How Satellite TV Works

Introduction to How Satellite TV Works

Photo courtesy DirecTV Satellite TV requires a satellite dish. See TV pictures.

When satellite television first hit the market in the early 1990s, home dishes were expensive metal units that took up a huge chunk of yard space. In these early years, only the most die-hard TV fans would go through all the hassle and expense of putting in their own dish. Satellite TV was a lot harder to get than broadcast and cable TV.

Today, you see compact satellite dishes perched on rooftops all over the United States. Drive through rural areas beyond the reach of the cable companies, and you'll find dishes on just about every house. The major satellite TV companies are luring in more consumers every day with movies, sporting events and news from around the world and the promise of movie-quality picture and sound.

TV Technology HDTV Plasma Displays Digital Converter Box

Satellite TV offers many solutions to broadcast and cable TV problems. Though satellite TV technology is still evolving, it has already become a popular choice for many TV viewers.

In this article, we'll find out how satellite TV works, from TV station to TV set. We'll also learn about the changing landscape of TV viewing and some basic differences that distinguish satellite TV from cable and over-the-air broadcast TV.

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Problems with Broadcast TV

Conceptually, satellite TV is a lot like broadcast TV. It's a wireless system for delivering television programming directly to a viewer's house. Both broadcast television and satellite stations transmit programming via a radio signal (see How Radio Works for information about radio broadcasting).

Broadcast stations use a powerful antenna to transmit radio waves to the surrounding area. Viewers can pick up the signal with a much smaller antenna. The main limitation of broadcast TV is range. The radio signals used to broadcast television shoot out from the broadcast antenna in a straight line. In order to receive these signals, you have to be in the direct line of sight of the antenna. Small obstacles like trees or small buildings aren't a problem; but a big obstacle, such as the Earth, will reflect these radio waves.

If the Earth were perfectly flat, you could pick up broadcast TV thousands of miles from the source. But because the planet is curved, it eventually breaks the signal's line of sight. The other problem with broadcast TV is that the signal is often distorted, even in the viewing area. To get a perfectly clear signal like you find on cable, you have to be pretty close to the broadcast antenna without too many obstacles in the way.

The Satellite TV Solution
Satellite TV solves the problems of range and distortion by transmitting broadcast signals from satellites orbiting the Earth. Since satellites are high in the sky, there are a lot more customers in the line of sight. Satellite TV systems transmit and receive radio signals using specialized antennas called satellite dishes.

Satellites are higher in the sky than TV antennas, so they have a much larger line of sight range.

The TV satellites are all in geosynchronous orbit, meaning that they stay in one place in the sky relative to the Earth. Each satellite is launched into space at about 7,000 mph (11,000 kph), reaching approximately 22,200 miles (35,700 km) above the Earth. At this speed and altitude, the satellite will revolve around the planet once every 24 hours -- the same period of time it takes the Earth to make one full rotation. In other words, the satellite keeps pace with our moving planet exactly. This way, you only have to direct the dish at the satellite once, and from then on it picks up the signal without adjustment, at least when everything works right. (See How Satellites Work for more information on satellite orbits.)

At the core, this is all there is to satellite TV. But as we'll see in the next section, there are several important steps between the original programming source and your TV set.

Satellite TV System

Early satellite TV viewers were explorers of sorts. They used their expensive dishes to discover unique programming that wasn't necessarily intended for mass audiences. The dish and receiving equipment gave viewers the tools to pick up foreign stations, live feeds between different broadcast stations, NASA activities and a lot of other stuff transmitted using satellites.

The Wild SideEarly satellite TV viewers who used C-band radio for their broadcasts were able to catch wild feeds of syndicated programs, sporting events and news. These broadcasts were free, but viewers had to hunt them down -- they didn't get previewed or listed like regular broadcast programming. These signals still exist, and Satellite Orbit magazine publishes a list of today's wild feeds.

Some satellite owners still seek out this sort of programming on their own, but today, most satellite TV customers get their programming through a direct broadcast satellite (DBS) provider, such as DirecTV or DISH Network. The provider selects programs and broadcasts them to subscribers as a set package. Basically, the provider's goal is to bring dozens or even hundreds of channels to your TV in a form that approximates the competition, cable TV.

Unlike earlier programming, the provider's broadcast is completely digital, which means it has much better picture and sound quality (see How Digital Television Works for details). Early satellite television was broadcast in C-band radio -- radio in the 3.7-gigahertz (GHz) to 6.4-GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range (11.7 GHz to 14.5 GHz ).

The Components
There are five major components involved in a direct to home (DTH) or direct broadcasting (DBS) satellite system: the programming source, the broadcast center, the satellite, the satellite dish and the receiver.

• Programming sources are simply the channels that provide programming for broadcast. The provider doesn't create original programming itself; it pays other companies (HBO, for example, or ESPN) for the right to broadcast their content via satellite. In this way, the provider is kind of like a broker between you and the actual programming sources. (Cable TV companies work on the same principle.)
• The broadcast center is the central hub of the system. At the broadcast center, the TV provider receives signals from various programming sources and beams a broadcast signal to satellites in geosynchronous orbit.
• The satellites receive the signals from the broadcast station and rebroadcast them to Earth.
• The viewer's dish picks up the signal from the satellite (or multiple satellites in the same part of the sky) and passes it on to the receiver in the viewer's house.
• The receiver processes the signal and passes it on to a standard TV.

Satellite TV Programming

Satellite TV providers get programming from two major sources: national turnaround channels (such as HBO, ESPN and CNN) and various local channels (the ABC, CBS, Fox, NBC and PBS affiliates in a particular area). Most of the turnaround channels also provide programming for cable TV, and the local channels typically broadcast their programming over the airwaves.

