Ariane 5
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Ariane 5 is an expendable launch system, designed and manufactured under the authority of the European Space Agency (ESA) by EADS SPACE Transportation, the Prime Contractor, leading a consortium of many sub-contractors, and is operated and marketed by Arianespace as part of the Ariane programme. EADS SPACE Transportation builds the rockets in Europe and Arianespace launches them from a space port at Kourou in French Guiana.
It succeeds Ariane 4, but it does not derive from it directly. Its development took ten years and cost EUR 7 billion. The ESA originally designed Ariane 5 to launch the manned mini shuttle Hermes, and thus intended it to be "human rated" from the beginning. After the ESA cancelled Hermes the rocket became a purely commercial launcher.
The main use of Ariane 5 is for delivering satellites into Geostationary transfer orbit. Two satellites can be mounted using a Sylda carrier. Three main satellites are possible depending on size. Up to eight secondary payloads, usually small experiment packages or minisatellites, can be carried with an ASAP (Ariane Structure for Auxiliary Payloads) platform.
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Components
Ariane 5’s cryogenic H158 main stage (H173 for Ariane 5 ECA) is called the EPC (Étage Principal Cryotechnique). It consists of a large tank with two compartments: one for liquid oxygen and one for liquid hydrogen, and at the base the Vulcain engine.
Attached to the sides are two solid propellant boosters, P238 (P241 for Ariane 5 ECA). These boosters can be recovered with parachutes, like the Space Shuttle's solid rocket motors. They may have been retrieved for examination on early missions, but are not reused.
The second stage is on top of the main stage and below the payload. The payload and all upper stages are covered at launch by the fairing, which splits off once sufficient altitude has been reached.
Variants
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The original version is dubbed Ariane 5G (Generic). Its payload capability to Geostationary transfer orbit (GTO) was initially specified as 5970 kg, but was increased after the qualification flights to 6200 kg.
Ariane 5G+ has an improved second stage, with a GTO capacity of 6950 kg for a single payload. It flew three times in 2004 and will be replaced by Ariane 5 GS, with 5 ECA solid boosters.
Ariane 5 ECA is a more powerful variant, with a GTO launch capacity of 10,000 kg for dual payloads or 10,500 kg for a single payload. This variant uses a new Vulcain 2 first-stage engine, and an ESC-A second stage, powered by an HM-7B engine, weighing 6,500 kg and carrying 14,000 kg of cryogenic propellant. The second stage was previously used as the third stage of Ariane 4; in ECA use, the tanks are modified to shorten stage length. The revised Vulcain has a longer, more efficient nozzle with more efficient flow cycle, and a denser propellant ratio. The new ratio demanded length modifications to the first-stage tanks. Also, the solid booster casings have been lightened with new welds, and packed with more propellant.
The ESC-A cryogenic second stage does not improve the performance to Low Earth orbit with respect to Ariane 5 G, and that for this reason the Ariane 5 ECA will not be used to launch the ATV.
Future developments
Ariane 5 ES ATV has been designed for launching the Automated Transfer Vehicle. It consists of the improved Vulcain 2-powered first stage and the upper stage from the Ariane 5 G, and can put up to 21,000 kg to LEO.
Ariane 5 ECB was planned to have a ESC-B upper stage using a new "Vinci" engine, an expander cycle type engine. The GTO capacity was to increase to 12,000 kg, but ECB was put on hold due to budget cuts. It was cancelled outright in May 2005 due to lack of demand in that payload range. The Vinci engine which was to power ECB's upper stage is still being developed, albeit at a lower pace, and considering the only important difference between ECA and ECB is the upper-stage engine we may presume a new and more powerfull stage will be available in the future.
Launch history
Ariane 5's first test flight (Ariane 5 Flight 501) on 4 June 1996 failed, with the rocket self-destructing 40 s after launch because of a malfunction in the control software, which was arguably 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. Efficiency considerations had led to the disabling of the software handler (in Ada code) for this trap, although other conversions of comparable variables in the code remained protected.
The second test flight, L502 on 30 October 1997 was a partial failure. The Vulcain nozzle caused a roll problem, leading to premature shutdown of the core stage. The upper stage operated successfully but could not reach the intended orbit.
A subsequent test flight on 21 October 1998 proved successful and the first commercial launch occurred on 10 December 1999 with the launch of the XMM-Newton X-ray observatory satellite.
Another partial failure occurred on 12 July 2001, with the delivery of two satellites into an incorrect orbit, at only half the height of the intended GTO. The ESA Artemis telecommunications satellite was able to reach its intended orbit on 31 January 2003, through the use of its experimental ion propulsion system.
The next launch did not occur until 1 March 2002, when the Envisat environmental satellite successfully reached an orbit 800 km above the Earth in the 11th launch. This was the rocket's heaviest payload to date, at 8500 kg.
