Numerous functions

At each stage of the launch campaign, the table moves and provides the link between the launcher and the ground facilities. Whether in the BIL, the BAF or at the ZL, the table is connected to the ground while the launcher is connected to it via the ground/onboard links. This design requires table/building connection systems for fluids, control and command, power, cooling and the operations control unit (RMO).

It therefore acts as Ariane’s umbilical cord by providing all its vital functions.

Fluid functions

All the ‘ground’ fluid functions that are vital to the launcher are embedded in the table, together with the auxiliary fluids which perform equally important ancillary functions, such as inerting nitrogen and control helium, ventilation and cooling.

Cleanliness and tightness must be verified for the ground/onboard links (LBSs) and the pneumatic base connectors (PCPs):

 - propellant fuelling lines (hydrogen, oxygen and helium), which are vacuum double-jacketed to maintain the cryogenic propellants in liquid form at 20K and 90K at the countdown sequence during fuelling and when topping up prior to launch,

- gas lines for pressurisation and depressurisation, connected to the tanks, pressurisation lines for the launcher’s other high-pressure helium and nitrogen tanks (several hundred bars).

Electrical and command-control functions

It must be possible to supply the launcher with electrical power from the ground and to transmit functional commands. To do this, wire connections and a command bus are used, via Electrical Base Connectors and Electrical Umbilical Connectors.  These links mainly provide the command functions (electro-pyrotechnic command on the igniters, powering-up command for the onboard equipment, etc.).

There are also 1553 BUS links for communicating with the launcher’s onboard computer, according to a protocol which operates equipment on board the launcher.

All these commands work using command-control systems (CCO and CCX) embedded in the table and connected to the checkout systems located in the launch centre (CDL). The checkout equipment in the CDL interacts with the front-end computer in the table and enables, for instance, automatic fuelling to take place, using the commands and reports from the table and the launcher.

The table is capable of managing the ignition phase alone. From T0-6.4 sec. all monitoring likely to interrupt the final countdown ceases and only an automatic system located in one of the table’s front-ends is run. It activates all the functions of the table or ZL that are needed for the ignition phase without any intervention from the CDL. 

Safety functions

The table contains several safety barriers, notably relating to the pyrotechnic commands. There are also safety functions unique to the table, for detecting gas, detecting and extinguishing fire, and inerting the interior of the table to avoid the risk of explosion or any possibility of inadvertent combustion. This is done by replacing air with nitrogen during the countdown, which explains why the personnel required to work in the table must carry low-oxygen detectors. The fire detection and extinction system enables any combustion to be detected, prevented and extinguished when there is nobody inside the table. As for the gas detector, this also has a system of visual and audible alarms. It is used to verify an adequate oxygen content in ambient air, and also to detect any over-oxygenation or presence of hydrogen during the fuelling phase.

… and various other functions

Different means of communication are also embedded in the table, such as telemetry and telecommunications links, video equipment, and optical equipment for analysing the launch.

When the launcher is being transferred from the BAF to the ZL, there is also an optical cable dispenser (DCO) which follows the convoy and enables Arianespace’s customer to continue interacting with its satellite even while rolling.

Power and cooling functions also require equipment to be embedded in the table, such as batteries, voltage regulator, and connectors to the chilled water and hot water systems.