The rare night test of the Alliant Techsystems rocket motor, nearly identical in design to those used to help lift the space shuttle into orbit, went off with barely a hitch, although for a time the test was threatened by unfavorable wind conditions.

When the motor was finally lit, it burned for 124 seconds and generated 15.4 million horsepower before a crowd of thousands.

Inside ATK's control center in an underground bunker less than a quarter of a mile away from the roaring engine, several dozen engineers and command personnel hunkered down and watched on video monitors as the motor exhausted its available supply of fuel.

"During the test you can feel the ground shake and hear the glass panels in this building rumble," ATK's Director of Test Services Kevin Rees said during a dry run of the rocket test days earlier. "It is a whole different perspective than what you get watching from over a mile away."

For ATK and the National Aeronautics and Space Administration, the firing was part of a continuing quality-assurance program to test the components used on the shuttle, said Jody Singer, manager of reusable solid rocket motors at NASA's Space Shuttle Propulsion Office. But the test also provided other useful information because NASA plans to use a similarly designed ATK solid-fuel rocket motor as the first stage of its next-generation Ares launch vehicle.

Unlike the space shuttle, which uses two booster motors, the Ares will use only one. And the Ares first stage will be a five-segment motor rather than the four-segment engines used on the shuttle.

That has raised the question of whether a single motor will generate torque during liftoff and result in the Ares vehicle rolling as it hurtles upward. When two booster motors are used together any torque produced by one engine would be canceled out by the other, explained Ronald D. Dittemore, president of ATK Launch Systems Group.

"We've never had to worry about our motors producing torque before," said Dittemore. "This test should let us know how much torque, if any, we'll have to deal with when Ares is launched."

Dittemore said NASA requested a night test firing - last done by ATK in 1992 - to test the positioning of its camera system that monitors space shuttle launches. NASA wanted to ensure it could capture all the details necessary to evaluate launches made at night when the glare from the rocket motor is most intense.

Just more than an hour before the test was scheduled to begin, arming team leader Ed Griggs in the command bunker was handed the firing control key that would be used in the final ignition sequence. Griggs and his team immediately left for the test bay, taking the firing control key with them.

At the test bay, Griggs and his team carefully checked an electric cable that eventually would transmit the electric signal that would ignite the motor. Only after determining there was no power or stray electricity running through the cable did the team connect it to the motor ignitor.

The team moved to a nearby instrument room and performed a similar test on an electric cable that originated in the command bunker. After determining that cable also was free of electricity, Griggs' team connected the two cables together by plugging a safety jumper into a panel in the instrument room. The connection transferred control of the rocket motor and its igniter back to the command bunker.

"Everything is checked and double checked," Griggs said. "We want to make sure there are no mistakes. Still, you're always nervous and wondering if maybe you've made a mistake. I'm never able to relax until after the test is over."

Their jobs in the test bay complete, Grigg's team, along with instrument room personnel, evacuated to the command bunker. There was less than five minutes before ignition.

Back inside the control center, and still holding the firing key, Griggs waited for the test range's safety officer at a vantage point several miles away to ring down over a secure line and give him the all clear.

Only then did he turn over the key to Howard Healey, ATK's test control coordinator. With the countdown continuing, Healey waited until there were 70 seconds to go before inserting the key into the firing console and giving it a quick turn to "commit the motor."

"The computer is looking and waiting for that key to turn. It takes over from there," Healey said, indicating command personnel still had the option of hitting an abort or hold button should an unexpected problem arise.

None did.

Although the ATK rocket motor burned for only a brief time, it will be months before the test data will be completely analyzed by NASA and ATK engineers, Rees said. ATK's team also will completely tear apart the motor and physically inspect all the components.

"The test firing is just the beginning of the work," he said.

steve@sltrib.com