Arianespace, Europe's commercial space-launcher organisation, has long intended that its Ariane 5 vehicle will become its workhorse, and that it would be able to retire the long-serving Ariane 4. However, following the failure of the first Ariane 5 launch from the Centre Spatial Guyanais (CSG), Kourou, satellite launch site in French Guiana in June 1996, the Ariane 4's career has been extended. An additional ten Ariane 4s were ordered following that accident, meaning that launches will now take place until 2001 instead of the previously planned 1998.
As a result, Ariane 4s and 5s will be operated side-by-side from Kourou for at least the next three years, and Arianespace has had to devise procedures for operating two entirely different launch systems simultaneously. While Ariane 5 flight 502 is being prepared for its vital, second development, mission, commercial Ariane 4 flights V95 and 96 are in preparation, with the V95 scheduled for launch on 11 April. The Ariane 5's commercial introduction, planned for flight 504, may now not take place until late 1998. During the transition period, the Ariane 4 and 5 vehicles will have to be operated from adjacent, but different, operations based at the ELA 2 and 3 industrial areas.
Compared with launch operations at Cape Canaveral, for example, the CSG's launch activity is quite compact. The Ariane 4 pad - adjacent to Ariane 5's - is just 1km (0.5nm) away from its assembly building. The closeness of the pads to buildings streamlines operations, but is also a reflection of the non-military influence in the development of the CSG, which has been a powerful economic influence in transforming this part of French Guiana into a vibrant industrial and space community.
Mature Ariane 4 operation
The Ariane 4 launch system is now a mature operation, having been used for more than 60 launches since June 1988. Arianespace and its 25-company industrial team, including Aerospatiale, Deutsche Aerospace and Matra Marconi Space, have to undertake over 4,800 separate operations to ready an Ariane 4 vehicle for launch at the ELA 2. The Arianespace-led team can prepare an Ariane 4 for flight every three weeks. Normal turnaround time is 27 days. This is a reflection of Arianespace's outstanding manifest of 41 satellites. Original " launch campaign" times were about 33 days for the Ariane 4, compared with the 60-plus days of processing time for the Ariane 1, 2 and 3 family. A record 14 Ariane 4 launches were achieved in a period of 11 months in 1995-6.
A total of 15 days is spent in the vehicle-assembly building as the three stages (barged or flown in from Europe) are mated vertically with the booster on its crawler transporter. Liquid strap-on boosters are mated to the vehicle in the assembly building but, for safety, solid-rocket boosters are mated to the booster at the pad. An Ariane vehicle can be flown with either liquid or solid-rocket boosters, or a mix of the two (42L, 44L, 42P, 44P and 44LP). If no boosters are carried (on a 40 model, for example), the processing time can be cut to 25 days, with time in the assembly building reduced from 15 to 13 days.
The Ariane 4 spends 12 days on the pad, having been rolled out on its 1km-long crawlerway, swopping with the mobile transporter used for the previous flight. The pad's gantry - the second-largest mobile structure in the world after the Space Shuttle mobile launcher platform - embraces the non-payload-carrying vehicle.
While the booster has been prepared in the assembly building, satellite payloads are prepared in two separate buildings, S3A and S3B. If two satellites are to be launched on one booster, they are mated in Building S3B. The payloads are housed within the payload shroud in S3B and, as the "upper composite", they are transported to the pad five days before launch, to be hauled to the top of the waiting Ariane.
Although the pad is only a short distance from the ELA 2 buildings, it is "-far enough to enable work to continue at the ELA 2 preparation area, during the launch campaign without breaking safety regulations", says Bernard Donat, Arianespace's head of operational production at the CSG. "The area has only to be evacuated six hours before launch," he adds.
This does not include the 160-strong team in the bunkered launcher-control centre (CDL2), which has overseen the preparation of the vehicle since the first day of the launch campaign, and which is prepared to hand over control of the launcher to the new CSG Jupiter 2 launch-control centre.
