The Ariane 5 ground operation at Kourou covers 2,500Ha (5,190 acres), and is split into three main areas: the ELA3 launch site; booster zone (containing the solid-propellant plant, booster-integration building and solid-booster test stand) and cryogenic-fuel preparation zone. The site is new, and cost around Fr6.3 billion ($1.27 billion).
The ELA3 can handle up to eight launches a year, with as little as one month between them. The obvious difference, compared with the ELA2, is that the ELA3 can accommodate the cryogenic-fuel system, and the mobile gantry for final assembly has been replaced with a permanent building.
From a distance, the pad itself looks relatively insignificant, containing as few fixed installations as possible, for safety. The most visible item is the 90m-high water tower, which dumps 1,500m3 (53,000ft3) of water at 20m3/s into the flame trench at lift-off, both for cooling and to reduce noise. There are three separate flame trenches (one each for the boosters and the Vulcain engine), a burn-off pool covering 310m2 (3,400ft2), and the liquid-oxygen and hydrogen connections.
A launch table, weighing 870t unloaded and 1,500t with the complete rocket aboard, supports the launcher throughout the assembly process. Pulled by a truck, the ensemble is transported on a double-rail track between the integration building, final-assembly building and pad (where it serves as the launch platform). It is fitted with a two-part umbilical mast, 58m high, containing the fluid and electrical terminals, which interface with the launcher.
The launch-control centre, integration building and final-assembly building are all in the same area. With an air-conditioned interior volume of 80,000m3, the integration building is used to assemble the cryogenic main stage, solid-propellant stage and vehicle-equipment bay on to the launch table. Then, the solid-propellant boosters from the booster-integration building are added and, after sealing and electrical tests, the launcher/table assembly is taken to the final-assembly building. So far, the process has taken 13 days.
The 90m-high final-assembly building became fully operational in early 1995. Payloads are added to the basic launcher, and final preparations, such as filling the solid propellant stage and attitude-control system, are carried out. Operations in this building last for eight days, and the launcher is transferred to the forward launch area 9h before launch.
The final component of the site is the preparation and launch-control centre, a fully protected, 2,700m2 building containing two independent control rooms, a control-and-command room reserved for ground-service equipment and three payload rooms.
The boosters are assembled in another new building at Kourou, to which the three segments of each booster are taken on a special multi-wheeled trailer from the solid-propellant-plant storage area to the building and assembled vertically on a pallet. Two booster stages can be assembled each month, and they remain on the pallets until launch.
To avoid safety problems in long-distance transportation, a new solid-propellant plant was also built at Kourou, and is claimed to have one of the most automated systems in the world. Covering 300Ha, the plant is responsible for preparing the solid fuel and filling the two lower booster segments (the top segment is filled in Italy). There are two 6,820litre mixers, two casting pits and six mixing tanks. The site also contains a non-destructive testing installation, a crushing and filtration installation and a liner-coating machine.
Booster testing is carried out at a Fr245 million site which is claimed to be the only one on the world which can test boosters in their upright launch position. The booster on test vents into an enormous trench 60m deep and 200m long cut out of solid granite.
Liquid hydrogen is produced by reforming methyl alcohol, and the production capacity of the plant is 33m3 daily, the hydrogen being stored in six mobile tanks. The liquid-oxygen plant liquefies air to produce liquid oxygen and liquid nitrogen, producing up to 14m3 of liquid oxygen and 60m3 of liquid nitrogen daily.
The Ariane 5 launch campaign, lasts a total of 22 days, with the rocket being transferred to the pad on the day of launch. Final countdown begins 6h before launch, and centres on filling the cryogenic main stage with liquid oxygen and hydrogen, as well as final preparation of all of the subsystems. The synchronised countdown begins at -6min 30s. In the event of a launch termination, another attempt can be made 24h later.
Source: Flight International
