. The Rush to the Space . Services of space radio communication . The Satellites
Notes about the video: Cameras mounted on the Soyuz Fregat upper stage that sent Sentinel-1A into space on 3 April 2014 captured this superb footage. It shows liftoff, the various stages in the rocket's ascent and the Sentinel-1A satellite being released from the Fregat upper stage to start its life in orbit around Earth.
The 2.3 tonne satellite lifted off on a Soyuz rocket from Europe's Spaceport in Kourou, French Guiana at 21:02 GMT (23:02 CEST). The first stage separated 118 sec later, followed by the fairing (209 sec), stage 2 (287 sec) and the upper assembly (526 sec). After a 617 sec burn, the Fregat upper stage delivered Sentinel into a Sun-synchronous orbit at 693 km altitude. The satellite separated from the upper stage 23 min 24 sec after liftoff. Sentinel-1 is the first in the family of satellites for Europe's Copernicus program. It carries an advanced radar to scan Earth's surface in all weather conditions and regardless of whether it is day or night. This new mission will be used to care for many aspects of our environment, from detecting and tracking oil spills and mapping sea ice to monitoring movement in land surfaces and mapping changes in the way land is used.
With this mission, SpaceX’s Falcon 9 rocket will deliver 11 satellites to low-Earth orbit for ORBCOMM, a leading global provider of Machine-to-Machine communication and Internet of Things solutions. The ORBCOMM launch is targeted for an evening launch from Space Launch Complex 40 at Cape Canaveral Air Force Station, Fla. Credit:
The Rush to the Space
In the course of history, several socioeconomic movements have marked the development of many countries and changed their destiny. In North America it was the gold rush, the crossing of the West, or the first industrial revolution.
The space market is called to change the destiny of several countries and peoples. For decades, the United States has played an important leadership by their immeasurable thirst of discovery and technological advancements in several strategic space areas. In general, the human spirit is nourished by its discovery, that of the other and everything that surrounds it and influence.
Satellites are used to discover, to learn from others and to understand our terrestrial environment, as well as those of our neighbors and nearby. In this spirit, satellites are the tools which enable mankind to go to the end of his curiosity what are for the climate, the civil or military communication, sciences, technologies and, of sure, its defense.
A leader must in
By the National Aeronautics and Space Administration - Act of 2010 & 2016, NASA wants to promote the full use of space. This national space policy enacts that, a strong and competitive commercial sector of the space is critical to continue the progress of the space industry. The American nation is committed to encourage and facilitate the growth that supports its needs and increases its leadership in the creation of new markets and innovative entrepreneurs.
In short, the space is to be cleared and conquer. The United States are committed to achieve this and, for that, private companies are necessary. In this context, NASA do more and more partnerships with the private space industry since many years.
The forecast of a lack of service for the ISS, following the overturned of the Space Shuttle, provided a timing time to offer the lucrative market of the transportation to the private sector.
To fill the need of a commercial transportation service to the ISS, NASA used its Space Act Agreement Authority and has launched the COTS program for this purpose. The partnership would be, and is, to the benefit of the private sector as well the public, or even the entire U.S. economy.
To meet the requirements of this NASA's program, the private industry had proceeded in two stages. In the first one, the company had to proved that it can develop and demonstrate the capacity of its transportation system to go in Low-Earth Orbit (LEO). As for the second stage, bidders were required to demonstrate their capacity to structurally integrate their space technologies to the ISS. Once done, they could obtain the necessary certification for a cargo service of replenishment (cargo resupply services or CRS), in order to support the extension of the operations of the ISS.
Thus, followed this historic partnership program, SpaceX and Orbital Sciences have respectively, developed the Falcon 9/Dragon and the Antares/Cygnus, two spacecrafts for the transport of goods to the ISS. Subsequently, these vehicles will carry astronauts or other passengers.
The first of The Planetary Society's two LightSail spacecraft will ride to space aboard an Atlas V rocket in May 2015. The mission is a shakedown cruise designed to test out the CubeSat's critical systems.
