A LEARNING LINK TO SPACE PLACE

Beat the heat -- or at least baffle it!

Summer's coming. You're looking forward to playing outside on warm, sunny days. But some days are so hot the only way to be outside is under a big shade tree. Why does shade make you feel cooler? Since air is moving all around you, and the air is all about the same temperature, why should it matter whether you are in the shade or not?

The reason is radiation. Radiation may sound terrible, but it's just a word to describe one way heat energy moves from place to place. Radiation moves energy without the need to pass through air or water or pipes or any other substance. In our case, heat from the sun radiates through space. A lot of the sun's energy bounces off or gets soaked up by the atmosphere. But some of it gets through to the surface of Earth, or to your skin, if you happen to be standing in the way.

Radiation

So, your skin absorbs these rays from the sun directly, and you feel them as heat. If you stand in the shade, you feel only the warm air that has been heated by Earth's surface -- the Earth's surface that was heated by the sun's rays, just as your skin was.

Now, imagine you are a spacecraft. There's no air at all out there in space. One side of you cooks in the sun, while your other side freezes in the shade. Inside you are computers, communications equipment, imaging instruments, and all sorts of other delicate, high-tech stuff. Most of your parts work best if they are neither too hot nor too cold. But, unfortunately, heaters and coolers take up lots of room, use a lot of electricity, and add a lot to the weight to the spacecraft at liftoff. What's to be done?

To the rescue comes the spacecraft thermal (meaning heat) engineer. Engineers with NASA's New Millennium Program have come up with some new ways to manage the heat energy in a spacecraft, without adding weight, using too much power, or taking up too much room. The Space Technology 8 mission, due to launch in 2009, will test this new miniature heat management system in space.

You can learn more about radiation and Space Technology 8's new Thermal Loop system while playing the "Beat the Heat" game at http://spaceplace.nasa.gov.

This Learning Link was written by Diane K. Fisher and provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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