A Japanese balloonist will abandon his attempt to cross the Pacific Ocean alone because of unfavorable winds, and he plans to land his craft in the ocean, an official said Friday.

Project spokesman Ren Kato said Fumio Niwa will bring his giant orange-and-blue balloon down Saturday after an airplane determines his exact location.Friday the balloon was floating 4.4 miles above the ocean 1,450 miles southeast of Tokyo.

A boat from the Maritime Safety Agency left Yokohama for the area Friday but was not likely to arrive until Sunday night, Kato said, so Niwa could end up bobbing in the sea in his tiny gondola for more than a day.

When he took off early Wednesday, Niwa hoped to travel 5,000 miles to San Diego in about four days and become the first person to cross the ocean alone in a balloon.

He planned to ride the jet stream - high-speed, high-altitude winds that generally blow west to east - but changed his mind when he discovered the jet stream would have pushed him north toward Alaska.

Niwa initially stayed at a low altitude and traveled south in an attempt to catch the southernmost edge of the jet stream. He then jettisoned most of his ballast and rose in altitude, but missed the high-speed winds, said Hiroaki Tanaka, another project spokesman.

"The loss of the ballast means he no longer is able to maneuver up and down to find a good wind," Tanaka said.