Uses of the ISS
The ISS will be used mostly for scientific research in the unique environment of microgravity. The ISS will be four times larger than Mir, and capable of staying in orbit much longer than the space shuttle, which orbits for three weeks. Researchers from governments, industry and educational institutions will be able to use the facilities on the ISS. The types of research that will be done include:
  • Microgravity science
  • Life science
  • Earth science
  • Space science
  • Engineering research and development
  • Commercial product development

Microgravity Science
Gravity influences many physical processes on Earth. For example, gravity alters the way that atoms come together to form crystals. In microgravity, near-perfect crystals can be formed. Such crystals can yield better semi-conductors for faster computers, or for more efficient drugs to combat diseases.

Photo courtesy NASA
Candle flame in microgravity

Another effect of gravity is that it causes convection currents to form in flames, which leads to unsteady flames. This makes the study of combustion very difficult. However, in microgravity, simple, steady, slow-moving flames result; these types of flames make it easier to study the combustion process. The resulting information could yield a better understanding of the combustion process, and lead to better designs of furnaces or the reduction of air pollution by making combustion more efficient.

The ISS will be equipped with a state-of-the-art laboratory for studying the effects of microgravity on these processes.

Life Science
Life as we know it has evolved in a world of gravity. Our body shape and plan have been influenced by gravity. We have skeletons to help support us against the force of gravity. Our senses can tell us which direction is up or down, because we can sense gravity. But exactly how does gravity influence living things? The ISS gives us the opportunity to study plants and animals in the absence of gravity. For example, when a plant seed sprouts, the roots grow down and the shoots or leaves grow up (gravitropism); somehow, the young plant must sense gravity to do this. So what would happen if seeds were to grow in microgravity? These types of experiments will be done on the ISS.

Long-term exposure to weightlessness causes our bodies to lose calcium from bones, tissue from muscles and fluids from our body. These effects of weightlessness are similar to the effects of aging (decreased muscle strength, osteoporosis). So exposure to microgravity may give us new insights into the aging process. If we can develop countermeasures to prevent the degrading effects of microgravity, perhaps we can prevent some of the physical effects of aging. The ISS will provide long-term exposure to microgravity that could not be obtained by using other spacecraft.

The ISS will allow us to test ecological life support systems that are similar to the way that the Earth provides life support. We can grow plants in large quantities in space to make oxygen, remove carbon dioxide and provide food. This information will be important for long interplanetary space voyages, such as a trip to Mars or Jupiter.

Earth Science
ISS's orbit will cover 75 percent of Earth's surface for observation. With on-board instruments, the astronauts will be able to:

  • Study climate and weather
  • Study geology
  • Gather information on atmospheric quality
  • Map vegetation, land use and mineral resources
  • Monitor health of rivers, lakes and oceans

Photo courtesy NASA / JPL
Space-based radar image of Cape Cod, MA, showing forests (green), marshes (dark blue), developed areas (pink) and ponds/sandy areas (black)

The data gathered from these studies will help us understand how the Earth's biosphere works and how to minimize mankind's devastating influences on it.

Space Science
The ISS will be an orbiting platform above the Earth's atmosphere. Like the Hubble Space Telescope, telescopes on board the ISS will have clear views of the sun, stars and planets, without the interference of the Earth's atmosphere. Instruments on board the ISS will look for planets around other stars and search in distant galaxies for clues to the origin of the universe. Instruments on the ISS will be able to be repaired and interchanged more easily than those on the Hubble Space Telescope.

Engineering Research and Development
Much of the ISS engineering research and development will go toward studying the effects of the space environment on materials and developing new technologies for space exploration, including:

  • New construction techniques for building things in space
  • New space technologies, including solar cells and storage
  • New satellite and spacecraft communications systems
  • Advanced life-support systems for future spacecraft
For example, to study the effects of the space environment (atomic oxygen in the upper atmosphere, cosmic rays, micrometeoroids), NASA launched a satellite called the Long Duration Exposure Facility (LDEF), in which materials were mounted on the outside of the satellite. After several years in orbit, the satellite was retrieved by the space shuttle, brought back to Earth, and analyzed.

Photo courtesy NASA
LDEF in orbit as seen from the space shuttle.

Photo courtesy NASA
Streak in the LDEF metal caused by prolonged exposure to atomic oxygen.

Materials can be placed on the ISS in open platforms and exposed to the space environment for years. These materials could be interchanged for analysis more easily than on satellites. The information retrieved will help design better materials for making satellites last longer in the space environment.

Commercial Product Development
As mentioned above, more perfect crystals can be grown aboard the space station, which will help to develop better drugs, catalysts for extracting oil, and semi-conductors. Again, the ISS will have dedicated laboratories for manufacturing these products, and a much longer time in orbit than could be achieved by the space shuttle.