The explosion is blamed on the rocket's steering system

CAPE CANAVERAL, Florida (CNN) -- The fiery nighttime explosion of a Delta III rocket Wednesday was caused by a steering system failure, Boeing Co.'s chief investigator said Friday.

The inaugural flight of the 12-story rocket ended in disaster about a minute after liftoff when the control system in three solid propellant boosters ran out of hydraulic fluid.

"It's like on your car when you don't have power steering," said Clarence Quan, Boeing's lead engineer investigating the $225 million disaster.

Out of control, the rocket swung 35 degrees to the right, broke up and finally exploded. Roger Devivo, a safety officer at Cape Canaveral, said the rocket exploded with a force equal to 500 pounds of TNT.

"Clearly, we missed something," said Quan. Both mechanical and electronic components could be responsible for the rocket wobbling out of control, he said.

Boeing engineers are trying to determine if the rocket's steering system overreacted to unexpected movements or if computer software or hardware problems were blame.

The rocket was carrying the Galaxy 10 communications satellite for PanAmSat Corp. The satellite crashed in a fireball into the Atlantic Ocean about 15 miles offshore.

As a precaution, Boeing will delay the launch of its less- powerful Delta II rocket, which was scheduled to lift off September 1 from Vandenberg Air Force Base in California.

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The Delta II will place five satellites into orbit for Motorola's Iridium mobile phone network.

Both Delta rockets use the same guidance system but different software, and Delta III can haul twice the cargo of Delta II.

It was designed by Boeing to compete with rivals European Ariane and Lockheed Martin CorpAtlas for lucrative commercial launch contracts.

The Associated Press and Reuters contributed to this report.