More than a decade after competing groups set out to raise money for gargantuan telescopes that could study planets around distant stars and tune into the birth of galaxies at the dawn of time, shovels and more sophisticated tools are now about to go to work on mountaintops in Hawaii and Chile in what is going to be the most expensive and ambitious spree of telescope-making in the history of astronomy.
If it all plays out as expected and budgeted, astronomers of the 2020s will be swimming in petabytes of data streaming from space and the ground.
On June 20, officials from the European Southern Observatory blew the top off a mountain in northern Chile called Armazones, breaking ground for what is planned to be the largest, most powerful optical telescope ever built. Known as the European Extremely Large Telescope, or E-ELT, it will have a segmented mirror 39 metres (about 128 feet) in diameter. The largest telescopes now operating are 10 metres in diameter.
The European Southern Observatory is a consortium of 14 European nations and Brazil, which has agreed to join but is still waiting for its Parliament to ratify the move. Brazil?s entrance would put the group more than 90 per cent of the way toward the $1.5 billion the telescope is projected to cost.
Two years ago, another group of astronomers blasted away the top of another mountain in Chile, Las Campanas, where they plan to build the Giant Magellan Telescope. That telescope will have at a set of seven eight-metre mirrors ganged together to make the equivalent of a mirror 25 metres (about 82 feet) in diameter. Three of those mirrors have been cast at the University of Arizona.
In Hawaii, there will be no blasting needed, just some grading with a bulldozer, on Mauna Kea, where yet another group of astronomers plans to build a telescope 30 metres (about 98 feet) in diameter ? the Thirty Meter Telescope ? on a plateau just below the nearly 14,000-foot summit. Mauna Kea, the highest peak in the Pacific, is already home to 12 telescopes, including the twin 10-metre telescopes at the Keck observatory and a pair of eight-metres, making it the busiest mountain in astronomy.
The view from these new telescopes, astronomers say, should be spectacular.
A telescope?s ability to gather light is determined by the area of its primary mirror. For a long time, the five-metre Hale reflector on Palomar Mountain, in San Diego County, was considered the practical earthly limit, but in the 1980s, astronomers devised ways to build bigger, thinner, mirrors that would not sag, leading to a bevy of eight-meter mirrors as well as the two 10-metre Kecks. The Magellan, the smallest of the new breed, however, will be six times as powerful as the Kecks in scooping up distant dim starlight; the others will be even more powerful.
And then there is the most expensive and high-flying ?big eye? of all, NASA?s James Webb Space Telescope. It is the successor to Hubble, but is almost three times its size, with a 6.5-metre-diameter mirror that will have to fold out like a flower in orbit.
The Webb telescope was built to study the first stars and galaxies that emerged in the hundred million years or so after the Big Bang, a missing period in cosmic history. It is designed to record infrared radiation rather than visible light because objects at that distance are flying away from us so fast, that their light has been ?redshifted? to longer wavelengths.
As it happens, infrared, or heat radiation, is an excellent way to study planets, which tend to emit relatively more heat than light compared to their stars. Astronomers have long hoped that spectroscopic observations of an exoplanet atmosphere might reveal the signatures of life, such as oxygen or chlorophyll.