Imaging radar works by bouncing a radar signal off the ground, then measuring the strength of the signal that comes back and how long it takes. From this information, we can answer questions like:
- Is the terrain high or low?
- Is it wet or dry?
- Is it rough or smooth?
- Are the surfaces straight up and down (like walls) or slanted (like hills)?
- Is the surface covered with grass or concrete?
If we are "looking" at the oceans or areas of ice, we can see such events as
- Oil spills
- Ocean currents
- Growing, shrinking, or moving of ice sheets and glaciers
Why would we want to know these things?
Well, for one thing, if we could tell the elevation (height) of the terrain, we could make a topo map, couldn't we? And if we could make an image of the ground both before and after an earthquake, we could tell exactly where the earth moved up or down. We might even begin to learn where the next earthquake would be most likely to occur.
If we could see how wet or dry the ground was over large areas, we could better predict weather and climate patterns, and maybe tell what areas would be most likely to flood in the next heavy rain.
If we can see how rough the surface is, we can tell what kind of trees are growing where and how much foliage they have. This information is important for managing the forests (deciding where to allow trees to be cut down and where to plant new ones). It also helps scientists understand how the forests affect Earth's atmosphere.
And there are many other uses of imaging radar data.
 The new LightSAR spacecraft will orbit Earth about every 90 minutes for five years, using radar to observe our lands and oceans. It will be able to observe almost anyplace on Earth every day. Thus, it will be able to observe all kinds of changes from week to week, month to month, and year to year.
Many people could benefit from LightSAR's data. NASA and JPL will share LightSAR's data with other people who want it, so that it will be put to the very best use.
|
