united
states communications
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In 500 years, when humankind looks back
at the dawn of space travel, Apollo's landing on the
Moon in 1969 may be the only event remembered. At the
same time, however, Lyndon B. Johnson, himself an avid
promoter of the space program, felt that reconnaissance
satellites alone justified every penny spent on space.
Weather forecasting has undergone a revolution
because of the availability of pictures from geostationary
meteorological satellites--pictures we see every day
on television. All of these are important aspects of
the space age, but satellite communications has probably
had more effect than any of the rest on the average
person. Satellite communications is also the only truly
commercial space technology- -generating billions of
dollars annually in sales of products and services.
The Billion Dollar Technology In fall
of 1945 an RAF electronics officer and member of the
British Interplanetary Society, Arthur C. Clarke, wrote
a short article in Wireless World that described the
use of manned satellites in 24-hour orbits high above
the world's land masses to distribute television programs.
His article apparently had little lasting effect in
spite of Clarke's repeating the story in his 1951/52
The Exploration of Space.
Perhaps the first person to carefully
evaluate the various technical options in satellite
communications and evaluate the financial prospects
was John R. Pierce of AT&T's Bell Telephone Laboratories
who, in a 1954 speech and 1955 article, elaborated the
utility of a communications "mirror" in space,
a medium-orbit "repeater" and a 24-hour-orbit
"repeater." In comparing the communications
capacity of a satellite, which he estimated at 1,000
simultaneous telephone calls, and the communications
capacity of the first trans-atlantic telephone cable
(TAT-1), which could carry 36 simul taneous telephone
calls at a cost of 30-50 million dollars, Pierce wondered
if a satellite would be worth a billion dollars. After
the 1957 launch of Sputnik I, many considered the benefits,
profits, and prestige associated with satellite communications.
Because of Congressional fears of "duplication,"
NASA confined itself to experiments with "mirrors"
or "passive" communications satellites (ECHO),
while the Department of Defense was responsible for
"repeater" or "active" satellites
which amplify the received signal at the satellite--providing
much higher quality communications.
In 1960 AT&T filed with the Federal
Communications Commission (FCC) for permission to launch
an experimental communications satellite with a view
to rapidly implementing an operational system. The U.S.
government reacted with surprise-- there was no policy
in place to help execute the many decisions related
to the AT&T proposal. By the middle of 1961, NASA
had awarded a competitive contract to RCA to build a
medium-orbit (4,000 miles high) active communication
satellite (RELAY); AT&T was building its own medium-orbit
satellite (TELS TAR) which NASA would launch on a cost-reimbursable
basis; and NASA had awarded a sole- source contract
to Hughes Aircraft Company to build a 24-hour (20,000
mile high) satellite (SYNCOM). The military program,
ADVENT, was cancelled a year later due to complexity
of the spacecraft, delay in launcher availability, and
cost over-runs.
By 1964, two TELSTARs, two RELAYs, and
two SYNCOMs had operated successfully in space. This
timing was fortunate because the Communications Satellite
Corporation (COMSAT), formed as a result of the Communications
Satellite Act of 1962, was in the process of contracting
for their first satellite. COMSAT's initial capitalization
of 200 million dollars was considered sufficient to
build a system of dozens of medium-orbit satellites.
For a variety of reasons, including costs, COMSAT ultimately
chose to reject the joint AT&T/RCA offer of a medium-orbit
satellite incorporating the best of TELSTAR and RELAY.
They chose the 24-hour-orbit (geosynchronous) satellite
offered by Hughes Aircraft Company for their first two
systems and a TRW geosynchronous satellite for their
third system. On April 6, 1965 COMSAT's first satellite,
EARLY BIRD, was launched from Cape Canaveral. Global
satellite communications had begun.
The Global Village: International Communications
Some glimpses of the Global Village had already been
provided during experiments with TELSTAR, RELAY, and
SYNCOM. These had included televising parts of the 1964
Tokyo Olympics. Although COMSAT and the initial launch
vehicles and satellites were American, other countries
had been involved from the beginning. AT&T had initially
negotiated with its European telephone cable "partners"
to build earth stations for TELSTAR experimentation.
NASA had expanded these negotiations to include RELAY
and SYNCOM experimentation. By the time EARLY BIRD was
launched, communications earth stations already existed
in the United Kingdom, France, Germany, Italy, Brazil,
and Japan. Further negotiations in 1963 and 1964 resulted
in a new international organization, which would ultimately
assume ownership of the satellites and responsibility
for management of the global system. On August 20, 1964,
agreements were signed which created the International
Telecommunications Satellite Organization (INTELSAT).
By the end of 1965, EARLY BIRD had provided
150 telephone "half- circuits" and 80 hours
of television service. The INTELSAT II series was a
slightly more capable and longer-lived version of EARLY
BIRD. Much of the early use of the COMSAT/INTELSAT system
was to provide circuits for the NASA Communications
Network (NASCOM). The INTELSAT III series was the first
to provide Indian Ocean coverage to complete the global
network. This coverage was completed just days before
one half billion people watched APOLLO 11 land on the
moon on July 20, 1969.
From a few hundred telephone circuits
and a handful of members in 1965, INTELSAT has grown
to a present-day system with more members than the United
Nations and the capability of providing hudreds of thousands
of telephone circuits. Cost to carriers per circuit
has gone from almost $100,000 to a few thousand dollars.
Cost to consumers has gone from over $10 per minute
to less than $1 per minute. If the effects of inflation
are included, this is a tremendous decrease! INTELSAT
provides services to the entire globe, not just the
industrialized nations.
