Future of the Space Communication and Challenges, Issue, Application and Technology
Future of the Space Communication and Challenges, Issue, Application and Technology Introduction
Satellite communication is an advanced stage of wireless communication systems of the by gone era. Satellites may have different shapes and sizes. Communication satellites made this world global, interconnected and interdependent. After the launch of the first satellite Sputnik into space by Russia in the year 1957, US launched Explorer I .By the end of 1958, satellite with Signal communication by orbital relay was made possible and the first ever message was broad cast. It operated for less than a fortnight. But the number of satellites launched by the then USSR and US was six. The number of satellites launched grew to 14 in the next year, 1959 and to 19 in 1960. In a couple of years from then, UK and Canada joined the race of launching satellites. These were not without draw backs. By the year 1965, complete earth coverage was made possible by the launch of INTELSAT into geostationary satellite. From then on the race speeded up, with more nations joining the space race and even developing nations entered the foray. And today there are innumerable satellites orbiting the earth, busy carrying communication between space and earth. The three main orbits into which satellites are launched are the Low Earth Orbit, Medium Earth Orbit and Geo Synchronous Orbit. The first ever communication satellite launched in space was in the year 1957. The first communication satellite was launched in 1960 by US, made of aluminized plastic balloon. It was equipped with a transmitter and receiver. The drawback of that was it allowed communication for about ten minutes out of ninety minutes that it took to orbit the earth. First ever television signals were relayed by Telstar1 and later Telstar 2. These were the Low-Earth Orbits. Syncom series of communication satellites were the geo synchronous and geo stationary satellites that paved the way to the live telephone calls between different nations. The basic difference between geo synchronous and geo stationary orbits is the existence of only one Geo synchronous orbit. Today there are a large number of satellites dotting this orbit, since it is the most widely used earth orbit. Geostationary satellites appear to be stationary, since these have their time periods synchronized with the earths 24 hours orbital period. Their orbit is circular and it lies in the plane of the earths equator. These had the ability to transmit signals to every part of the earth, Polar Regions alone remaining an exception. Thousands of telephone signals were transmitted across the various nations. That was the time when the live telecast of major events was being transmitted live to different parts of the globe. Middle Earth Orbit satellites, were used along with Geostationary Orbit satellites. The basic difference between Low Earth Orbit satellites and Geo Stationary orbit satellites lies in their antennas. The Defense communication satellite system were launched, a few years later .Twenty six satellites, in groups of four, were let into geo stationary orbits. These initial military related satellites have now seen major developments, with all the features of advanced digital technology Maritime and aviation communications also have undergone tremendous changes due to the reliability, flexibility and accuracy of the satellite communication systems. All of these operate in groups in the geosynchronous orbits with signals at in the Extremely-high, Super-high and Ultra-high frequency modes as per the requirement. The Fleet Satellite Communication systems provide global operational capabilities for naval aircraft, ships and submarines in the US (Evans, B.G. 1999.p. 22-26).
UK began its space adventures with the launch of skylark in the year 1957. Todays satellite networking covers a wide range of operations related to secure military communications, satellite based broad casting, astronomy, earth sciences and in many other fields of study.UK has now grown into the worlds one of the most competitive global mobile satcom operators (UK Space Agency, 2010).
The Indian competence has grown over the past four decades in relation to the space technology programs. It has attained significant heights in every possible fields that satellite communications can reach out, most successful being the indigenously developed INSAT and GSAT systems. These have revolutionized the nation, giving it an entirely new position on the global satellite communication technology map (Thorpe, E. 2008.p. 35).
The different types of satellite connectivity includes fixed to fixed, fixed to mobile and inter connectible systems. Remote areas did not have access to most of the developments in the field of information technology. Extended Satellite communication network brought even such remote, inaccessible corners of the planet into the rhythm of the developed nations.
Earth based infrastructures may be susceptible to different types of catastrophes, manmade or otherwise. The features of non-earth based platforms provide features that are unique with respect to public safety. Satellite communication systems, applied to all walks of life seem to have guided the technological innovations through a new era. A brief look into the satellite communication systems shows that it is independent of terrestrial infrastructure, it is the sole, highly reliable network that connects people where other conventional systems fail and has multitudes of load capacity, enough to connect the entire world in the least time. A group of satellites can give an entire coverage of the earths surface.
