Currently, the topic of satellite images has become very relevant. This topic attracts the attention of ordinary people. A surge of interest followed a terrible catastrophe that occurred in the skies over the Donbass in July 2014. Then, near Donetsk, a Malaysia Airlines passenger airliner was allegedly shot down from the ground. All 298 people on board the Boeing 777 were killed. Both sides of the conflict in eastern Ukraine blamed each other for what happened. Actually, it was this disaster that raised the degree of interest in satellite images.
In the immediate aftermath of the disaster, US officials said their spy satellites had detected the launch of a surface-to-air missile. However, the matter did not go beyond words, and the pictures were never presented to the public. In response, the Russian Ministry of Defense organized a press conference, at which it presented its satellite images, which proved the deployment of Ukrainian air defense systems in the conflict zone, in particular, the Buk air defense system.
Actually, already according to the photographs published by Russia, it is possible to draw some conclusions about the capabilities of such a reconnaissance tool. It's funny that at the same time on TV at that time they were retelling the myths of the Cold War in every way. We have all heard these myths more than once. These are arguments about the ability to "read the newspaper, the number of the car and count the stars on the officer's shoulder straps." However, today no country in the world possesses such capabilities and technologies. Moreover, the images published by the Russian Ministry of Defense give us a rough idea of the capabilities of reconnaissance satellites. On them (first of all, specialists) can distinguish an infantry fighting vehicle from a tank, a tank from an air defense system, and so on. There is no question of reading car numbers from space, and this is not required.
Pictures released by NATO were taken by private company DigitalGlobe
Moreover, there are no idiots in the military department. That is why the Russian army purchases and is actively interested in inflatable models of various military equipment. Modern mass-sized models can deceive any enemy, because it is almost impossible to determine from space which tank is in front of you - an inflatable or a real one. Modern pneumatic models, which are able to simulate even running engines, effectively solve the problems they face. Namely, they distract the enemy's strikes from real equipment, mislead him about the number of equipment, its location on the ground and places of deployment.
Now, in real photographs, we will consider what modern space optics is really capable of, and whether everything is visible from above. A special thank you to the blogger who collected the material with these photos on the web.
To begin with, a small discovery. The popular Google Map service does not publish images with a resolution exceeding 50 cm per pixel. Moreover, until recently, the commercial distribution of images of such detail was banned in the United States. Therefore, if you come across a photograph somewhere that shows people walking along the streets, as well as other smaller details, then this is an aerial photography. The publication of aerial photographs is allowed. This contradiction worried private companies for a very long time, and they still managed to lobby for a weakening of the law. They are now allowed to sell images with a resolution of 25 cm per pixel. This figure is the limit for modern commercial satellite imagery.
As you can easily understand, satellite photography is photographing the Earth's surface from satellites. And aerial photography is photographing the earth's surface from aerial cameras that are installed on atmospheric flying vehicles (airplanes, helicopters, airships, their unmanned counterparts). The first aerial photography was made back in 1858 by the French photographer and balloonist Gaspard-Felix Tournachon, who captured Paris from the air.
It is worth noting that even taking pictures with a resolution of 25 cm per pixel requires a very expensive, extremely sophisticated technique. For example, DigitalGlobe's modern WorldView-3 satellite is capable of capturing images with a resolution of 31 cm per pixel. At the same time, the satellite uses a telescope with a mirror diameter of 1.1 meters, and the total cost of the satellite is nearly $ 650 million. This satellite was launched into orbit on August 13, 2014.
The most advanced civilian ERS spacecraft Worldview-3
The Worldview-3 observer satellite was designed by the specialists of DigitalGlobe, which is a recognized leader among the world providers providing content for high-resolution maps of the earth's surface. The services of this company are resorted to by NASA, as well as various US federal services. All Internet cartographic services, including Google Maps, Bing and Yandex Maps, also use the services of this company. At the same time, the more correct name of the Worldview-3 apparatus is the Earth remote sensing spacecraft (ERS).
This spacecraft consists of a 1, 1-meter telescope equipped with an aperture filter, a shortwave infrared radiation scanner (SWIR - Shortwave Infrared, the technology allows you to shoot through fog, haze, dust, smog, smoke and clouds) and specially developed by The Ball Aerospace sensor CAVIS (Clouds, Aerosol, water Vapor, Ice, and Snow), which allows for atmospheric correction of images. Every day, such an ERS spacecraft can photograph up to 680,000 square kilometers of territory. The device is located in a sun-synchronous orbit at an altitude of 620 kilometers above the Earth's surface.
Already at the end of August 2014, DigitalGlobe presented the images taken by the WorldView-3 device - these are test images of Madrid with a resolution of 40 cm per pixel. These are the most detailed images of the earth's surface ever published in the public domain. The images taken on August 21 make it much easier for users to determine the type of vehicles (trucks or cars, their models), as well as the direction of movement and speed. According to the company's specialists, for some people this can be very valuable information.