The Jupiter 2 centre monitors launcher readiness, and the readiness of the base and its supporting telemetry, radar, weather and other monitoring stations. It was inaugurated for the launch of the V82 in January 1996, taking over from the original Ariane Jupiter control centre. A launch dress-rehearsal takes place in the Jupiter 2 centre during the test loading of the Ariane 4 third stage after it has arrived on the pad. Propellants are loaded onto the Ariane 4 one day before launch. Actual fuelling of the third stage is 3h 30min before lift-off.
After a successful launch, preparations for the next flight begin at ELA 2, three days later, assuming that analysis has confirmed that every parameter from the previous launch was within acceptable limits. "If there is an anomaly, we don't go ahead with the next launch until we fully understand it," says Donat.
Near the ELA 2 pad are the remains of the original ELA 1 launch pad used for 25 Ariane 1, 2 and 3 launches. The ELA 1 itself was built using as its basis the original pad used to launch the ill-fated Europa vehicle (with its British Blue Streak first stage), while, nearby, is the Diamant booster pad, used to launch French science satellites in the1970s.
A different pad for Ariane 5
Closer still to the ELA 2 is the ELA 3 launch pad, its configuration reflecting a different vehicle, the Ariane 5, and its different processing style. The ELA 3 area is dominated by the large Ariane 5 launcher-integration building (BIL), where the booster's cryogenic main stage, solid boosters and vehicle-equipment bay are mated. Ariane 5 satellites are prepared for flight in the ELA 2's S3A and S3B buildings, but the satellite payloads and fairing are mated to the booster in the final assembly building (BAF), rather than on the launch pad itself, as they are for an Ariane 4 launch.
While the CSG awaits delivery of the main parts of the Ariane 502, which will probably be launched in September, preparation of the solid-rocket boosters for the Ariane 506 has been started.
The solid propellant is produced by Regulus of Italy and by France's SNPE. The boosters are assembled in the Europropulsion booster integration building (BIP). They are then rolled on for mating with the Ariane 5itself. With the boosters of the 502 stacked and ready to flyand the booster segments of the 503 awaiting stacking, the BIP is filled with 1,300t of solid propellant.
Booster examination
Russian-provided parachute systems have been added to the boosters for the 502/504, so that the recovered units can be examined. There is no plan for them to be recovered regularly, however, although Arianespace may ask for periodic inspections during commercial operations. The boosters were not designed to be re-used.
For early launches, the whole Ariane 5, attached to its umbilical tower on the crawler transporter, and with its third stage already loaded with storable propellants, is rolled out 3km to the ELA 3 pad a day before lift-off.
When Ariane vehicles are operational, the roll-out will take place 9h before launch. The operational plan is for the craft to spend 13 days in the BIL and eight days in the BAF, with the roll-out occurring on the 21st day. The launcher-control centre (CDL 3) monitors preparations of the Ariane 5 before handing over to the Jupiter 2 for the launch. A second CDL 3 control room is also planned.
This streamlined Ariane 5 operation has an added advantage. There is no need for a huge gantry on the ELA 3 pad. The only structure on the pad, apart from a water tower for the sound-suppression system and four tall lightning conductors, is a steel lattice-framework windbreak, which has been added to the pad structure recently and which stands flush behind the umbilical tower of the mobile launch-platform. The Ariane 5's first-stage cryogenic propellants are loaded from under the pad.
"The launch pad is as simple as possible and the reason is that, in the event of an accident during lift-off, the damage will be minimal, allowing operations to resume as soon as possible" says Donat. He likens Ariane 5 processing to the "Titan philosophy". Titans are prepared at Cape Canaveral, where a second mobile-launch platform will be operational in 1998.
"The main reason for this method is simply to make the process simpler", says Pierre Collet, operations director at Arianespace's headquarters in Evry, France. "The Ariane 4 gantry complex is also expensive to maintain and would receive heavy damage in the event of an accident. It could take one year to 18 months to repair. The Ariane 5 pad is essentially bare".
Like its predecessor, the Ariane 5 will be launched every three weeks, and will be capable of placing 16 communications and other satellites into orbit each year.
Source: Flight International