In 2016, the second LightSail spacecraft will piggyback into orbit aboard the first operational flight of SpaceX's new Falcon Heavy rocket for a full-fledged solar sailing demonstration. For more information, visitsail.planetary.org.
ViviSat's in-orbit life extension and protection services are flexible, scalable, capital-efficient and low-risk, and can add years to the revenue producing life of a satellite. ViviSat opens the door to the satellite servicing market.The founding strategic investors of ViviSat are U.S. Space LLC and ATK.
The Antares rocket of Orbital Sciences has been successfully launched at 5 p.m., April 21, 2013, from the Mid-Atlantic Regional Spaceport's, in Virginia. The Antares launch vehicle made its maiden flight-test that served as the precursor to demonstrate the capacity of its Cygnus to resupply the International Space Station later this year. Antares will be delivering a mass simulator payload to orbit 10 minutes after launch designed to mimic the Cygnus spacecraft's weight and characteristics.
On June 4th, 2010 at 14:30 UTC the first ever Falcon 9 rocket lifted off from Space Launch Complex 40, Kennedy Space Center, Florida. Carrying the Dragon Spacecraft Qualification Unit this flight was designed to test not only the vehicle itself but also begin tests of the Dragon capsule. Oh yeah, and AWESOME names for the vehicles!
Proba V Satellite. Artiste view
The ripple effect of this collaboration was a profusion in the development of launch vehicles and private commercial rockets for the placing in orbit of satellites. See at right >>>
Why is this important?
Because they are located in altitudes, satellites can look more large surfaces of the earth. In doing so, they quickly collect more data than the instruments installed on the ground. In addition, these minis space stations see the space better than terrestrial telescopes, because they fly above the clouds, dust and molecules of the atmosphere.
Before the arrival of the satellites, the signals of the television not traveled not very far, because they could not circulate that in straight line. Then, because of the curvature of the Earth, the signals fade away in the space. A few times, too, the mountains or the large buildings were hampering their radiation.
The same phenomenon could create for the phone which, in addition, the infrastructure were very expensive. With the satellites, signals for the television and the telephone are sents to the satellites which them, almost instantly, the references to different locations on the earth.
Services of space radio communication
Regulations of radio communication refer to the services defined as the transmission and reception of radio waves for applications of specific telecommunications:
Fixed Satellite Service (FSS)-Mobile Satellite Service (MSS)-Broadcasting Satellite Service (BSS0-Earth Exploration Satellite Service (SEA)-the Space Research Service (SRS)-Space Operation Service (SOS)-Radio determination Satellite Service (RSS)-Inter-Satellite Service (ISS)-Amateur Satellite Service (SSA).
The allocation of frequencies in the frequency bands allocated can be exclusives for a given service or share between several services. The allowances follow the division of the world into three distinct groups:
-Region 1: Europe, Africa, the Middle East, the former USSR;
-Region 2: the Americas;
-Region 3: Asia Pacific, except the Middle East and the former USSR.
For example, fixed services of the satellites are in the following bands:
- The C band, which is around 6 GHz for the up link and 4 GHz for the down link, are occupied by the old systems such as INTELSAT, American domestic systems, etc. and are saturated. Regulation Radio # 13.
- The X band, which is around 8 GHz up and 7 GHz DN, be found of bands reserved by agreement to civil administrations, even for the government use.
- The Ku Band, which is around 14 GHz up link and 12 GHz down link, it is found in the Operations Sector of current development, such that offers the EUTELSAT satellite.
- The Ka band, which is around 30 GHz up link and 20 GHz down link, is a growing interest since it is located in a wide-bandwidth available and that there is little of interference due to its use rather limited now.
The bands above 30 GHz will be ultimately used in agreement with the technology in development.
The satellite service mobile uses the following bands:
- For the VHF (Very High Frequency) - 137 to 138 MHz for the down link / 148 to 150 MHz for the up link and, for the UHF (Ultra High Frequency) - 400 to 401 MHz for the down link / 454 to 460 MHz for the up link. These bands are only for systems non-geostationary.
