Chile: Astronomy in a seismic country

 

Chile is a country that, because of its suitable weather conditions, safety and governmental stability, hosts a large number of important scientific observatories. Some of them have a long time operating such as La Silla (ESO), CTIO (AURA) or the Paranal Observatory (VLT). Others are a little more recent like the Gemini South Observatory or SOAR both belonging to NOAO, and some are still yet to come, for example the ALMA and APEX project, consisting in very powerful antennas for the analysis of infrared wavelengths of  light, the LSST, and the possible construction of the E-ELT that will become the largest telescope in the world.

However, there was a fact that seemed to be forgotten about this country and the last 8.8 magnitude earthquake that affected the southern part of Chile reminded us what was it, Chile is a really seismic country. Hence, how are these sensitive scientific observatories protected from damage?

Observatorio La SillaWell, of course, this characteristic of Chile was taken into account when the telescopes were designed. Anil Ananthaswamy explains it better in his book Edge of Physics: “The primary mirror (VLT, Paranal Observatory) is 18 centimeters thick. Because of its weight, the mirror’s precise shape can warp when it is tilted, so 150 actuators, upon which the mirror rests, continually push and pull at least once a minute to ensure that the optimal curvature is maintained. More impressive than the actuators are the clamps around the edges of the mirror, which can, at a moment’s notice, lift the entire mirror, all 23 tons of it, off the actuators and secure it to the telescope’s support structure in case of an earthquake (moderate quakes, of less than 7.75 Richter, are not uncommon here, thanks to the ongoing collision of the Nazca and South American plates). The entire telescope is designed to swing during an earthquake, and securing the primary mirror prevents it from rattling against the metal tubes that surround it.”

Now, regarding the earthquake of February 27, this affected 5 regions of the country from Santiago to the south, so observatories, both tourists and scientists, did not suffer any damage. Robert Naeye, chief editor of Sky and Telescope magazine wrote the following: “Despite the tragic earthquake, Chile remains a wonderful place for astro-tourism, especially because the regions of greatest interest to amateur astronomers are in northern Chile, which suffered minimal or no damage from the quake.”

Daniel Luna, Product Manager.

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