Ariane (rocket)

I

Introduction

Ariane (rocket), family of rockets used primarily to launch artificial satellites for telecommunications companies. The French space agency Centre National d'Etudes Spatiales (National Space Studies Center) began developing the first Ariane rocket in 1973 with funding from the European Space Agency (ESA). Arianespace, an independent French corporation, now produces the rockets and administers rocket launches, which take place at the ESA’s Guiana Space Center in Kourou, French Guiana.

The first Ariane rocket launched in 1979, carrying a capsule and ballast that simulated a typical satellite payload. The next year, the newly created Arianespace corporation began developing the subsequent Ariane models. The current models, Ariane 4 and Ariane 5, first flew in 1988 and 1996.

Ariane rockets have launched more than 100 missions. An Ariane 1 rocket launched the ESA's Giotto space probe, which successfully flew by Halley’s Comet in 1986. Also in 1986 France launched the Spot 1 Earth observation satellite on an Ariane 1. An Ariane 4 launched the Hipparcos satellite, an ESA satellite designed to gather accurate measurements of stars and planets, in 1989. Ariane 5's 1996 maiden flight ended in an explosion resulting from a failure in the rocket’s flight control system, but the rocket performed flawlessly on its second flight in 1997.

II

Ariane 4

All Ariane 4 rocket models measure 58 m (190 ft) tall. The most powerful version of the Ariane 4, Ariane 44L, weighs 470,000 kg (1.04 million lb) when fully fueled. Ariane 4 rockets are powered by three engines, or stages, stacked on top of one another. The first stage lifts the rocket into the upper atmosphere, then burns out and falls to Earth as the second, then third stages carry the rest of the vehicle and its cargo farther into space. The first and second stages burn UH25 liquid fuel and nitrogen tetroxide oxidizer, and the third stage burns liquid hydrogen and liquid oxygen oxidizer. Ariane 4 rockets get additional power from up to four strap-on booster rockets, which burn the same fuel as Ariane 4’s first and second stages.

---

---

Ariane 44L can deliver a 9,600-kg (21,000-lb) payload into a low Earth orbit of 185 km (100 mi). The same model can send payloads of up to 4,520 kg (9,965 lb) into geostationary orbit, where they hover above the equator at an altitude of 35,800 km (about 22,200 mi). Artificial satellites in geostationary orbit, such as weather and communications satellites, remain in one place above the Earth because their orbit speed matches the rate of the Earth’s spin.

III

Ariane 5

The Ariane 5 measures up to 54 m (177 ft) tall and weighs about 710,000 kg (1.57 million lb). The rocket’s power sources consist of a liquid hydrogen/liquid oxygen core stage, an upper stage that burns UH25 and nitrogen tetroxide, and two strap-on boosters that burn HTPB solid fuel. Ariane 5 can deliver 18,000 kg (39,600 lb) into low Earth orbit. It can place either a single satellite weighing 6,800 kg (15,000 lb) or two satellites with a combined weight of 5,970 kg (13,200 lb) into geostationary orbit.

	More from Encarta
	•  Presidential Myths Quiz •  Coffee break: Recharge your brain