_Background+Information

The answer is that these astronauts, together with hundreds of scientists and engineers on the ground for whom they are performing experiments and tests in space, are not at all "studying microgravity". In fact, they use microgravity as a special tool for a better understanding of fundamental questions and for the solution of problems on Earth. This allows to improve and to optimise physical, chemical and biological processes on Earth that are important in science, medicine, engineering and technology for all of us.  **From basic research to industrial applications** The motivation for such studies often begins with a purely scientific interest to question, observe and understand certain fundamental laws and basic phenomena. But, as the short history of the development of semiconductors clearly illustrates, the answers to purely scientific questioning can quickly be taken up and applied to practical problems in the development of technical systems and, from time to time, in the discovery and introduction of new systems with a major industrial and economic impact. The absence of gravitational effects in a microgravity environment like on a space station means, for example, that temperature differences in a fluid do not produce convection, buoyancy or sedimentation. The physical picture is thus simplified and underlying processes can be more readily observed and analysed. The changes in fluid behaviour in space lie at the heart of the studies in materials science, combustion and many aspects of space biology and life sciences.  **Research in Fluid Physics under Microgravity** By using the microgravity environment on the International Space Station - or other manned and unmanned spacecraft - the fundamental processes in fluids of many types can be more readily explored. Without the complications of gravity-driven convection flows on Earth, it becomes possible to test in space fundamental theories of three-dimensional laminar, oscillatory and turbulent flow generated by various other forces. All are of substantial practical as well as theoretical interest on Earth. By improving the basics for predicting and controlling the behaviour of fluids, we open up possibilities for improving a whole range of industrial processes, including the efficiency of power plants, recovery processes, and food and pharmaceuticals production.  **Research in Material Science** Materials production in industry inevitably includes steps that are strongly influenced by gravity-driven processes. The opportunity to investigate these steps under microgravity will help to develop a more fundamental understanding of the production process and hence improve product quality and yield, and, in some cases, lead to the introduction of new products.  **Basic questions in Life Science** By using the weightless conditions in an Earth orbit, life scientists and biomedical researchers can observe the functional changes in cells, plants, animals and humans when the effect of gravity is removed. This can reveal the working of underlying processes which on Earth are often confused by gravity. Life began and developed on Earth more than 3500 million years ago, with gravity as an ever-present influence. Gravity causes sedimentation, buoyancy and convection in fluids, it gives rise to hydrostatic pressure in liquids and it modifies the behaviour of liquid films on surfaces. It is therefore not surprising that all life has developed with some gravity-sensitive processes and systems. After all, living systems are principally composed of liquids and use surfaces to isolate their different constituents as well as to facilitate and control the myriad reactions that support the process we call life. The underlying fundamental mechanisms responsible for the sensitivity of living systems to gravity remain, however, to be fully understood. By removing the effects of gravity in space, it becomes possible to study fundamental life processes down to the cellular level. This gives researchers a greater insight into that cellular machinery and its functioning. For example, radical changes in the structure and connections of the nerve cells occur during the early development of the nervous system. As those changes are regulated by mechanical and biochemical factors, it is thought that gravity may play an important role in stimulating the proper development of the nervous system on Earth. It has been observed that animals deprived of the opportunity to walk during their first weeks after birth never learn to walk properly. Studying how that development proceeds in animals under weightlessness will help to define the respective roles of genetic determination and environment experience.  **Microgravity - a tool for medical research** Understanding the nature of the critical periods of neural development has important implications for children medicine. It could also help in the treatment of those persons suffering from neuromuscular diseases. The International Space Station will not solve all of these problems but it will provide better opportunities for research, offer repeated testing procedures, and enormously improve the fest facilities available for life sciences investigations. This will provide valuable information for medical research on the Earth in general and lead to improvements in the health and welfare of the six billion people which live under the influence of gravity on the Earth's surface. ||
 * What is Microgravity good for? ([]) ||
 * [[image:http://www.spaceflight.esa.int/im_layout/shim.gif width="1" height="10"]] ||
 * <span style="font-family: Helvetica,Arial,sans-serif;">Can we really justify sending six happy and healthy astronauts on an expensive mission to a space station for the "study of microgravity", while the other six billion inhabitants of the Earth live anyhow under the influence of gravity, many of them in misery and in unhealthy living conditions? Who cares about knowing more on microgravity?

> Experiments have shown that in microgravity, crystals with improved chemical properties and a greater degree of structural perfection can be obtained. In particular, the growth of some protein crystals is enhanced, allowing these important biological substances to be analysed by X-ray diffraction, and as a result their structure and biological functions can be determined. The biological function of proteins plays an important role in research into new drugs. > <span style="font-family: Helvetica,Arial,sans-serif;">In the area of cell biology evidence has emerged, especially as a result of the flights of the ESA Biorack, that some biological cells and unicellular organisms function differently in microgravity conditions than they do on Earth. This may help our understanding of how evolution works at the cellular level, since all life on Earth evolved in the presence of gravity. > <span style="font-family: Helvetica,Arial,sans-serif;">Space experiments in human physiology have given new and significant insight into the working of the human balance system as well as the functioning of the human heart/blood and fluid distribution systems. These results will help our understanding of how astronauts adapt to weightless conditions in space, and may also have a considerable impact on the future treatment of patients on the ground. > <span style="font-family: Helvetica,Arial,sans-serif;">Researchers in the fluid sciences have found that a fluid at the critical point, as well as surface- tension driven flows, can be more easily investigated in a microgravity environment. This research is already leading to a better understanding of industrial processes on the ground. <span style="font-family: Helvetica,Arial,sans-serif;"> **Discoveries in Microgravity** <span style="font-family: Helvetica,Arial,sans-serif;">Here are some specific examples for discoveries which have been made under microgravity conditions:
 * Experiments in Microgravity ([]) ||
 * [[image:http://www.spaceflight.esa.int/im_layout/shim.gif width="1" height="10"]] ||
 * [[image:http://www.spaceflight.esa.int/images/redbul.gif align="baseline"]] **The interest of experiments in microgravity**
 * <span style="font-family: Helvetica,Arial,sans-serif;">**Crystals**
 * **Cell Biology**
 * **Human Physiology**
 * **Fluid Sciences**
 * <span style="font-family: Helvetica,Arial,sans-serif;">the discovery that the fluid (blood, water etc.) distribution in the human body is controlled by a recently identified hormone;
 * <span style="font-family: Helvetica,Arial,sans-serif;">the discovery that the major component of the human balance system (located in the inner ear) is not governed by convection, as is currently proposed in the textbooks;
 * <span style="font-family: Helvetica,Arial,sans-serif;">the demonstration (as predicted by theory) that crystal growth processes are greatly simplified and optimised in low-gravity conditions;
 * <span style="font-family: Helvetica,Arial,sans-serif;">the isolation of the effects of surface tension forces in the production of technologically important alloys, and the subsequent optimisation of the ground process itself, such as the production of self-lubricating bearings and automobile and aircraft structures. ||