Shielding the Extremely Large Telescope from the Atacama Desert

by Kate Green

October 19, 2024

The Extremely Large Telescope (ELT), currently under construction in the Atacama Desert, is set to become the world's largest optical/near-infrared telescope. Once completed, it will have a segmented primary mirror 39 meters in diameter, allowing it to capture unprecedented levels of detail in the universe. The Atacama Desert, with its high altitude, clear skies, and extremely dry conditions, is an ideal location for such an advanced astronomical instrument.

The harsh environment of the desert poses challenges, such as temperature extremes, wind, and dust. To address this, the ELT's steel dome is being covered with specialized cladding, which includes insulating layers and sheets of aluminum. This protective covering will help regulate internal temperatures, minimize expansion and contraction of materials, and protect the delicate optics from external elements, such as wind, dust, and thermal variations.

Balancing structural durability with maintaining a stable internal environment for the telescope’s optics is critical, especially in extreme conditions like those in the Atacama Desert.

1. Thermal Regulation: The insulating layers in the cladding prevent rapid temperature fluctuations, which can affect both the steel structure and the telescope's optics. The aluminum sheets reflect sunlight and minimize heat absorption during the day, while insulation prevents heat from escaping too quickly at night. This ensures that the internal environment stays stable despite drastic temperature changes outside.

2. Vibration Damping: The cladding also helps dampen vibrations caused by wind, reducing their impact on the telescope’s sensitive instruments. Additionally, the steel dome is designed with materials and shapes that absorb or deflect these forces to minimize interference.

3. Environmental Sealing: The cladding, combined with precise engineering of joints and seals, protects against dust, sand, and moisture. Even in a dry environment, dust particles can be damaging to delicate optics over time. The sealing and layers will prevent these contaminants from infiltrating the dome.

4. Active Climate Control: In addition to the cladding, the team is using active climate control systems to manage temperature and humidity levels inside the dome. This ensures the telescope’s environment stays within strict operational limits.

5. Material Selection: The steel used for the dome is designed to withstand the environmental conditions while minimizing thermal expansion. This, combined with the cladding, ensures that structural integrity is maintained without causing stress to the telescope's components.

The ELT will play a critical role in advancing our understanding of the universe, contributing to research on exoplanets, black holes, and the formation of galaxies. Its capabilities will surpass those of any existing telescope, making it a key asset for astronomers worldwide.

Video Credit: European Southern Observatory (ESO)