Fragment of satellite imagery of Madrid using WorldView-3
The published images of Madrid show a lot of detail. Cars are easily distinguished from trucks, and somewhere you can even see people swimming in pools, albeit just in the form of small dots. Madrid was not chosen as a test survey: the closer the area is to the equator, the less cloud cover. Also, the largest city in the UAE, Dubai, is often chosen to demonstrate the capabilities of modern satellites. There are a lot of interesting objects on the territory of the city, and the desert weather is conducive to shooting.
The huge financial costs for the development of such private spacecraft, providing such a quality of imaging, raises a reasonable question: how do they pay off? The secret is simple: more than 50% of the orders of the private company DigitalGlobe are orders straight from the Pentagon. The rest is paid for by companies like Google and individual customers. However, it is still a commercial private satellite. But what about the spy satellites that, for example, the CIA has?
Here everything is much more complicated, but quite predictable. Currently, the most famous and most powerful American spy satellite is the Keyhole-11 series. Key Hole is translated from English as "Keyhole". A total of 16 satellites of this type were launched. The first launch took place on December 19, 1976, the last one on August 28, 2013. Almost nothing is known for certain about these satellites, even their appearance is not completely clear. Only amateur astronomers sometimes manage to consider them. It is worth noting that it was the Keyhole-11 (KH-11) series devices that became the first spy satellites in the United States, in which an optoelectronic digital camera was used and which could transmit an image to Earth almost immediately after the shooting was completed.
At the same time, it is known that the world's most famous space telescope, Hubble, was assembled on the same production lines from which these spy satellites descended. Several years ago, the National Reconnaissance Office - the National Aerospace Intelligence Agency - donated two telescopes with a diameter of 2.4 meters to the NASA agency, which were "lying around" in their warehouse. Taking this into account, and the fact that both the reconnaissance satellites and the Hubble telescope were launched into orbit in the same containers, it can be assumed that the Keyhole-11 spy satellites also have a 2.4-meter mirror.
The most famous space telescope Hubble
If we make a simple comparison with the most advanced civilian satellite WorldView-3, in which the telescope mirror is 1.1 meters, then by simple calculations it can be established that the quality of the images of the spy satellite should be about 2.3 times better (this is a rough calculation). There is also a difference. The WorldView-3 satellite moves in an orbit with an altitude of 620 km, and the youngest spy satellite of the Keyhole-11 series (USA-245) flies at an altitude of 270 to 970 kilometers above the surface of our planet.
It is known that under ideal shooting conditions, the Hubble space telescope, located at an altitude of 700 kilometers, could photograph the Earth with a resolution of up to 15 cm per pixel, if technical capabilities allowed it. Accordingly, the Keyhole spy satellite at the lowest point of its trajectory could provide an image with a resolution of up to 5 cm per pixel. But it should be noted that this is possible only under ideal conditions, in the absence of various atmospheric distortions, when there is no smog, no fog, no dust, no clouds over the subject. Due to the influence of the atmosphere and other factors, the actual shooting resolution would hardly be lower than the same 15 cm per pixel as that of the Hubble telescope.
At the same time, it is necessary to take into account the fact that the higher the resolution issued by the spy satellite, the closer the spacecraft is to the earth's surface. And this means that the strip of his shooting, and the opportunity to see what is happening on the sides, is less. This method of shooting is most expedient only when the shooting party already has information about the objects being surveyed. In this case, it is necessary to take into account both the weather (clear weather is desirable) and the time at which the camera can be above the shooting location. That is, you need to prepare for such a shoot in advance, already having a rough idea of what exactly needs to be shot and where.
It is for this reason that the US military and various intelligence agencies are willing to pay private companies for the provided photographic material. They simply lack their technical means of control. It is much easier to buy the necessary images from private companies than to create a huge number of reconnaissance satellites, the cost of which is currently comparable to the cost of large warships in the fleet. Russian self-propelled guns MSTA-S or MLRS "Grad" can equally well be photographed by modern civil satellites and spy satellites. In this case, the resolution of the latter in this case may even be excessive.
Approximate resolution scheme based on aerial photography
In order to visualize the quality of images in different resolutions, the above is a picture, which is built on the basis of data obtained using aerial photography of the area. The picture gives a clear idea that even in the most ideal conditions, having theoretically achieved a resolution of 5 cm per pixel, just one spy satellite will help you see the license plate on the car. In this case, you will see the license plate in the form of a row of white pixels, that is, you will know that it is, but under no circumstances will you be able to read the number on it, not to mention reading newspapers and looking at the shoulder straps: such tricks are simply physically impossible so far.
