أنظمة الاستشعار المحمولة جواً وفضائياً .... Sensing systems, airborne and space

Sensing systems, airborne and space -

Remote sensing, in a manner of photography by high-altitude airborne equipment, not note recently, but dates back to 1783, where the two Frenchmen, "Orland" Arland and "Roser" Roseer trip took half an hour by private balloon around Paris.

Predicted quite a few scientists of the importance of this achievement, not the conquest of space, but what followed the events will be provided with a tool to study the human forms of the earth's surface, and the prospects for observations of air. That has been associated with technological development in data recording and processing systems, and means of air transport.

The applications started in the first place in a limited fashion, visual observation only, and air platforms has become of great importance, when Intel discovered photographs on the basis of the presence of certain chemical compounds are sensitive to light.

First: the importance of aerial photographs

The invention of cameras made it possible to get photocopies of the land. Photographer has been able to Gaul, with one of the owners of balloons, in 1858, to capture the first image of a successful air. The first aerial photograph taken in the United States was the city of Boston in 1865, and the first aerial photograph was taken in Russia in 1886, the balloon of the cities "Kronstand" Kronstand and Petersburg Petsberg.

And used kites for aerial photographs, and the first that France was also sexual, in the year 1858, in England, the first aerial photograph taken in 1882 using kites.

Rose the enormous benefits of aerial photography, especially for military purposes during World War II, Axis forces Fastkhaddmth widely in the invasion of France, and was successful studies carried out by these forces, using air exploration, the impact of the plan hit the airports, the Allies on the western front and the success of . Although more than the Germans, at the beginning of World War II, in the art of aerial navigation, but some of the Allied Powers, especially the United States and the United Kingdom, Russia, and after that they understand the importance of this effective weapon, conducted intensive studies to build their own computers and remote exploration, and this progress after that play an important role during the siege of Leningrad, and in the Pacific battles.

And began using aerial photography in the science of imaging geological Photogeology, (see aerial photo radar), particularly in dry regions, as it did in North Africa and Gulf countries, where climatic conditions permit, and the scarcity of vegetation, easy to use aerial photography to detect environment in these areas in detail, to scale 1: 50000, while in the United States, was the most aerial photography, uses the scale 1: 20000.

II: the use of aircraft in remote sensing

With the progress of aviation, aircraft have become the principal means of access to aerial photographs, (see the picture of the system Kahrobbar Airborne), which now covers most parts of the globe, has resulted in improvements made to the aircraft, camera systems, and photographs, to the considerable improvement in aerial photographs . Conventional aerial photography is used only part of a narrow 4000 7000 Engstrom [1] Angstrom of the electromagnetic spectrum.

It has evolved and recording media catalog Airborne gradually in the sixties, and became the term remote sensing broader meaning of the image light air Air Photography, and the means found much more useful is the image of small scale, we get from airborne radar ever vision side Side Looking Airborne Radar (SLAR).

Third: the sensor, the Canadian Airborne

In 1990 provided a private Canadian company that specializes in electronics, optics, imaging systems and sensors on the apparatus after the first in the field of remote sensing, airborne, which is known as the "imaging device Alisbactromitri Almndguet and airborne," which captures the electromagnetic emission in the spectral range of 430 to 870 nm, which is called the data term Hyperspectral Data, any "captured data through a large number of wavelengths."

The quality of photography, and therefore the number of channels, and the spectral range, for each channel. The landscape consists of one of a number of key points, the number of which depends on the quality of photography. Also vary the degree of differentiation, the basic point, depending on the scan rate, speed and high flying.

Fourth: the use of balloons and a means for carrying remote sensing instruments

Archimedes was the first to discover the principle of buoyancy, in 240 BC, which could balloon to rise into the atmosphere, but it took another year to 2000, before the balloons are placed under the actual use, in the late eighteenth century. The use of balloons in the scientific research has begun only in the late nineteenth century, when put into practice a new technique for measuring temperature and relative humidity in the first attempts to study the atmosphere.

The balloons had been produced, for the first time, for military purposes, during the American Civil War, to be used pads to control the movements of belligerent forces. In the late forties and early fifties of the twentieth century, the draft of the U.S. Navy the use of polyethylene for the development of modern airships, which could rise to a height of between 15 and 50 km in the atmosphere, carrying the largest weights, flying for longer periods.

The tasks helped balloons, led by the people, the U.S. space program of manned flights, through its contribution in the test clothing worn by the astronauts, and evaluate human responses in the near environment of space.

