SAN ANTONIO, Texas USA — A rocket waits on the launch pad and all systems are go as mission control completes its checklist. "Is the range clear?" launch officer Brianna Campbell asks. "The range is clear," range officer James Espinosa-Mazuca replies.

Campbell inserts a yellow plastic safety key into her launch controller and then places her thumb on the firing button.

VIDEO: See Clark JROTC rocketry team in action.

"Launch in five ... four ... three ... two ... one," she says before pressing the button down.

In a split second, the rocket engine ignites and sends the missile skyward with a loud whoosh and a trail of white smoke. Fifty feet and a couple of seconds later, the engine stops, the rocket slows and its nose cone pops off. A red streamer comes out, easing the rocket's return to Earth.

It lands about 10 feet from an orange cone on a soccer field behind Clark High School.

"Not bad," Espinosa-Mazuca, a 17-year-old junior at Clark, says to Campbell, a 15-year-old freshman. "That's a lot closer than the last one."

The model rocket launch is a practice flight in advance of the Fiesta Blast Model Rocketry Meet, one of the new events on this year's Fiesta San Antonio calendar. Espinosa-Mazuca and Campbell are members of the rocketry team and the Air Force JROTC program at Clark.

More than a dozen rocketry teams are expected at the competition at the school on Saturday, including some from Austin and Houston. The launches will start promptly at 9 a.m. and are expected to end by noon. The event is free for spectators and $50 for team entries.

The competition will test each team's ability to precision-land their rockets closest to targets placed at 30, 70 and 100 yards from the launch pad.

Espinosa-Mazuca, a cadet first lieutenant and commander of Clark's rocketry team, has been involved with the group for three years.

"It's been the best three years of my life in ROTC," he says. "This has given me an escape out of class and it's helped me to keep good grades. It's made me want to be involved."

The Clark team has a display case full of trophies won at rocketry meets. In competition and in practice, the team's demeanor, attitude and appearance are studies in military precision. Unlike most other rocket teams, which usually compete in blue jeans and T-shirts, the 15 members of Clark's crew dress in all-black "battle dress uniforms" and baseball caps.

"Sometimes, we'll go to a meet and everyone will say, 'Hey, the SWAT team is here,'" says Bob Teddlie, a retired Air Force master sergeant and JROTC instructor at Clark.

Model rockets range in size from just a couple of inches high to multistage monsters that are 3 feet long or more. All of them use disposable "engines." The tubes of heavyweight cardboard, about the size of a short, fat cigar, are filled with varying amounts of solid, nontoxic propellant, depending on the size of the rocket to be launched and the range desired. On the launch pad, igniters are shoved into the engines and then connected to electrical wires that lead to battery-powered controllers.

The biggest rocket in Clark's arsenal is a yard-long, black-and-silver monster that can reach an altitude of 1,000 feet. It was built nine years ago by students at Clark, who named it Thumper. Launched only on days with little or no wind, Thumper needs 500 feet of ground clearance from its launch pad in all directions to ensure safe recovery.

"It's the biggest rocket we're able to launch without a license," Teddlie says.

Not every launch is a success. Sometimes, engines fail to ignite or something goes wrong during flight or re-entry. At the conclusion of one of the Clark team's recent practice flights, the nose cone on a rocket failed to pop off. Its engine spent, the missile turned earthward and then augered straight into the soft dirt of the soccer field, wrinkling its fuselage like the bellows on an accordion.

"We always have one mistake," Ashley Campbell, a Clark senior who is Brianna's 18-year-old sister, said with a sheepish grin.

Model rocketry in America grew up with the nation's full-scale space program. As real-life astronauts walked on the moon in the late 1960s and early 1970s, model rocketry reached its apex. Cadets in Clark's JROTC program have been launching rockets since the mid-1970s.

Donald E. Shackelford, the head of the JROTC program at Clark, knows more than a little about rockets. A retired Air Force major, he worked on Minuteman III ICBMs and cruise missiles and also served on "Looking Glass," the Strategic Air Command's airborne nuclear command post.

Besides "learning a little bit about science and flight and rockets," cadets in the rocketry program at Clark also learn how to work as a team in competition, Shackelford says. The JROTC program has 14 other extracurricular activities for cadets, ranging from drill teams to a newly-formed remote-control model airplane club.

"Here at Clark, we have a tradition of excellence," says Shackelford, dressed in an Air Force uniform with decorations that include his missile man's badge. "We just don't do it for fun. If we get into something, we try to do it to the best of our ability, which is one of our core values in the Air Force, excellence in all we do."

Before this year's official designation as the Fiesta Blast Model Rocketry Meet, the school held an annual competition called the Northside ISD/San Antonio Model Rocket Championship. Shackelford has loftier plans for the future.

"What we're trying to do is build this thing up with the help of Fiesta," he says. "Hopefully, over the next couple of years, we'll call it the National Rocketry Meet and we'll have teams from all over the United States coming in."

Copyright © 2007, San Antonio Express News.