How far away is the moon?
How fast does light travel?
How do detergent enzymes trounce laundry stains?
Visitors to the Smithsonian's National Museum of American History in Washington, D.C., will explore these questions at hands-on experiment stations developed by scientists at the Commerce Department's National Institute of Standards and Technology for the museum's permanent new exhibition, "Science in American Life."
Three interactive displays created by scientists at NIST and the Center for Advanced Research in Biotechnology will be part of the exhibit opening April 27.
Two NIST displays designed by research physicist John Travis of Gaithersburg, Md.; physicist David King of Washington, D.C.; and electronics engineer Alan Band of Derwood, Md., will teach visitors about lasers and the speed of light. The displays will be located together in the exhibit's Hands On Science Center.
A third interactive display, developed by NIST biologist Travis Gallagher of Rockville, Md., will be in "Looking Ahead," an area focusing on the science and public perceptions of biotechnology. Gallagher prepared molecular images for this interactive computer display at CARB, a research cooperative of NIST, the University of Maryland Biotechnology Institute and Montgomery County, Md.
Two NIST displays will illustrate how scientists used properties of light to measure the distance from the Earth to the moon. Travis, a research physicist in NIST's Chemical Science and Technology Laboratory, designed a table-top display to illustrate the advantages of laser light for measuring distance. Using hand controls on the display, visitors will be able to compare how white light and laser light travel over a distance. They will also be able to pass a white light and a laser through four color filters to illustrate how filters can reduce the influence of moonlight on the experiment.
Laser and white light also pass through a tank containing a milky solution that illuminates the paths the light beams follow. As light scatters off particles in the solution, different colors are visible from different angles, Travis explains.
Next to this table-top display, another NIST experiment allows visitors to calculate the actual distance to a target on a picture of the moon approximately 25 meters away. In this display, designed by Band and King in the NIST Physics Laboratory, visitors will use a control to aim the laser at a reflector on the picture of the moon. Laser pulses start a timer on their way to the moon. The reflector on the moon sends the laser light back, which stops the timer. A computer displays how long it takes for a single pulse to travel to the reflector and back, about 100 nanoseconds (100 billionths of a second.)
A visitor can then multiply the time by the speed of light in meters per second to calculate the distance the laser traveled. Directions and a calculator are provided at the display.
A third interactive display created at CARB will be located in "Looking Ahead," a special area dedicated to biotechnology. The interactive display will introduce visitors to advances in molecular biology and computer graphics and, at the same time, familiarize them with a practical, everyday application of biotechnology.
Visitors will use a colorful computer graphics model to explore the structure-function relationship between an enzyme and a protein substrate. The enzyme, subtilisin, is a common laundry detergent additive that helps dissolve protein-containing stains, such as blood or gravy, by cleaving the protein substrate into smaller, more soluble pieces.
"Visitors will be able to move the substrate in three dimensions to the docking site on the enzyme with touch-screen controls," says Gallagher, the biologist who designed the display.
The protein substrate appears to float in front of the enzyme until it is placed in the docking position. Whether or not a visitor successfully guides the substrate to the docking site, the final sequence of the computer display simulates the enzyme cleaving a larger protein molecule.
The three NIST interactive displays will be part of a large permanent exhibition that traces the history of science in American life from 1876 into the present and then looks ahead to the 21st century. Developed by a team of curators, educators, writers, designers and scientific consultants, the exhibition is based on the theme that society and science are inseparable in modern America--that science has grown into a complex enterprise interwoven to all aspects of life.
CARB was established in 1984 by NIST, the University of Maryland and Montgomery County, Md., as a unique center for government, academic and industry scientists.
As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.