The assembly of the International Space Station is a major aerospace engineering endeavor currently being conducted in low-orbit earth by a consortium of governmental and inter-governmental space agencies.
Zayra, the first ISS module, was launched by a Proton rocket in November 1998. The STS-88 shuttle mission followed two weeks after Zarya was launched, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained unmanned for the next one and a half years, until in July 2000 the Russian module Zvezda was added, allowing a minimum crew of two astronauts or cosmonauts to be on the ISS permanently.
When assembly is complete, the ISS will have a pressurized volume of
approximately 1,000 cubic meters, a mass of approximately 400,000
kilograms, approximately 100 kilowatts of power output, a truss 108.4
meters long, modules 74 meters long, and a crew of six. Building the
complete station will require more than 40 assembly flights. Of these
flights, currently 35 are planned to be Space Shuttle flights, with 26
ISS-shuttle flights currently flown and 9 more planned between 2008 and
2010. Other assembly flights consist of modules lifted by the Russian Proton rocket or in the case of the Plrs airlock by a Soyuz rocket.
The space station is located in orbit around the Earth at an altitude of approximately 360 km (220 miles), a type of orbit usually termed low Earth orbit (the actual height varies over time by several kilometers due to atmospheric drag and reboosts). It orbits Earth in a period of about 90 minutes; by August 2007 it had completed more than 50,000 orbits since launch of Zarya on November 20, 1998.
A total of 14 main pressurized modules are currently scheduled to be part of the ISS by its completion date in 2010.A number of smaller pressurized sections will be adjunct to them (Soyuz spacecrafts (permanently 2 as lifeboats - 6 months rotations), Progress transporters (2 or more), the Quest and Plrs airlocks, as well as periodically the Multi-Purpose Logistics module, the Automated Tranfer Vehicle and the H-II Transfer vehicle).
The ISS, when completed, will consist of a set of communicating pressurized modules connected to a truss, on which four large pairs of photovoltalc modules (solar panels) are attached. The pressurized modules and the truss will be perpendicular: the truss spanning from starboard to port and the habitable zone extending on the aft-forward axis. Although during the construction the station attitude may vary, when all four photovoltaic modules are in their definitive
position the aft-forward axis will be parallel to the velocity vector.
In addition to the assembly and utilization flights, approximately 30 Progress spacecraft flights are required to provide logistics until 2010. Experimental
equipment, fuel and consumables are and will be delivered by all
vehicles visiting the ISS: the Shuttle, the Russian Progress, the
European ATV (currently docked) and the Japanese HTV.