WORKING IN SPACE

BACKGROUND INFORMATION:

Engineers face exciting challenges as men and women begin to explore, live and work in space. Here on Earth, gravity pulls everything towards the Earth's center. We've all seen pictures of astronauts floating weightless in space. You may have seen footage from the late 1960's and early 1970's when American astronauts walked (or sometimes bounced on the moon).

There are many different activities that you do everyday on earth which will be much more challenging in space.

There are science laws or rules that determine how objects move. Three of these are called Newton's Laws. Sir Isaac Newton was a physicist. Physics is a branch of science that deals with how objects move. Newton's First Law states that a body in motion tends to stay in motion unless affected by another force. Newton's Second Law defines what a force is in mathematical terms: Force = Mass x Acceleration. Newton's Third Law states that for every action there is an equal and opposite reaction.

Gravity is one form of acceleration. On Earth, gravity is 32.2 ft/sec². On the space shuttle, objects experience about .000001 the amount of Earth's gravity. That's very small! Scientists and engineer's refer to this as "microgravity".

In the absence of gravity other forces begin to dominate the motion of objects. If you were in a "tug of war" who would win? The team pulling with the most force! What would happen if all of a sudden 5 people on one team stopped pulling? There would be less force on that side, and the other team might be pulling with a lot more force and winning!

In the same way once the effects of gravity are removed, there is no force pulling objects toward the Earth and other forces begin to dominate an object's motion.

For example, have you seen pictures of astronauts in space? How do their faces look? They are typically puffy, red and a bit swollen. This is because in the absence of gravity some of your body fluids rise towards your head.

Eating can be quite a challenge in space. There is no reason for solid food to stay on a plate! As a matter of fact, there's no reason for the plate, table, utensils or chairs to stay in place is there? Many of the foods are in small containers and if they are "sticky" enough the food will hold together and can be eaten with a spoon.

What about drinking? On Earth, you might place your juice in a cup. Now what do you do? You raise the glass up and pour the juice into your mouth. You take advantage of gravity to pour the juice into your mouth. What happens when you pour a liquid in space? There is no gravity! Liquids tend to form small droplets. Some materials will even crawl up and over the side of their containers.

What about using a straw? How does a straw work on Earth? You suck the liquid up into your mouth and swallow. When you stop sucking the liquid drops back through the straw and into the cup or can. What do you think happens in space? Remember Newton's 1st Law: a body stays in motion until another force acts on it. If you suck a liquid up into a straw in space and then stop, Earth's gravity does not pull the liquid back through the straw and into the cup. The liquid will travel out the top of the straw once you take your mouth off of the straw!

Combustion (burning something) works differently in space. If you light a candle on Earth, the candle flame rises into a plume. The hotter gases rise. In space the particles do not rise. A candle flame would look like a hemisphere instead of a plume.

On Earth, astronauts practice many of their space walk activities under water. Like weightlessness, the astronauts feel like they are floating when they are in water. Astronauts practice and rehearse for their missions. They go over each motion they will make.

Engineers need to understand how objects move in microgravity. They learn how to take advantage of the low gravity environment. For example, there's no floor and no ceiling on the space shuttle! Since astronauts float inside, engineers can design their living and working space on all the walls. Engineers also study how new products and technology can be developed. For example, crystals and new drugs may be manufactured in space. In the absence of gravity, small particles do not settle to the bottom - the small particles do not weigh more than the other materials. This means that new materials can be developed which are very uniform in content and shape.