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__** Unlocking Mysteries in Microgravity: NASA Glenn Provides the Keys With the Fluids and Combustion Facility **__ []

Gravity is a force that governs motion throughout the universe. It holds us to the ground and keeps the Earth in orbit around the Sun. Microgravity describes the environment in orbital space flight, which has very weak gravitational effects (one-millionth of what is felt on Earth) and which is sometimes referred to as a state of "weightlessness." The condition of microgravity occurs when an object is in "free fall." In free fall, an object falls faster and faster, accelerating with exactly the speed of attraction caused by gravity. Objects travelling around the Earth in a state of continuous free fall, or orbit, are essentially weightless even though their mass remains the same.
 * What Is Microgravity?**

Conducting research in a microgravity environment gives researchers a unique opportunity to study the true nature of processes and materials without having to consider the effects of Earth's gravity. Thus, physics theories can be tested at levels of accuracy that are impossible on Earth. Microgravity experiments uncover the mystery of how gravity affects processes such as combustion science and fluid physics. This knowledge can then help to improve the way we do things on Earth.

Combustion Science
Combustion, or burning, is a process in which a substance reacts with oxygen to give off heat and light. Combustion meets almost 85% of the U.S. energy needs. While it does a good job of powering how we live on Earth, combustion is a major contributor to air pollution. The cost of combustion energy is about $450 billion each year in the U.S. In any area of the economy where a huge amount of money is spent, even the smallest improvements in efficiency can mean savings of very large amounts of money. A mere 1 percent increase in fuel efficiency, like improving your gas mileage from 25 miles per gallon to 25.25 miles per gallon, would translate into a savings to America of nearly 100 million barrels of oil a year (roughly $5.5 million per day at today's cost). Although today combustion is vital to transportation, materials processing, hazardous waste disposal, and many other areas, there is still only limited understanding of many of its fundamental characteristics.

There are over 2,500 fatalities and tens of billions of dollars in property damage each year in accidental fires. Combustion research in microgravity can lead to advances in fire prevention, detection, and fighting. In addition, combustion research in microgravity can lead to more efficient use of energy, reduced pollution, and improved processes for making high-technology materials. Glenn Research Center's experience with jet engines provides a solid background in combustion and Glenn scientists have already begun to study combustion in space.

A simple example of microgravity's effect in combustion is the behavior of flames in space. On Earth, hot air rises around a candle flame, which causes the flame to flicker and take on an elongated shape. In microgravity, however, no such distortion takes place. The flame, without the effects of gravity, has a steady, spherical, shape. The FCF allows researchers to study aspects of combustion, such as flame behavior, that are impossible to observe on the ground. Their research will lead to a better understanding of whole processes, such as soot production, which will aid development of improvements in fire fighting and pollution reduction.

Fluid Physics
Of the four states of matter--solid, liquid, gas, and plasma--three are fluid, meaning they flow in response to an applied force. An understanding of fluid physics is not only vital to advancing aircraft and spacecraft applications, such as air flow and propellant management, but is also essential to understanding the human body, aspects of everyday life, and many industrial processes. In microgravity, fluid positioning and flow characteristics can be studied from a new perspective. Scientists at NASA Glenn Research Center have played an important role in fluid physics research since the 1940's. With orbiting spacecraft, microgravity fluid physics became an important research area in which NASA Glenn has always played a leading role. Glenn is currently focusing its research on the enabling technology for space exploration (water and fuel flow, life support systems, temperature control, etc.) as well as on using the space environment (reduced gravity) to provide insight into phenomena that are important for Earth-based applications. A recent spinoff of the special nonintrusive instruments and techniques developed to perform the fluid experiments is a dynamic light scattering (DLS) probe and Hruby lens holder that make early detection of cataracts and other eye diagnoses easier. Glenn researchers have also experimented with the behavior of colloidal suspensions. A colloid is a system of fine particles suspended in a fluid. Italian salad dressing provides a simple illustration of the effects of microgravity on the behavior of colloidal suspensions. In space you would need to shake the dressing only once, rather than between uses, which is needed on Earth. Paint, ink, milk, and orange juice are also common examples. Though these products are routinely produced and used, scientists know little about the underlying structure of colloidal systems because they are difficult to study in ground-based laboratories. Understanding their structures may allow scientists to manipulate the physical properties of colloids for the creation of new materials and products or to improve the manufacturing of known products.