A project to build a pioneering telescope in Chile got a $30-million US boost Thursday with donations from Microsoft chairman Bill Gates and former company executive Charles Simonyi.

Simonyi is donating $20 million and Gates $10 million to pay for three major mirrors that will be used in the Large Synoptic Survey Telescope, a nearly $400-million project designed to survey the entire sky every three nights — something never done before.

Astronomers anticipate surveying the heavens for 10 years, with observations starting in 2015.

"People can find out what's going on everywhere in the sky, and no one has ever done that before — not even come close," said Donald Sweeney, manager of the LSST Project, a partnership headquartered in Tucson and split among 23 universities, national laboratories and private entities.

The telescope is to be built on the 2,743-metre Cerro Pachon in northern Chile. It will take an image every 15 seconds nightly, and its camera — the world's largest and most powerful digital device — will read out the image in two seconds.

"There are lots of things that happen every night in the sky, and no one has been able to track them and detect them," Sweeney said.

With the telescope operating, he said, scientists will be able to quickly find Earth-threatening asteroids and exploding stars called supernovas and will be able to map out 100 billion galaxies.

'LSST is truly an internet telescope, which will put terabytes of data each night into the hands of anyone that wants to explore it.'—Bill Gates, Microsoft chairman

The two donations put the amount raised at $50 million.

Gates gave his donation directly, while the other gift came from the Charles Simonyi Fund for Arts and Sciences, Jacoby said.

Simonyi said through spokeswoman Lee Keller that he was attracted to the project through "its imaginative use of technology to create a new view of our universe."

Gates called the telescope imaginative in its technology and approach.

"LSST is truly an internet telescope, which will put terabytes of data each night into the hands of anyone that wants to explore it," Gates said.

Its camera will be able to produce what project spokeswoman Suzanne Jacoby called "a flip book of the sky."