Chapter 1. high-power rockets Your finger hovers over the red button, and you move the microphone close to your mouth. You test the public-address system and are relieved to find that it works: When you speak, your voice is clearly heard all over the firing range. Several hundred feet away is the launch pad, and on it stands the culmination of many hundreds of hours of labor and many thousands of dollars of your hard-earned discretionary income. It is your rocket, a 15-foot-tall accurate scale model of an American early 1960s solid-fuel Pershing I nuclear ballistic missile. It is a machine that you designed and built from scratch. Your rocket is loaded with two stages of powerful chemical engines. Like the original Pershing, your motive power comes from two stages of precisely packed chemical fuel arranged in solid form.

Each rocket engine is designed such that after it ignites, the gas from the burning chemicals will issue rearward in a high-velocity, high-temperature stream from the ceramic nozzle and propel the rocket up toward the stratosphere. Your rocket will reach empyreal heights, tens of thousands of feetif all goes well. You pay rigid attention to the preflight checklist. So far, everything looks like a go. There are small indicator lamps on the firing controls that signal launch status, and the ignition lamp shows green. This means that you have a working circuit, and so when the Fire button is pushed, enough current will be sent through the thin metal wire rammed into the motor to heat it red hot and thereby initiate the self-sustaining chemical reaction that occurs within the main motor's combustion chamber. The countdown begins. Ten.

Nine. Eight . At zero, you push the button and instantly great plumes of white smoke surround the base of the rocket. For a moment, the rocket doesn't move, and you too hold your breath. Then suddenly it leaps toward the sky with neck-jerking acceleration. The noise from the launch comes a split second after you see it leave, and when the noise does come, it is nearly deafening. The rocket climbs 100, 200, 500, 1,000 feet, its speed escalating logarithmically as it ascends. It climbs and climbs, and it becomes difficult, then nearly impossible, and then totally impossible to see the rocket itself, although the smoke and nozzle fire remain visible.

Everyone congratulates you on a successful launch. There is applause and backslapping, high fives all around. But the celebration is cut short by the sound of the range safety officer's warning horn: Whoop! Whoop! Whoop! The RSO's voice is plainly heard over the public-address system. "Attention! Look up! Look up! We have a rocket coming in hot!" This is not good for you. This is not good for anybody. In fact, this is trouble with a capital T. What has happened is this: your rocket has two stages. The first stage consists of several large chemical rocket engines that lift the entire rocket for the initial or "booster" phase of the flight.

When expended, the booster rocket falls away, and a second engine, mounted above it, is supposed to automatically ignite and continue powering the remaining components upward. But the second stage, powered by its own very large engine, has ignited later than it was supposed to. In fact, it ignited after the rocket reached apogee and had already turned and begun to head back to earth. So the engine is not powering the rocket to fly up higher. Your rocket is being driven back down to earth not only by gravity, but also by the second-stage engine. There is a real danger that the rocket will reach the ground and your launch area before this engine is burned out and triggers the timed ejection charge that deploys the recovery parachutes. The curr.