He's at it again.

The U.S. tightrope artist who crossed Niagara Falls last year will try to do the same at the Grand Canyon -- but this time much further up and without a safety harness.

Nik Wallenda will attempt his highest ever wire walk on June 23, the Discovery Channel, which will broadcast the event live, said Monday.

The 34-year-old's stunt will take him 1,500 feet (457 meters) above the Little Colorado River -- that's higher up than the top of New York's Empire State Building, Discovery said in a statement.

On June 15, Wallenda, who hails from the Flying Wallendas family of tightrope walkers, crossed a wire suspended 200 feet up between the roaring Niagara Falls' US and Canadian banks cheered on by a rapturous audience.

But at the insistence of broadcaster ABC, which televised that event with a five second delay, he was attached to a harness that would have allowed him to climb back onto the high wire if he slipped and fell.

There will be no such safeguards this time around.

"The stakes don't get much higher than this," Discovery quoted Wallenda as saying of his Grand Canyon effort.

"The only thing that stands between me and the bottom of the canyon is a two-inch (5 centimeter) thick wire. I'm looking forward to showing the audience a view of the canyon they've never seen before."

Wallenda said the stunt would fulfill a lifelong dream and give him the chance to honor his great-grandfather, Karl Wallenda, who fell to his death while attempting to walk between two tall buildings in Puerto Rico in 1978.

The Grand Canyon is one of the most-visited tourist destinations in the United States.