Turnaround channels usually have a distribution center that beams their programming to a geosynchronous satellite. The broadcast center uses large satellite dishes to pick up these analog and digital signals from several sources.

Most local stations don't transmit their programming to satellites, so the provider has to get it another way. If the provider includes local programming in a particular area, it will have a small local facility consisting of a few racks of communications equipment. The equipment receives local signals directly from the broadcaster through fiber-optic cable or an antenna and then transmits them to the central broadcast center.

The broadcast center converts all of this programming into a high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity of data -- about 270 megabits per second (Mbps) for each channel. In order to transmit the signal from there, the broadcast center has to compress it. Otherwise, it would be too big for the satellite to handle. In the next section, we'll find out how the signal is compressed.

Cable: Satellite's Biggest ContenderWith emerging technologies in each service, the hardest decision in TV viewing is no longer just what channel to watch -- it's what service to choose. Cable advantages: Advancements in digital cable provide improved audio and picture quality with additional channels at a lower cost than satellite. You can also access cable channels from multiple rooms in your house fairly easily. Cable disadvantages: Cable has limited access in rural areas, and you should prepare for increased service costs as your provider updates its equipment. Your service costs are also subject to local taxes. Satellite advantages: Satellite offers movie-quality audio and picture display with hundreds of channels. This service is readily available in rural and urban areas and provides access to more digital and high definition programming. Satellite disadvantages: It is expensive to purchase all the equipment at the outset (and you can't typically rent it). If you want to access satellite TV in multiple rooms, be prepared for extra fees. Also, satellite TV is subject to weather-related malfunctions.

Satellite TV Signal

Satellite signals have a pretty long path to follow before they appear on your TV screen in the form of your favorite TV show. Because satellite signals contain such high-quality digital data, it would be impossible to transmit them without compression. Compression simply means that unnecessary or repetitive information is removed from the signal before it is transmitted. The signal is reconstructed after transmission.

Standards of Compression
Satellite TV uses a special type of video file compression standardized by the Moving Picture Experts Group (MPEG). With MPEG compression, the provider is able to transmit significantly more channels. There are currently five of these MPEG standards, each serving a different purpose. DirecTV and DISH Network, the two major satellite TV providers in the United States, once used MPEG-2, which is still used to store movies on DVDs and for digital cable television (DTV). With MPEG-2, the TV provider can reduce the 270-Mbps stream to about 5 or 10 Mbps (depending on the type of programming).

Now, DirecTV and DISH Network use MPEG-4 compression. Because MPEG-4 was originally designed for streaming video in small-screen media like computers, it can encode more efficiently and provide a greater bandwidth than MPEG-2. MPEG-2 remains the official standard for digital TV compression, but it is better equipped to analyze static images, like those you see on a talk show or newscast, than moving, dynamic images. MPEG-4 can produce a better picture of dynamic images through use of spatial (space) and temporal (time) compression. This is why satellite TV using MPEG-4 compression provides high definition of quickly-moving objects that constantly change place and direction on the screen, like in a basketball game.

In the next section, we will see how satellite tv signals are encoded for transmission.

MPEG StandardsAll MPEG standards exist to promote system interoperability among your computer, television and handheld video and audio devices. They are: MPEG-1: the original standard for encoding and decoding streaming video and audio files. MPEG-2: the standard for digital television, this compresses files for transmission of high-quality video. MPEG-4: the standard for compressing high-definition video into smaller-scale files that stream to computers, cell phones and PDAs (personal digital assistants). MPEG-21: also referred to as the Multimedia Framework. The standard that interprets what digital content to provide to which individual user so that media plays flawlessly under any language, machine or user conditions.

Satellite TV Encoding and Encryption

At the broadcast center, the high-quality digital stream of video goes through an MPEG encoder, which converts the programming to MPEG-4 video of the correct size and format for the satellite receiver in your house.

Encoding works in conjunction with compression to analyze each video frame and eliminate redundant or irrelevant data and extrapolate information from other frames. This process reduces the overall size of the file. Each frame can be encoded in one of three ways:

• As an intraframe, which contains the complete image data for that frame. This method provides the least compression.
• As a predicted frame, which contains just enough information to tell the satellite receiver how to display the frame based on the most recently displayed intraframe or predicted frame. A predicted frame contains only data that explains how the picture has changed from the previous frame.
• As a bidirectional frame, which displays information from the surrounding intraframe or predicted frames. Using data from the closest surrounding frames, the receiver interpolates the position and color of each pixel.

This process occasionally produces artifacts -- glitches in the video image. One artifact is macroblocking, in which the fluid picture temporarily dissolves into blocks. Macroblocking is often mistakenly called pixilating, a technically incorrect term which has been accepted as slang for this annoying artifact. Graphic artists and video editors use "pixilating" more accurately to refer to the distortion of an image. There really are pixels on your TV screen, but they're too small for your human eye to perceive them individually -- they're tiny squares of video data that make up the image you see. (For more information about pixels and perception, see How TV Works.)

Purposeful Pixilation When is pixilation not just an adverse effect of decoding? When it's employed as a means of censorship. Legislation passed in 2006 licenses the Federal Communications Commission (FCC) to impose a $325,000 fine on TV stations that violate its standards of decency. In an effort to avoid fines, many TV stations now not only bleep out or muffle explicit language but also digitally manipulate or pixilate the speakers' mouths to safeguard against the audience lip-reading the words. In The New York Times article "Soldiers' Words May Test PBS Language Rules," PBS considers how to protect itself from FCC fines while maintaining the authenticity of its documentary programming.

