The Atacama Large Millimeter/submillimeter Array consists of 66 individual radio telescopes that can be moved to zoom in on a patch of sky. But how do they move those 100-ton beasts around the desert?
Otto, the red-railed transport crawler. Twin transporter Lore has green rails. Image credit: José Velásquez/ESO
A telescope array functions by coordinating signals from a collection of antennas to treat them as one much larger antenna. The distance between the antennas is crucial: changing the distance in between the individual antennas to trade off between field-of-view and angular resolution. By moving the antenna locations, the entire array can zoom in on a particular patch of sky, or zoom out to get a bigger picture view. Being able to move the antennas is an essential part of making an array a flexible, functional telescope, but how does the European Southern Observatory (ESO) transport these enormous, fragile pieces of equipment?
Very, very carefully using a pair of massive transporters: Otto and Lore.
Otto and Lore each sport a pair of 700 horsepower diesel engines, using that 1400 horsepower to shuffle the radio antennas up a steep, winding road to the high-altitude Chajnantor Plateau in Chile's Atacama desert. Located at 5,000 meters elevation, the air is so thin that Otto and Lore's drivers sometimes need supplemental oxygen during transportation. Once on-location, the trucks can be controlled by remote to enable the operators a clear view when positioning the antennas to their new locations. That clear view is essential, as each antenna is placed with millimeter accuracy!
Otto carrying an antenna from base camp up to the Chajnantor Plateau. Screenshot from ESOCast 56, credit ESO
The powerful trucks are custom-designed for ESO by the German manufacturer, Scheuerle Fahrzeugfabrik. The company has a long history of building relentless beasts for astronomical loads, also constructing the crawler used to shift the Antares rocket. Each transporter sports 14 wheels, mounted in pairs, that are individually controlled. Once the 7-meter or 12-meter diameter dishes are lifted onto the crawler, they are locked down to keep them safe just in case one of Chile's frequent earthquakes strikes during transport.
A puny human engineer is dwarfed by Lore's massive paired wheels. Screenshot from ESOCast 56, credit ESO
Learn more about the transporters, and the tricky process of resizing an array, in this ESOcast video:
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