May 27, 2005

Exploring the Physics of Spaceflight

NASA -- As the Millennium Force climbed to the peak of its first hill, 20 students took a deep breath and braced themselves for a high-speed plunge toward the ground. The ride began its descent, and they rose unwillingly from their seats only to be caught by the lap bars just in time.

The Millennium Force is a 310-foot-tall roller coaster at Cedar Point Amusement Park in Sandusky, Ohio. And the sensation the students felt as the coaster plummeted down its famous first hill was similar to what astronauts feel as the Space Shuttle orbits the Earth.

"Students really get into experiments when an amusement park is the laboratory," NASA's Richard DeLombard said. "It makes physics real to them."

DeLombard is Project Manager for Exploration Outreach and Education at the Glenn Research Center. He and his team use amusement park rides to teach science lessons at Cedar Point's annual Physics Day.

Roller coasters cause a series of low- and high-gravity sensations that mimic the free falls and accelerations of airplanes and spacecraft. As a coaster reaches the bottom of a hill, the students feel their bodies pressing into their seats.

"That's the sensation of gravity and the acceleration of the roller coaster car catching them to start up the next hill," DeLombard said. Similarly, acceleration during launch makes astronauts in the Space Shuttle feel two to three times heavier than they are.

NASA uses a variety of facilities to create the high- and low-gravity conditions of space travel. The Johnson Space Center, for example, operates a low-g flight research aircraft that flies in up and down motions called parabolas.

Shaped like roller coaster hills, the parabolas create 20-25 seconds of weightlessness so that researchers can investigate microgravity's impact on astronauts and experiments. A typical mission is two- to three-hours long and consists of 30 to 40 parabolas. Much like a roller coaster, the aircraft has gut-wrenching effects that have earned it the nickname, "The Vomit Comet."

Coasters aren't the only amusement park attractions that can make students feel like space travelers. Other rides, such as Cedar Point's Power Tower, plunge vertically from high in the air. For a brief period, while the passenger cars free-fall, gravity seems to be suspended. Like the students on the roller coaster, the passengers rise out of their seats.

Because they and the car are falling at the same rate, the passengers' bodies aren't pushing on the seats any more. The passengers become weightless and actually float inside the car. Any loose objects, like jewelry and purses, float along with them.

The same thing happens onboard the Space Shuttle or Space Station. Rather than falling toward Earth, however, the spacecraft falls around Earth in a curved pattern called an orbit. If an astronaut tries to stand on a scale in orbit, the scale will read zero because the astronaut, the scale and the spacecraft all fall together.

Contrary to popular belief, NASA doesn't have so-called anti-gravity chambers. But it does use several facilities to simulate the weightless conditions of orbit. Glenn's Zero Gravity Research Facility is a large evacuated shaft measuring 500-feet deep. It allows scientific experiments to free-fall for five seconds. In this state of free fall, experiments are weightless like the passengers on Power Tower.

Every year, amusement parks across the country host Physics Day events to show students how the laws of physics apply to rides. For the past 12 years, scientists, engineers and educators at NASA Glenn have participated in Physics Day at Cedar Point and Geauga Lake & Wildwater Kingdom in Aurora, Ohio, where they show kids how rides that climb up to 450 feet above the Earth's surface compare to space vehicles flying 250 miles above Earth.

The National Center for Space Exploration Research on Fluids and Combustion (NCSER) at Glenn hosts workshops to help middle-school and high-school educators prepare for physics days. NCSER has developed an educator resource called "Amusement Park Physics with a NASA Twist." This resource includes classroom and park activities that instruct students to collect data on ride heights, speeds and accelerations. Educators can request a copy from the Glenn Educator Resource Center by e-mailing erc@grc.nasa.gov.

Physics days have been recognized for their high educational value by the American Association of Physics Teachers.

"Creating real world physics labs, where you not only see but also experience the laws of physics, excites students," said David DeFelice, who leads Glenn's Community Relations activities. "People don't always realize that learning can be fun. That's why NASA is working with educators to turn amusement parks into effective outdoor classrooms."


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