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Ariane 5
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Ariane 5 is a European expendable launch system designed to deliver payloads into geostationary transfer orbit or low Earth orbit.
It is manufactured under the authority of the European Space Agency (ESA) and the Centre National d'Etudes Spatiales (CNES), with EADS Astrium Space Transportation (Astrium) as prime contractor, leading a consortium of sub-contractors. The rocket is operated and marketed by Arianespace as part of the Ariane programme. Astrium builds the rockets in Europe and Arianespace launches them from the Guiana Space Centre.
It succeeded Ariane 4, but does not derive from it directly.
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Encyclopedia
Ariane 5 is a European expendable launch system designed to deliver payloads into geostationary transfer orbit or low Earth orbit.
It is manufactured under the authority of the European Space Agency (ESA) and the Centre National d'Etudes Spatiales (CNES), with EADS Astrium Space Transportation (Astrium) as prime contractor, leading a consortium of sub-contractors. The rocket is operated and marketed by Arianespace as part of the Ariane programme. Astrium builds the rockets in Europe and Arianespace launches them from the Guiana Space Centre.
It succeeded Ariane 4, but does not derive from it directly. Its development took 10 years and cost $7 billion. Ariane 5 has been refined since the first launch in successive versions, G, G+, GS, ECA, and most recently, ES. ESA originally designed Ariane 5 to launch the manned mini shuttle Hermes, and thus intended it to be "human rated" from the beginning. After ESA cancelled Hermes, the rocket became a purely robotic launcher.
Two satellites can be mounted using a SYLDA carrier (SYstème de Lancement Double Ariane). Three main satellites are possible depending on size using SPELTRA (Structure Porteuse Externe Lancement TRiple Ariane). Up to eight secondary payloads, usually small experiment packages or minisatellites, can be carried with an ASAP (Ariane Structure for Auxiliary Payloads) platform.
By mid 2007, Arianespace has ordered a total of 99 Ariane 5 launchers from Astrium. The first batch ordered in 1995 consisted of 14 launchers, while the second—P2—batch ordered in 1999 consisted of 20 launchers. A third—PA—batch consisting of 25 ECA and 5 ES launchers was ordered in 2004. The latest batch ordered in mid 2007 consist of another 35 ECA launchers. Through these orders, the Ariane 5 will be the workhorse of Arianespace at least through 2015.
Components
Cryogenic main stage
Ariane 5’s cryogenic H158 main stage (H173 for Ariane 5 ECA) is called the EPC (Étage Principal Cryotechnique - Cryotechnic Main Stage). It consists of a large tank 30.5 metres high with two compartments, one for 130 tonnes of liquid oxygen and one for 25 tonnes of liquid hydrogen, and a Vulcain engine at the base with thrust of 115 tonnes-force (1.13 meganewtons). This part of the first stage weighs about 15 tonnes when empty.
Solid boosters
Attached to the sides are two solid rocket boosters (SRBs or ARPs from the French Les Étages d’Accélérations à Poudre), P238 (P241 for Ariane 5 ECA), each weighing about 277 tonnes full. Each delivers a thrust of about 630 tonnes-force . These SRBs are usually allowed to sink to the bottom of the ocean, but like the Space Shuttle Solid Rocket Boosters they can be recovered with parachutes, and this is occasionally done for post-flight analysis. (Unlike Space Shuttle SRBs Ariane 5 boosters are not reused.) The most recent attempt was for the first Ariane 5 ECA mission. One of the two boosters was successfully recovered and returned to the Guiana Space Center for analysis. Prior to that mission, the last such recovery and testing was done in 2003.
In March 2000 the nose cone of an Ariane 5 booster washed ashore on the South Texas coast, and was recovered by beachcombers.
Second stages
The second stage is on top of the main stage and below the payload. The Ariane 5G used the EPS (Étage à Propergols Stockables - Storable Propellant Stage), which is fueled by monomethylhydrazine (MMH) and nitrogen tetroxide, whereas the Ariane 5 ECA uses the ESC (Étage Supérieur Cryotechnique - Cryogenic Upper Stage), which is fueled by liquid hydrogen and liquid oxygen.
Fairing
The payload and all upper stages are covered at launch by a fairing, which splits off once sufficient altitude has been reached. Ariane 5G+ used and Ariane 5 GS and ES use an improved EPS upper stage.
Multiple upper stage burns
The EPS upper stage is capable of re-ignition, which has been demonstrated twice. The first demonstration occurred during flight V26, which was launched on 5 October 2007. This was purely to test the engine, and occurred after the payloads had been deployed. The first operational use of restart capability as part of a mission, came on 9 March 2008, when two burns were made to deploy the first Automated Transfer Vehicle into a circular parking orbit. Following spacecraft separation, a third burn took place to de-orbit the upper stage.
Variants
- The original version is dubbed Ariane 5G (Generic) with a launch mass of 737 tonnes. Its payload capability to geostationary transfer orbit (GTO) was initially specified as , but was increased after the qualification flights to .
- The Ariane 5G+ had an improved second stage, with a GTO capacity of for a single payload. It flew three times in 2004.
- It was replaced in 2005 by the Ariane 5GS, with the same solid EAP as the Ariane 5 ECA and a modified first Stage with a Vulcain 1B engine. It can carry a single payload of to GTO.