The astronomers used the balloons to study the ultraviolet radiation emitted from the sun, they call these balloons - after providing them with the necessary - to the upper atmosphere to correspond to radiation in its path, before it enters the atmosphere.

1. Moon Almntady "Eco - 1"

In the sixties of the twentieth century AD, carrying a missile fired by "NASA" Mntadi first experimental communications satellite, called "Echo - 1" Echo-1, remained in orbit for about eight years, at an altitude of about 1600 km. And then twenty-five years, making an international team led by the former Soviet Union, which includes France and the United States, Mntadin, and succeeded in withdrawing Bitalagahma Venus at an altitude of 54 kilometers from the planet's surface.

2. Balloon to see Supernova

In 1987, she was able balloon-borne sensors to see Supernova "Supernova" Super Nova within three months of the discovery of this supernova is the explosion of stars occurs once every 400 years or so. This means that he spoke to the star a terrible disaster, with all its matter to explode in space, Veetmzk into small pieces. For this reason, many of the devices, which are installed on modern spacecraft, built on the basis of the techniques, which have been tested before in the tasks of using balloons.

3. Types of scientific balloons and benefits

There are two types of scientific balloons now. The first type is called Balloon "zero pressure" Zero Pressure, and the other so-called balloon "high pressure". Most of the balloons used by the agency "NASA" is one of the first type, which springs from the ground when filling in sufficient quantity of helium gas, equivalent to a total weight, including the net weight [2] Payload.

In order to increase the balloon, it must be to provide helium gas has pushed more of the weight of the balloon and gave him a net combined. When the balloon rises decreasing density of the atmosphere around it, increasing the volume of gas inside it, until it is filled completely. Thus becomes the pressure inside the balloon and outside, and one, which is why so-called zero-pressure balloon.

But the balloon will fly because it weighed less the weight of the air banter. When the balloon reaches the desired elevation, which is between 36 and 40 km, and is usually done in a period of between two and three hours, working the holes in the base of the balloon to vent excess gas to keep it stable at high, and to prevent tearing the cover made of thin cloth of polyethylene . Because some of the hot-air balloon called a raid in the atmosphere, said the design of the balloon zero: It is "open" on the air.

4. The impact of advanced technologies on the balloons

Because the balloon is the oldest and rights of way invented flight, and it is flying in the sky for more than 200 years, and is used by scientists since long in different research tasks, however, the survival of flying was a challenge, always, the extent of benefit from it. But now, thanks to advanced technologies and sophisticated designs, it has become possible to produce balloons flying over the longer distances, up to a new high altitudes.

Balloons flew, they provide great benefits to the scientists who use them. In many cases could balloon to provide a return on investment greater than provided by spacecraft. This is the main reason, which makes scientists are making significant efforts to improve the way invented the first human to fly.

Fifth: remote sensing systems space

Space has room for scientific technological revolution, had negative repercussions on civilian and military life on Earth, and provided the major states, or those that made great strides in the use of satellite information in all areas.

In peacetime, these satellites surveyed territories of States, and mapping, and to explore its natural resources, and monitoring of weather conditions, acts of navigation and registration.

In the military sphere, using satellites in the evaluation of offensive operations, and identify military targets and distinguish them, and provide information in times of crisis, intelligence, surveillance, procedures, communications, surveillance, and reconnaissance, navigation, and meteorology. In addition, the satellites used in operations to ensure compliance with treaties on arms control and disarmament.

1. Space images

Satellite image covers a large area on the surface of the Earth (see picture of Djebel Amour in Algeria), and this is what provides the ability to view comprehensive, comparison, and known ratios landmarks. And provides satellite image data one enormous land surface considered, and the lid, vegetable and shaped by geological, and so on, up, sometimes, if the image of the "Landsat", to nearly eight million information, and this is what could be a better evaluation of the topics for study.

Due to the rotation of the satellite passing over the same region, approximately every two weeks, or every 18 days, the frequency of the satellite image the same areas, during periods of short temporal and equal, able to examine changes caused by the elements of nature or human hand on the surface of the earth, and follow its development, then influence the course and direction in the curve of the required positive.

This enables multiple images also to choose the best image of the study area and in the best climatic conditions, we can get the best results, and show the importance of this follow-up to large construction projects, and study the evolution of crops, or natural disasters, and others.

The speed with which we get our information and data record; because the satellite completes its orbit in about 105 minutes, and a speed of about 29 thousand kilometers per hour.

