Scientists to search space for life with Extremely Large Telescope

A remote mountain top in Chile’s Atacama desert is home to a unique project – after years of preparations, construction has finally begun on the Extremely Large Telescope (ELT), the largest optical telescope in the world.The main lens has a diameter of 39 metres, and it will offer scientists an unparalleled glimpse of the heavens, enabling them to observe Earth-like planets, stars and galaxies more closely than ever before.It’s also hoped that it will offer new insight into the elusive subject of dark matter.  The telescope is being constructed on Cerro Armazones, a mountain 130 kilometres south of the city of Antofagasta in northern Chile.Two years ago the mountaintop was flattened to allow the telescope’s platform to be built on top of it, and at the end of last month, President Michelle Bachelet officially launched construction at a ground-breaking ceremony.If all goes to plan the telescope will become operational in 2024.The Chilean desert offers an ideal location for the telescope, a project led by the European Southern Observatory (ESO), a consortium of 15 European countries and Brazil.Thanks to the so-called Humboldt Current, its skies are almost permanently clear. Clouds remain either over the Pacific Ocean or on the Argentinian side of the Andes.Scientists can observe the stars around 90 per cent of nights in the clean, dry desert atmosphere. “The difference between current telescopes and the ELT is as big as the difference between Galileo’s eye and his telescope,” says Dutch astronomer Tim de Zeeuw, ESO director-general.The ELT’s main mirror will be around five times bigger than today’s most powerful telescope and it will be able to catch around 13 times as much light, enabling much sharper pictures to be taken. One of the project’s main goals is to explore exoplanets, planets that are outside of our solar system, for signs of life – the race is on to find the first habitable planet outside of Earth.One planet circling the dwarf star Trappist-1 and another circling the Proxima Centaura red dwarf star will be particularly interesting for scientists following recent discoveries which indicate they could potentially support life.De Zeeuw believes that it is entirely possible that a habitable planet will be found in the next decade.“It’s funny that this telescope in one of the most uninhabited parts of the world, the Atacama desert, can help us find signs of life elsewhere,” he says.ESO, which has its headquarters in the German city of Munich, already has three observation posts in the Chilean desert.Its current flagship Very Large Telescope (VLT) is the world’s most advanced optical instrument, allowing scientists to see details 25 times more sharply than with individual telescopes.The ELT will be kitted out with five enormous mirrors. The biggest, with a diameter of 39 metres, will be made up of 800 hexagonal pieces each with a diameter of 1.4 metres – all must fit perfectly together.It took years for De Zeeuw to convince politicians to stump up the 1.1 billion euros (1.24 billion dollars) needed to fund the project.The ELT project came into being at the end of the 1990s, when scientists at the ESO were wondering whether it was possible to build a telescope 100 metres in diameter.That would have cost 3 to 4 billion euros and so they made do with a diameter of 39 metres. The ELT is not the only project currently underway aimed at better exploring the heavens.In the United States, there are two initiatives trying to obtain public funding to build a giant telescope.One is a 30-metre telescope planned by the California Institute of Technology and which it wants to build in Hawaii.The other is the Carnegie Institution for Science’s Giant Magellan Telescope, with a mirror measuring 24.5 metres across, which is also due to be built in northern Chile.De Zeeuw believes it can only benefit science to have more than one giant telescope in action at the same time.“There’s a friendly rivalry,” he says. “You work faster and better when you have to compete with someone. That’s to everyone’s advantage.” — DPA