Vehicle description

Ariane 5's cryogenic H173 main stage (H158 for Ariane 5 G, G+, and GS) 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 liquid oxygen and one for liquid hydrogen, and a Vulcain 2 engine at the base with a vacuum thrust of 1,390 kilonewtons (310,000 pounds-force). The H173 EPC weighs about 189 tonnes, including 175 tonnes of propellant.^[8] After the main cryogenic stage runs out of fuel, it re-enters the atmosphere for an ocean splashdown.

Attached to the sides are two P241 (P238 for Ariane 5 G and G+) solid rocket boosters (SRBs or EAPs from the French Étages d’Accélération à Poudre), each weighing about 277 tonnes full and delivering a thrust of about 7,080 kilonewtons (1,590,000 pounds-force). They are fueled by a mix of ammonium perchlorate (68%) and aluminum fuel (18%) and HTPB (14%). They each burn for 130 seconds before being dropped into the ocean. The 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 has occasionally been 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.^[9] Prior to that mission, the last such recovery and testing was done in 2003.

The French M51 SLBM shares a substantial amount of technology with these boosters.

In February 2000 the suspected nose cone of an Ariane 5 booster washed ashore on the South Texas coast, and was recovered by beachcombers before the government could get to it.^[10]

The second stage is on top of the main stage and below the payload. The original Ariane—Ariane 5 G—used the EPS (Étage à Propergols Stockables—Storable Propellant Stage), which was fueled by monomethylhydrazine (MMH) and nitrogen tetroxide, containing 10 tonnes (22,000 lb) of storable propellant. The EPS was subsequently improved for use on the Ariane 5 G+, GS, and ES. Ariane 5 ECA uses the ESC (Étage Supérieur Cryotechnique—Cryogenic Upper Stage), which is fueled by liquid hydrogen and liquid oxygen.

The EPS upper stage is capable of multiple ignitions, first demonstrated 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, followed by a third burn after ATV deployment to de-orbit the stage. This procedure was repeated for all subsequent ATV flights.

The payload and all upper stages are covered at launch by a fairing, which is jettisoned once sufficient altitude has been reached (typically above 100 km). The fairing is also used for aerodynamic stability and protection from heating during supersonic flight and acoustic loads.

Variants

Launch system status: Retired · Cancelled · Operational · Under development

Launch pricing and market competition

As of November 2014, the Ariane 5 commercial launch price for launching a "midsize satellite in the lower position" was approximately US$60 million,^[16] competing for commercial launches in an increasingly competitive market.

The heavier satellite launched in the upper position on a typical dual-satellite Ariane 5 launch is priced higher than the lower payload,^[17] on the order of €90 million as of 2013.^[18]^[19]

Total launch price of an Ariane 5—which can transport up to two satellites to space, one in the "upper" and one in the "lower" positions—is around 150 million Euro as of January 2015.^[19]

Future developments

The Ariane 5 ME (Mid-life Evolution) was in development into early 2015, and was seen as a stopgap between Ariane 5 ECA/Ariane 5 ES and the new Ariane 6. With first flight planned for 2018, it would have become ESA's principal launcher until the arrival of the new Ariane 6 version. ESA halted funding for the development of Ariane 5 ME in late 2014 to prioritize development of Ariane 6^[20]

The Ariane 5 ME was to use a new upper stage, with increased propellant volume, powered by the new Vinci engine. Unlike the HM-7B engine, it was to be able restart several times, allowing for complex orbital maneuvers such as insertion of two satellites into different orbits, direct insertion into geosynchronous orbit, planetary exploration missions, and guaranteed upper stage deorbiting or insertion into graveyard orbit.^[21]^[22] The launcher was also to include a lengthened fairing up to 20m and a new dual launch system to accommodate larger satellites. Compared to an Ariane 5 ECA model, the payload to GTO was to increase by 15% to 11.5 tonnes and the cost-per-kilogram of each launch is projected to decline by 20%.^[21]

