A rocket carrying a Japanese broadcasting satellite was blown up by remote control after apparent engine trouble sent the $100 million mass of metal tumbling toward Earth.

The Air Force sent self-destruct commands six minutes after liftoff Thursday. The two-engine Centaur guidance system - with the satellite still attached - was detonated over the Atlantic Ocean about 240 miles from the launch site.Rocket builder General Dynamics Corp. called the incident "a great disappointment."

"There is a risk in every venture and, unfortunately, these risks sometimes result in failure," said Allen Lovelace, chairman of General Dynamics Commercial Launch Services.

"It's clearly a disappointing event for us but also for our customer," Lovelace said.

The explosion was too far away to be seen from shore.

It was a devastating blow to General Dynamics, which endured heavy financial losses in its rocket program last year. It also was bitter news for GE Astro Space Division, which built the satellite for the Japan Broadcasting Corp.

The Atlas-Centaur flight began smoothly enough.

The 14-story rocket blasted into an overcast sky from Cape Canaveral Air Force Station at 7:30 p.m. The launch was delayed 16 minutes because of high winds.

Lovelace said the problem occurred just after the 30-foot Centaur upper stage separated from the Atlas booster five minutes into the flight as planned. Early evidence indicates one of the Centaur's two liquid hydrogen and oxygen engines ignited, causing the Centaur to lose speed and veer out of control, he said.

Japan's national NHK television network ordered the satellite to replace one that was destroyed in the explosion of a European Ariane rocket in February 1990. The satellite lost Thursday, like the one demolished last year, was insured.

"It certainly was a service NHK was counting on," said Lawrence Greenwood, an official for GE Astro. "We share in their disappointment because we very much wanted to have that in operation in the next 30 days."

Greenwood said he had not talked to Japan Broadcasting officials as of late Thursday night "to see what their contingency plans might be in order to provide their customers with service."