The rate of compression depends on the nature of the programming. If the encoder is converting a newscast, it can use a lot more predicted frames because most of the scene stays the same from one frame to the next. In more fast-paced programming, things change very quickly from one frame to the next, so the encoder has to create more intraframes. As a result, a newscast generally compresses to a smaller size than something like a car race.

Encryption and Transmission
After the video is compressed, the provider encrypts it to keep people from accessing it for free. Encryption scrambles the digital data in such a way that it can only be decrypted (converted back into usable data) if the receiver has the correct decryption algorithm and security keys.

Once the signal is compressed and encrypted, the broadcast center beams it directly to one of its satellites. The satellite picks up the signal with an onboard dish, amplifies the signal and uses another dish to beam the signal back to Earth, where viewers can pick it up.

In the next section, we'll see what happens when the signal reaches a viewer's house.

Satellite Dish

When the signal reaches the viewer's house, it is captured by the satellite dish. A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam.

The curved dish reflects energy from the feed horn, generating a narrow beam.

The dish on the receiving end can't transmit information; it can only receive it. The receiving dish works in the exact opposite way of the transmitter. When a beam hits the curved dish, the parabola shape reflects the radio signal inward onto a particular point, just like a concave mirror focuses light onto a particular point.

The curved dish focuses incoming radio waves onto the feed horn.

In this case, the point is the dish's feed horn, which passes the signal on to the receiving equipment. In an ideal setup, there aren't any major obstacles between the satellite and the dish, so the dish receives a clear signal.

In some systems, the dish needs to pick up signals from two or more satellites at the same time. The satellites may be close enough together that a regular dish with a single horn can pick up signals from both. This compromises quality somewhat, because the dish isn't aimed directly at one or more of the satellites. A new dish design uses two or more horns to pick up different satellite signals. As the beams from different satellites hit the curved dish, they reflect at different angles so that one beam hits one of the horns and another beam hits a different horn.

The central element in the feed horn is the low noise blockdown converter, or LNB. The LNB amplifies the radio signal bouncing off the dish and filters out the noise (radio signals not carrying programming). The LNB passes the amplified, filtered signal to the satellite receiver inside the viewer's house.

Satellite Receiver

Photo courtesy DirecTV

The end component in the entire satellite TV system is the receiver. The receiver has four essential jobs:

• It de-scrambles the encrypted signal. In order to unlock the signal, the receiver needs the proper decoder chip for that programming package. The provider can communicate with the chip, via the satellite signal, to make necessary adjustments to its decoding programs. The provider may occasionally send signals that disrupt illegal de-scramblers as an electronic counter measure (ECM) against illegal users.
• It takes the digital MPEG-2 or MPEG-4 signal and converts it into an analog format that a standard television can recognize. In the United States, receivers convert the digital signal to the analog National Television Systems Committee (NTSC) format. Some dish and receiver setups can also output an HDTV signal.
• It extracts the individual channels from the larger satellite signal. When you change the channel on the receiver, it sends just the signal for that channel to your TV. Since the receiver spits out only one channel at a time, you can't tape one program and watch another. You also can't watch two different programs on two TVs hooked up to the same receiver. In order to do these things, which are standard on conventional cable, you need to buy an additional receiver.
• It keeps track of pay-per-view programs and periodically phones a computer at the provider's headquarters to communicate billing information.

Receivers have a number of other features as well. They pick up a programming schedule signal from the provider and present this information in an onscreen programming guide. Many receivers have parental lock-out options, and some have built-in digital video recorders (DVRs), which let you pause live television or record it on a hard drive.

Thank You Dan Landreth is the Vice President of Engineering at EchoStar Satellite L.L.C. Special thanks to Dan for his help with portions of this article.

These receiver features are just added bonuses to the technology of satellite TV. With its movie-quality picture and sound, satellite TV is becoming a popular investment for consumers. Digital cable, which also has improved picture quality and extended channel selection, has proven to be the fiercest competitor to satellite providers. The TV war is raging strong between satellite and digital cable technologies as well as between the providers who offer these services. Once considered luxuries in most households, satellite and digital cable are becoming quite common as providers bundle TV with Internet and phone services to offer competitive deals and win over customers.

Satellites

Satellite is a word that simply refers to one body in orbit around another. There are natural satellites, such as our Moon, which orbits the Earth and artificial, man-made satellites that can serve a number of different purposes. They may be part of a television or telephone network or they can carry instruments to investigate the Earth and its atmosphere. Others monitor the Sun, or travel for many years carrying probes or landers to investigate the mysteries of the distant planets.

Until 4 October 1957, the Earth's only satellite was the Moon. Then the Soviet Union launched the first artificial satellite, a tiny metal sphere called Sputnik, and the world stood transfixed as it circled the Earth once every 90 minutes. Civilisation would never be the same again. Many thousands of satellites have been sent aloft since Sputnik launched the Space Age. Most have orbited the Earth, but several hundred have travelled to the Moon and beyond.

The Soviet Luna 1, launched on 2 January 1959, became the first man-made object to leave the Earth's gravitational influence and fly past the Moon. Its rocket was the first to reach the 25 000mph needed to escape the Earth's gravitational field.

By the early 1960s, the United States and the Soviet Union had begun to look further afield. NASA's Mariner 2 spacecraft skimmed past Venus in December 1962 and the first successful mission to Mars followed two years later.

During the 1970s, more advanced orbiters and landers were sent to Venus and Mars. By using planets to give spacecraft a gravitational 'kick' as they flew past, scientists discovered a faster, cheaper way to deliver satellites to their targets. This technique enabled Mariner 10 to investigate the innermost planet, Mercury, and opened the way for a 'grand tour' of the outer solar system by two Voyager spacecraft.

