Construction of the world's largest telescope, the European Extremely Large Telescope (E-ELT), will finally push through with the approval of the funding for the project, according to the European Southern Observatory (ESO.

A joint collaboration between 15 countries, the telescope which will be built in Chile, will be the world's largest ground-based optical telescope. ESO officials said preparatory work will soon begin at the planned site of the E-ELT at the Cerro Armazones mountain in the central part of Chile's Atacama Desert.

The ESO chose the location because of the optimal weather conditions, such as clear skies and around 320 nights of the year, in the area.

The E-ELT's primary mirror will be a staggering 138 feet (42 meters) wide, bigger that the Keck Observatory in Hawaii which has a mirror that measures 33 feet (10 meters) wide, and the Subaru telescope, also in Hawaii, that has 27 feet (8.2 m) wide.

The approved 2012 budget includes funding for initial work on the E-ELT project, such as the development of access roads to the telescope site and early construction efforts on one of the telescope's five mirrors which are expected to begin in early 2012, ESO officials said in a statement.

"The E-ELT is starting to become reality," ESO Director General Tim de Zeeuw said. "However, with a project of this size it is expected that approval of the extra expenditure will take time. Council at the same time recognizes that preparatory work must start now in order for the project to be ready for a full start of construction in 2012."

The ESO governing body is expected to make a final approval decision for the entire E-ELT project in mid-2012, with the world's largest telescope finally operational early in the next decade, ESO officials said.

ESO already has three observatories in Chile, including the Paranal Observatory, which houses the Very Large Telescope, and the La Silla Observatory, which hosts the New Technology Telescope.