How can spy satellites see thru buildings and underground bunkers?

Question

Does anyone have a link to a site that explains how this technology works?

http://www.chron.com/disp/story.mpl/headline/nation/5058308.html

Answer 1

Because humans can only see in one kind of light, the 'visible' spectrum. Spy satellites can pick up infrared and ultraviolet as well. This doesn't mean that they can 'see' everything, but they can see some things. If the building is deep enough underground, then even the most powerful spy sat. won't be able to see anything, but seeing through buildings isn't a problem. The view would basiclly just show heat signatures, though. You couldn't read a book or the writing on a computer screen, for example.

Answer 2

I don't have a site to send you to, but I can tell you that with

Infrared Sensors
Ultraviolet Sensors
Radar Sensors

You can get a lot moreinformation than you can with just
plain optical equipment in a spy vehicle. Radar waves can
penetrate quite a few feet into the surface of the Earth, or
into a common stick built or average brick house. As long as
the human body temperature of about 98 Degrees F. is significantly different from the environmental temperatures, say in the desert at night (50 - 60 degrees F), or in the desert during the day (120 - 140 degrees F) then pretty good digital images may be produced by electronic sensor systems.

Radar can, for example, penetrate through tree cover, wood and shingle roofs, etc...

Infrared sensors can detect heat from gas engines, fireplaces, etc.

Nuclear blasts give off X-Ray, Gamma Ray, and Ultra
Violet Radiation, etc. And, of course they also give off lots
of heat.

Answer 3

How about providing a link stating that there are satellites that can see through buildings and underground bunkers?

Answer 4

I would say heat-seeking technology is imbedded in the satellite's circuitry.

Isn't it amazing the detail they can pick up? I've heard that you could even read a license plate, and that the view can be refined to eliminate pixilation.