The Voyager spacecraft which was sent to explore the gas giants in the outer Solar System
Image credit: NASA

By modern standards, the satellites launched at the dawn of the Space Age were small and unsophisticated, although the size of the spacecraft largely depended on the performance of the available rockets. In this respect, the Soviet Union was well ahead of its American competitors.

Both superpowers and Europe continued to launch new missions so that, by the early 1960s, space was populated by satellites performing a variety of tasks devoted to weather, navigation, communications and military reconnaissance.

Satellites to find out about our weather

The weather experienced at any point on the Earth's surface is controlled by the state of the atmosphere. For centuries meteorologists have been measuring and recording atmospheric elements, such as pressure and temperature. However, it was not until the 1960s that it was possible to study the atmosphere from space. The first meteorological satellite, called TIROS I, was launched by the USA in 1960.

A meteorological satellite image of Hurricane Hugo
Image credit: ESA

Today many countries operate meteorological satellites and there is worldwide co-operation so that all countries can benefit from the data collected. There is increasing concern about the possible effects of global climatic change caused by human action, such as the depletion of ozone and the Greenhouse Effect. Weather satellites are playing a major role in monitoring the changing climate. Successful weather forecasting for one location depends on accurate observations of the atmosphere over a large area.

Satellites that tell you where you are

Global Navigation Satellite Systems (GNSS) were first developed for military applications. The best-known system is the Global Positioning System (GPS) developed by the United States. It consists of 24 satellites at an altitude of about 20 000 km providing virtually continuous global coverage. Each satellite has a very accurate clock on board and sends out radio signals. We know that radio waves travel at a certain speed (the speed of light), therefore the time taken for the radio signals to travel from at least 3 satellites can be used to calculate the position of a receiver on the Earth's surface. Positions on the Earth's surface can be located to millimetre accuracy.

Galileo will be Europe's own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It is planned to be compatible with GPS, so that a user will be able to take a position with the same receiver from any of the satellites in both systems.

Europe's planned Galileo GNSS (Credit: ESA)

Satellites for communication

Satellite Communication Systems allow the high-speed transmission of telephone calls, television pictures and news around the globe. This use of satellites was established at the same time as the development of weather satellites - from the 1960s onwards.

The shape of the Earth, and features such as mountains, can block signals transmitted by land-based systems. Satellites provide a clear line of sight and can act as relay stations, linking a number of ground-based antennas. Satellites make it possible to telephone anywhere in the world and over 30% of all transatlantic phone calls now go via satellite.

In many countries of the world people still do not have access to telephones. Land-based telephone networks are expensive to build and maintain. Satellites enable a simpler system, without cables, to provide a vital link for people everywhere.

Satellites for military purposes

Over the years, the methods Man has used to defend his land and to attack others have become increasingly sophisticated. Governments and defence agencies like the North Atlantic Treaty Organisation (NATO) are prepared to spend large sums of money protecting their civilians.

The need to locate enemy positions and map features of the land or the ocean floors has led to the development of many remote-sensing techniques. These techniques are often useful for a whole range of non-military applications, providing further benefits. Radar, for example, was invented during the Second World War as a means of detecting the presence of enemy ships or aircraft.

Satellites can detect tanks hidden under trees and distinguish decoys (plastic or cardboard "pretend" tanks) from the real thing.

Global Navigation Satellite Systems (GNSS) were first developed for military applications. They enabled military targets to be located to millimetre accuracy ensuring civilian casualties could be minimised. Rapid and reliable communication systems are essential to the military and satellites are a key tool for defence agencies.

Geoscape Canada

Geoscape Calgary

Satellite image of Calgary

The Geoscape Calgary area comprises the city of Calgary and its hinterland to the west, including Canmore and the Bow Valley, as well as Bragg Creek along the Elbow River Valley.

View the satellite image below or watch the video flyovers to view the area that comprises Geoscape Calgary.

CURRENT RESEARCH

Our goal is to better understand the chemical composition of the atmosphere, its perturbation by human activity, and the implications for life on Earth. We use advanced global models of atmospheric composition to interpret observations from satellites, aircraft, ground networks, and other sources. We view our models as part of an integrated observing system bridging the information from different data sets to increase our understanding of atmospheric composition in a way that serves both fundamental knowledge and the need to address pressing environmental issues.

GLOBAL MODELS. A central tool in our research is the GEOS-Chem global 3-D model of atmospheric composition, developed by a large grass-roots research community at Harvard and elsewhere and applied to a very wide range of problems. See the GEOS-Chem web site for more details. We also work with the NASA/GISS general circulation model for simulations of climate change, including coupling with GEOS-Chem for study of chemistry-climate interactions and of past and future atmospheres.	AIRCRAFT MISSIONS. Aircraft provide a critical sampling platform for atmospheric chemistry. They enable detailed chemical characterization of atmospheric composition from the surface to the stratosphere and over the scale of the globle. We have been engaged in a large number of aircraft missions over the past 20 years in different regions of the world. We are presently involved in the NASA ARCTAS mission to the Arctic and the NSF HIPPO pole-to-pole mission. Our role in these missions includes overall mission design, flight planning, forecasting, and post-mission data analysis.	SATELLITE MISSIONS. Satellite observations are revolutionizing atmospheric chemistry research by providing global and continuous data sets of atmospheric composition. These data sets require advanced models for interpretation and we are in the thick of it. We serve on the Science Teams of the TES, MOPITT, and OCO instruments, and are also engaged in the analysis of data from MODIS, MISR, GOME, SCIAMACHY, and OMI. Our activities involve direct retrievals of satellite spectra using radiative transfer models, chemical data assimilation, inverse model analyses,and other data interpretation.