Where remote regions need connectivity and costs of fiber networking are prohibitive, satellite service is the best option. These can connect with any other type of communication solutions like wifi or VOIP through cross band equipment. Day to day weather prediction and high quality weather imaging is made possible through this networking. Global broadcasting service can transfer large volumes of data, that includes videos, maps, charts , weather patterns and digital data, all at one go within seconds. The development of picosats that weigh about 2 pounds is a revolution in the field of aerospace technology. Picosats are launched from a micro satellite(Dailywireless, 2010).
Satellite communication systems are inevitable in the present day life. These are similar to radio-relay stations in space. Telecommunication network has its functioning governed by the satellite network Systems. Covering the entire range of the planet geographically has made it an indispensable part of weather mapping and predicting weather related information, there by forecasting hazards of natural disasters in advance for the people and government to act in a timely manner.
Satellite systems use radio waves as signal for transmission and receiving. Global broad cast services like transfer of large volumes of digital data, one way, to large number of receivers simultaneously, is the technology related to commercial T V broadcasts. Different services are allocated different frequency ranges in accordance with the international regulations. Geostationary orbits of about 36000 km altitude in have the least constraints related to tracking of earth stations. Low earth orbits at about 1000 km altitude are used for mobile and personal communication systems. Middle earth orbits are between LEO and GEO, which are again useful in the mobile communication fields. This vast range of services being utilized vastly has now led to congestion of the space orbits, as using 18 to 24 satellites is required for their operation, for a continuous global coverage. Greater traffic handling capacity and greater overlapping capabilities ensure the mitigation of satellite network failure. Reliability of satellite systems improved the accuracy of aviation and maritime communications. Even though fiber optics, microwave technology, submarine cables compete with satellite communications, flexibility provided by satellite communications meets the essential requirements and demands of military operations. In US for example, the defense satellite communication system is operates at super high frequency ranges and is comprised of geo synchronous satellites, ground terminals varying over a large range and a common control segment. On the whole this functions as Global Command and Control System providing every type of communication, meeting the requirements of defense information systems network, defense message system, and in the helping of other nations too. The Navy and Air force use air borne and ground borne terminals(Fortescue,P.W.et al. 2003.p. 618-622).
Many satellites have been put into orbit to conduct research and scientific experiments like the SOHO. As a result, space research and astronomical observations are more accurate now than ever. Weather pattern studies are improvised due to remote sensing abilities of the satellites and the meteorological data collected by these is useful in geographical mapping of locations and pre- warnings of weather related disasters has become more common. This enables the government and civilians to act appropriately. The GPS developed originally for the military usage is now being used to find the location of a place, its exact latitude, longitude and altitude, anywhere on earth. The orientation of future satellite communications is taking mobile telephony and connectivity to any part of the planet(Wilson, J. 1996.p. 35).
Coming to the present scenario, more than 200 nations across the world rely on these for every aspect of domestic, regional , global broadcast and telecommunication services. It is now an industry that has seen an expansive growth, especially in the mobile communications sector. From the days of research, its a billion dollar industry thriving ubiquitously.
Applications
The applications of satellites are too many. Inter-connectivity of continents is of major significance. Fixed service satellites, Direct broad cast satellites, satellite radio, mobile satellite technologies are all now in the forefront of the day to day life of the common man of almost every nation .are responsible for the television network.
The basic communication networks find applicability in weather mapping, TV and radio broadcasting, communicating live events across the globe, telecommunication networks, without which the present day world cannot be imagined, mobile and cellular services, data transfer in large volumes, internet services and many other forms of global communication systems. Bringing the most remote locations much closer to the internet routes is an advancement achieved through the satellite networking system. Land and water resources management , weather forecasting, natural disaster forecasts, meteorological studies, Bio information technology ocean sats for study of oceans, connecting transport and conveyance across the globe, guiding the economy through stock exchange updates through streams of data transfer are the latest developments applied in everyday life of all developed and developing nations in todays world.
A group of orbiting satellites can cover the entire earths surface. By placing each satellite at a specific location around the planet, complete coverage is maintained. This is independent of the terrestrial infrastructure. Temporary usage can also be aimed at in times of need for the coverage of a particular event or activity. These support high level communications at no additional expenditure. Military effectiveness and precision of mapping routes and targets is achieved by satellite to satellite communications apart from the satellite to ground relays. For instance, the DSCS of the US operates at SHF .This has multiple ground terminals, remote control segments and geo synchronous satellites. Aviation technology bloomed in the advent of space projects and thats the most dominating wing in the present day political outlook of the developed nations. It is the MEOs that offer the real time services. Data transfer via internet is routed through the LEOs. Since these LEOs and MEOs are located in orbits much closer to earth, these reduce the space loss and propagation delay. The possibility of reusability of frequency is also higher. Proper maneuvering of these satellites provides continuous coverage of the earth, including the Polar Regions. This gives them an upper hand above the GEOs Different sets of users being able to pick up or choose their own channels or data streams, through a nano device is the major trend setting development. The future developments may see a communication network based on other planets also which might be used to resourcefully empower our own planet earth (Carter, A.B. 1987.p. 249-251).