- For the geostationary systems, such as INMARSAT, the band offers 1.6 GHz for the up link and 1.5 GHz for the down link. The systems non-geostationary for satellites such Globalstar, the up link is 1626,5 MHz and the down link is 1610 MHz.
For the satellite component IMT2000, International Mobile Telecommunications, it offers 2.2 GHz of down link and 2 GHz of up link.
Bands frequencies are also allocated to levels more senior as the Ka band.
The satellite service for television uses some 12 GHz for the down link. As to the up link, it is operated in the Bands FSS is called feeder link.
The currently largest active rocket in the world has been successfully launched with the U.S. Top Secret NROL-37 payload . The Delta IV Heavy launched from Space Launch Complex 37B at 17:51 UTC, June 11th 2016. This was the 32nd Delta IV launch, and the 9th Delta IV Heavy launch.
A satellite can be as much a moon, planet or machine that orbit a planet or a star. In this spirit, the Earth is a satellite of the sun and the Moon is that of our planet, just as a machine launched in space that orbit around a planet or of another body. In the latter case, there is talk of artificial satellite since it was manufactured. And, of course, the Moon is the natural satellite of the earth.
For more than fifty years, thousands of artificial satellites orbits the earth. Some take pictures of the planet to help meteorologists to predict the weather and follow the storms. Still others take photos of distant planets, the sun, black holes, dark matter or galaxies doting the universe. These photos are helping scientists better understand what surrounds us.
Image: Thales Alenia.
The Iridium-NEXT satellites are based on Thales Alenia’s ELiTeBus-1000 (Extended LifeTime Bus) satellite platform, each weighing 860 Kilograms at launch and measuring 3.1 by 2.4 by 1.5 meters in size in its stowed configuration. ELiTeBus has been utilized for the Globalstar second generation communications satellites and the O3b internet satellites that serve developing countries from an equatorial orbit.
The Iridium-NEXT satellites have been designed for an operational life of 12.5 years with a stretch goal of 15 years, holding sufficient propellants to support an extended mission.Read more at http://spaceflight101.com/spacecraft/iridium-next/#YbMFzHBAkYV8DqZb.99
Other satellites are used primarily for communications, as the transmission of signals for television and the telephone calls around the world. These commercial services can be fixed or mobile.
Types of orbits
The choice of the Orbit depends on the nature of the mission, the acceptable interference and the performance of the launchers.
The orbit is the path followed by the satellite. This trajectory is in a plan and is trained as an ellipse with a maximum extension to the peak, and a minimum in the Perigee. The satellite moves more slowly in its trajectory as its distance from the Earth increases.
The elliptical orbit inclined at an angle of 64 compared to the equatorial plane is particularly stable. It is all the more by renort to irregularities of the Earth's gravity and, thanks to its position, the satellite is able to cover the large portions of the Regions in high altitudes when it passes the Perigee. This type of orbit has been adopted by the USSR for the satellites of the scheme MOLNYA for periods of 12 hours.
The satellite remains above the regions located under the peak for a time interval of 8 hours. Continuous coverage can be ensure with three satellites placed on different orbits. Several studies relates the elliptical orbit with a period of 24 hours - orbit Tundra - or a multiple of 24h. These orbits are particularly useful for satellite system of communication such as mobile where obstacles are caused by high buildings and trees in the bottom angles, including at least 30 degrees.
In fact, the elliptical orbits inclined can provide the possibility of links to mid latitudes when the satellite is close to the peak with an angle close to 90 degrees. These favorable conditions can only be provided at the same latitude as the geostationary satellites.
Toward the end of the years 1980, in the framework of its program Archimedes, the European Space Agency has studied the use of highly orbits inclined elliptical (HEO) for its communications audios digital and mobile of broadcasting organizations. The concept has become a reality at the end of the 1990s with the scheme Syrius who issued radio services to digital million policyholders, including motorists, in the United States using three satellites on the Orbit HEO TUNDRA, either the ATK-08.
