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Microgravity Research Program
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Using both space flight and ground-based experiments, researchers throughout the nation, as well as international partners, are working together to benefit economic, social and industrial aspects of life for the United States and the entire Earth. Ten U.S. universities, designated by NASA as "Commercial Space Centers," share these space advancements with U.S. industry to create new commercial products, applications and processes.
Under the NASA Headquarters' Office of Life and Microgravity Sciences and Application, the Microgravity Research Program supports NASA's strategic plan in the Human Exploration and Development of Space Enterprise.
Microgravity research has been performed by NASA for just more than 25 years. The term "microgravity" literally means a state of very little gravity. The prefix "micro" comes from the Greek word mikros, meaning "small." In metric terms, the prefix means "one part in a million" (0.000001). Onboard view of the second United States Microgravity Payload (USMP-2) photographed in the bay of the Space Shuttle Columbia during the March 1994 STS-62 mission. The mission was one of a series of materials science research flights gathering information important to the country's storehouse of technical data. Gravity dominates everything on Earth, from the way life has developed to the way materials interact. But aboard a spacecraft orbiting the Earth, the effects of gravity are barely felt. In this "microgravity environment," scientists can conduct experiments that are all but impossible to perform on Earth. In this virtual absence of gravity as we know it, space flight gives scientists a unique opportunity to study the states of matter (solids, liquids and gases), and the forces and processes that affect them.
Marshall Space Flight Center in Huntsville, Ala. is the lead center for NASA's Microgravity Research Program. The program manages Microgravity Science and Applications Project Offices at the Lewis Research Center in Cleveland, Ohio, the Jet Propulsion Laboratory in Pasadena, Calif., and also project offices at the Marshall Center.
Under the project offices, the Microgravity Research Program is divided into nine major areas: five science disciplines, three research infrastructure programs and the Space Product Development Office.
The science disciplines include Biotechnology, Fluid Physics, Materials Science, Combustion Science and Fundamental Physics. The infrastructure activities include Acceleration Measurement, Advanced Technology and the Glovebox Flight Programs.
Marshall Center manages the Biotechnology program and Material Science program as well as the Glovebox Flight program and the Space Products Development office. Lewis Research Center manages the Fluid Physics, Combustion Science and Acceleration Measurement programs, while the Jet Propulsion Laboratory manages the Fundamental Physics and the Advanced Technology Development program..
Microgravity Biotechnology
Biotechnology is the application of engineering and technology to life sciences research. NASA partnerships with private industry and academia in space-based, biotechnological research are helping ensure that scientific advances in the field continue to produce technical innovations for improved health care on Earth. Biotechnology research in space focuses on protein crystal growth -- growing organic crystals with thousands of atoms -- and on cell/tissue culturing -- the study of how cells interact in a low-gravity or low-shear environment.
Pure, precisely ordered protein crystals of sufficient size and uniformity for X-ray analysis are in demand by the pharmaceutical industry as tools for research. Structural information gained from protein crystals can provide a better understanding of the role of a given protein in the body's immune system. Protein crystal research could ultimately aid in the development of more effective drugs and life-saving treatments for many diseases.
Since the mid-1980s, NASA has sponsored protein crystal growth experiments to learn about the effects of space on the growth process and to refine techniques for obtaining the highest quality crystals in space and on the ground. The result is that generally, protein crystals produced in space are larger and more precisely ordered than those produced on Earth. These improvements are important to scientists who analyze a crystal's three- dimensional structure -- the key to understanding a protein's activity -- and possibly develop new and more effective medicines.
The other focus of biotechnology in microgravity is cell and tissue culturing experiments. Located at Johnson Space Flight Center in Houston, Texas, the goal of this research is to grow cells on a tissue in near-weightlessness, that otherwise is unachievable on Earth.
The medical benefit of microgravity tissue and culture engineering may lead to new research models in cellular and molecular biology. These studies also are developing new tissues for potential transplant operations.
