Geneva ? Scientists switched on the world’s largest atom smasher Friday night for the first time since the $10 billion machine suffered a spectacular failure more than a year ago.

It took a year of repairs before beams of protons circulated late Friday in the Large Hadron Collider for the first time since it was heavily damaged by a simple electrical fault.

Circulation of the beams was a significant leap forward. The European Organization for Nuclear Research has taken the restart of the collider step by step to avoid further setbacks as it moves toward new scientific experiments — probably starting in January — regarding the makeup of matter and the universe.

Progress on restarting the machine, on the border between Switzerland and France, went faster than expected Friday evening and the first beam circulated in a clockwise direction around the machine about 10 p.m., said James Gillies, spokesman for the European Organization for Nuclear Research.

“Some of the scientists had gone home and had to be called back in,” Gillies told The Associated Press.

The exact time of the start of the Large Hadron Collider was difficult to predict because it was based on how long it took to perform steps along the way, and in the end it happened about nine hours earlier than expected, Gillies said.

This is an important milestone on the road toward scientific discoveries at the LHC, which are expected in 2010, he said.

About two hours later the scientists circulated another beam in the opposite direction, which was the initial goal in getting the machine going again and moving it toward collisions of protons, CERN said.