- The Ariane 5 ECA (Evolution Cryotechnique type A) has a GTO launch capacity of for dual payloads or for a single payload. This variant uses a new Vulcain 2 first-stage engine, and an ESC-A (Etage Supérieur Cryogénique-A) second stage, powered by an HM-7B engine, weighing and carrying 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 denser propellant ratio. The new ratio demanded length modifications to the first-stage tanks. Also, the solid EAP 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 compared to Ariane 5G, and for this reason the Ariane 5 ECA will not be used to launch the Automated Transfer Vehicle (ATV).
- The Ariane 5 ES-ATV (Evolution Storable-) is used to launch the Automated Transfer Vehicle. It includes all the performance improvements of Ariane 5 ECA on EPC (Etage Principal Cryogénique - main stage) and EAP (Etage d'Accélération à Poudre - solid rocket booster) stages while the second stage is the EPS (Etage à Propergols Stockable) used on Ariane 5GS variants. It is estimated that the Ariane 5 ES-ATV can put up to in LEO. The first such launch occurred at 04:03 GMT on 9 March 2008.
Comparable rockets:
Delta IV -
Atlas V -
Chang Zheng 5 -
GSLV Mk.III -
Angara -
Proton -
Falcon 9 -
H-IIB
Future developments
Ariane 5 ECB development restarted
Ariane 5 ECB was planned to have an ESC-B upper stage using a new Vinci expander cycle type engine. The GTO capacity was to increase to , but ECB was put on hold due to budget cuts.
At an ESA conference (December 2005) in Berlin there was no decision to restart or cancel the program, meaning it is currently on hold. The Vinci engine, which is designed to power the Ariane 5 ECB upper stage, is still being developed, though at a lower pace. At the ESA's Council of Ministers 25-26 Nov. 2008 there was an agreement for the funding of a modernized second stage ( see )
Solid propellant stage
Work on the Ariane 5 EAP motors have been continued in the Vega programme.
The Vega 1st stage engine—the P80 engine—is a shorter derivation of the EAP. The P80 booster casing is made of filament wound graphite epoxy, much lighter than the current stainless steel casing. A new composite steerable nozzle has been developed while new thermal insulation material and a narrower throat improve the expansion ratio and subsequently the overall performance. Additionally, the nozzle now has electromechanical actuators which have replaced the heavier hydraulic ones used for thrust vector control.
These developments will probably later make their way back into the Ariane programme. The incorporation of the ESC-B with the improvements to the solid motor casing and an uprated Vulcain engine would deliver to LEO. This would be developed for any lunar missions but the performance of such a design may not be possible if the higher Max-Q for the launch of this rocket poses a constraint on the mass delivered to orbit.
Launch history
Ariane 5's first test flight (Ariane 5 Flight 501) on 4 June 1996 failed, with the rocket self-destructing 37 seconds 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 above the Earth in the 11th launch. At , it was the heaviest single payload until the launch of the first ATV on March 9, 2008 (~9000 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 SA 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 what was at the time the heaviest telecommunication satellite ever, Anik F2, weighing almost .
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.
On 11 August 2005, the first Ariane 5GS (featuring the Ariane 5 ECA's improved solid motors) boosted Thaïcom-4/iPStar-1, the heaviest telecommunications satellite to date at , into orbit.
On 16 November 2005, the third Ariane 5 ECA launch (the second successful ECA launch) took place. It carried a dual payload consisting of Spaceway-F2 for DirecTV and Telkom-2 for PT Telekomunikasi of Indonesia. This was the rocket's heaviest dual payload to date, at more than .
On 11 March 2006, the fourth Ariane 5 ECA launch boosted another dual payload to orbit. This payload consisted of Hot Bird 7A for Eutelsat (a replacement for the Hot Bird 7 satellite lost in the first Ariane 5 ECA launch), and SPAINSAT, a Spanish government telecommunications satellite for HISDESAT.
On 27 May 2006, an Ariane 5 ECA rocket set a new commercial payload lifting record of 8.2 tonnes. The dual-payload consisted of the Thaicom 5 and Satmex 6 satellites.
On 4 May 2007 the Ariane 5 ECA set another new commercial record, lifting into transfer orbit the Astra 1L and Galaxy 17 communication satellites with a combined weight of 8.6 tonnes, and a total payload weight of 9.4 tonnes. This record was again broken by another Ariane 5 ECA, launching the Skynet 5B and Star One C1 satellites, on 11 November 2007. The total payload weight for this launch was .
On 9 March 2008, the first Ariane 5 ES-ATV was launched to deliver the first ATV called Jules Verne to the International Space Station.
On 18 April 2008, an Ariane 5ECA launched Star One C-2, and Vinasat-1, Vietnam's first satellite.
On 20 December 2008, an Ariane 5ECA launched Hot Bird 9 and W2M, both communications satellites developed for Eutelsat.
On 12 January 2009, an Ariane 5ECA Launched Hot Bird 10 and NSS-9 Telecomunication satellites, Along with two spirale early warning satellites for the French government.
Ariane 5 flights
Upcoming flights
- Ariane 5GS unit 532 is the final GS model to be launched.
See also
External links
- Ariane 5 technical notes, available as PDF from http://www.arianespace.com/site/documents/document_sub_index.html
- (webcast begins 20 mins before launch).
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