Biotechnology research results have provided significant advances in the understanding of many diseases including AIDs, heart disease, cancer, diabetes and hepatitis.
Microgravity Fluid Physics
Everyone has practical experience with fluids -- liquids and gases -- and knows how a fluid will behave under "normal" circumstances. Steam rises from the surface of a hot spring or a boiling pot, and water spilled on a tabletop runs over, then off, the surface. Gravity drives much of the fluid behavior we are accustomed to on Earth.
Many of our intuitive expectations do not hold up in microgravity, though, because other forces such as surface tension control fluid behavior. Surface tension causes drops of any liquid to form almost perfect spheres when the influence of gravity is absent. On Earth, gravity distorts the shape when liquid is resting on or attached to a surface. While these differences in fluid behavior often present engineers and astronauts with practical problems, they also offer scientists unique opportunities to explore different aspects of the physics of fluids.
Research conducted in microgravity is increasing our understanding of fluid physics to provide a foundation for predicting, controlling and improving a vast range of technological processes. The behavior of fluids is at the heart of many phenomena in materials science, biotechnology and combustion science. Surface tension-driven flows, for example, affect some techniques of semiconductor crystal growth, welding, and the spread of flames on liquids. The dynamics of liquid drops are an important aspect of chemical process technologies and meteorology.
Results from microgravity Fluid physics research will lead to better understanding of the effects of miniaturization of electronic materials. Advances in the field will lead to even smaller and more efficient electronic devices with reduced costs for the consumer.
Microgravity Materials Science
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Materials science investigates the relationships between the structure, properties and processing of materials. Structure is the arrangement of the atoms in the material. Properties include physical, chemical, electronic, thermal and magnetic characteristics. Processing is the method by which materials are formed. They can be solidified, evaporated and condensed, or dissolved and then separated from a solution. NASA's materials science microgravity program uses the unique characteristics of the microgravity space environment to study these fundamental relationships in materials solidification and crystal growth. In the production of electronic materials, crystals have achieved far greater value as conductors than they ever had as gemstones. Pioneering research is leading to next-generation commercial crystal products.
Material science also has a focus on the production of alloys and composites. High-strength metals are needed in the aviation, aerospace, power generation and propulsion industries. Processing these materials in space helps researchers understand how to make better materials on Earth and is allowing scientists to create new metal alloys. Alloys are mixtures of metals or metals and nonmetals. When combined, they can produce materials with improved strength or better resistance to corrosion.
On Earth, when a melted alloy solidifies, it forms pine-tree-shaped crystals called dendrites. These dendrites play a very important role in determining the properties of the alloy and its subsequent usefulness. Gravity causes fluid flows in the alloy, leading to the formation of irregular dendrites that weaken the alloy or metal structure. This type of processing is so complex that it is difficult to measure and predict, and even more difficult to control. In space, gravity-related phenomena such as convection are reduced, thus simplifying the process for study.
Ceramics and glass experiments also are part of the Material Science program. Optical engineering is being revolutionized by new glasses, crystals and other materials that surpass conventional substances in quality. However, production of these superior materials is difficult. Some glasses have chemical mixes that react with their containers. Others are extremely sensitive to contamination levels from impurities of even a few parts per billion. For example, certain fluoride glasses are of great interest for their infrared transmission properties. These glasses can be made on Earth, but trace contaminants from processing containers have prevented them from reaching their highest potential.
Containerless processing, in which a sample is suspended and manipulated without touching contaminating containers, is an attractive solution to these problems. Containerless processing on massive samples can only be done in the microgravity environment of space where the forces used for suspending and manipulating the samples are not overwhelmed by gravity.
Microgravity Materials results will contribute to future models of industrial and manufacturing processes. This will lead to new, stronger, lighter alloys with never-seen-before properties.
Microgravity Combustion Science
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NASA's combustion research program focuses on understanding the important processes of ignition, flame spreading and flame extinction during combustion in low gravity. Research is directed at gaining basic knowledge of combustion processes, as well as addressing issues of fire safety in space.
