What of the Telescopes in Chile?

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The ESO Very Large Telescope atop Cerro Paranal in the Atacama desert region of Northern Chile (European Southern Observatory).

There are many international telescopes in Chile making use of the low humidity conditions in the Chilean mountains and high-altitude deserts. But as one of the most seismically active countries in the world, many of these observatories are built on shaky ground.

In the wake of the deadly 8.8 magnitude Chilean earthquake that hit the South American nation on Saturday, causing a tsunami to rush across the Pacific, how are these sensitive observatories protected from damage? The quake was reported as far away as 1,800 km from the epicenter, so there’s little doubt that the Chile-based observatories would have felt it.

Among the international astronomical projects is the Gemini Observatory (South) at 2,700 meters (8,858 ft) elevation on Cerro Pachón (a mountain in the Chilean Andes) and the European Southern Observatory’s (ESO) Very Large Telescope (VLT) on Cerro Paranal, a 2,635 meter (8,645 ft) high mountain in the Atacama desert.

Gemini South is approximately 800 km (500 miles) north of the epicenter and the VLT is approximately 1,370 km (850 miles) north of the epicenter. Undoubtedly both locations would have experienced some seismic activity.

But this isn’t the first major earthquake that would have shaken these observatories. According Anil Ananthaswamy, author of the forthcoming Edge of Physics (to be published in March), observatories such as the VLT have some novel anti-earthquake safety measures in place:

The primary mirror 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.

Also, in Helen Gavaghan’s 2006 article for Science, People and Politics, she describes what life is like working on Cerro Paranal, a location perfect for astronomy, but not-so-perfect as the foundations for a telescope:

Patat has made perhaps 10 trips to Paranal. He is an experimentalist and one of the ESO staff. Most of the time that he is in Chile he is supporting the work of other astronomers, sometimes doing his own work and other times commissioning an instrument. Though he can almost guarantee clear nights — the sky is clear for 330 of 365 nights — he cannot guarantee the site will be free from Earthquakes, and there is a routine for closing down the telescope if quakes reach more that 6 on the Richter scale. Patat has not experienced one of these, but he has worked though lesser quakes. I asked him what that was like. Safe, he said. Both residence and observatory are designed and built to high standards, something reflected in a special acclamation by the jury awarding the Dedalo Minosse prizes in 2003-2004.

According to the Universe Today, Gemini South’s servers are back online, but other observatories in the area have experienced power cuts, taking their servers offline.

So it seems unlikely these observatories will have suffered any serious damage in this most recent earthquake (there are currently no reports of such), but I wish the same can be said for the populated region surrounding the epicenter in central Chile. There has been severe damage to buildings and infrastructure and over 200 people have been reported dead (at time of press).

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