Herb Lehr hasn't been to Trinity Site (search) since the day a mushroom cloud filled the early morning sky in the New Mexico desert.

Standing 12 miles from the blast, he looked toward the Oscura Mountains and watched as scientists detonated the first atomic bomb 60 years ago Saturday, ushering in the nuclear age.

"All of a sudden this very bright light came out and where I was, it was intense enough that the whole mountain range itself was completely whited out," he said. "I could see the ball and fire rising up. It was sort of awe-inspiring."

This Saturday, Lehr will guide a tour bus from the National Atomic Museum (search) in Albuquerque to the Trinity Site, on what is now the Army's restricted White Sands Missile Range.

More than 5,000 people visited the site for the 50th anniversary, and officials said they are prepared for an increase for the 60th. But just like the 50th anniversary, no special events or speeches are planned.

For more than a year, Lehr was part of the top-secret Manhattan Project (search) in Los Alamos that developed two atomic bombs that essentially stunned Japan into surrender and ended World War II. Tens of thousands of people died when the bombs were dropped on Hiroshima and Nagasaki in August 1945.

Lehr said he never fully understood the impact the bombs would have. Nevertheless, he said he would do it again.

"In a lot of respects I felt as if I had done something worthwhile," said Lehr, 83. "I am in no way ashamed of what I had done in any way, shape, matter or form. I did what I was told to do. I did it to the best of my ability."

At Trinity Site, visitors can walk on Ground Zero, where the bomb was detonated from a 100-foot steel tower that was vaporized by the blast.

Ground Zero, now a gentle depression in the desert, is marked by a lava obelisk with a simple inscription: "Trinity Site, Where the World's First Nuclear Device Was Exploded on July 16, 1945."

Along the fence line hangs a pictorial history of what happened there.

Not everyone is happy with that history.

Anti-war groups planned to protest the anniversary at the National Atomic Museum on Friday. Bob Anderson of Stop the War Machine said celebrating the development of weapons sheds blood on the nation's morality.

"It glosses over all the political and human tragedies that occurred as a result of the Trinity blast and the use of weapons on Japan," Anderson said. "We just think that's probably a more important message than trying to glorify the weapons."

Lehr said it is unfortunate the bombs were used for war. But the development of a nuclear bomb was a race among scientists around the world that couldn't be stopped, he said.

"I'm just interested in going and seeing it and maybe getting some memories back," said Lehr, who now lives in Mesa, Ariz. "Los Alamos was a whole interesting experience. It was something unique. I worked very hard down there."