Challenges
The future of communication satellites has to deal with the security challenges, imbalance between available resources and needs of the ever increasing population, Growing of number of satellites in the space are a threat to collisions between the satellites. Due to rise in demand from all quarters, band width shortage is becoming a problem. New challenges faced are related to improvisation in the technology of satellites, population of satellites in space, with more and more nations joining the band wagon of space communications, debris management to avoid long term affects on existing , working satellites, international space management regulations and policies, geographical variations that are spear heading fast due to various factors affecting the global transitions, and national international security threats requirements. These challenges are common to all nations. Every nations infrastructure depends basically on the communication networks. To build an authentic, cost effective satellite networking, reducing the satellite related infrastructure, thus maintaining simplicity in their management brings a lot of changes in the typical networking bases.
Every public or private sector are interrelated in one way or the other through this feature These are most vulnerable to attacks from adversaries, in the form of damaging potential military controls and command systems. If computer based infrastructure or networking is attacked, it badly affects an entire nations functioning, not merely in technology world but also in every other aspect like the governing bodies functionaries failing to meet the safety and requirements of its people and also has the dangers of getting de linked from other nations. The use of computer networking operations and space communication protocols, more so in military , aviation and maritime has rendered even the worlds most advanced nations also insecure. In what way seems obvious. This is the most crippling challenge in front of the scientists and space technologists to develop means to protect the existing advanced space based technologies from the attacks of the terrorists. Urban populations, growing by leaps and bounds are another factor that affects imaging and tracking of critical information.
Major military operations like testing nuclear weapons in the atmosphere, in outer space have to be stopped. The increasing costs globally, make the research development of future technology a burden on the nation. To build and maintain the satellite communications systems required to meet the basic infrastructure needs of a nation turn out to be a burden on the countrys economy.
Offering proper bandwidth, with the increase in the number of broadcasting and mobile communication systems, dotting the space is a day to day crisis, to be resolved by joint multinational operations. The coming years will see a strengthening of nations in the field of space research and an advanced communication systems network internationally and mutual co-operation and understanding among the space rich nations. Strictly implemented rules need to be followed for the protection of the space orbits. Nations compete to be in the prime supplier category ,in view of international commercial competence in the space technology
What is the source of orbital debris Most of the orbital debris (50 or more) is derived from the upper stages of rockets, left in space after a space craft is launched in orbit and the small particles of aluminum oxide from the exhaust of these upper stages , paint and particles from thermal insulation , fragmentation , propulsion related problems, deliberate destruction of satellites that undertake space weapons testing are all orbital debris, that need immediate attention of space- research capable nations.
Orbital debris is the immediate space environment growing problem that requires solution in the near future. Orbits of orbital debris are in the full range of the earths orbit, orbiting in different directions at speeds of 4 kms to 7 kms. This may continue to orbit earth for several centuries. This poses a threat to a working satellite. Developing cost effective strategies to reduce orbital debris reduction is a major option. But not having adequate data on the distribution of data hampers steps to its reduction. Lot of uncertainty exists in the nature and extent of damage that may occur due to smaller particles. Nations should also avoid deliberate fragmentation of satellites in space. Making the satellites passive through electric shorts, reducing their altitude and thus bringing them to earths atmosphere levels, so that atmospheric drag brings them down, is one of the options. This is an expensive option but to avoid future failures of space missions should be given higher prominence. The risks involved in removing debris from low earth orbits are to be handled cautiously to avoid harm to human life. This problem needs international treaties to be developed among all the space capable nations to devote to this problem (National Research Council (U.S.). Committee on Space Debris. 1995. P. 154)
Almost all nations, the world over depend largely on computer network operations. The communication network, emergency services, government and public services, economy, health and so on all rely to a greater extent on computer network operations. And these wide range communication net works, in turn depend on satellites. The developed nations are particularly vulnerable to attacks on their communication networks. Terrorists are not the only enemies of a state or nation. Cyber-warriors pose a greater threat. During the Gulf war 1991-2003, air power dominated. But Iraq 2003 -2008 Afghanistan war, air power faced target ambiguity challenge due to the random movements of opponents. Such difficulties are overcome only through smarter satellite based communication net workings. Micro and nano satellites are growing in number with more nations eyeing these. Placing these nano satellites into orbit needs special launching vehicles and these can be put into orbit by launching them in groups (Cordesman, A.H. 2003. 195-200)
The global pace of present developments in computer technology , nano technology bio technology et al are driven by commercial interests . Even though this makes regulations on space difficult, these have the technology to bring about a radical change and in the revolutionary breakthrough in air and space power capabilities. Unmanned-Aerial Systems and Directed Energy Weapons illustrate this fact. Space communication through satellites is bound to bring radical changes in all types of developments related to defense and military. Future operations are most likely to be of varying endurance and intensity handling the multiple challenges of urban clutter. Air and space power are reliant on computer networking operations. This leads to the requirement of enhanced air based surveillance .Global positioning systems plays a vital role in both civil and military applications. This in turn demands GPS security or guide access to alternate positioning systems. By the year 2030, more international agreements will be needed by the developed nations to reach an agreement on access to key orbital positions of satellites. Regulatory frame work for satellite communications will be required periodically , over the coming years (Chun, C.K.S. 2001.p. 295-300).