The satellite receives information from the purposes to be studied, and then send them to capture the moment of ground equipment, in the form of radio pulses, and then translated into information and real time images for use in assessing the situation and take the appropriate decision.

2. The sensitivity of Space Imaging

Of the sensitivity of satellite imagery to the extent that they can control tiny objects, photographed, and no larger than three cubic feet, from a height of up to 200 miles.

Because the data that feed into the ground stations are digital, the advanced computers used to read these data, especially in the analysis of the images. Thanks to this computer has become possible to distinguish between a tank made of plastic and camouflage tank is real.

3. The transfer of satellite images

The first generations of satellites equipped with cameras, and after a scan is dropped inside the capsules movies at set intervals, and when they enter the atmosphere, open the umbrella, when a certain altitude, speed and less thrust, and launch rockets to reduce the speed bounce, then pick up the capsule, either by aircraft, or from the ocean (see the form of phases of restoration capsule).

The main disadvantages of this method is slow and waste of precious time, as well as the possible loss of the capsule. This was followed by the development of satellites, providing a television camera, you take pictures, then sent to the earth, through television as well.

The satellite systems are among the programs that kept the most absolute secrecy in the world. A year ago in 1986, the world had never heard some of the programs the American satellites, including the "rhyolite" Rhyolite, and "Shalit" Chalet, and "Magnum" Magnum, and "Corona" Corona, and "Kihwl" Keyhole.

And then a decade, States have become able to buy airtime satellite, or purchase a specific geographic coverage, the owners of systems, in France and Russia.

Recognizing the vast potential of this technology, which was born, of course, military applications for surveillance systems, has begun the dominant satellite reconnaissance in the development of associated technologies, in particular the development of types of sensors.

Can be summarized unique features of remote sensing satellites are as follows:

A. Survey large areas, quickly and economically.

B. The possibility of establishing systems for monitoring and periodic follow-up.

C. Detection of environmental changes is the slow, gradual, as well as the huge and sudden.

D. Beyond political boundaries and geographical boundaries, allowing to deal with the world as an environmental unit and geographically contiguous.

E. Is not affected by the vagaries of weather, owing to the reliance on monitoring stations manned, and the ability to penetrate the atmosphere.

And. The possibility of applying technology to unfavorable climatic zones, and hubs such polar-Saharan Africa.

G. The possibility of applying computer technology directly to the information extracted; allowing development to take advantage of this information, and the possibility of dealing with massive amounts of data, as the satellite digital data are available, as well as images, that allows for analysis and quantitative studies.

H. Journal information, which means the possibility of obtaining the same type of information to a particular area, for different periods of time, this can be made dynamic studies, which relate to study the evolution of the phenomenon or a characteristic. Available periodic information as a result of repeated visits satellites.

4. Land-based sources satellites ERS: [3]

Launched the European Space Agency ESA satellite called "moon land-based sources" Earth Resource Satellite: ERS-1, (see the picture of the satellite ERS-1) on board the rocket, "Ariane-4" in the July 16, 1991 at an altitude of 777 km, cycle of 35 days and one-third today. The program cost the ERS satellites devoted to the study of the oceans 860 million dollars, and participated in the study data and analysis of several thousands of ocean scientists and satellite from all over the world. A second satellite was launched from the group ERS itself, is the ERS-2 in 1995.

Results of the use satellite land-based sources

The satellite has achieved significant results in the monitoring of oceans, where it showed that the topography of the ocean-like topography of the land, and is not intended to seabed topography under the water, but is intended to lay the surface of the water itself.

It was shown that the ocean surface is not uniform equal height in both regions, with the exception of local wave heights, but there are vast areas in the ocean, raising the water's surface where the overall level of the ocean about 100 meters, and other low surface where such value.

The reason for this large variation in the surface, which could not be detected only satellite, the difference in the gravitational field and topography under the water in different regions of the ocean.

Based on these measurements, drew a map of the ocean surface, indicating that there are mountains of water, the size of continents, one of which lies to the north-east of Australia, rising up to the surface of the water and eighty-five meters above the average level of the ocean, and the other to the west near India, reduced the water's surface where the record level of the ocean surface about 105 meters, bringing the contrast between Artvai surface of the water in these two neighboring regions about 190 meters.

5. Satellite "Landsat"

A. The first generation of satellites, "Landsat-1"

Started in the U.S. space agency, "NASA" NASA after the mission "Apollo", which carried the first man to the moon, in the July 20, 1969, in the allocation for the development of satellite remote sensing, fired the Moon "Landsat -1" Landsat-1, in the July 23, 1972 to polar orbit at an altitude of 9900 km;, who will cover the Earth's surface every 18 days by flight paths inclined at an angle of nine degrees on the vertical axis at ground level.