Exploring space

SAILOR: As terrestrial telecoms dial into satellite networks

Improving the integration of satellite networks with more traditional terrestrial telephone infrastructures, will help next generation telephony move from concept towards reality, as researchers are demonstrating. The IST-funded SAILOR project demonstrated the viability of combining telecom services from both terrestrial and satellite-based UMTS networks, to produce communication services that combine the best of the advantages from these widely differing infrastructures.

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• ICT Results Feature
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The new system provides more flexibility in terms of quality of services; saves network capacity through the ability to exploit the advantages of satellite technology; and minimises costs of new services for telecoms operators and equipment manufacturers by making possible the design and use of low-cost communication terminals.

The SAILOR platform embraces high-speed data as well as voice services, and exploits the special features of satellite communication to best advantage, i.e. providing coverage to geographic areas suffering from limited or no telecommunications service (which can include ships at sea as well as land-based destinations), and boosting the bandwidth and hence speed of all connections. The platform also focuses on an ‘exploitable’ approach to combining the different architectures; the services offered are designed to be affordable as well as high-quality.

SATNEX: A pan-European space for satellite communications

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• Project Leaflet (pdf)
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• Project Factsheet (pdf)

Satellite communication’s wide coverage and speed to deliver new services are going to be key to fulfilling the higher data rate radio interfaces required to meet the consumer demand of being optimally connected anywhere, anytime. Satellites, used for broadcast, mobile and broadband communication, give Europe its competitive edge in Information and Communication Technologies and guarantee the EU autonomy in space. The combined efforts of R&D initiatives of the European Space Agency and the EU’s Framework Programmes have created a solid industrial base. However, until the IST-funded SATNEX project, there was limited cooperation and a lack of critical mass.

Members of the SATNEX consortium have a collective research portfolio and developed a common base of knowledge. By working together they avoid duplication. To ensure effective communication among SATNEX members, they established a common pan-European platform to provide equitable access to real-time communication services. This platform, which overcomes the disparities between the various national ground network infrastructures and/or local security policies, provides a wide range of opportunities for day-to-day communications, research and training. Training is another important part of the SATNEX project and is supported through numerous initiatives, including hosting internship projects, establishing an annual summer school and disseminating tutorial papers.

GAWAIN: Satnav and 3G cellular services on one mobile phone

The IST funded GAWAIN project aims to combine satellite and 3G telephony facilities within one device. This would achieve to combine satellite positioning (Galileo/GPS) with 3G mobile phone technology on a single chip. The result could unlock the future for applications like smart tourism services, smart transport management and even electronic guide dogs for the blind.

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• Project Flyer (pdf)
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An integrated chip like this reduces the number of components and power consumption. The advent of such an integrated chip could finally unlock the future potential for location-based services. For example, in smart transport the devices could be used to tell commuters when the next bus will arrive at a particular stop. Smart tourism services could also supply information that is relevant to the user's present location. The real advantage of services like these, however, is the many as-yet-unimagined services that they could make possible.

INSPIRE: Bringing satellite broadband to Britain

There still remain many areas of Europe without access to broadband internet, but a project supported by the European Space Agency’s Satellite Telecommunications Department is helping to bridge this digital divide.

It aims to provide broadband connectivity primarily to home users in rural areas of the UK and Ireland. Equipped with a range of applications, INSPIRE not only proves the commercial viability of such a service, but also demonstrates the benefits of both basic and advanced broadband services. The applications have been designed especially with rural users in mind. Key among these is a community channel, which allows users to create their own community websites with locally produced content. This is especially important for local businesses which could otherwise not afford such a capability.

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Because rural residents are not only far from urban centres but also far from other members of their own community, other applications have been added. VoIP (Voice over Internet Protocol) can be used as an alternative to telephone. Eventually the service will also offer video-chat for residential users and video-conferencing applications for businesses.

Applications alone will not bridge the digital divide. To be a success, any solution also needs to be affordable. Although more expensive than terrestrial solutions, technical advances have increased the competitiveness of satellite broadband.

Land Cover and Change Detection

Satellite Remote sensed data and GIS for land cover, land use and its changes is a key to many diverse applications such as Environment, Forestry, Hydrology, Agriculture and Geology. Natural Resource Management, Planning and Monitoring programs depend on accurate information about the land cover in a region. Methods for monitoring vegetation change range from intensive field sampling with plot inventories to extensive analysis of remotely sensed data which has proven to be more cost effective for large regions, small site assessment and analysis.

Satellite Imaging Corporation provides a large amount of satellite remote sensing data at different spatial, spectral, and temporal resolutions by using the appropriate combination of bands to bring out the geographical and manmade features that are most pertinent to your project for detecting changes. Satellite Image data is expected to contribute to a wide array of global change-related application areas for vegetation and ecosystem dynamics, hazard monitoring, geology and soil analysis, land surface climatology, hydrology, land cover change, and the generation of orthorectified digital elevation models (DEMs).

