People are now trying to determine the
forest's condition from year to year by using satellite images.
Most satellites, so-called optical satellites, take a picture of
reflected sunlight, just like a photo camera or indeed our own eyes.
The problem with this method, however, is that you can't see through
clouds, and for most of the year tropical areas are generally covered
by a thick layer of clouds.
A new type of camera was therefore developed, the radar or SAR,
which sends out microwaves and captures their reflected signals.
Microwaves and radio waves can penetrate clouds. The EcoSar project
now wants to develop techniques for monitoring the evolution of
the tropical rain forest with such radar images.