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Ariane 5

The Ariane 5 is an expendable launch system, designed by the European Space Agency and manufactured, operated and marketed by Arianespace. The rockets are built in Europe and launched from a space port at Kourou in French Guiana.

It is usually used to put satellites in Earth orbit. It is the successor to the Ariane 4, but it is not directly derived from it. Its development took 10 years and cost EUR 7 billion. It was originally designed to launch the manned mini shuttle Hermes too, thus it was intended to be "man rated[?]" from the beginning. With this spacecraft canceled by the European Space Agency, the rocket became a purely commercial launcher. The current payload capability to geostationary transfer orbit (GTO) is about 6,200 kg. Upgrades are already underway to boost this to 12,000 kg, making it possible to launch two "heavy" satellites at once.

Its first test flight on June 4, 1996 was a failure, with the rocket self-destructing 40 seconds after launch because of a malfunction in the control software, resulting in one of the most expensive computer bugs in history. A data conversion from 64-bit floating point to 16-bit signed integer value had caused a processor trap (operand error). The floating point number had a value too large to be represented by a 16-bit signed integer. The software handler (in Ada code) for this trap had been disabled for efficiency reasons, although other conversions of comparable variables in the code were protected.

Subsequent test flights on October 30, 1997 and October 21, 1998 were successful and the first commercial launch occurred on December 10, 1999 with the launch of the XMM-Newton X-ray observatory satellite.

Another partial failure occurred on July 12, 2001, when two satellites were delivered to an incorrect orbit. One of these was the ESA Artemis telecommunications satellite, which managed to get to its correct orbit using fuel intended for orbit maintenance, but in the process reducing the expected life of the satellite.

The following launch did not occur until March 1, 2002, when the Envisat environmental satellite was successfully placed in orbit 800km above the Earth by the 11th launch. This was the heaviest payload to date at 8500kg.

A new variant of the Ariane 5 is scheduled to increase the GTO launch capacity to 10,500kg. However the first launch of an ESC-A on December 11, 2002 ended in failure when a main booster problem caused the rocket to veer off-course, forcing its self-destruction three minutes into the flight. Its payload of two communications satellites valued at about EUR 630 million was lost in the ocean. The fault was determined to have been caused by a leak in coolant pipes allowing the tail nozzle to overheat. After this failure, the expected January 2003 launch for the Rosetta mission was delayed to an undefined date.

The ESC-A upper stage is powered by an HM-7B engine, weighing 6,500kg and carrying 14,000kg of cryogenic propellant and previously used as the third stage of the Ariane 4. A future ESC-B upper stage is planned using a new engine "Vinci", an expander cycle[?] type engine which is to increase the GTO capacity to 12,000kg.



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