Ariane 4

Origins In 1973, eleven nations decided to pursue joint collaboration in the field of space exploration and formed a new pan-national organisation to undertake this mission, the European Space Agency (ESA). Six years later, in December 1979, the arrival of a capable European expendable launch system was marked when the first Ariane 1 launcher was successfully launched from the Centre Spatial Guyanais (CSG) at Kourou, French Guiana. The Ariane 1 soon became considered to be a capable and competitive launcher in comparison to rival platforms offered by the Soviet Union and the United States of America, and it was quickly followed by improved derivatives in the form of the Ariane 2 and Ariane 3. By early 1986, the Ariane 1, along with the Ariane 2 and Ariane 3, had become the dominant launcher on the world market. In January 1982, the ESA issued its authorisation for the development and construction of the Ariane 4; the development programme had the stated objective of increasing the usable payload by 90%. Work on the Ariane 4 was substantially eased via drawing heavily on both the technology and experiences gained from producing and operating the earlier members of the Ariane rocket. The total development cost for the Ariane 4 was valued at 476 million European Currency Units (ECU) in 1986. Posed with the requirement to produce a rocket with substantially greater thrust, the design team considered various approaches to achieve this. This had the function of allowing a pair of satellites, one placed on top of the other; several different SPELDA nose fairings could be installed, including normal and extended models. The SPELDA was considerably lighter than its predecessor; the guidance system also used much more accurate ring laser gyroscopes. In conjunction with the development of the Ariane 4 itself, a new purpose-built launch preparation area and launch pad for the rocket, collectively designated as ELA-2, was constructed at the Centre Spatial Guyanais to service the Ariane 4 and provide a launch rate of 8 launches per year (this feat was near-unprecedented for a single large rocket, other than within the Soviet Union). Unlike the earlier ELA-1 which had been used for the previous members of the Ariane family and other rockets, preparation activity for the rocket would be performed in a purpose-built tall hall rather than on the pad itself; the completed rocket was then transported using a specially-designed railway to slowly traverse from the hall to the launch pad, taking one hour. This railway provided the additional benefit of enabling faulty rockets to be withdrawn from the pad and be substituted for relatively quickly. On 15 June 1988, the first successful launch of the Ariane 4 was conducted. In January 1985, the Ariane 5 had been officially adopted as an ESA programme. It lacked the high levels of commonality that the Ariane 4 had with its predecessors, and had been designed not only for launching heavier payloads of up to and at a 20% cost reduction over the Ariane 4, but for a higher margin of safety due to the fact that the Ariane 5 was designed to conduct crewed space launches as well, being intended to transport astronauts using the proposed Hermes space vehicle. Development of the Ariane 5 was not without controversy as some ESA members considered the more mature Ariane 4 to be more suited for meeting established needs for such launchers; it was for this reason that Britain chose not to participate in the Ariane 5 programme. For some years, Ariane 4 and Ariane 5 launchers were operated interchangeably; however, it was eventually decided to terminate all Ariane 4 operations in favour of concentrating on the newer Ariane 5. == Design ==

The Ariane 4 was the ultimate development from the preceding members of the Ariane rocket family. Compared with the Ariane 2 and Ariane 3, the Ariane 4 featured a stretched first (by 61%) and third stages, a strengthened structure, new propulsion bay layouts, new avionics, and the SPELDA (Structure Porteuse Externe de Lancement Double Ariane) dual-payload carrier. The basic 40 version did not employ any strap-on motors, while the Ariane 42L, 44L, 42P, 44P, and 44LP variants all used various combinations of solid and liquid boosters. Originally designed to place payloads in geostationary orbit, the six Ariane 4 variants, aided by strap-on boosters, enabled the launch of payloads in excess of on several occasions. The Ariane 4 launcher reduced the launch costs per kilo by 55% in comparison to the original Ariane 1. Atop the third stage was a vehicle equipment stage which housed a computer that performed various functions, including sequencing, guidance, control, tracking, telemetry and an explosive-based self-destruct. The Ariane 4 AR 40 was the basic version, with three stages: high, a diameter of , a liftoff mass of and a maximum payload of to GTO or to low Earth orbit (LEO). Main power was provided by four Viking 2B motors, each producing of thrust. The second stage was powered by a single Viking 4B motor, and the third stage was equipped with an HM7-B liquid oxygen/liquid hydrogen motor. The Ariane 4 AR 44L, which was outfitted with the maximum additional boost of four liquid fuel rocket strap-ons, was a four-stage rocket, weighing and capable of transferring a payload of to GTO, or alternatively to LEO. == Operational history ==

In June 1988, the inaugural flight of the Ariane 4 occurred, which was a success. Since then, Ariane 4 has flown 116 times, 113 of which were successful, yielding a success rate of . On 22 February 1990, the first failure occurred during the eighth Ariane 4 launch, flight V36. The rocket exploded 9 km above Kourou. The failure occurred because a worker assembling a Viking rocket motor had left a handkerchief in one of the motor's coolant tubes. He had done so as a reminder to himself to inform his superior, as per procedure, of an unplanned polishing he had made to fit the tube. But he fell ill before he could do so and was replaced by other workers who did not notice the handkerchief. In flight, the handkerchief blocked the coolant tube, the motor overheated and failed, and the Ariane self-destructed after veering off its trajectory. Its payload, two communications satellites worth 500 million US dollars (Superbird-B and BS-2X) landed in pieces in the swamps near Kourou. The ensuing investigation recommended 44 modifications, including numbering and checking all pieces of cloth used in the rocket's assembly. The system became the basis for European satellite launches with a record of 113 successful and three launch failures. Ariane 4 provided a payload increase from for Ariane 3 to a maximum of to geostationary transfer orbit (GTO). The record for Ariane 4 to GTO was . On 15 February 2003, the final launch of Ariane 4 rocket occurred, placing Intelsat 907 into geosynchronous orbit. Arianespace had decided to phase out the Ariane 4 launcher in favour of the newer heavy-lift Ariane 5 rocket, which had already been in service for some years. In 2011, the medium-lift Soyuz ST complemented the offering of launch vehicles from the Centre Spatial Guyanais. Spacecraft launched by the Soyuz reused the payload platform and dispenser which had been originally designed for the Ariane. == Comparable rockets ==

• Delta II (retired) • GSLV Mk II • GSLV Mk III • Long March 3B • Soyuz-U (retired) == See also ==