The National Imagery and Mapping Agency of the U.S. Department of Defense, along with NASA and the Jet Propulsion Laboratory, are making the most detailed and accurate topographic map ever of almost the whole world. The Shuttle Radar Topography Mission flew on the Space Shuttle Endeavour in February 2000. It used a technology called imaging radar . Imaging radar bounces a radar signal off the ground, then measures how long the signal takes to come back and how strong it is. And imaging radar can see all this day or night, cloudy or clear.
Telescopes use light to see things.
Imaging radar uses a different kind of light, but at a much longer, lazier wavelength that our eyes do not see. That is why radar can penetrate clouds. It passes right through them. We have flown imaging radar missions before and made radar images of different parts of the world. The beautiful colors were put in later to make the details easier to see.