Color Infrared	Green Vegetation Index	Soil Index

(QuickBird — Copyright © 2008 DigitalGlobe)

Satellite Imagery Analysis allows for:

• Fast and accurate overview
• Quantitative green vegetation assessment
• Underlying soil characteristics

Satellite remote sensing is an evolving technology with the potential for contributing to studies for land cover and change detection by making globally comprehensive evaluations of many environmental and human actions possible. These changes, in turn, influence management and policy decision making. Satellite image data enable direct observation of the land surface at repetitive intervals and therefore allow mapping of the extent and monitoring and assessment of:

• Crop health
• Storm Water Runoff
• Change detection
• Air Quality
• Environmental analysis
• Energy Savings
• Irrigated landscape mapping
• Carbon Storage and Avoidance
• Yield determination
• Soils and Fertility Analysis
• Identification of

Wetlands Encroachment	Irrigation Pattern	Production Monitoring

Crop Health Variations	Urban Forest and Turf	Soils and Fertility Analysis

(QuickBird — Copyright © 2008 DigitalGlobe)

Satellite Imaging Corporation can provide automated datasets for vegetation and land cover use by updating your projected area and incorporating a more recent image to determine the changes. Evaluation of the static attributes of land cover (types, amount, and arrangement) and the dynamic attributes (types and rates of change) on satellite image data may allow the types of change to be regionalized and the approximate sources of change to be identified or inferred.

QuickBird Satellite Image Vegetation Index

Green Vegetation Index	Soil Brightness Map	Vegetation Hue (color)

Change Map	Sharp Vegetation Index	Black and White

Color Infrared	Natural Color

(QuickBird — Copyright © 2008 DigitalGlobe)

Satellite Imaging Corporation utilizes and provides advanced Remote Sensing techniques, Color and Panchromatic image data processing services including orthorectification, pan sharpening with image data fusion, image enhancements, Georeferencing, mosaicing and color/grayscale balancing for GIS and other Mapping applications.

Satellite Imaging Corporation offers satellite imaging acquisition from various commercial satellite sensors providing different resolutions including

Satellite Sensor Resolution at Nadir

• QuickBird 0.61m
• IKONOS 0.82m
• SPOT-5 2.5m/5m/10m
• Landsat 7 +ETM 14.25m/28.5m
• ASTER 15m/30m

Rapid Acquisition

RUSH tasking orders for satellite image data around the world are accepted by SIC in support of live events, natural disasters, global security, and various other applications in which FAST delivery of image data is critical. In most instances, we can provide image data within 24 hours after the initial data has been acquired and delivered via FTP and DVD media.

U.S. May Shoot Down Errant Satellite

The U.S. spent around a billion dollars on a dud spy satellite, and now, the military is considering plans to shoot it down. That's right, the Lockheed Martin-built satellite that is floating around in space -- soon to re-enter Earth's atmosphere -- may be shot out of the sky.

Now, if a missile defense test costs on average between $80 and $100 million, I'd have to guess that Operation Broken Satellite (okay, I made that up) would be something in the general price range of the tens of millions of dollars. Heck, why don't they just use the missile defense system, which is supposed to be kind of, sort of deployed (or deployable), to blow it out of the sky.

This is high comedy, I mean, suppose they miss?

Anyhow, Aviation Week & Space Technology has a fascinating story on the life and coming death of this errant satellite:

The concern is that the spacecraft carries a full tank of hydrazine - a toxic propellant - that would have been used to reposition the satellite in orbit. Government analysts say the odds are that the tank will crack open during re-entry or than it will land in the ocean, which makes up 70% of the area where the breaking up satellite might land. There also is concern in some quarters that debris could reveal U.S. national security secrets if recovered by other nations. It is expected to re-enter the atmosphere late this month or in early March.

Analysts at the Missile Defense Agency and NRO have put hundreds of hours into analysis and have studied closely the accuracy of surveillance capabilities of U.S. radars in Japan, Alaska and possibly elsewhere to give more targeting options to those assessing the danger of the satellite falling to Earth.

A senior official with insight into the planning says that a rumor that the satellite carried a small, nuclear generator is "absolutely and totally incorrect." However, government agencies including MDA and NRO "are studying options that include" hitting the satellite with a weapon so that it breaks up in space - and ruptures the hydrazine tank -- before beginning its descent.

A nuclear generator? Wow, and I thought I kept up on my satellite technology conspiracy theories. Anyhow, I'm guessing that, in fact, the U.S. is concerned about spy sat technology falling into the wrong hands, because in my heart of hearts, I just don't believe that the NRO spends all day worrying about a satellite, even a toxic one, falling in somebody's backyard. But hey, I could be wrong.

Update:

My bad, DANGER ROOM's Kris Alexander (and a couple commenters) have noted that that having a small nuclear generator is hardly a conspiracy theory. It's been used on a number of spacecraft.

Nano-Satellites – Future of the Future

Third millennium has started not very long ago and brought us a new stage of development of tiny space vehicles – micro- and nano-satellites. The period of single breakthroughs and first successful test models of small satellites has ended, and now it’s time to start systematic development of regular space systems on the basis of ultra-small space vehicles. Small space crafts are already widely used for Earth remote sensing, ecological monitoring, earthquake predicting and studies of ionosphere.

In the nineties of the previous century universities and small private companies have spent a lot of their time on design and development of small space vehicles, and today giant corporations express vivid interest in tiny spacecrafts and actively participate in their development. Russian pioneer in the field of nano-satellites – science and research institute of space instrumentation – has already created a programme for development and introduction of technological nano-satellites “TNS”, designed for flight exercise of advanced space vehicles and basic technologies for said vehicles. “TNS-0 1” nano-satellite has already performed successful tests of a brand-new technology of spaceship control via “Globalstar” satellite system. Now institute professionals are working on the next generation of nano-satellites for various technological and research purposes.

Another perspective field for nano-satellites is using these little vehicles as basic platforms for performing experiments in nanotechnologies, which are scientific field of high priority in Russia today, tests of nano-materials and nano-components. Possible applications of nano-materials in space industry include coatings of solar batteries, which are made of silicon dioxide nano-particles. Such nano-coatings are optically transparent and at the same time “repel” any possible dirt. Space industry is longing for nano-materials, which show high solidity, durability and plasticity at the same time - a combination, impossible for any materials, built from macro-particles.

