family of launch vehicles (launch vehicle) developed as a means of independent access to space for the European Space Agency (ESA) and as a launcher for commercial payloads. Among the many European satellites launched by Ariane have been Giotto, the probe to Halley's Comet; Hipparcos, the stellar distance-measuring satellite; Rosetta, a comet rendezvous mission; and Envisat, a large Earth-observing satellite.

After the failure of efforts during the 1960s to develop a space launch vehicle through cooperation between several European countries, France in 1973 persuaded its European partners to give it the lead role in a new program to create such a vehicle, named after Ariadne (Ariane in French), the mythical Cretan princess who helped Theseus escape from the Labyrinth. The French space agency, Centre National d'Études Spatiales (CNES), has managed Ariane development and upgrades under the auspices of the ESA, with a number of European countries contributing to the program's budget and carrying out a share of development and production work.

The first launch of the Ariane 1 vehicle took place in December 1979. Ariane 1 was 50 metres (164 feet) tall and had a thrust at liftoff of 2,400 kilonewtons (550,000 pounds), which allowed it to launch an 1,850-kg (4,070-pound) satellite into geostationary orbit. Ariane 1 was liquid-fueled; it originally used a mixture of unsymmetrical dimethylhydrazine (UMDH) and nitrogen tetroxide. However, after a launcher exploded in May 1980, the fuel mixture was changed to the more stable mixture of UMDH and hydrazine.

Improved versions of Ariane were developed during the 1980s; the first Ariane 3 vehicle was launched in August 1984, but the first Ariane 2 (which had the same launch vehicle design as the Ariane 3 but without the two solid-fuel strap-on boosters) debuted in May 1986. Ariane 3, the more powerful of the two new models, had a thrust of 4,000 kilonewtons (900,000 pounds), which could carry a 2,700-kg (5,900-pound) satellite to geostationary orbit.

The first Ariane 4 vehicle was launched in June 1988. Ariane 4 was even more powerful than Ariane 3. With a thrust of 5,700 kilonewtons (1.3 million pounds), it could place a 4,800-kg (11,000-pound) satellite in geostationary orbit. The first two stages of Ariane 2–4 were fueled by a mixture of UMDH and hydrazine, with nitrogen peroxide as an oxidizer; the third stage used cryogenic fuel. The first four generations of Ariane shared the same basic design but achieved increased performance and flexibility through modifications of that design; by the end of its 15-year-long career, Ariane 4 had achieved over 97 percent reliability.

In 1985 the ESA decided to develop the more powerful Ariane 5 launcher with a totally new design based on a cryogenically fueled first stage, flanked by two large solid-fuel boosters, and having a second stage fueled by monomethylhydrazine with nitrogen peroxide as the oxidizer. A strong impetus for developing the more powerful Ariane 5 was the ESA's ambition to launch a manned space glider named Hermes. However, the Hermes project was canceled in 1992. Since then, Ariane 5 has launched only unmanned satellites.

With a much more powerful upper stage than previous Ariane models, the Ariane 5 is capable of carrying a 10,500-kg (23,100-pound) satellite to geostationary orbit. The first test launch of the Ariane 5, in June 1996, was a spectacular failure, but in subsequent years the vehicle operated reliably. Since the Ariane 4 was retired from service in 2003, all ESA launches have used Ariane 5, and there has been a continuing effort to lower its costs and improve its reliability and performance, particularly its ability to launch two communications satellites to geostationary orbit. The Ariane 5 ECA version can launch two satellites with a combined weight of 9,600 kg (21,000 pounds) to that orbit. The Ariane 5 has achieved 89 percent reliability.

In January 1980 the ESA decided to entrust Arianespace—an organization owned by both public and private sector entities—with the management of Ariane production and launch for government use and also with the marketing of the vehicle to commercial customers. Arianespace succeeded in establishing the Ariane family as the single largest provider of commercial launch services in the world.

The Ariane launch site is in Kourou, Fr.Guia., just 5 degrees north of the Equator. This location allows launches to take full advantage of the velocity imparted by Earth's rotation, meaning that the spacecraft's onboard fuel can be conserved, thus extending orbital life. This is a particular advantage for revenue-producing commercial satellites, which can get an extra year or more of life from being launched near the Equator.