Scientists are interested in the physical characteristics of flame, such as size and shape, and the role of soot formation in combustion. Investigations also study air flows and the transfer of heat and mass in fuel vapors, liquid pools, paper and metal solidsbustion. Investigations also study air flows and the transfer of heat and mass in fuel vapors, liquid pools, paper and metal solids.
Since the physical and chemical mechanisms that cause flames to spread on Earth are strongly influenced by gravity, researchers are finding out flames behave very differently in the low-gravity of an orbiting spacecraft. It is well known that material flammability and flame growth are strongly affected by the environment, including oxygen content, pressure and air flow. However, the effects of these conditions in the microgravity environment are largely unknown. Scientists want to understand combustion to improve efficiency of our fuel-driven machines and to evaluate potential fire hazards aboard spacecraft.
Combustion research will lead to more efficient fuels, better fire safety and a cleaner environment.
Microgravity Fundamental Physics
Fundamental physics researchers use the low-gravity environment of space to test basic scientific theories not possible in the gravity environment on Earth in fields such as thermophysical measurements, atomic physics and relativistic physics.
This research is important because it seeks to uncover principles that govern the behavior of the physical world, such as the influence of heat energy, new forms of matter and low-temperature physics.
Fundamental physics research in microgravity is driving the development of new technologies that will advance scientific knowledge and improve life on Earth. The benefits of this research can be seen in improvements in ultra- sensitive detectors of temperature and magnetic fields, as well as valves that can function at temperatures close to absolute zero. Also, scientists have discovered the transition between different forms of matter -- whether magnetic or non-magnetic, solid or liquid -- and the similarities between the different systems. Theories resulting from studies of superfluid helium in microgravity can help to understand many other systems. Scientists can use these theories to better understand the formation of weather systems such as tornadoes and hurricanes, how water seeps through soil, and how cracks propagate in metals.
New understanding of nature's processes have made much exploratory surgery unnecessary with the advent of magnetic resonance imagers (MRIs). Another application of this research is liquefied gases. Liquid oxygen is used to supply breathing gas in hospitals, and helps fuel the powerful rockets that have made human exploration of space possible.
Acceleration Measurement Program
The Acceleration Measurement Program is an operational space flight infrastructure program to measure and track accelerations with a recording system. Acceleration is the force that pushes the passengers in a car against the side opposite of a turn. Acceleration measurement systems serve a wide variety of microgravity science and technology experiments. These systems can measure and record low-gravity accelerations at as many as three experiment sites simultaneously. They can be mounted on or near an experiment to measure the accelerations experienced by the experiment. Understanding the interactions of accelerations contributes to improved microgravity research. Units mounted on spacecraft exteriors historically have had the capability for remote commanding from the ground and downlinking mission data.
Units mounted inside recently have been modified to incorporate this capability. The data are displayed at NASA's Lewis Telescience Support Center in Cleveland, Ohio or NASA's Marshall Payload Operations Control Center (POCC) in Huntsville, Ala.
Advanced Technology Development Program
The Advanced Technology Development Program was developed by NASA's Microgravity Science and Applications Division in response to the challenges researchers face when defining experiment requirements and designing associated hardware. The program provides efficient, cost-effective, state- of-the-art technological support for microgravity science investigations. The Advanced Technology infrastructure program enables new types of scientific investigations and gives researchers capable, high-quality experimental hardware to overcome existing technology-based constraints. The goal is to investigate and develop high-risk microgravity research technologies before they are needed on the critical development path for actual flight hardware.
Historically, Advanced Technology projects have encompassed a broad range of activities. Project funding includes the development of diagnostic instrumentation and measurement techniques, observational instrumentation and data recording methods, acceleration characterization and control techniques, and advancements in methodologies associated with hardware design technology.