Main task, which space professionals face today, is reducing weight, size and energy characteristics of micro- and nano-satellites (weighing less than 10 kilograms). Another important problem is placing said small vehicles to Earth’s orbit, which now is solved by means of cluster launches of nano-satellites on large carrier vehicles, however, this technique has its drawbacks. Scientists are working on a special launching vehicle for small satellites, and suggest following solutions: aerospace complex, based on MIG-3 plane or on short-range missiles “Iskander”, as well as light carrier vehicles “Shtil 2.1”, usually launched from submarine trunks. However, the latter technique is too expensive, thus Russian scientists suggest a project of so-called cannon launching system, which promises to be quite cheap and is based upon a complex of electromagnetic cannons, supplied with energy from same bank of condensers.

The Future of Satellites

New Problems and New Players in the Satellite Game

Over the past four decades, satellites in orbit around the earth have become absolutely critical to commerce, communication, and national security. Military and commercial dominance of (or at least basic competence in) the satellite business will be a key to America’s success in the coming years. But recent press reports indicate that the nation’s military reconnaissance satellite program is in poor shape, and that an unprecedented proliferation of foreign-owned commercial “microsatellites” is near-at-hand.

The U.S. has spent about $200 billion on its military satellite program since its inception some four decades ago. Most estimates suggest that the American military and intelligence community now have roughly 100 satellites in orbit dedicated purely to national security reconnaissance and communication. These satellites are operated by the highly secretive National Reconnaissance Office (NRO), run out of the Pentagon and staffed jointly by Defense Department and intelligence community personnel.

The NRO has for years been accused of mismanagement and gross inefficiency, though the classified nature of its budget and operations has made a public accounting impossible. In August, U.S. News & World Report published the results of a six-month investigation into the agency, and its findings were not encouraging. Despite its $7 billion budget, the NRO is routinely in the red, and rarely on schedule. Perhaps more importantly, it has run into a series of technical problems in recent years that have deprived the American intelligence community of some potentially crucial eyes and ears—at a time when the nation, slogging through a multi-front war on terrorism, cannot afford an intelligence lapse.

Two NRO satellites launched in the past two years have malfunctioned in ways that have seriously hindered their performance; this has caused the agency to delay several planned launches of new satellites, until the problems with the existing ones can be diagnosed. Meanwhile, a substantial number of America’s spy satellites are nearing the end of their planned lifespans, and replacements are slow to come.

All of this has led to two key changes in policy. First, the military and the intelligence community have begun to make greater use of civilian satellites, operated by private companies, both for communication and for reconnaissance. Second, the CIA—apparently with support from Defense Secretary Donald Rumsfeld—has opened a new office to manage future spy satellite operations, potentially doing an end-run around the NRO.

Meanwhile, as the future of America’s large and expensive cutting-edge spy satellites remains less than certain, a new breed of small, highly mobile satellites geared for non-military use is hitting the scene. These “microsatellites,” in some cases weighing less than 50 pounds each (larger satellites weigh thousands of pounds), offer greater flexibility and control, and can dramatically reduce the costs of simple overflight and reconnaissance tasks.

The European Space Agency is leading the way in microsatellite operations with its PROBA (Project for On-Board Autonomy) program. The first PROBA satellite is already in orbit. It can navigate itself—using GPS signals and sophisticated constellation mapping—and can receive and automatically prioritize work-requests (for climate monitoring, ocean surveys, and other information-gathering) from scientists around the world.

Although the Europeans are the biggest players in the microsatellite game, they are not alone. Some smaller nations have begun similar programs. Nigeria and Turkey, not normally known as leaders in the aerospace industry, both recently began such projects, with microsatellites launched from Russia in September; others, including Thailand and Vietnam, may soon do the same.

In the early years of man’s forays into space, the satellite game was a clash of superpowers. Today, smaller nations and private interests are increasingly involved, which suggests that America’s old approach to keeping an eye on the national interest from space is in need of a serious overhaul

Bright Future for Solar Power Satellites

WASHINGTON -- Two new studies looking at the feasibility of space-based solar power - orbiting satellites that would serve as high-tech space dams - suggest the concept shouldn't be readily dismissed and could generate both Earth-bound and space-based benefits.

These "powersats" would catch the flood of energy flowing from the Sun and then pump it to Earth via laser or microwave beam. On earth it would be converted to electricity and fed into power grids to be tapped by terrestrial customers.

The thought of beaming energy to Earth via satellite was first brought to light in the late 1960s by Peter Glaser, a technologist at Arthur D. Little in Cambridge, Massachusetts. Into the 1970s and 1980s, the challenges of Space Solar Power (SSP) were reviewed numerous times. NASA, the Department of Energy, other government, industry and private groups have given the concept the once-over.

A swarm of unknowns and criticisms always fly in tight formation around the prospect of energy-beaming satellites actually having any economic benefit to Earth.

Among them: The size, complexity, and cost of an SSP undertaking are daunting challenges. International legal, political, and social acceptability issues abound. Health or environmental hazards from laser or microwave beams broadcast from space appear worrisome. Additionally, in the battle of energy market forces on Earth, any SSP constellation may prove far too costly to be worth metering.

In 1995, NASA embarked on what's tagged as a Fresh Look study. SSP feasibility, technologies, costs, markets, and international public attitudes were addressed. In general, NASA found that the march of technology and America's overall space prowess has re-energized the case for SSP. NASA did point out, however, that launch cost to orbit remains far too high - but that this problem was being attacked.

Investment strategy

For the last few years, interest in SSP has grown, not only at NASA, but also in the U.S. Congress and the White House Office of Management and Budget. For its part, the space agency has scripted a research and technology, as well as investment roadmap. This SSP stepping stone approach would enhance other space, military, and commercial applications.

