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ESO 32/07 - Associated Images

30 July 2007
For Immediate Release

Birth of a Colossus on Wheels

First ALMA Transporter Ready to Go

Front view of the ALMA antenna transporter, a colossus on wheel that is 10 metre wide and 6 metre high. The driver's cabin was placed below the main structure to provide the driver with a good view of the wheels and help avoiding accidents.
A video is also available with this story.

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The ALMA antenna transporter is motorised by 2 powerful engines of 500 kW each - i.e. as much as twice a Formula 1 engine - that drive individually each of the 28 wheels. These powerful engines are necessary to climb the 10% slopes that exists on the Chajnantor site and to bring the 240 tons of the vehicle and antenna from the 2900m high base camp to the observing site at 5000m altitude. The transporter has on board a power generator to keep the antenna and its cryogenic systems alive while being transported.

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The ALMA antenna transporter is supported by 28 wheels, all independently driven. The ALMA transporter is able to turn around a 12-m antenna. This is required when the transporter has to remove or place an antenna in the middle of the most compact configuration, as in this case, the manoeuvring space can be as small as a few metres, which is not a lot for a 20 m long vehicle. A laser detection system is also installed on the truck to avoid collisions. In case of emergency, this system automatically stops the transporter. The sophisticated lorry has been optimised to reduce the cost of the road on which it circulates. Its relatively small weight of 130 tons is the result of a dedicated lightweight design. The transporter is also designed to resist to a major earthquake, as are all the ALMA antennas.

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The two inclined elevators on the side of the vehicle are necessary when lifting up the heavy antennas to ensure that the load is supported by all the wheels. The two ALMA antenna transporters have to be highly reliable as they will be operating at 5000m altitude in the driest place on Earth, 365 days a year.

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When lifting an antenna, the driver will be at the rear of the vehicle and manipulate it as a 'toy-car', to achieve the best possible precision and to watch as closely as possible the critical operation. The transporter will be able to position the antennas with millimetric precision and is therefore helped by a dedicated guiding system. As the transporters will be operated at an altitude with significantly reduced oxygen levels, a range of redundant safety devices were installed to protect both personnel and equipment from possible mishaps or accidents.

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Artist's rendering of an ALMA antenna being transported from the base camp to the 5000m high observing site. The transporter can move with a maximum speed of 12 km/h when loaded with a 115-ton antenna.