Logistics flights are to the International Space Station what breath is to life. Its very existence is dependent on the precise execution of an extremely well-planned and coordinated program carried out by reliable spacecraft.
Many of the U.S. Space Shuttle missions to the ISS will include logistics duties such as the carrying of water and pressurized cargo -- almost nine tons of it when carried in Italy's "Leonardo" Multi-Purpose Logistics Module beginning in late 1999.
The other, more specialized logistics vehicles that will keep the ISS going include the:
Progress M1, a Russian-funded upgrade of the Russian Space Agency's "Progress M." It was launched from Baikonur Cosmodrome on a Soyuz booster. Progress M1 is used for orbital re-boost and to refuel ISS position ("attitude") control rockets. It hauls pressurized cargo such as oxygen, food and water, personal items and clothing to the Station and haul trash out. The vehicle can be filled with refuse as its cargo is consumed. When its stores have been emptied, it undocks from the ISS and re-enter Earth's atmosphere to burn up over the Pacific Ocean. The first Progress spacecraft flew in 1978 to re-supply Russia's Salyut crewed orbiter.
Automated Transfer Vehicle, to be supplied by the European Space Agency. Like Russia's "Progress M1," it will provide reboost-ing, refueling and hauling services. The spacecraft will be about three times the size of Progress. It will be launched on the Agency's Ariane 5 rocket from Kourou, French Guiana. The uncrewed Vehicle will dock automatically with the Russian Service Module and deliver up to nine tons of cargo. About half of the cargo will consist of food, clothing and the like. Propellant for re-boosting the ISS, water, oxygen and nitrogen, and ISS fuel will make up the other half. It will be incinerated when it re-enters Earth's atmosphere.
Hope Transfer Vehicle, a National Space Development Agency of Japan spacecraft that is scheduled to be completed in 2007 and launched from the Tanegashima Space Center. It will ride to the ISS as the uncrewed second stage of Japan's H-IIA launcher, an improved version of the H-II rocket that was first launched in 1994. The Hope Transfer Vehicle will carry only pressurized cargo -- no fuel or other unpressurized items. It will rendezvous with the forward end of the ISS, where a robotic arm will grapple it to a docking station.