The first launch of the ECA variant on 11 December 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 (Stentor and Hot Bird 7), 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 nozzle to overheat. After this failure, Arianespace delayed the expected January 2003 launch for the Rosetta mission to 26 February 2004, but this was again delayed to early March 2004 due to a minor fault in the foam that protects the cryogenic tanks on the Ariane 5.
On 27 September 2003 the last Ariane 5 G boosted three satellites (including the first European lunar probe, SMART-1), in Flight 162. On 18 July 2004 an Ariane 5 G+ boosted the heaviest telecommunication satellite ever, Anik F2, weighting almost 6,000 kg.
The first successful launch of the Ariane 5 ECA took place on 12 February 2005. The payload consisted of the XTAR-EUR military communications satellite, a 'SLOSHSAT' small scientific satellite and a MaqSat B2 payload simulator. The launch had been originally scheduled for October 2004, but additional testing and the military requiring a launch at that time (of an Helios 2A observation satellite) delayed the attempt.
Ariane 5 flights
| Date (UTC) | Flight | Model | Serial number | Payload | Result |
|---|---|---|---|---|---|
| 04.06.1996 12:34:06 | V-89 | Ariane-5G | 501 | Cluster | Failure |
| 30.10.1997 13:43:00 | V-101 | Ariane-5G | 502 | MaqSat H & TEAMSAT | Partial failure |
| MaqSat B | |||||
| YES | |||||
| 21.10.1998 16:37:21 | V-112 | Ariane-5G | 503 | MaqSat 3 | Success |
| ARD | |||||
| 10.12.1999 14:32:07 | V-119 | Ariane-5G | 504 | XMM-Newton | Success |
| 21.03.2000 23:28:19 | V-128 | Ariane-5G | 505 | Insat 3B | Success |
| AsiaStar | |||||
| 14.09.2000 22:54:07 | V-130 | Ariane-5G | 506 | Astra 2B | Success |
| GE 7 | |||||
| 16.11.2000 01:07:07 | V-135 | Ariane-5G | 507 | PAS 1R | Success |
| Amsat P3D | |||||
| STRV 1C | |||||
| STRV 1D | |||||
| 20.12.2000 00:26:00 | V-138 | Ariane-5G | 508 | Astra 2D | Success |
| GE 8 (Aurora 3) | |||||
| LDREX | |||||
| 08.03.2001 22:51:00 | V-140 | Ariane-5G | 509 | Eurobird 1 | Success |
| BSat 2a | |||||
| 12.07.2001 22:58:00 | V-142 | Ariane-5G | 510 | Artemis | Partial failure |
| BSat 2b | |||||
| 01.03.2002 01:07:59 | V-145 | Ariane-5G | 511 | Envisat | Success |
| 05.07.2002 23:22:00 | V-153 | Ariane-5G | 512 | Stellat 5 | Success |
| N-Star c | |||||
| 28.08.2002 22:45:00 | V-155 | Ariane-5G | 513 | Atlantic Bird 1 | Success |
| MSG 1 | |||||
| MFD | |||||
| 11.12.2002 22:22:00 | V-157 | Ariane-5ECA | 517 | Hot Bird 7 | Failure |
| Stentor | |||||
| MFD A | |||||
| MFD B | |||||
| 09.04.2003 22:52:19 | V-160 | Ariane-5G | 514 | Insat 3A | Success |
| Galaxy 12 | |||||
| 11.06.2003 22:38:15 | V-161 | Ariane-5G | 515 | Optus C1 | Success |
| BSat 2c | |||||
| 27.09.2003 23:14:46 | V-162 | Ariane-5G | 516 | Insat 3E | Success |
| eBird 1 | |||||
| SMART-1 | |||||
| 02.03.2004 07:17:44 | V-158 | Ariane-5G+ | 518 | Rosetta | Success |
| 18.07.2004 00:44:00 | V-163 | Ariane-5G+ | 519 | Anik F2 | Success |
| 18.12.2004 16:26:00 | V-165 | Ariane-5G+ | 520 | Helios 2A | Success |
| Essaim 1 to 4 | |||||
| PARASOL | |||||
| Nanosat 01 | |||||
| 12.02.2005 21:03:00 | V-164 | Ariane-5ECA | 521 | XTAR-EUR | Success |
| Maqsat B2 | |||||
| SLOSHSAT-FLEVO |
Upcoming flight
The next flight, V-166, was planned for 14 April, 2005 with the payload Syracuse 3A and TELKOM 2. In early March 2005 this launch target was abandoned. An official press release of Arianespace now states that the next launch is scheduled for 8th July 2005 with an IPStar comsat. This will be the first flight of Ariane 5 GS, which has the same improved P241 solid rocket boosters as the Ariane 5 ECA.
External links and references
- ESA description of the Ariane 5 (http://www.esa.int/export/SPECIALS/Launchers_Access_to_Space/ASEVLU0TCNC_0.html)
- Ariane 5 technical notes, available as PDF from http://www.arianespace.comcs:Ariane 5