The low earth orbit circular (Circular low Earth orbits - LEO), is a constant altitude and equal for several hundreds of kilometers. The period is of the order of an hour and a half. With an inclination of nearly 90 degrees, this types of orbit ensures a global coverage in the long term and this, thanks in particular to a rotation in tandem of the Earth and the satellite. This is the reason that the satellites of observations Use this orbit. For example, the SPOT satellite is positioned at an altitude of 830 km with an inclination of 98.7 degrees for a period of 101 minutes.
A constellation of several tens of satellites in circular orbits low, such IRRIDIUM with 66 satellites at 780 km, can provide a communication in real time on the whole planet. The orbits non polar with a tilt of less than 90 degrees, can also be considered - for example, Globalstar has a constellation of 48 satellites at an altitude of 1414 km, of which the inclination of the orbit is 52 degrees.
The Medium earth Orbit (MEO) or intermediate is a circular orbit at an altitude of nearly 10 000 km with an inclination of about 50 degrees. The period of 6 hours, paired with a constellation of 10 to 15 satellites, guaranty a continuous coverage of the Earth, providing communications in real time.
The equatorial orbit with an inclination of zero, is the preferred location for the geostationary satellite. This orbit at an altitude of 35 786 km, the satellite moves around the Earth at the same speed as the Earth rotates on itself. This is what it gives the impression of being at a fixed point in the sky and ensures a continuous operation, such as the relay radio in real time for about 43% of the land surface.
Some systems may include combinations of orbits with circular and elliptical orbits. Such a design was envisaged for the ELLIPSO system.
Currently, a satellite that follows a low Earth orbit offers only a limited coverage of the earth, and for a limited duration on a targeted region. The geostationary satellite appears therefore as particularly useful for a coverage in continues of the regions. However, this is not possible to cover the polar regions which are that only accessible with satellites whose inclined orbits are polar or elliptical.
The elevation of the angle (tilt) - a satellite in a polar orbit inclined elliptical can appear above a certain time. This position, whose angles of élévatiion are between 0 and nearly 70 degrees, makes communication possible in urban areas without encountering obstacles such as buildings.
With a geostationary satellite, the anglle of Elevation decreases with increases the difference in latitude or longitude between the earth station and satellite.
Time and Duration of transmission - the geostationary satellite provides a continuous relay to stations visible but the time of propagation of waves of a station to another is 0.25 second. This therefore requires special protocols for the transmission data (or licenses of echo-control on the phones).
A satellitese moving into low Earth orbit offers a the propagation time of reduced. The transmission time is therefore low between the stations that are close to or simultannéement visible in the satellite, but which can be very long (several hours) for remote stations if one considers only the stotage and the sending of data.
The interference - the geostationary satellites occupy a fixed position in the sky in relation to the stations with which they communicate. The protection against interference between systems is ensure by planning the frequencies networks and the orbital positions.
The small orbital space between the adjacent satellites operating on the same frequencies bring an increase in the level of interference and this hampers the installation of new satellites. The systems will be able to use different frequencies but it is limited by the small number of frequency assigned for space radiocommunications by the regulations of radiocommunication. In this context, one can refer to a spectrum-orbital which, by contrast, is limited.
With the satellites in orbits, the geometry of each system changes with the time and the geometry of each system in relation to another is variable and difficult to synchronize. The probability of interference is then high.
The performance of the launchers - the earth that can be launched normally decreases to the extent that it increases in altitude.
The geostationary satellite is certainly the most popular because, currently, there were some 600 in operation with a orbital arc integer from 360 degrees. However, this space begins to be pretty darned congestion, including above the American continent and Europe.
Initially designed as ‘trunks’ which duplicate long-distance terrestrial links, satellite links have rapidly conquered specific markets. A satellite telecommunication system has three properties which are not, or only to a lesser extent, found in terrestrial networks; these are: —the possibility of broadcasting; —a wide bandwidth; —rapid set-up and ease of reconfiguration.
The preceding section describes the state of technical development and shows the development of the ground segment in respect of a reduction in the size of stations and a decreasing station cost. Initially a satellite system contained a small number of earth stations (several stations per country equipped with antennas of 15 to 30 m diameter collecting the traffic from an extensive area by means of a ground network). Subsequently, the number of earth stations has increased with Services 15 a reduction in size (antennas of 1 to 4 m) and a greater geographical dispersion. The stations have become closer to the user, possibly being transportable or mobile. The potential of the services offered by satellite telecommunications has thus diversified.