Originally known as the Ariane 5 ECB, Ariane 5 ME was to have its first flight in 2006. However, the failure of the first ECA flight in 2002, combined with a deteriorating satellite industry, caused ESA to cancel development in 2003.^[23] Development of the Vinci engine continued, though at a lower pace. The ESA Council of Ministers agreed to fund development of the new upper stage in November 2008.^[24] In 2009, EADS Astrium was awarded a €200 million contract,^[25] and on April 10, 2012 received another €112 million contract to continue development of the Ariane 5 ME^[26] with total development effort expected to cost €1 billion.^[27]

On 21 November 2012, ESA agreed to continue with the Ariane 5 ME to meet the challenge of lower priced competitors. It was agreed the Vinci upper stage would also be used as the second stage of a new Ariane 6, and further commonality would be sought.^[22] Ariane 5 ME qualification flight was scheduled for mid-2018, followed by gradual introduction into service.^[21]

On 2 December 2014, ESA decided to stop funding the development of Ariane 5 ME and instead focus on Ariane 6, which was expected to have a lower cost per launch and allow more flexibility in the payloads (using two or four P120C solid boosters depending on total payload mass).^[20]

Work on the Ariane 5 EAP motors has been continued in the Vega programme. The Vega 1st stage engine—the P80 engine—is a shorter derivation of the EAP.^[28] 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.^[22]^[29] The incorporation of the ESC-B with the improvements to the solid motor casing and an uprated Vulcain engine would deliver 27,000 kilograms (60,000 lb) 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.^[30]

The design brief of the next generation rocket Ariane 6 called for a lower-cost and smaller rocket capable of launching a single satellite of up to 6.5 tonnes to GTO.^[31] However, after several permutations the finalized design was nearly identical in performance to the Ariane 5,^[32] focusing instead on lowering fabrication costs and launch prices.

Development is projected to cost €4 billion. In 2018, its first test launch was set to not earlier than July 2020.^[33] As of March 2014, Ariane 6 was projected to be launched for about €70 million per flight or about half of the Ariane 5 current price.^[31]

Notable launches

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.^[34] A data conversion from 64-bit floating point value to 16-bit signed integer value to be stored in a variable representing horizontal bias caused a processor trap (operand error)^[35] because the floating point value was too large to be represented by a 16-bit signed integer. The software was originally written for the Ariane 4 where efficiency considerations (the computer running the software had an 80% maximum workload requirement^[35]) led to four variables being protected with a handler while three others, including the horizontal bias variable, were left unprotected because it was thought that they were "physically limited or that there was a large margin of safety".^[35] The software, written in Ada, was included in the Ariane 5 through the reuse of an entire Ariane 4 subsystem despite the fact that the particular software containing the bug, which was just a part of the subsystem, was not required by the Ariane 5 because it has a different preparation sequence^[35] than the Ariane 4.

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 it could not reach the intended orbit.

A subsequent test flight (L503, on 21 October 1998) proved successful and the first commercial launch (L504) 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 until the launch of the first ATV on 9 March 2008 (19,360 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. As of June 2017, the failure of the first ECA launch was the last failure of an Ariane 5; since then, 82 consecutive launches have been successful, from April 2003 with the launch of INSAT-3A and Galaxy 12 satellites,^[36] to flight 240 in December 2017.

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 a Helios 2A observation satellite) delayed the attempt.

On 11 August 2005, the first Ariane 5 GS (featuring the Ariane 5 ECA's improved solid motors) boosted Thaïcom-4/iPStar-1, the heaviest telecommunications satellite to date at 6,505 kg,^[37] 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 8,000 kg.

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.^[38]

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.^[39] 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 9,535 kg.^[40]

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. The ATV was the heaviest payload ever launched by a European rocket, providing supplies to the space station with necessary propellant, water, air and dry cargo. This was the first operational Ariane mission which involved an engine restart in the upper stage. (The ES-ATV Aestus EPS upper stage was restartable while the ECA HM7-B engine was not.)

