PARIS — Europe’s heavy-lift Ariane 5 rocket successfully placed a 20-metric-ton unmanned freighter into low Earth orbit March 23, from where it will use its own power to dock with the international space station (ISS) on March 28.

The launch from Europe’s Guiana Space Center in French Guiana, on the northeast coast of South America, was the 47th consecutive success for the Ariane 5 and the first of a planned seven missions scheduled for 2012.

The Ariane 5 ES variant, with a storable-propellant upper stage permitting re-ignition, placed the 20,060-kilogram Automated Transfer Vehicle (ATV) into a 260-kilometer orbit.

It was the third of a planned five ATVs that the European Space Agency (ESA) is building as part of a barter arrangement with NASA, the space station’s general contractor. ESA uses the ATV missions to pay its 8.3 percent share of the station’s common operating costs.

ATV-3, named Edouardo Amaldi after the Italian physicist, carries 6,600 kilograms of cargo and 3,150 kilograms of fuel to catch up to the station, orbiting at an altitude of about 380 kilometers. ATV-3 is scheduled to use its optical navigation gear to dock automatically to the Russian side of the space station on March 28.

ATV-3 will remain docked at the station for five months, during which time it will perform up to 10 firings of its engines to reboost the 400,000-kilogram station into higher orbit, and if necessary to maneuver the station to avoid orbital debris. It is carrying 860 kilograms of fuel intended for these station-moving chores.

Once it is unloaded, the ATV-3 will be filled with garbage and sent on a controlled, destructive re-entry into Earth’s atmosphere over the southern Pacific Ocean in a corridor that will have been cleared of maritime traffic for the event.

Two more ATVs are in production at Astrium Space Transportation in Bremen, Germany, and Thales Alenia Space in Turin, Italy, and are scheduled for launch in 2013 and 2014.

Once the fifth has completed its mission, ESA will have satisfied its obligations to NASA to 2017. But NASA and the other station partners have agreed to keep the orbital complex operating through 2020, and perhaps beyond.

With ATV production shutting down, ESA must decide what it can build that NASA wants enough to offset Europe’s share — valued at about 150 million euros ($200 million) per year — of the station’s operating costs.

NASA has asked ESA to consider an ATV derivative to serve as the propulsion module for the Orion manned capsule that NASA is developing.

France and Italy — respectively the second- and third-largest European contributors to the station, after Germany — argue that the Orion-related mission is not sufficiently interesting. The heads of the French and Italian space agencies say ATV-derived technologies could be used to build a vehicle to perform multiple tasks in low Earth orbit, perhaps including removal of dead satellites.

The German Aerospace Center, DLR, has indicated it is willing to consider several ATV-derived barter elements for NASA.

Such a vehicle as proposed by France and Italy likely would cost far more than an Orion propulsion system, and far more than what ESA owes to NASA for the station. It is also unclear whether NASA would accept the vehicle as a barter element.

ESA governments are scheduled to meet in November in Italy to determine their space budget and strategy for the coming years.