Have you ever wondered what the inside of ESO’s Very Large Telescope looks like? Well, wonder no more, as this picture of the week shows the internal structure of one of the VLT’s Unit Telescopes (UTs) — specifically UT3, otherwise known as Melipal.
Seen here, lit by moonlight, is the main steel structure of the Unit Telescope’s optical assembly. The main mirror, measuring 8.2 metres in diameter and weighing in at more than 23 tonnes, requires a sturdy frame to allow it to rotate within the structure, while maintaining high optical resolution. This movable steel frame itself weighs over 430 tonnes, about the same as a fully loaded jumbo jet!
The structure, optics and electronics are housed within a further steel enclosure, which provides protection from the harsh Atacama environment.
Melipal is named after the Mapuche term for the constellation of the Southern Cross. All four of the VLT’s Unit Telescopes have Mapuche names relating to well-known and prominent astronomical features: Antu, Kueyen, Melipal, and Yepun, or the Sun, Moon, Southern Cross, and Venus respectively. The Mapuche people are indigenous to the Southern Central region of Chile, and have a long history of astronomy.