On 1 July 2009, an Ariane 5 ECA launched TerreStar-1 (now EchoStar T1), which was then, at 6,910 kg (15,230 lb), the largest and most massive commercial telecommunication satellite ever built at that time^[41] until being overtaken by Telstar 19 Vantage, at 7,080 kg (15,610 lb), launched aboard Falcon 9 (although the satellite was launched into a lower-energy orbit than a usual GTO, with its initial apogee at roughly 17,900 km).^[42]

On 28 October 2010, an Ariane 5 ECA launched Eutelsat's W3B (part of its W Series of satellites) and Broadcasting Satellite System Corporation (B-SAT)'s BSAT-3b satellites into orbit. But the W3B satellite failed to operate shortly after the successful launch and was written off as a total loss due to an oxidizer leak in the satellite's main propulsion system.^[43] The BSAT-3b satellite, however, is operating normally.^[44]

On 22 April 2011, the Ariane 5 ECA flight VA-201 broke a commercial record, lifting Yahsat 1A and Intelsat New Dawn with a total payload weight of 10,064 kg to transfer orbit.^[45] This record was later broken again during the launch of Ariane 5 ECA flight VA-208 on 2 August 2012, lifting a total of 10,182 kg into the planned geosynchronous transfer orbit,^[46] which was broken again 6 months later on flight VA-212 with 10,317 kg sent towards geosynchronous transfer orbit.^[47] In June 2016 the GTO record was raised to 10,730 kg,^[48] on the first rocket in history that carried a satellite dedicated to financial institutions.^[49] The payload record was pushed a further 5 kg to 10,735 kg (23,667 lb) on 24 August with the launch of Intelsat 33e and Intelsat 36.^[50] On 1 June 2017, the payload record was broken again to 10,865 kg (23,953 lb) carrying ViaSat 2 and Eutelsat 172B.^[51]

On 25 January 2018, an Ariane 5 ECA launched SES-14 and Al Yah 3 satellites. About 9 minutes and 28 seconds after launch, a telemetry loss occurred between the rocket and the ground controllers. It was later confirmed, about 1 hour and 20 minutes after launch, that both satellites were successfully separated from the upper stage and were in contact with their respective ground controllers,^[52] but that their orbital inclinations were incorrect as the guidance systems might have been compromised. Therefore, both satellites conducted orbital make-up procedure, extending commissioning time.^[53] SES-14 needed about 4 weeks longer than planned commissioning time, meaning that entry into service was reported early September instead of July.^[54] Nevertheless, SES-14 is still expected to be able to meet the designed lifetime. This satellite was originally to be launched with more propellant reserve on a Falcon 9 rocket since the Falcon 9, in this specific case, was intended to deploy this satellite into a high inclination orbit that would require more work from the satellite to reach its final geostationary orbit.^[55] The Al Yah 3 was also confirmed healthy after more than 12 hours without further statement, and like SES-14, Al Yah 3's maneuvering plan was also revised to still fulfill the original mission.^[56] As of 16 February 2018, Al Yah 3 was approaching the intended geostationary orbit, after series of recovery maneuvers had been performed.^[57] The investigation showed that invalid inertial units' azimuth value had sent the vehicle 17° off course but to the intended altitude, they had been programmed for the standard geostationary transfer orbit of 90° when the payloads were intended to be 70° for this supersynchronous transfer orbit mission, 20° off norm.^[58] This mission anomaly marked the end of 82nd consecutive success streak since 2003.^[59]

Launch history

Ariane 5 rockets have accumulated 105 launches since 1996, 100 of which were successful, yielding a 95.2% success rate. Between April 2003 and December 2017, Ariane 5 flew 82 consecutive missions without failure, but the rocket suffered a partial failure in January 2018.

All launches are from Kourou ELA-3.

See also

List of Ariane launches

Comparison of orbital launchers families

Comparison of orbital launch systems

Future Launchers Preparatory Programme (ESA, beyond Ariane 5)

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