The ability to move the antennas is one of the characteristics that make ALMA such a powerful telescope. Each antenna weighs over 100 tons and contains cutting-edge technological components that need a constant power supply; therefore, they require specially designed vehicles to move them. Engineers had to create vehicles that were resistant and durable enough to transport each antenna along the 28 kilometers that separate the Operations Support Facility (OSF), at an altitude of 2,900 meters above sea level, from the Chajnantor Plateau, situated at an altitude of 5,000 meters above sea level, and to relocate them on the same plateau.
ALMA uses two giant trucks with these characteristics: Otto and Lore. Each truck is 20 meters long, 10 meters wide and 6 meters high, and moves on 28 wheels. The empty weight of each is 130 tons. Transportation of that much weight requires a great deal of power. Each truck is equipped with two diesel engines of approximately 700 horsepower (500 kW) and two 1,500-liter tanks. Despite their size and strength, these yellow titans are capable of positioning the antennas on the pads with millimetric precision and keeping them connected to a power source throughout their transportation.
The construction of Otto and Lore was not without challenges. Special brake systems and safety devices were installed to prevent accidents and protect the costly ALMA antennas. The driver’s seat back was designed to enable the driver to use an oxygen tank while he drives, which is necessary at such a high altitude. However, the driver is not the only one to feel the effects of the altitude: each of Otto’s and Lore’s 700-horsepower engines can barely push 450 horsepower (320 kW) upon reaching the plateau situated at 5,000 meters above sea level.
The trucks move at a maximum speed of 20 km/h, which reduces to 12 km/h when they are transporting an antenna. This may not be very fast but in their design, priority was given to safety and precision. During antenna loading and unloading processes, or in any other delicate maneuver, the trucks can be operated by remote control, which allows the driver to be outside the truck and watch over the process from nearby.
Without these impressive machines to transport the antennas, the ALMA radio telescope would be impossible to operate. A modern observatory requires many leading technologies. Otto and Lore play a key role at ALMA.