SANTIAGO — The world's largest network of radio telescopes is ready to begin the first phase of operations in northern Chile's Atacama Desert, an observatory announced Thursday.

The ALMA complex, under construction for over a decade, received on Wednesday the 16th of 66 total antennas, enough to "begin its first science observations, and is therefore an important milestone for the project," said the European Southern Observatory, which operates Chile's Paranal observatory.

Antenna 16, measuring 12 meters (40 feet) in diameter and weighing nearly 100 tons, is the first European contribution to the Atacama Large Millimeter/submillimeter Array project as part of a collaboration with United States and Japan.

It was delivered at the Chajnantor plateau, 5,000 meters (16,400 feet) above sea level, where it joined antennas from the other international ALMA partners. The European AEM Consortium, under contract from ESO, manufactured the antenna.

"ALMA's Early Science observations are planned to begin later this year. Although ALMA will still be under construction, the 16-antenna array that will be available already outmatches all other telescopes of this kind," ESO said in a statement.

Astronomers from around the world have submitted nearly a thousand proposals for the first scientific observations -- about nine times the number of observations expected to be performed during the early phase, it said.

The first antenna was installed in September 2009. Construction of the radio telescopes is expected to end in 2013 with 66 state-of-the-art antennas in place working together as one powerful telescope to study the origin of planets, stars, galaxies and the universe.

When it reaches full operational capacity, ALMA will have a resolution 10 times greater than the Hubble Space Telescope.

The program has an estimated budget of $600 million.