Thus, the moon passes always on the bright side or part of the land. And the moon passes every 103 minutes equator line, and even the rate of the Moon receding from the Earth with the rate of movement of the earth around the sun, so keep at a constant altitude of the satellite above the earth.

(1) the satellite "Landsat - 2"

The success of the Moon "Landsat-1" This technology has proven, and entered the world of remote sensing application, in the January 22, 1975 launched a satellite "Landsat - 2", which is similar to the first moon in the specifications. With these satellites, it became possible to obtain data for an area of the globe every nine days.

(2) the launch "Landsat - 3"

As a result of the inability of satellite first performance of his functions, has launched the third satellite in March 1978, and represents the end of the first generation of U.S. satellites, which are running a multi-wave survey Multispectral Scanning: MSS, the spectral measurements of emissions, with multiple wavelengths.

B. The second generation of satellites, "Landsat"

And then headed the United States to launch the second generation of satellites, "Landsat", (see the table of properties of channels of the second generation of the "Landsat" areas to use all of them), it launched the "Landsat -4", and "Landsat-5" in 16 July 1982, and the first in March 1984, respectively, and characterize this generation of high accuracy, and then grew in measurements taken to an area of land.

It contains two types of satellite sensors Sensors, the first of which is running MSS, which is similar in general characteristics of his generation, one of the "Landsat", while the other sensor, it is Thematic Mapper: TM and is credited with the high accuracy of the second generation of the "Landsat "(see the picture of the valley Rahabi Algeria).

Satellites and is located "Landsat-4, 5" in semi-polar circular orbit [4] at an altitude of 705 km, the orbit is located in the great circle, with the level of the poles or close to them, and cleared land in this satellite view all the tapes of which 185 km every 99 minutes . And thus each of the satellites, "Landsat" five years around the Earth every 24 hours, and the planet is cleared in full every six weeks. This means that the moon wipe strip of land is different at each session, and then return to the same area after 16 days.

C. The use of satellites, "Landsat" for applied research

The Administration explained that the U.S. satellite research tool based on the method applied, which aims to raise the efficiency of resource management and use of land. The U.S. administration has indicated that in its mission of these satellites is to supply were made by the spectral, multi-band, an iterative nature, the strength of explanation is high, and sends information "Landsat" either directly to the receiving stations, or this information is recorded on tape, when the moon is outside the reception area of the stations.

All of this led to the development of a program, "Landsat" Landsat. It has launched three models, almost identical, under the management of the status of "Godard," Aviation Space Agency's "NASA". The results in the level of the most optimistic forecasts.

(1) Photos Moon "Landsat"

Sent a multi-spectral scanner sensors that take place in polar orbits at an altitude of 950 km, a barrage of pictures, comprehensive and frequent, every picture in the section currently covers an area of 185 km from the Earth's surface of 33,800 square kilometers, and you need a plane to catch A picture to cover an area similar ground. Seizing the 30000 image can "Landsat" image of the earth registration once every 18 days.

(2) uses Applied
.
This broad vision have attracted geologists, even those who were skeptical at first. And see many of them maps of mountain ranges, and discovered areas of the cracks extended in the "Alaska", which can be linked to mineral deposits.

They pushed oil and mining companies to buy these images. Rumor has it that some of the major oil discoveries, partly due to information provided by the "Landsat". And the rural economy experts proved that they can make a quick inventory of agricultural crops.

It emerged from the initial experiments that the images of "Landsat" unable to distinguish between 29 different species of plants, and can identify differences in the fields between what is old or newly plowed, and newly harvested or still holds the crop. And benefit from the information "Landsat" More than a hundred countries, some of which receives this information directly in its stations for, and everyone uses this information in the follow-up crops, forests and water resources.

6. NOAA satellites

Launched the "Administration National Oceanic and Atmospheric" National Oceanic and: NOAA Atmospheric Administration: United States of America a group of satellites known as the NOAA in order to study or observation of weather phenomena and the heat of the ocean surface, and was the first of this series in 1960, with a The average height of flight of the first generation satellites about 1500 km above the Earth's surface, while the second generation of NOAA satellites, it was marked down the high flying to 834 kilometers. And in 1978 joined this generation satellite TIROS-N.

