Last week, the European Space Agency (ESA) completed the first rollout test of its 90 meter (295 ft)-tall mobile gantry, where the next generation of Ariane rockets will be assembled and protected at the launch zone prior to blasting off. The first Ariane 6 rocket is currently slated to make its maiden flight in the second half of 2020, when it will launch multiple satellites for the communications firm OneWeb.
Construction began on the gantry, which is located at Europe's spaceport in French Guiana, back in November 2017. Once completed it will weigh an impressive 8,200 tonnes (9,039 US tons), which, according to a recent ESA press release, is over a thousand tonnes heavier than the iconic wrought iron structure of the Eiffel Tower.
The mobile gantry will follow tracks as it moves to and fro between the launch pad and its pulled-back position. It moves on 16 bogies (a bogie is a chassis that carries a wheelset), each of which travels on eight wheels of their own. One hundred and twenty-eight electric motors – one for each wheel – drive the movement of the structure.
Retractable work platforms positioned throughout the mobile gantry will grant engineers easy access to the rocket, allowing them to make significant adjustments without the need to transport the launch vehicle away from the pad, and back to a separate facility.
The liquid fuel main and upper stages that make up the cores of the future Ariane 6 rockets will first be joined together in the Launcher Assembly Building, which is located around 1 km (0.6 mile) from the pad. The core of an Ariane 6 will then be moved to and erected in the mobile gantry, where a configuration of two or four solid fuel side boosters can be attached depending on the thrust requirements of the mission.
Once the boosters are attached, the payload, nestled safely in its aerodynamic fairing, will be mated to the top of the launch vehicle. The gantry will remain in station around the launch pad, protecting the Ariane 6 from the elements until roughly five hours before blast off. At this point the vast structure will expose the rocket to the (hopefully) clear skies above French Guiana, and retreat to the safety of its pull-back position to watch the fireworks.
During last week's test, engineers tracked the gantry's speed, power consumption and motor synchronization as it ponderously trundled along 97 m (318 ft) of tracks. Despite its imposing size, moving the platform requires little more than the selection of a direction and the press of a button.
"There are three speeds," explains Jean-Michel Rizzi, ESA's Ariane 6 Launch Base Project Manager. "The first and last meter are done at the slowest speed of a meter per minute. This increases to a 'cruising' speed of 7.6 m (24.9 ft) per minute for a 130 m (427 ft) stretch and then slowed back down to 3 m (9.8 ft) per minute in the decelerating phase over a distance of 9 m (29.5 ft). The full rollout of 141 m (463 ft) takes 22 minutes."
ESA plans to conduct several more rollout tests in the coming weeks, with a view to having all launch infrastructures integrated by the end of the year.
Scroll down to watch time lapse footage of the first-ever Ariane 6 mobile gantry rollout.
Source: ESA
