Creating Materials in a Weightless Environment

The weightless environment on space stations was of as much interest to materials scientists as to any others. Scientists are interested in a variety of physical properties of materials, such as melting points, molding properties, and the combining or separating of raw materials into useful products. Before the first space stations, materials scientists could perform simple experiments of very short duration aboard plummetingairplanes¹ and from tall drop towers. Through these studies, scientists discovered that gravity plays a role in introducing defects in crystals, in the combination of materials, and in other processing activities requiring the application of heat. Until the advent of space stations, however, they were not able to sustain a weightless environment long enough to thoroughly study these phenomena.

The advent of space stations allowed the study of new alloys, protein crystals for drug research, and silicon crystals for use in electronics and semiconductors. Materials scientists theorized that improvements in processing in weightlessness could lead to the development of valuable drugs, high-strength, temperature-resistant ceramics and alloys, and faster computer chips.

Using the ISS's Microgravity Science Glovebox, an astronaut studies the effects of weightlessness on various materials. In a weightless environment, scientists are able to remove impurities from most materials.

One of the Mir components, the Kristall module, was partially dedicatedto experiments in materials processing. One objective was to use a sophisticated electrical furnace in a weightless environment for producing perfect crystals of gallium arsenide and zinc oxide³to createabsolutely pure computer chips capable of faster speeds and fewer errors. Although they failed to create absolutely pure chips, they were purer than those they could create within Earth's gravitational field.

More recently, fiber-optic cables are also being improved in weightlessness. Fiber-optic cables, vitalfor high-speed datatransmission, microsurgery, certain lasers, optical power transmission, and fiber-optic gyroscopes4, are made of a complex blend of zirconium, barium, lanthanum, aluminum, and sodium5. When this blend is performed in a weightless environment, materials scientists are finding them to be more than one hundred times more efficient than fibers created on Earth.

In 2002 the ISS began the most complex studies of impurities in materials and ways to eliminatethem in a microgravity environment. One of the most interesting causes of impurities, for example, is bubbles. On Earth, when metals are melted and blended, bubbles form. According to materials scientist Dr. Richard Grugel, "When bubbles are trapped in solid samples 6, they show up as internal cracks7 that diminish a material's strength and usefulness." In a weightless situation, however, although bubbles still form, they move very slightly thus reducing internal cracks. Secondarily, their slow movement allows researchers to study the effect of bubbles on alloys more easily and precisely.

According to Dr. Donald Gillies, NASA's leader for materials science, the studies of bubbles and other mysteries of materials production hold promise for new materials:

We can thank advances in materials science for everything from cell phones to airplanes to computers to the next space ship in the making8. To improve materials needed in our high-tech economy and help industry create the hot new products of the future, scientists are using low gravity to examine and understand the role processing plays in creating materials. (533 words, about 3400signs) [4]

Notes to the text:

¹ plummetingairplanes – падающие самолеты

²drop towers - вышки для ударных испытаний (сбрасывания высоты)

³gallium arsenide and zinc oxide – арсенид галлия и оксид цинка

4optical power transmission, fiber-optic gyroscopes – передача оптической энергии, волоконно-

оптические гироскопы

5zirconium, barium, lanthanum, aluminum, and sodium – цирконий, барий, лантан, алюминий и

натрий

6 when bubbles are trapped in solid samples – когда пузырьки застревают в твердом образце

7 they show up as internal cracks – они выглядят как внутренние трещины

8 in the making – в процессе становления, в процессе развития