Weighing more than 300 automobiles, or nearly 500 tons, the ISS or International Space Station began deployment in 1998. More than three dozen manned missions since late 2000 have included scientific experiments and work to assemble the station. Several assembly missions launched from the now retired NASA Space Shuttle platform, but the bulk of the heavy lifting to date has been from Russian Soyuz programs.
The resupply and refueling missions are currently handled by Russian missions, with plans to expand refueling and resupply operations to Space-X and Cygnus missions. Cygnus is a government and private industry partnership with Orbital Sciences and Alliant Tech Systems, both companies merged and are located near Washington DC.
Space-X is a venture related to Elon Musk and the Tesla Motor Car, at least the visionary Musk is central to both companies.
Both refueling efforts use the “Harmony” docking system, which is one of at least four different docking systems on the International Space System. Russian systems for refueling seem to include at least the Pirs, Rassvet and Nauka docks, which has to do with the amount of Russian components built into the ISS.
Proponents of the USA private/public space exploration effort look forward to the certification and implementation of the Space-X platform, which may yet occur in 2015.