7. Satellite "SPOT"

France had argued that the management of natural resources of the country, requires the development of a system for collecting information, the moon, which provides as follows:

A. Conducting an inventory of ongoing sources of natural air, and water, and soil surface.

B. Note these environments and the evolution of each of them.

C. Predict the development and appreciation is expected to occur in each of these environments.

D. Facilitate certain economic activities, such as management of irrigation systems, drainage, and mineral exploitation.

So I thought France, in 1971, in the production of a satellite, to achieve such goals, therefore, established a development of remote sensing, air and space, and in 1973 joined this group by the Office of geological research and mineral resources. In 1974, project was the first satellite to observe the Earth and study, and called "SPOT" Satellite Pour Observation de le Terre: SPOT.

The main topics of the project are:

A. Of the system of multi-tasking, able to carry the devices, which help to study all of the land and oceans.

B. This system provided high-precision device, or ever explain high, and in the visible and near infrared.

A. Launch satellites "Spot"

In 1977 the French government approved the project, and what did not find enthusiastic partners in the European Space Agency ESA, has decided to implement the project itself, taking the brunt of the cost and effort, and the contribution of a small amount to 4%, from both Sweden and Norway. Was to launch moon "Spot -1" SPOT-1 in the February 22, 1986 from the city of "Toulouse", and on board the rocket Union "Irian -4" to a circular polar orbit at an altitude of 825 km.

Was chosen so that the moon's orbit passes over the same area every 26 days, but that a change in the design of smart cameras, makes it possible for cameras to the moon, when it passed the bar next door, that tend to restore the previous footage of the land. The result of this design, too, to the possibility of producing three-dimensional images of the terrain, which makes it easier topographic mapping.

B. The second satellite of the series "SPOT"

On January 22, 1992 launched a second satellite in the series "Spot", in a polar orbit similar to the first round, but it orthogonal, in other words, if we think like a first orbit around the Earth and vertical poles with, the level of the orbit will look like the earth is divided into two halves. It seems as liaison second orbit perpendicular to the other, and Madaran together to share the land into four sections. This has resulted in all the new to reduce the period between the successive two surveys of any point on the ground one of the satellites to 13 days, instead of 26 days.

C. Advantages of satellite "SPOT"

The satellite orbits take them down around the globe, which fly at altitudes ranging between 500 and 900 km in a polar orbit, or semi-polar, is the best option for the task of remote sensing. The French satellite "SPOT - 2" SPOT-2, flying at an altitude of 822 km and one of these satellites, and has the ability to shoot sector width of 120 km, and shows (Table satellite channels, "Spot"), frequency channels are working on satellite "SPOT ".

And scanning the moon "Spot" Earth in the form of tapes, each presented 108 km. However, the angle of vision of the moon surveillance tape of the land currently 120 km, and this difference ensures that there is coherence between the successive strips, and not waste any part without scanning.

D. Imaging satellites in the "SPOT"

Bodies of photography in the Moon "spot" of the two cameras Tlskopeten, covering each and every one of them displayed a strip of 60 km, and can move each camera angle 27 degrees from vertical, and taking into account the rising moon, that control the tendency of the cameras makes it possible to control the distance between tapes, can be separated, so that the distance between them about 800 km or so Tqribema Itlasqan, Vicuan together a tape double display of 120 kilometers.

The technology allows the focus to film sites of interest at the expense of other important sites, or re-shoot some sites, when the moon passes along them again, tilting the camera towards it.

E. Devices complementary to satellite "SPOT"

In addition to the cameras a "SPOT" devices "Allimitri" Telemetry transmitters sensing, remote control devices to guide the satellite and adjust its course, then there are the batteries, which it had the capacity, which shipped with solar energy, where picked up by solar panels wide. There is also the engine settings, the gas tanks and jets to maintain the orbit and to adjust the direction of the moon in orbit.

It can pick up signals directly if the moon was in the field of "vision" of a ground receiving station, or recorded signals on tape, and then sent to the bulk receiving station in the city "Toulouse", France, and others in Sweden, when the moon is in the field of "vision" of these stations.

And. Resolution Satellite Images "Spot"

Governs the accuracy of satellite remote sensing images coefficient "distinction" Resolution, and this factor depends on the strength of lenses Moon unfolding according to size. The satellite "Landsat" America is stuck at 30 meters partition coefficient, America did not allow less than this, but France did not respect this prohibition, and landed the moon, "Spot," the French partition coefficient from 10 to 20 meters, is planned to increase this resolution to 5 meters, a high accuracy, and thus can distinguish features of these images are small, such as buildings and installations