Measuring 4.57 metres (15.0ft) in diameter and 5.47 metres (17.9ft) in length, Unity was built at NASA's Marshall Space Flight Center. It is the first of three connecting modules, joined by Harmony and Tranquility.
Launch and initial berthing
Unity (with its two attached PMAs) was carried into orbit as the primary cargo of the Space Shuttle Endeavour (OV 105) on STS-88, the first Space Shuttle mission dedicated to assembly of the station. On December 6, 1998, the STS-88 crew mated the docking port of the PMA on the aft berthing port of Unity with the forward hatch of the already orbiting Zarya module. (Zarya was a mixed Russian-U.S. funded and Russian-built component launched a few days before aboard a RussianProtonlaunch vehicle from Baikonur, Kazakhstan.)
Essential space station resources such as fluids, environmental control and life support systems, electrical and data systems are routed through Unity to supply work and living areas of the station. More than 50,000 mechanical items, 216 lines to carry fluids and gases, and 121 internal and external electrical cables using six miles of wire were installed in the Unity node.[2] The primary structure of Unity is constructed of aluminium.[3]
During the space station construction, a crew member placed two speed limit signs on the hatch (leading into the FGB) in 2003, noting the orbital velocity in mph and km/h.[4]
Prior to its launch aboard Endeavour, conical Pressurized Mating Adapters (PMAs) were attached to the aft and forward berthing mechanisms of Unity. Unity and the two mating adapters together weighed about 11,600kg (25,600lb). The adapters allow the docking systems used by the Space Shuttle and by Russian modules to attach to the node's hatches and berthing mechanisms.[2] PMA-1 now permanently attaches Unity to Zarya, while PMA-2 provided a Shuttle docking port. Attached to the exterior of PMA-1 are computers, or multiplexer-demultiplexers (MDMs), which provided early command and control of Unity. Unity also is outfitted with an early communications system that allows data, voice and low data rate video with Mission Control Houston, to supplement Russian communications systems during the early station assembly activities. PMA-3 was attached to Unity's nadir berthing mechanism by the crew of STS-92.
Other nodes
Node 3 (Tranquility) in space
The two remaining station connecting modules, or nodes, were manufactured in Italy by Alenia Aerospazio, as part of an agreement between NASA and the European Space Agency (ESA). Harmony (also known as Node 2) and Tranquility (also known as Node 3) are slightly longer than Unity, measuring almost 6.4m (21ft) long in total. In addition to their six berthing ports, each can hold eight International Standard Payload Racks (ISPRs). Unity, in comparison, holds just four ISPRs. ESA built Nodes 2 and 3 as partial payment for the launch aboard the Shuttle of the Columbus laboratory module, and other ESA equipment.
1 2 "Unity Node". NASA. Archived from the original on June 14, 2014. Retrieved November 8, 2013. This article incorporates text from this source, which is in the public domain.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets).
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