Glovebox Flight Program
The Glovebox Flight Program is a microgravity infrastructure program that provides facilities for performing investigations not requiring large, specialized equipment. The glovebox offers scientists the capability to conduct experiments, test science procedures, and develop new technologies in microgravity. The facility enables crew members to handle, transfer and manipulate experiment hardware and materials that are not approved for use in the open Spacelab.
By providing hardware, development and investigation integration services, the program allows researchers to concentrate on scientific objectives -- rather than facility development and vehicle and mission issues. The Glovebox Flight Program lowers cost and allows for quicker and easier access to space for proof-of-concept demonstrations and new investigations. The program office is developing laboratory support equipment items for the International Space Station.
Space Product Development Office
The Space Product Development office examines the opportunities for space commerce, offering a full range of support capabilities to demonstrate the commercial value of space. To ensure continued growth of U.S. industry, the office initiates and guides pilot projects in an effort to eliminate barriers to viable space commercialization.
The Space Product Development Office manages projects such as a new advance in insulation called "Aerogel," a NASA flight project aimed at revolutionizing window insulation and light emitting diodes, a project originally aimed at developing plant growth facilities for space flight and today is funding state-of-the-art cancer-fighting treatments.
Ground-Based Research
A major challenge facing NASA's space-based microgravity program is to conduct scientifically significant and productive research through the wisest possible use of space. To achieve this, NASA uses a ground-based research program to assess whether scientific investigations are worthy of a space flight opportunity. These studies are then refined for the ultimate experimental test during a space mission.
To create low-gravity environments on Earth for research, free-fall facilities are used in a variety of ways. Releasing experiment samples from tall drop towers provides about four seconds of microgravity. Research aircraft can expose experiments to about 30 seconds of low-gravity while the aircraft approaches the top of a steep climb and begins a sharp descent. This parabolic curve is generally repeated about 40 times during each flight, which is used primarily to perform experiments requiring short times for experimental equipment tests or for crew training.
Low-cost sounding rockets, such as Space Processing Applications Rockets, also have parabolic flight paths -- they ascend and then descend, rather than proceeding into orbit around the Earth. Sounding rocket flights provide five to seven minutes of low-gravity. Although these periods of microgravity are brief, the test facilities are beneficial both for space flight preparation and for some actual microgravity research.
Shuttle-Mir Microgravity
The Microgravity Research Program Office manages the development and integration of microgravity science experiments of the Shuttle-Mir program. Both United States and international microgravity science partners used the facilities aboard Mir to conduct investigations in fluid physics, combustion, biotechnology and materials science. The microgravity facilities aboard the Mir space station included furnaces, glovebox and a system to isolate experiments from the stationÍs vibration environment.
The Future of Microgravity Science — The International Space Station
The NASA Microgravity Research Program is evolving to take maximum advantage of the upcoming International Space Station. The Space Station will permit long-duration microgravity experiments in an environment otherwise more similar to Earth-based laboratories -- minus the gravity.
Rather than experiments being limited to a week or two -- as they are aboard the Shuttle -- Space Station microgravity experiments will stretch over long periods of time. This longer duration will greatly increase the number and types of materials that can be processed to full term. This will be a great advantage to experiments in areas such as solution and vapor crystal growth, which require 15 to 30 days of continuous growth to produce crystals of the desired size.
On the Space Station, with crew members to observe experiments and with equipment for analyzing samples in orbit, it will not be necessary to return all specimens to Earth for analysis before running the next experiment. This will allow researchers to conduct experiments in a series which builds on prior results -- without waiting years for another flight opportunity.
Future space research will stress both scientific and commercial goals. Products will include crystals, metals, ceramics, glasses and biological materials. Processes will include solidification of metals and alloys, as well as transporting fluids and chemicals in microgravity. As research in these areas develops, the benefits will become increasingly apparent on Earth: new materials, more efficient use of fuel resources, new medicines, advanced computers and lasers and better communications. Like space, opportunities offered by microgravity science are vast, and only beginning to be explored.
NASA's Microgravity Research Program Office at Marshall Center is responsible for the definition and development of microgravity science and space product development projects planned for the International Space Station.