Large LSST telescope starts to take shape in the north of Chile

Its construction is the most advanced among the South American country’s three new mega observatories and it is expected to start operating in 2020.

Towering on the Cerro Pachón ridge, close to the well-known Cerro Tololo telescope, a giant bursts among the hills surrounding the Elqui valley, about 500 kilometers from Santiago. This is the Large Synoptic Survey Telescope (LSST), or large mapping telescope, being built in Chile through an international collaboration led by the United States.

The main building is almost finished while construction of the dome will be complete in a few weeks. In the middle of next month the telescope’s vacuum tank will arrive, an instrument that is used to coat the mirrors with a thin layer of aluminum, making the surface reflective.

It will have to be transported to the LSST site at night to minimize its impact on the roads, which will take about five days. With its nine-meter width, it is an engineering challenge. “The road to the hill will have to be widened a little to be able to take it up,” says Leonor Opazo, responsible for Education and Diffusion at Cerro Tololo.

Once installed, the next step will be to bring the mounts for the mirrors from Spain, where they are already ready. This will take place in the first half of next year, he says. Then the mirrors will be delivered from Arizona, United States.

If installation goes at the planned pace, the 8.2-meter mirror will be able to make its first observations around 2020.

When it is fully operational, the telescope will be able to map the complete sky every four days with a 3.2 gigapixel digital camera, providing an unprecedented volume of information which will be available on the internet at almost real time.

The other giant already in full construction is the European Southern Observatory’s (ESO) Extra Large Telescope or Extremely Large Telescope (ELT). Once complete, it will the world’s largest telescope with a 39-meter segmented mirror.

The structure began to be built last year atop Cerro Armazones, south of Antofagasta and next to Cerro Paranal.

"The excavation for the foundations is 80% complete," says Jimmy Arancibia, an engineer in charge of construction. He estimates this will be finished by the end of this year.

Throughout 2019 the concrete wall will be built, reaching a height of 12 meters, and then the metal dome will be installed; an Italian company is in charge of its design and construction. That will take approximately another year.

While civil works advance in Chile, the 798 hexagonal segments that will make up the main mirror are being manufactured in the installations of the company Schott in Mainz, Germany. Each piece is 1.4 meters wide and 5 centimeters thick. It will be delivered at the beginning of the next decade.

The third colossus is the Giant Magellan Telescope (GMTO) that is being built by an international consortium, led by the Carnegie Institution for Science, on Cerro Las Campanas on the border of Atacama and Coquimbo regions. Last August, excavation of the rock began for the foundations and the concrete structure, which should be complete at the beginning of next year.

The instrument is also being developed. “As a whole, the project is 40-45% complete; five of its seven 8.5-meter mirrors are in different stages of manufacture, the designs of the frame that will support the mirrors is very advanced and by the end of this year the company that will build it will be selected,” says astronomer Miguel Roth, GMTO representative in Chile.

It is estimated that this telescope could make its first observations between 2023 and 2024. And if it finishes before the ELT, it will temporarily hold the title of the world’s largest telescope.

Would you like to know more about Chile’s contribution to world astronomy? Read this article.

Source: El Mercurio