An astronomy organization consisting of 15 European countries, as well as Chile and Brazil, has signed a €400 million ($450 million) contract to move forward with the construction of a large dome and structure to support a massive optical telescope that will have a 39-meter wide main mirror.

The European Southern Observatory said the contract keeps it on track to begin observing the night sky with its European Extremely Large Telescope (EELT) as early as 2024. The telescope will operate from a 3,000-meter mountaintop site in northern Chile. The agency said that this is the most expensive contract ever awarded by ESO and the largest contract ever in ground-based astronomy. However, it represents only a fraction of the telescope's overall multi-billion dollar cost.

The largest optical telescopes in the world today are only about 10 meters in diameter. The European instrument is part of a new generation of much larger telescopes being built to extend the ability of astronomers to peer back further into the history of the universe, when the first stars and galaxies formed. The newly possible observations may also elucidate the nature of dark matter and dark energy and could potentially sniff out the signatures of life in the atmospheres of exoplanets. As such, there is a tremendous race to reach first light and begin using these large instruments. Nobel Prizes await.

A consortium of US and international institutions have begun construction of the 24.5-meter Giant Magellan Telescope in Chile, which may begin operating as early as 2023. Another group of largely US-based institutions is seeking to build the Thirty Meter Telescope in Hawaii, but native Hawaiians are protesting the facility on top of Mauna Kea, saying it desecrates sacred ground. The protests have held up construction.

There have not been similar concerns raised in Chile over the EELT or Giant Magellan Telescope, so for both groups, the race to the finish line is largely about raising funds in excess of $1 billion and ensuring that their complicated instruments function as intended—no small matter when building the world's mightiest telescopes.