For decades, the Atacama Desert has beguiled astronomers and structural engineers alike. With its soaring mountain peaks and clear night skies, the Chilean desert is one of the top places in the world for studying the universe. There are over 300 clear nights per year in the Atacama, making it unmatched for stargazing. Unfortunately, Chile also rides the seismically hyperactive circum-Pacific belt, aka the “Ring of Fire,” where 81 percent of the world’s earthquakes occur, including the M9.5 Chilean Earthquake of 1960, the largest earthquake of the century.
Building an observatory is a challenge even on the most stable footing. The instrumentation and systems that power modern telescopes have become so complicated and intricate that they must be constantly monitored and protected from vibration and any other interference to their movement and stability. This makes construction of large telescopes unfeasible in seismic regions.
All of that is changing with the construction of the massive Giant Magellan Telescope in Las Campanas. With over $500 million raised to construct a revolutionary 22-story telescope at 8,200 feet, the GMTO Corporation has set out to prove that it is possible to build a cutting-edge telescope in a region prone to earthquakes.
Even a minor tremor could cause substantial damage to the Giant Magellan Telescope and its seven massive mirrors, rendering it inoperative for months and incurring significant repair costs. The moving parts and mirrors that allow the telescope to work must be able to withstand every shake and tremor from an earthquake. The challenge isn’t so much preventing the 13.6-million-pound machine from collapsing in an earthquake as limiting the movements and forces transferred into the telescope by a seismic event.
To mitigate the effects of earthquakes and vibrations, the engineers who designed the observatory devised an innovative seismic isolation system to protect their telescope. The seismic isolation system is designed to allow the telescope to return to full functionality within hours to weeks after a seismic event and has a probability of failure of 0.5 percent over the expected 50-year life of the observatory. This level of defense against earthquakes is unprecedented for a large telescope.
The GMT’s seismic isolation system functions with two separate lines of defense—the isolation system itself that supports and protects the telescope’s instruments from ground motion and the pier recentering system that will return the telescope to its upright and operating position in the event of a major earthquake that causes it to shift on its base. The pier recentering system is a hydraulic system that can return the massive telescope to within a fraction of an inch of its position before an earthquake.
This system is a huge breakthrough for the astronomical and engineering communities alike, making it possible to explore new horizons in space from one of the best locations on the planet. An independent review and test of the system received top marks, which could pave the way for even more expansion and construction of modern observatories. Space is our final frontier, and engineering marvels like the Giant Magellan Telescope will fuel the next century of exploration and discovery.