Uncrewed spaceflights to the International Space Station
Uncrewed spaceflights to the International Space Station are made primarily to deliver cargo, however several Russian modules have also docked to the outpost following uncrewed launches. Resupply missions typically use the Russian Progress spacecraft, European Automated Transfer Vehicles, Japanese Kounotori vehicles, and the American Dragon and Cygnus spacecraft. The primary docking system for Progress spacecraft is the automated Kurs system, with the manual TORU system as a backup. ATVs also use Kurs, however they are not equipped with TORU. Progress and ATV can remain docked for up to six months. The other spacecraft — the Japanese HTV, the SpaceX Dragon and the Northrop GrummanCygnus — rendezvous with the station before being grappled using Canadarm2 and berthed at the nadir port of the Harmony or Unity module for one to two months. Under CRS-2 Cargo Dragon will dock autonomously at IDA-2 or 3 as the case may be. As of June 2020, Progress spacecraft have flown most of the uncrewed missions to the ISS.
in Kazakhstan is the oldest and busiest spaceport. The first module of the ISS was launched from Baikonur Cosmodrome Site 81 as the uncrewed spacecraftZarya in 1998 and flew uncrewed for about two years before the first crew arrived. The Progress spacecraft is the most frequent cargo ship sent from Baikonur to the station, bringing supplies such as food, fuel, gas, experiments, and parts. Its light payload is offset by its ability to deliver critical replacement parts at short notice. Fresh fruit and vegetables from the earth are an important part of the crew's diet.
Located in Japan on an island south of Kyūshū, the Tanegashima Space Center is the launch site for H-II Transfer Vehicle, called, used to resupply the KibōJapanese Experiment Module and the ISS. The name Kounotori was chosen for the HTV by JAXA because "a white stork carries an image of conveying an important thing, therefore, it precisely expresses the HTV's mission to transport essential materials to the ISS". White Kounotori can carry of cargo in total, about of which is accessible by the crew in the pressurized section, the remainder is unpressurised cargo on Exposed Pallet to be handled by the ISS's robotic arm.
The European Space Agency uses the Guiana Space Centre or, more commonly, Centre Spatial Guyanais. It is a French spaceport near Kourou in French Guiana. Operational since 1968, it is particularly suitable as a location for a spaceport due to its proximity to the equator, and that launches are in a favorable direction over water. The near-equatorial launch location provides an advantage for launches to low-inclination Earth orbits compared to launches from spaceports at higher latitude, the eastward boost provided by the Earth's rotation is about at this spaceport. The ESA's Automated Transfer Vehicle weighs at launch and has a cargo capacity of , with up to two gases per flight, and up to of propellant for the re-boost and refueling the station.
Cape Canaveral
, located in Florida, United States, has been operational since 1950; with its first orbital launch occurring in 1958. All of NASA's crewed Mercury and Gemini missions were launched from the Cape, along with some of the earlier Apollo missions. Cape Canaveral is adjacent to the Kennedy Space Center, where the majority of Apollo missions and all the Space Shuttle missions were launched from. Under contract with NASA, SpaceX launches the Dragon spacecraft to resupply the American portion of the ISS. The Dragon can transport of pressurized and unpressurized cargo and can return to Earth. It is the only uncrewed resupply vehicle capable of returning a payload.
The Mid-Atlantic Regional Spaceport, located at Wallops Island, Virginia, United States, is the launch site for the Northrop Grumman Cygnus spacecraft for resupplying the American portion of the ISS.
Current and completed spaceflights
This is a list of uncrewed spaceflights to the International Space Station. Assembly flights are indicated in bold text. Note: Russia has delivered cargo via the uncrewed missions of Progress since the launch of the ISS, while the U.S. had used Space Shuttles for hybrid human/cargo missions, resulting in a greater number of Russian uncrewed flights to the ISS. Since the discontinuation of the Space Shuttle program in 2011, the numbers of crewed and uncrewed flights by the U.S. and Russia are more closely matched.
