Thiokol Corp. officials say the firing of an obsolete space shuttle booster rocket, to recover the steel case and test a new nozzle material, went off without a hitch.

"The initial data from the two-minute ignition was excellent. All of our measurements appear to be normal. All of the test criteria were met, according to the engineering team," spokesman Steve Lawson said.The firing at the Box Elder County test facility Tuesday was deemed a success, "based on a quick look at the computer data and a walk around" the 126-foot-long rocket motor after the burn of 1.1 million pounds of solid-fuel propellant, Lawson said.

However, he added, it will take more than one month to take apart the four sections and completely evaluate all the information.

The test was the seventh of 11 scheduled in the so-called technical evaluation motor series, but it was the first of three using rayon material from North American Rayon Corp. in construction of the exhaust nozzle. The material has yet to be approved for manned space flights.

In January 1986, all Thiokol existing motors became "excess" after the Challenger explosion, Lawson said. The current shuttle motor is a redesigned version of those motors used for testing a half-dozen "modifications," such as new nozzle material.

But since the steel case, nozzle and igniter hardware are worth more than $4 million and can be reused, the test allows Thiokol to recover the materials and reuse the hardware.

In addition, the firings provide data on storage and aging effects on the rocket's insulation materials, liner, propellant, and on rocket-joint heaters.

The eighth test in the series and the second involving the rayon nozzle tentatively is scheduled for March 28.