—Trunking telephony and television programme exchange; this is a continuation of the original service. The traffic concerned is part of a country’s international traffic. It is collected and distributed by the ground network on a scale appropriate to the country concerned. Examples are INTELSAT and EUTELSAT (TDMA network); the earth stations are equipped with 15 to 30 m diameter antennas.
—‘Multiservice’ systems; telephone and data for user groups who are geographically dispersed. Each group shares an earth station and accesses it through a ground network whose extent is limited to one district of a town or an industrial area. Examples are TELECOM 2, EUTELSAT, SMS, and INTELSAT (IBS network); the earth stations are equipped with antennas of 3 to 10 m diameter.
—Very small aperture terminal (VSAT) systems; low capacity data transmission (uni- or bidirectional), television or digital sound programme broadcasting [MAR-95]. Most often, the user is directly connected to the station. VSATs are equipped with antennas of 0.6–1.2min diameter. The introduction of Ka band will allow even smaller antennas (USAT, Ultra Small Aperture Terminals) to provide even larger capacity for data transmission, allowing multimedia interactivity, data-intensive business applications, residential and commercial Internet connections, two-way videoconferencing, distance learning and telemedecine.
—Digital audio, video and data broadcasting; the emergence of standards for compression, such as the MPEG (Motion Picture Expert Group) standard for video, has triggered the implementation of digital services to small earth stations installed at the user’s premises with antennas of the order of a few tens of centimetres. For television, such services using the DVB-S standard are progressively replacing the former broadcasting of analogue programmes. Examples of satellite systems broadcasting digital television are ASTRA, HOT BIRD, DirectTV, ASIASAT, etc. For sound, several systems incorporating on-board processing have been launched in such a way as to allow FDMA access by several broadcasters on the uplink and time division multiplexing (TDM) on a single downlink carrier of the sound programmes. It avoids the delivery of the programmes to a single feeder earth station, and allows operation of the satellite payload at full power; This approach combines flexibility and efficient use of the satellite. Examples of such satellite systems are Worldspace, Sirius/XM-Radio. The ability of the user terminal to process digital data paves the way for satellite distribution of files on demand through the Internet, with a terrestrial request channel or even a satellite-based channel. This anticipates the broadband multimedia satellite services.
—Mobile and personal communications; despite the proliferation in cellular and terrestrial personal communication services around the world, there will still be vast geographic areas not covered by any wireless terrestrial communications. These areas are open fields for mobile and personal satellite communications, and they are key markets for the operators of geostationary satellites, such as INMARSAT, and of non-geostationary satellite constellations, such as IRIDIUM and GLOBALSTAR. The next step bridging the gaps between fixed, mobile and broadcasting services concerns satellite multimedia broadcast to fixed and mobile users, known as satellite digital mobile broadcasting (SDMB). Mobile TV services are available on terrestrial 3G networks in a point-to-point mode, not optimised to deliver the same content to many users at the same time. Smart overlay broadcast networks based on hybrid satellite– terrestrial mobile systems will efficiently provide end users with a full range of entertainment services with interactivity [WER-07]. A dedicated standard (DVB-SH) has been developed for these mobile broadcast applications.
—Multimedia services; these services aggregate different media, such as text, data, audio, graphics, fixed or slow-scan pictures and video, in a common digital format, so as to offer excess potential for online services, teleworking, distance learning, interactive television, 16 Introduction telemedicine, etc. Interactivity is therefore an embedded feature. They require an increased bandwidth compared to conventional services such as telephony. This has triggered the concept of an information superhighway. Satellites complement terrestrial, high-capacity fibre, cablebased networks with the following characteristics: use of Ka band, multibeam antennas, wideband transponders (typically 125 MHz), on-board processing and switching, a large range of service rates (from 16 kbit/s to 10 Mbit/s) and quasi-error-free transmission (typically 10 10 bit error rate).
THE WAY FORWARD