The most dominating space debris challenges are It may interfere with scientific, commercial and military space activities. For example, Hubble space telescope has the problem of none functioning or getting damaged due to collision with space debris particles. Possible solutions to this include removal of 2 to 5 per year which brings stability in LEO environment. Community consensus, cost effective technology , ownership and liability and alternate target selection criteria are a few long standing possible solutions in the wake of the serious orbital debris and LEO environment challenges to space-research oriented nations. Special concern should be given when spaceflights carry humans, because orbital debris may pose a threat to them. There seems to be no effective way of removal of orbital debris. So designing satellites in ways that reduce the debris production, after their life time is finished is one way to manage it. The number of inactive satellites in space outnumbers the working satellites. Protection against impact of particles and protection through the avoidance of collisions using physical protection shielding are important. Human crew in space should be protected through various operational procedures. The astronomical observations, made by astronomers completely get disturbed by the orbiting space debris. Taking in view of seemingly large problem looming ahead the long term remedial measures should be adopted through ground based operation terminals.
Collisions between satellites ,like the most recent one between Iridium satellite and the defunct cosmos 2251 satellite in space increases the dangers of significant rise in space collisions that gives away to further collisions with active satellites. This recent collision happened at an altitude of 770 km, the most crowded region in space and increased the risk of more collisions(National Research Council. 2009. p. 46).
Both mechanically and electronically controlled radar beams can be used to detect and identify space debris. Mechanically radars are used in tracking and imaging satellites while electronically controlled radar beams are used for tracking and searching satellites. This tracking procedure helps in identifying physical properties like the debris mass, properties, orbital life time.
Technology
In general a satellite should be given a speed of 17000 mph to orbit the earth. Positioning in the orbit and the stability in orbit are the key deciding factors, for effective data relay transfers. Solar powered batteries, with the solar panels installed for electricity generation meet the electricity needs of the satellites. Communicating from ground station to satellite is the uplink and from satellite to ground is the down link. The transponder of the satellite converts this uplink frequency and is received by another downlink earth station. The receivers and transmitters are inevitable for the functioning of a satellites. It is the radio waves that get transmitted , at various frequency ranges like the extremely high frequency, ultra high frequency and the like. Uplink downlink frequencies depend on the orbit of the satellite. The equipment used by a satellite is the payload. This pay loads designing differs from one satellite to another, based on the utility of that satellite. Digital cameras, radar equipment, electronic devices and antennas will all be a part of a pay load (Chartrand, Mark R. 2004. p.91).
As per Fortescue(2003), LEO is at about 300 miles altitude and a GEO at 23000 miles altitude approximately. So according to their requirements, due to differences in altitude, antennas are designed o suit their respective orbits and orientations. Defense satellite communication systems now include thermal infrared aerial and satellite imagery systems are of utmost clarity, giving real-time images used for the military purpose. These military and spy satellites are often powered by miniature nuclear power plants for their internal electric current supply, and are loaded with the most powerful sensors.
