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Simulate It

In the dream phase, you gave free rein to your creative imagination. Now you must judge your ideas to see if they have real value.

Rocket scientists simulate space missions with computers linked to actual hardware and to mock-ups (models of the spacecraft). To simulate means to imitate the real thing. So rocket scientists do what we see children do all the time: they pretend. When it comes to space exploration, this act of pretending can be very sophisticated and very expensive. Full-scale mock-ups are built. Inside the cockpit are instrument panels and joysticks, outside are projection screens showing views of outer space, the moon, or Mars. When the astronaut moves the joystick, the instrument panel indicates a change in attitude. Sound effects and motion actuators make the experience seem real. Astronauts in actual space flight have often remarked, "That's the best simulation we've ever had!"

In fact, most of the time the experience the astronauts get in the simulator is far worse than the real thing. The reason is that they practice emergency procedures more than the nominal (expected) mission. Mission controllers make up problems for the astronauts to solve; if the astronauts don't react correctly, it could mean certain death for the crew. In the weeks leading up to the launch of Neil Armstrong, Buzz Aldrin, and Michael Collins for the first manned landing on the moon, the astronauts were "getting killed" in the simulator so often that the engineers started having serious doubts about the flight. But this was a good thing. The hard reality of the dangers of a lunar landing was not softened. Any mistake was likely to be fatal. The mission controllers were not sadists—they were able to imagine a lot of problems and were pretty scared themselves.

Eventually, the Apollo 11 crew learned self-defense. Like karate students, they learned to parry every blow their trainers threw at them. Finally, they were ready for the real thing.

Rocket scientists don't always need billion-dollar simulators and neither do you. When I was working at the Jet Propulsion Laboratory, I discovered that several engineers had sets of Tinker Toys. Tinker Toys come in a cylindrical can. When you dump the can out, you get a bunch of sticks of varying lengths and a lot of little wooden wheels with holes into which the sticks can be jammed. By connecting the wooden hubs with sticks, kids can make cars, windmills, buildings—virtually anything. And rocket scientists can make spacecraft.

When we planned the maneuvers for the Galileo spacecraft, which eventually flew to Jupiter, a question would come up about "dual-spin dynamics" and one of the guys would say, "Wait a minute, let me get out my spacecraft." And he'd pull a Tinker Toy model of the Galileo off his desk. To a visitor, we must have looked like a couple of overgrown kids playing with their toys. (And actually that is what we were.) We were playing with our Tinker Toys to simulate the complex maneuver modes of a spacecraft headed for Jupiter.

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