Tranquility was built within the ESA–NASA ISS bartering system. Under this arrangement, ESA agreed to provide NASA with the fully integrated
Harmony and
Tranquility node modules, along with additional equipment and parts, in exchange for the launch of ESA’s
Columbus module and its initial payload aboard the Space Shuttle. This barter allowed ESA to secure launch services without a direct financial transaction, and enabling those funds to remain within ESA member states. To build the nodes, ESA partnered with the
Italian Space Agency and
Thales Alenia Space, which manufactured them at its facility in
Turin, Italy. The module’s pressure shell is constructed from
2219 aluminum, while its
debris shield is made from hardened
6061 aluminum. The metal is heat-treated, giving the shield ballistic resistance comparable to stainless steel.
Tranquility provides six
berthing locations with power, data and commanding, thermal and environmental control, and crew access for more attached habitable volumes or for crew transportation vehicles or stowage, or an appropriate combination of all of these. One of the berthing locations is used by the
Cupola, which houses a Robotic Work Station inside it to assist in the assembly/maintenance of the ISS, and offers a window for
Earth observations.
Tranquility was launched with the
Cupola attached to its port-facing
Common Berthing Mechanism (CBM). After mating
Tranquility with the port CBM of
Unity, the
Cupola was transferred to the
nadir facing port of
Tranquility where it will stay. The module has three berthing ports that were not scheduled to be used prior to the end of the Space Shuttle program, although there is a
Power Data Grapple Fixture reserved for the
Special Purpose Dexterous Manipulator (
Dextre), which is located on the
zenith berthing location. In the current ISS configuration
Tranquility is docked to the port berthing location of
Unity. As such, the three unused berthing locations of
Tranquility were disabled as the node's close proximity to other segments would prohibit the port's direct use for cargo spacecraft or using the docking module
PMA-3, which was relocated from
Harmony to the port berthing location of
Tranquility for storage. At the time, the move of PMA-3 to the port location of
Tranquility was required because NASA decided to leave the
Multi-Purpose Logistics Module (MPLM)
Leonardo permanently attached to the ISS, which will be located at the nadir side of
Unity. In 2001, NASA considered changing the design of the module. This idea for an extended or "stretched" module, was a result of the deferral/deletion of the
Habitation Module. The stretched module would have held 16 racks, compared with the baseline capacity of eight racks. This modification was not funded and the plans were abandoned. == Purpose ==