS-98 delivered the "Destiny" in February 2001, "Destiny" was berthed to that hatch while PMA-2 was moved to the forward hatch of the Z1 truss. It was finally moved to the forward hatch of "Destiny". cite web
last = STS-98
first = Mission Control Center
title = Status Report # 07
publisher = NASA
date = February 10, 2001
url = http://science.ksc.nasa.gov/shuttle/missions/sts-98/news/sts-98-mcc-07.txt
accessdate = 2007-01-18 ] (The removal of PMA-2 from "Unity" was the first time the Common Berthing Mechanism (CBM) was used to disconnect two ISS components. [cite web
last = Harwood
first = William
title = Atlantis crew to attach Destiny lab to station today
publisher = Spaceflight Now
date = February 10, 2001
url = http://spaceflightnow.com/station/stage5a/010210fd4/
accessdate = 2007-01-15 ] )After STS-120 had delivered "Harmony" at the station in October 2007, Canadarm2 relocated PMA-2 to its final location at the forward hatch of "Harmony" on november 12, 2007. Two days later, the combined package of "Harmony" and PMA-2 was moved to its final location, the forward hatch of "Destiny". PMA-2 will stay berthed at the forward port of "Harmony" for the remaining duration of the ISS.

When a shuttle docks with the station, its "final approach [is] at a relative velocity of one-tenth of a foot per second. [As it] makes contact with Pressurized Mating Adapter 2 [latches] automatically attach the two spacecraft together. Once relative motion between the spacecraft stops, [a shuttle astronaut] retracts the docking ring on [the shuttle's] mechanism, closing latches to firmly secure the shuttle to the station." [cite web
last = STS-102
first = Mission Control Center
title = Status Report # 03
publisher = NASA
date = March 9, 2001
url = http://science.ksc.nasa.gov/shuttle/missions/sts-102/news/sts-102-mcc-03.txt
accessdate = 2007-01-18 ] )

PMA-3

In October 2000 STS-92 brought PMA-3, mounted on a Spacelab pallet, to the station. [cite web
last = STS-92
first = Mission Control Center
title = Status Report # 10
publisher = NASA
date = October 16, 2000
url = http://science.ksc.nasa.gov/shuttle/missions/sts-92/news/sts-92-mcc-10.txt
accessdate = 2007-01-18 ] It was initially attached to the nadir (bottom, or Earth-facing) hatch of "Unity". One and a half months later, when STS-97 delivered the P6 solar array truss structure, "Endeavour" docked at PMA-3. [cite web
last = STS-97
first = Mission Control Center
title = Status Report # 05
publisher = NASA
date = December 2, 2000
url = http://science.ksc.nasa.gov/shuttle/missions/sts-97/news/sts-97-mcc-05.txt
accessdate = 2007-01-18 ] Also, when STS-98 moved PMA-2 from "Unity" to "Destiny", "Atlantis" was docked at PMA-3.PMA-3 was moved in March 2001 to "Unity"'s port hatch by the crew of STS-102 to make room for the docking of a Multi-Purpose Logistics Module (MPLM). [cite web
last = STS-102
first = Mission Control Center
title = Status Report # 07
publisher = NASA
date = March 11, 2001
url = http://science.ksc.nasa.gov/shuttle/missions/sts-102/news/sts-102-mcc-07.txt
accessdate = 2007-01-18 ] On August 30, 2007 PMA-3 was moved to the nadir hatch of "Unity" to make room for the temporary docking of the "Harmony" module that was delivered by STS-120. [cite web | url = http://www.cbsnews.com/network/news/space/currentglance.html | title = SHUTTLE/SOYUZ/ISS PROCESSING MILESTONES | publisher = CBS News] ) Its final location will be the nadir hatch of Node 3 when this will be berthed to "Unity", a configuration scheduled for 2010. While Node 3 is being added to ISS, PMA-3 will be temporarily docked to the nadir port of "Harmony".

History

Pressurized Mating Adapters were constructed by Boeing, as was a similar adapter which allowed the U.S. Space Shuttle to dock with Russia's Mir space station. [ [http://www.boeing.com/defense-space/space/spacestation/components/pma.html Boeing: Integrated Defense Systems - NASA Systems - International Space Station - Pressurized Mating Adapters ] ]

See also

* ISS assembly sequence

References