A special study group of the National Research Council (NRC) has taken a new look at NASA's current SSP efforts. Their findings are in the NRC report: Laying the Foundation for Space Solar Power - An Assessment of NASA's Space Solar Power Investment Strategy.

Richard Schwartz, dean of the Schools of Engineering at Purdue University in West Lafayette, Indiana, chaired the 9-person NRC panel.

While not advocating or discouraging SSP, the advisory team said "it recognizes that significant changes have occurred since 1979 that might make it worthwhile for the United States to invest in either SSP or its component technologies." The study urges a sharper look at perceived and/or actual environmental and health risks that SSP might involve.

The NRC study group singled out several technological advances relevant to SSP:

• Improvements have been seen in efficiency of solar cells and production of lightweight, solar-cell laden panels;
• Wireless power transmission tests on Earth is progressing, specifically in Japan and Canada;
• Robotics, viewed as essential to SSP on-orbit assembly, has shown substantial improvements in manipulators, machine vision systems, hand-eye coordination, task planning, and reasoning; and
• Advanced composites are in wider use, and digital control systems are now state of the art - both developments useful in building an SSP.

ISS test platform

Overall, the NRC experts gave NASA's SSP approach a thumbs-up. The space agency's current work is directed at technical areas "that have important commercial, civil, and military applications for the nation." A top recommendation is that industry experts, academia, and officials from other government agencies -- such as the Department of Energy, Defense Department, and the National Reconnaissance Organization -- should be engaged in charting SSP activities, along with NASA.

The panel said that significant breakthroughs are required to achieve the final goal of SSP cranking out cost-competitive terrestrial power. The ultimate success of the terrestrial power application of powering-beaming satellites critically depends on "dramatic reductions" in the cost of transportation from Earth to geosynchronous orbit, the group reported.

Furthermore, the SSP reviewers call for ground demonstrations of point-to-point wireless power transmission. NASA should study the desirability of ground-to-space and space-to-space demonstrations. In this area, the International Space Station could act as a platform to test out SSP-related hardware, the study group said.

Energy as hope

In summary, the NRC panel members noted that for any SSP program to churn out commercially competitive terrestrial electric power, breakthrough technologies are required.

That being said, even if the ultimate goal of supplying competitive energy is not attained, the experts added: "…the technology investments proposed will have many collateral benefits for nearer-term, less-cost-sensitive space applications and for non-space use of technology advances."

Hubert Davis, a committee member on the NRC study, sees SSP as perhaps the right technology for today. Throughout the 1970s, he managed future programs for the NASA Johnson Space Center in Houston, Texas, and is now an independent aerospace consultant.

"In looking at our current world situation, I believe that what is most needed is hope. Power from space may be one of the best means for us to offer that hope," Davis told SPACE.com.

Davis said that an exploratory research, development and demonstration program for power from space is needed. It would be accompanied by a major international aid effort using terrestrial photovoltaics. In areas where no power exists, village "life support systems" can be established to provide potable water, lights, modern communications, refrigeration, information, and perhaps a few sewing machines, he said."These complementary steps may buy us the time we need to fulfill this new hope…for everyone," Davis said.

In-orbit power plug

Following on the heels of the NRC's new look at SSP is an assessment completed by Resources for the Future (RFF) a Washington-based group that studies energy and environmental policy. It focuses on off-planet uses of an in-orbit "power plug", or as some label it, a "solar array on steroids." The idea is to have a filler-up facility for electrically hungry satellites, observatories, space platforms and the like.

That study is titled: An Economic Assessment of Space Solar Power as a Source of Electricity for Space-Based Activities. RFF's Molly Macauley and James Davis of The Aerospace Corporation authored the piece.

They observe that customers of a future SSP station could be many. Commercial telecommunications and remote sensing spacecraft, governmental research and defense satellites, space manufacturing facilities, as well as space travel and tourism industries could draw energy from such a station. There is a potentially large market that might benefit from this pay for power approach.

Another attractiveness of a space-based power station is leaving heavy solar panels back on Earth. Less massive spacecraft would be cheaper to orbit. That also means more science gear could be crammed onboard a satellite.

"Our study argues that we could do testing and demonstrations of in-space power sooner than for terrestrial power," Macauley told SPACE.com. The researcher was also a member of the NRC study on SSP.

Show me the energy

Macauley and Davis surveyed satellite designers and operators, gleaning insight about the value of having an SSP "power depot" in space. Whisking watts of power through space to run commercial geostationary satellites looks like a very lucrative and large market, they report.

On the other hand, while the willingness of potential customers to adopt a new power technology like SSP is promising, flight testing the idea would help boost adoption of the in-space energy idea. Early on, supplying power from an SSP could gain greater acceptance as a supplement, rather than a substitute for, an existing power system on a spacecraft, Macauley and Davis note.

Macauley said that in future years the space-based power market could be really big in dollar terms. Still to be determined is where to place an SSP, or whether or not there's need for a constellation of SSP satellites.

"Given our estimate of the market, can SSP designers create an SSP that's financially attractive? We also realize that other technological innovation in spacecraft power is proceeding apace with SSP," Macauley said. "So SSP advocates need to 'look over their shoulders' to stay ahead of those innovations and to capitalize on those that are complementary with SSP," she said.

"The ownership and financing of SSP may be handled as a commercial venture," Macauley and Davis report, "perhaps in partnership with government during initial operation but then becoming a commercial wholesale cooperative."

Once an SSP is fully deployed, the private sector is likely to be a far more efficient operator of the power plug in space, the researchers said.