How do satellites take detailed detailed photos of the country?
You may have wondered how reconnaissance satellites take detailed detailed photographs of our home, country. The answer is that they use high -resolution CCD cameras associated with large lenses to shoot the ground directly below them as they pass. Photos taken during bad weather are likely to be filtered. Even in the middle of the 80s, the reconnaissance satellites delivered their pictures back on the ground using fragile film canisters mounted on the falls and lifted with airplanes in the air. Today they send images using encrypted transmission.
Most information about modern spy satellites is highly classified. Our information about how these devices can work is based on estimates and can be speculative. The equation includes sinθ = 1.22 λ/d, where λ is a wavelength of light, θ is an angular resolution and D is a lens diameter or mirror. Assuming that the satellite working in the low orbit of the Earth at an altitude of about 300 km, with a mushroom size lensBle 2.4 m, we look at the light of a typical visible wavelength of about 550 nm, we get an angular resolution of 229 nanoradians, which is translated at a resolution of about 7 cm per pixel at 300 km. This does not take into account atmospheric occultization or imperfections in the lens, but it seems a fair estimate.
A lot of pressing international intelligence communities, commercially available color images with high -resolution of the world have recently been available using services like Google Earth. These commercial services offer a resolution around 20 cm per pixel or better in some areas, probably approaching spy satellites. The primary difference is that images for such services tend to be around 1-3 years old, while military exploration satellites are likely to update their pictures every time they orbit on the ground, which is approximately every 45 minutes. The difference in news between them is of course giantVS.
Recently, it was deployed in orbit around the red planet, which was deployed by the exploratory orbiter Mars in the US and also returned to the high -resolution body. Google Earth and Google Moon already exist, it is only a matter of time until we start seeing Google Mars and Google Asteroids.