It was the science fiction author Arthur Clarke who in 1945 imagined communication by geostationary satellite via a satellite positioned in a circular earth orbit whose period of rotation is the same as that of the Earth, the force of gravity being moreover equal to the centripetal force. […]
Since the launch of the first Russian satellite Sputnik in 1957, a large family of satellites was developed, and today we can distinguish several families of satellites classified according to their orbit (circular or elliptical) or by their altitude (geostationary orbit, high, medium or low elliptical orbit).
A satellite communication system comprises satellites whose orbits have different planes so as to be able to cover the entire terrestrial sphere. The propagation of electromagnetic waves in space often involves parabolic antennas or laser transmissions.
The first generations of satellites were primarily intended for mobile communication (Intelsat, Immarsat, Iridium, GlobalStar, Orbcomm, etc.). They have given way to a new generation of satellite systems for high speed video and data transmissions.
The allocation of DBS (Direct Broadcast Satellite) frequencies has been regulated internationally, and television broadcasts from around the world can be relayed by satellite and received through very small aperture terminals (VSAT). Over the years, technological mastery of higher frequencies has made it possible to operate with smaller antennas.
Versatile satellite applications
Satellites are used as a means of land, air or sea navigation (American GPS, Russian Glonass, European Galilee, Chinese Beidou, Indian NAVIC and Japanese QVSS systems). They find their application in meteorological or space observation, the evolution of climate change, the measurement of variations in the terrestrial magnetic field, the management of road traffic or the best planning of agriculture. International space stations (Skylab, Mir) carry out advanced research in materials science and biological research under conditions of microgravity.
The 6G cell generation will integrate satellites into the 5G cellular network in order to serve the entire globe and the seventh generation 7G will include transhumance (roaming) in the space.
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The European Planck satellite and the American James Webb space telescope (which orbit the Sun, but always behind the Earth so as to observe space away from solar emissions) map space with a precision whose resolution angular and thermal are the highest and will allow a better understanding of the structure and formation of the universe.
Gone are the romanticism of starry nights?
For a long time, poets and dreamers admired the sky and sang its mysteries. However, nearly 50% of Europeans and 80% of Americans are no longer able to observe the Milky Way due to light pollution caused, among other factors, by street lighting. What’s more, the plethora of low-level artificial satellites are likely to dominate night vision. More and more nanosatellites, not shooting stars or meteorites, roam our night sky and occasionally reflect sunlight.
There are nearly 3,500 active communications satellites orbiting the planet, and that number will surpass 40,000 by the end of the decade. Let us mention the low-altitude satellite systems projects underway which include the American systems Kuiper and Starlink, the French LeoSat, the British OneWeb and the Canadian Telesat. License applications for 100,000 communications satellites by 2030 have been filed with the International Telecommunication Union (ITU).
The trend which seems to dominate the market is the launch of nanosatellites (Tubesat, Cubesat, Ardusat…). Cubesats are 10 cm square cubes weighing 1.2 kg. Several dozen can be launched into space by a single rocket.
Militarization of space
Military satellites perform reconnaissance, surveillance and wiretapping missions. They can also detect ballistic missile launches in real time.
Satellites are also used to improve the trajectory of missiles and drones and are closely watched when they are not a priority target. However, the development of anti-satellite weapons calls into question the principle of non-interference with satellite communications and increases the risks of false perception of the adversary’s intentions. Indeed, the satellites are equipped with ultra-sensitive sensors which allow close monitoring of the nuclear arsenals of adversary countries and compliance with treaties on the limitation of strategic armaments (such as SALT and START). China, the United States, France, India and Russia have set up units that are interested in the militarization of space.
The satellite destruction tests carried out by China and Russia further encumber the ring of satellites or debris from satellites orbiting the earth. The destruction of a satellite can release tens of thousands of shards of metal. Destructive and dangerous collisions with orbiting satellites can ensue. In addition, operations of electromagnetic jamming of satellite signals or the emission of electromagnetic pulses of high energy (EMP) could literally burn all the electronic circuits. Imagine for a moment the impact that the interruption of the GPS location service could have on everyday life …
Any technological advance has civil and military repercussions. Dazzling technological advances are solving a lot of problems and creating new ones. The space treaty ratified in 1967 prohibits the use of weapons of mass destruction (nuclear weapons) in space, but does not take into account other types of weapons such as powerful laser beams.
Commercial and national interests currently have the force of law, and it would be wise to realize their implications and act accordingly.