Ariane 5 is a retired European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It was launched from the Centre Spatial Guyanais (CSG) in French Guiana. It was used to deliver payloads into geostationary transfer orbit (GTO), low Earth orbit (LEO) or further into space. The launch vehicle had a streak of 82 consecutive successful launches between 9 April 2003 and 12 December 2017. Since 2014,^[4] Ariane 6, a direct successor system, is in development.^[5]

The system was designed as an expendable launch system by the Centre national d'études spatiales (CNES), the French government's space agency, in cooperation with various European partners. Despite not being a direct derivative of its predecessor launch vehicle program, it was classified as part of the Ariane rocket family. ArianeGroup was the prime contractor for the manufacturing of the vehicles, leading a multi-country consortium of other European contractors. Ariane 5 was originally intended to launch the Hermes spacecraft, and thus it was rated for human space launches.

Since its first launch, Ariane 5 was refined in successive versions: "G", "G+", "GS", "ECA", and finally, "ES". The system had a commonly used dual-launch capability, where up to two large geostationary belt communication satellites can be mounted using a SYLDA (Système de Lancement Double Ariane, meaning "Ariane Double-Launch System") carrier system. Up to three, somewhat smaller, main satellites are possible depending on size using a SPELTRA (Structure Porteuse Externe Lancement Triple Ariane, which translates to "Ariane Triple-Launch External Carrier Structure"). Up to eight secondary payloads, usually small experiment packages or minisatellites, could be carried with an ASAP (Ariane Structure for Auxiliary Payloads) platform.

Following the launch of 15 August 2020, Arianespace signed the contracts for the last eight Ariane 5 launches, before it was succeeded by the new Ariane 6 launcher, according to Daniel Neuenschwander, director of space transportation at the ESA.^[6][5] Ariane 5 flew its final mission on 5 July 2023.^[7]

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

As of November 2014^[update], the Ariane 5 commercial launch price for launching a "midsize satellite in the lower position" was approximately €50 million,^[20] competing for commercial launches in an increasingly competitive market.

The heavier satellite was launched in the upper position on a typical dual-satellite Ariane 5 launch and was priced higher than the lower satellite,^{[21][clarification needed]} on the order of €90 million as of 2013^[update].^[22][23]

Total launch price of an Ariane 5 – which could transport up to two satellites to space, one in the "upper" and one in the "lower" positions – was around €150 million as of January 2015^[update].^[23]

The design brief of the next generation launch vehicle Ariane 6 called for a lower-cost and smaller launch vehicle capable of launching a single satellite of up to 6,500 kg (14,300 lb) to GTO.^[35] However, after several permutations the finalized design was nearly identical in performance to the Ariane 5,^[36] focusing instead on lowering fabrication costs and launch prices. As of March 2014^[update], Ariane 6 was projected to be launched for about €70 million per flight, about half of the Ariane 5 price.^[35]

Initially development of Ariane 6 was projected to cost €3.6 billion.^[37] In 2017, the ESA set 16 July 2020 as the deadline for the first flight.^[38] As of June 2022, Arianespace expects the maiden flight to occur in 2023.^[39]

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.^[40] 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)^[41] because the floating-point value was too large to be represented by a 16-bit signed integer. The software had been written for the Ariane 4 where efficiency considerations (the computer running the software had an 80% maximum workload requirement^[41]) 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".^[41] 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 than the Ariane 4.^[41]

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.^[42]

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 of 800 km (500 mi) above the Earth in the 11th launch. At 8,111 kg (17,882 lb), it was the heaviest single payload until the launch of the first ATV on 9 March 2008, at 19,360 kg (42,680 lb).

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 €630 million, was lost in the Atlantic 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. The failure of the first ECA launch was the last failure of an Ariane 5 until flight 240 in January 2018.

On 27 September 2003, the last Ariane 5G boosted three satellites (including the first European lunar probe, SMART-1), in Flight 162. On 18 July 2004, an Ariane 5G+ boosted what was at the time the heaviest telecommunication satellite ever, Anik F2, weighing almost 6,000 kg (13,000 lb).

The first successful launch of the Ariane 5ECA 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 scheduled for October 2004, but additional testing and a military launch (of a Helios 2A observation satellite) delayed the attempt.

On 11 August 2005, the first Ariane 5GS (featuring the Ariane 5ECA's improved solid motors) boosted Thaicom 4, the heaviest telecommunications satellite to date at 6,505 kg (14,341 lb),^[43] into orbit.

On 16 November 2005, the third Ariane 5ECA 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 launch vehicle's heaviest dual payload to date, at more than 8,000 kg (18,000 lb).

On 27 May 2006, an Ariane 5ECA launch vehicle set a new commercial payload lifting record of 8,200 kg (18,100 lb). The dual-payload consisted of the Thaicom 5 and Satmex 6 satellites.^[44]

On 4 May 2007, the Ariane 5ECA set another new commercial record, lifting into transfer orbit the Astra 1L and Galaxy 17 communication satellites with a combined weight of 8,600 kg (19,000 lb), and a total payload weight of 9,400 kg (20,700 lb).^[45] This record was again broken by another Ariane 5ECA, launching the Skynet 5B and Star One C1 satellites, on 11 November 2007. The total payload weight for this launch was of 9,535 kg (21,021 lb).^[46]

On 9 March 2008, the first Ariane 5ES-ATV was launched to deliver the first ATV called Jules Verne to the International Space Station (ISS). The ATV was the heaviest payload ever launched by a European launch vehicle, 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 5ECA 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^[47] until being overtaken by Telstar 19 Vantage, at 7,080 kg (15,610 lb), launched aboard Falcon 9. The satellite was launched into a lower-energy orbit than a usual GTO, with its initial apogee at roughly 17,900 km (11,100 mi).^[48]

On 28 October 2010, an Ariane 5ECA 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.^[49] The BSAT-3b satellite, however, is operating normally.^[50]

The VA253 launch on 15 August 2020 introduced two small changes that increased lift capacity by about 85 kg (187 lb); these were a lighter avionics and guidance-equipment bay, and modified pressure vents on the payload fairing, which were required for the subsequent launch of the James Webb Space Telescope. It also debuted a location system using Galileo navigation satellites.^[51]

On 25 December 2021, VA256 launched the James Webb Space Telescope towards a Sun–Earth L₂ halo orbit.^[52] The precision of trajectory following launch led to fuel savings credited with potentially doubling the lifetime of the telescope by leaving more hydrazine propellant on-board for station-keeping than was expected.^[52][53] According to Rudiger Albat, the program manager for Ariane 5, efforts had been made to select components for this flight that had performed especially well during pre-flight testing, including "one of the best Vulcain engines that we've ever built."^[53]

Wikimedia Commons has media related to Ariane 5.

• List of Ariane launches
• Ariane 6, two initial variants
• Heavy-lift launch vehicle
• Comparison of orbital launchers families
• Comparison of orbital launch systems
• Future Launchers Preparatory Programme (ESA, beyond Ariane 5)