Ariane 5

Ariane 5 lifts off with the Rosetta probe on 2 March 2004.

Ariane 5 is an European expendable launch system designed to deliver satellites into geostationary transfer orbit and to send payloads to Low Earth orbit.

It is manufactured under the authority of the European Space Agency (ESA) with EADS SPACE Transportation as prime contractor, leading a consortium of sub-contractors. The rocket 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 succeeded Ariane 4, but does not derive from it directly. Its development took 10 years and cost €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.

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.

Components

Vulcain engine

Ariane 5's cryogenic H158 main stage (H173 for Ariane 5 ECA) is called the EPC (Étage Principal Cryotechnique/Cryogenic First 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.

Attached to the sides are two solid propellant boosters, P238 (P241 for Ariane 5 ECA), each weighing about 277 tonnes full. Each delivers a thrust of about 630 tonnes-force (6.2 MN). These boosters can be recovered with parachutes, like the Space Shuttle Solid Rocket Boosters. 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 Ariane 5G uses the EPS (Étage à Propergols Stockables/Storable Propellant Stage), which is fueled by monomethylhydrazine (MMH) and nitrogen tetroxide, where the Ariane 5 ECA uses the ESC (Étage Supérieur Cryotechnique/Cryogenic Upper Stage), which is fueled by liquid hydrogen and liquid oxygen. The payload and all upper stages are covered at launch by the fairing, which splits off once sufficient altitude has been reached.

Variants

The ATV will be delivered into orbit by an Ariane 5 rocket

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 5970 kg, but was increased after the qualification flights to 6200kg.

The Ariane 5G+ had an improved second stage, with a GTO capacity of 6950kg for a single payload. It flew three times in 2004.

It was replaced in 2005 by the Ariane 5GS, with the same solid boosters as the Ariane 5 ECA and a modified first Stage with a Vulcain 1B engine. It can carry a single Payload of 6100 kg

The Ariane 5 ECA has 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 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 compared to Ariane 5G, and for this reason the Ariane 5 ECA will not be used to launch the Automated Transfer Vehicle (ATV).

Comparable rockets:Delta IV -Atlas V -Chang Zheng 5 -Angara

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 5G, and can put up to 21,000 kg in LEO.

Ariane 5 ECB development hold

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 12,000 kg, 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. Consequently, a restart of the ESC-B program is not impossible at the ESA conference in 2008. The uncertainty regarding the Ariane 5 ECB creates a major commercial weakness for Ariane 5: lacking a reignitable cryogenic engine, unlike all its competitors, it is unable to deliver payloads directly to geostationary orbit.

Launch history

Comparison of Ariane 5 to Proton and Soyuz rockets

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 800 km above the Earth in the 11th launch. At 8111 kg, it was the heaviest single payload to date.

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 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.

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 6505 kg [1], into orbit.

On 13 October 2005, the second Ariane 5GS boosted a dual payload to orbit. This consisted of Syracuse 3A, a French military satellite, and Galaxy 15 for PanAmSat.

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 8000 kg.

On 21 December 2005, the third Ariane 5GS boosted another dual payload to orbit. This payload consisted of INSAT 4A for the Indian Space Research Organization (ISRO), and MSG-2 for the European organization Eumetsat.

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. [2]

Ariane 5 flights

|11.08.2005 08:20:00

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, 2, 3 and 4
				PARASOL
				Nanosat 01
12.02.2005 21:03:00	V-164	Ariane-5ECA	521	XTAR-EUR	Success
				Maqsat B2
				Sloshsat
V-166	Ariane-5GS	523	Thaïcom 4-iPStar 1	Success
13.10.2005 22:32:00	V-168	Ariane-5GS	524	Syracuse 3A	Success
				Galaxy 15
16.11.2005 23:46:00	V-167	Ariane-5ECA	522	Spaceway F2	Success
				Telkom 2
21.12.2005 22:33:00	V-169	Ariane-5GS	525	Insat 4A	Success
				MSG 2
				MFD C
11.03.2006 22:32:50	V-170	Ariane-5ECA	527	Spainsat	Success
				MFD C
				MFD C
				Hot Bird 7A
26.05.2006 21:08:50	V-171	Ariane-5ECA	529	Satmex 6	Success
				Thaicom 5

Upcoming flights

Date (UTC)	Flight	Model	Serial number	Payload	Result
11 August 2006	V-172	Ariane-5ECA	531	JCSat 10	Planned
				Syracuse 3B
September 2006	V-173	Ariane-5ECA	533	DirecTV-9S	Planned
				Optus D1
				LDREX-2

External links and references

*ESA description of the Ariane 5
* Ariane 5 technical notes, available as PDF from http://www.arianespace.com/site/documents/document_sub_index.html
* Arianespace: Ariane 5 (engl.)
* Actually Launch on Arianespace Homepage (engl.)
* The last and the next Launch (engl.)
*BBC News report on the (delayed) successful launch of the Ariane 5 ECA flight on November 16, 2005.
*Vinci Engine development
*Watch an Ariane 5 launch (webcast begins 20 mins before launch).
*YouTube video of Ariane 5 launching XMM-Newton