Despite the spectacular explosion in the first test of its Titan IV upgrade motor Monday, Hercules' Magna operation intends to pursue building the rocket motor, according to a memorandum distributed to employees.

The 112-foot motor was destroyed in a blast at Edwards Air Force Base, Calif., where it was being test-fired on the ground. There were no injuries, and a cloud of rocket exhaust smoke climbed to a high altitude and dispersed rapidly, the Air Force said.A $525 million initial contract to build the upgrade motors has been a cornerstone of Hercules' efforts. The motors are cast at the Bacchus West Works in Magna. But the program has been plagued by delays and accidents.

An Air Force panel is being assembled to determine the cause of Monday's detonation.

"It is too early to assess the actual impact on the Titan program and manufacturing schedule, but the information we have today tells us that this program is needed and will continue," Ron G. Peterson, vice president and general manager of Hercules' Bacchus Works, wrote in the memo.

"While this is a major setback for all of us, it is still vital that we aggressively pursue critical Titan program issues."

He said he asked W.G. Wilson, vice president of business development for Hercules Aerospace Co., to head the Hercules team that is supporting the investigation of the explosion.

The Titan IV motor that Hercules is developing is an upgrade designed to give the rocket enough thrust to lift heavier military payloads.

But the Titan IV can fly without the upgrades.

In fact, "we have flown four Titan IVs, out of 41," said Terry Monrad, public relations administrator for Martin Marietta Astronautics Group, the Titan IV's prime contractor, based in Denver.

Under the Air Force's contract with Martin Marietta, 41 Titan IVs are to be produced. With the four that were launched earlier, "there are 37 left to fly over the next several years, probably throughout this decade," Monrad said.

"The Titan IV currently is flying with a solid rocket motor that is built by United Technologies Corp., specifically, (its) Chemical Systems Division in San Jose," he said. The explosion of the Hercules motor "has little impact right now" on the program.

In a press release from Edwards Air Force Base, Col. Frank Stirling, the Titan IV program director, stressed that the developmental solid rocket motor produced by Hercules does not affect any Titan IV launches planned for the near future. The upgrades that Hercules is developing are intended for use starting around 1993.

"The current solid rocket motor production line will continue to provide motors for use until the motor is qualified," Sterling said.

The upgrade motors are the "strap-on" rockets on either side of the main rockets. The upgrades would provide 25 percent greater lift, because they are made of graphite composite instead of the earlier steel casings.

However, the Titan IV can fly with the earlier solid rocket motors, "unless there is a payload that requires this additional lift," Monrad said.

He stressed that it wasn't an operational-type Titan IV that exploded. "It was a prototype motor bolted down into a test stand, and that's what exploded. The Titan IVs are going to continue to fly."

Hercules has a contract to produce 15 sets of solid rocket motor upgrades, 30 altogether. "That contract has not been changed as a result of the test yesterday," Monrad said Tuesday.

He is not certain about delays in the program before now, but said, "I believe they were going to attempt the first test firing before this year."

If the test had succeeded, "the timetable would have been four more test firings this year, followed by the first flight in '93. Obviously this didn't have a good impact and it's going to have some effect."

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(Additional information)

Titan IV was A.F.'s answer to space shuttle

In the wake of the space shuttle Challenger disaster, the Titan IV rocket was the Air Force's answer to the shuttle. It is "designed to ensure U.S. access to space for critical national security payloads," according to the Titan IV project's prime contractor, Martin Marietta Astronautics Group, based in Denver.

It is an improvement over the shuttle in terms of payload and orbit level, capable of lifting 39,000 pounds into low-Earth orbit or 10,000 pounds into geosynchronous orbit at 22,300 miles above the planet. A geosynchronous orbit keep a satellite stationary over a particular part of the equator.

In 1985, Martin Marietta was chosen to build and launch 10 of the new rockets. In August 1986, the program was expanded so that there would be 23 of them; in November 1989, the company won a contract for 18 more, bringing the total to 41.

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GRAPHIC

Titan IV Solid Rocket Motor Upgrade

Length: 112.4 feet

Diameter: 10.5 feet

The upgrade solid rocket motors (positioned on either side of main engine) are manufactured by Hercules.

Designed to increase the lifting capability of the Titan IV by 25%.

Test firing

Where: Edwards Air Force Base, Calif.

When: Monday, April 1, 1991

Result: Motors exploded