High Altitude Platforms are a sound alternative to the preventive rising expenses, in this arena. Around 4750 MHz frequency and reusability of frequency seem to be a better alternative, signal tenacity being no compromise. Satellites operational band width is important, and band width availability is the growing space challenge at present. Geostationary orbit is only one but there are innumerable polar orbits. Satellite to ground station, satellite to satellite crosslink systems and hybrid systems are in operation. The days ahead are bound to see advances in multi sensor data fusion, electronic warfare target location systems, anti-jamming channel coding models, self organizing mesh networks and automatic communications with multi-resolution channel systems. Parasitic antennas are being developed for cellular communications. To have an overview of the present frequency bands in usage, the most popular are the C - , Ku- and Ka- bands. C is the most common bands readily available. But this is prone to more radio frequency interference. The higher bands are more expensive than C band , and these make use of satellite capacity effectively. But signal disturbances due to bad weather conditions have to be overcome. The satellites with different polarizations can be collocated to enhance their capacity by using dual gridded reflectors. These dual gridded reflectors improvise the cross polarization effects. Methods are developed for frequency reuse and system capacity increase. The military satellites are designed to orbit in the geo synchronous orbits at Operable UHF, SHF and EHF, range of frequencies. High gain parabolic antennas are used for quick relays (Evans, B.G. 1999. P.586-596).
The transition from analog to digital television transmissions has improved the quality of the signals. Where analog signals occupy vast range of frequencies on a satellites transponder, digital signal are able to compress the signals and deliver high quality range of channels. Personal Video Recorders provided directly via satellites to individual customers is a land mark achievement in TV broad casting.
The onset of satellite era changed the outlook of military, aviation and maritime operations. The first fully operative military satellite began operations in the early 1970s. Advancement of technology led to spy satellites being launched in space. It was first done by US and erstwhile USSR, but now several nations took to the race of spy satellites. The most advanced sensors and high resolution cameras being a part of their payload. Tracking of far reaching regions require high resolution systems.
The latest technologies are looking at high-level operational concepts of command and control in relation to military and aviation sectors. The viability of future implementations has to be looked into from all ends, including cost effectiveness and then optimal implementation of that infrastructure is bound to benefit both national and international security scenario. Application Programming Interface helps users to choose required components suitable for their requirement middleware infrastructure provided by the standardized interfaces. Space surveillance can reach the zenith by coordinating geo synchronous orbit satellite and another satellite in an elliptical orbit with a common ground system (Dimov Licev, Stojce, 2005. p.8).
To conclude the advent of satellite technology has now out grown. In spite of increasing demands of domestic needs of the nations. From the days of a 4600 kg satellite, its now a Pico satellite of 1 kg that comes with all the advancements that technology has necessitated. From the early days of civilian remote sensing data, it has now developed into multi faceted consumer oriented corporate business. Remote sensing satellites selling high resolution data to nations that cannot launch satellites and are in need of assistance for military and civilian requirements are on the rise (Information Gatekeepers, Inc. 1997. p. 14-16)
According to latest reports, air transport will double in the coming decade. The present communication management systems cannot cope with this unless strategies to improvise the safety and security measures are taken by the government aided policies. Technically, VHF and HF that are being at present used have limitations. The existing technology in military satellites is not sufficient to meet the needs of present day seemingly troubled, insecure world. Much more reliable and stable breakthrough in the field of information technology, with faster communication systems alone could save the planet from the potential attacks of terrorist and natural disasters. Networking is the basis to this because interlinking various command centers and being able to operate these from a single station serve the purpose well. Protected communication network system enables the misuse of data transfer and also unauthorized usage. Advanced narrow band and wide band frequencies provide the protected network in a channelized way (Evans, B.G. 1999. P.586-596).
Future of satellite communication goes on hand-in-hand with the market needs. Bringing solar power, generated in space to earth, to meet the power needs is the future solar powered satellite, which needs to be prioritized. From unmanned to manned satellites is the future agenda of this space age.
The Space communications reached the peak of its significance in the industry not just of media, but also of some other social functions. It has been a great help in delivering of information that benefit the government and a lot of people across the globe. It was primarily created and used to provide wider scope of communication functions then later used to help people in everyday living but throughout the years, this powerful manmade tool was devised to benefit an isolated people in gaining power as it was used in warfare. The role of space communication has tremendous pace of increasing thus, the ability of mankind to moderate its capability to make it biased in favor of majority.
Space communication is a showcase of power devoted to be in the service of the people and any act using this which can harm anyone or invade interests of anybody spoiled the great idea that its pioneering persons envisioned. The extent of its ability remained a valid consideration why we need to have its potential threat and benefits observed. Only thru endeavors in keeping this communication mean as a public tool will keep it on track of valuable improvement. Its pace of improvement is terrible and keeps on surprising us. This pace made it so dynamic that the call for keen moderation seems to be necessary.
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