Hello Guam: Domestic Communications
In 1965, ABC proposed a domestic satellite
system to distribute television signals. The proposal
sank into temporary oblivion, but in 1972 TELESAT CANADA
launched the first domestic communications satellite,
ANIK, to serve the vast Canadian continental area. RCA
promptly leased circuits on the Canadian satellite until
they could launch their own satellite. The first U.S.
domestic communications satellite was Western Union's
WESTAR I, launched on April 13, 1974. In December of
the following year RCA launched their RCA SATCOM F-
1. In early 1976 AT&T and COMSAT launched the first
of the COMSTAR series. These satellites were used for
voice and data, but very quickly television became a
major user. By the end of 1976 there were 120 transponders
available over the U.S., each capable of providing 1500
telephone channels or one TV channel. Very quickly the
"movie channels" and "super stations"
were available to most Americans. The dramatic growth
in cable TV would not have been possible with out an
inexpensive method of distributing video.
The ensuing two decades have seen some
changes: Western Union is no more; Hughes is now a satellite
operator as well as a manufacturer; AT&T is still
a satellite operator, but no longer in partnership with
COMSAT; GTE, originally teaming with Hughes in the early
1960s to build and operate a global system is now a
major domestic satellite operator. Television still
dominates domestic satellite communications, but data
has grown tremendously with the advent of very small
aperture terminals (VSATs). Small antennas, whether
TV-Receive Only (TVRO) or VSAT are a commonplace sight
all over the country.
New Technology
The first major geosynchronous satellite
project was the Defense Department's ADVENT communications
satellite. It was three-axis stabilized rather than
spinning. It had an antenna that directed its radio
energy at the earth. It was rather sophisticated and
heavy. At 500-1000 pounds it could only be launched
by the ATLAS- CENTAUR launch vehicle. ADVENT never flew,
primarily because the CENTAUR stage was not fully reliable
until 1968, but also because of problems with the satellite.
When the program was canceled in 1962 it was seen as
the death knell for geosynchronous satellites, three-axis
stabilization, the ATLAS-CENTAUR, and complex communications
satellites generally. Geosynchronous satellites became
a reality in 1963, and became the only choice in 1965.
The other ADVENT characteristics also became commonplace
in the years to follow.
In the early 1960s, converted intercontinental
ballistic missiles (ICBMs) and intermediate range ballistic
missiles (IRBMs) were used as launch vehicles. These
all had a common problem: they were designed to deliver
an object to the earth's surface, not to place an object
in orbit. Upper stages had to be designed to provide
a delta-Vee (velocity change) at apogee to circularize
the orbit. The DELTA launch vehicles, which placed all
of the early communications satellites in orbit, were
THOR IRBMs that used the VANGUARD upper stage to provide
this delta-Vee. It was recognized that the DELTA was
relatively small and a project to develop CENTAUR, a
high-energy upper stage for the ATLAS ICBM, was begun.
ATLAS-CENTAUR became reliable in 1968 and the fourth
generation of INTELSAT satellites used this launch vehicle.
The fifth generation used ATLAS-CENTAUR and a new launch-vehicle,
the European ARIANE. Since that time other entries,
including the Russian PROTON launch vehicle and the
Chinese LONG MARCH have entered the market. All are
capable of launching satellites almost thirty times
the weight of EARLY BIRD.
In the mid-1970s several satellites were
built using three-axis stabilization. They were more
complex than the spinners, but they provided more despun
surface to mount antennas and they made it possible
to deploy very large solar arrays. The greater the mass
and power, the greater the advantage of three-axis stabilization
appears to be. Perhaps the surest indication of the
success of this form of stabilization was the switch
of Hughes, closely identified with spinning satellites,
to this form of stabilization in the early 1990s. The
latest products from the manufacturers of SYNCOM look
quite similar to the discredited ADVENT design of the
late 1950s.
Much of the technology for communications
satellites existed in 1960, but would be improved with
time. The basic communications component of the satellite
was thr traveling-wave-tube (TWT). These had been invented
in England by Rudoph Kompfner, but they had been perfected
at Bell Labs by Kompfner and J. R. Pierce. All three
early satellites used TWTs built by a Bell Labs alumnus.
These early tubes had power outputs as low as 1 watt.
Higher- power (50-300 watts) TWTs are available today
for standard satellite services and for direct-broadcast
applications. An even more important improvement was
the use of high-gain antennas. Focusing the energy from
a 1-watt transmitter on the surface of the earth is
equivalent to having a 100-watt transmitter radiating
in all directions. Focusing this energy on the Eastern
U.S. is like having a 1000-watt transmitter radiating
in all directions. The principal effect of this increase
in actual and effective power is that earth stations
are no longer 100 -foot dish reflectors with cryogenically-cooled
maser amplifiers costing as much as $10 million (1960
dollars) to build. Antennas for normal satellite services
are typically 15-foot dish reflectors costing $30,000
(1990 dollars). Direct-broadcast antennas will be only
a foot in diameter and cost a few hundred dollars.
Mobile Services
In February of 1976 COMSAT launched a
new kind of satellite, MARISAT, to provide mobile services
to the United States Navy and other maritime customers.
In the early 1980s the Europeans launched the MARECS
series to provide the same services. In 1979 the UN
International Maritime Organization sponsored the establishment
of the International Maritime Satellite Organization
(INMARSAT) in a manner similar to INTELSAT. INMARSAT
initially leased the MARISAT and MARECS satellite transponders,
but in October of 1990 it launched the first of its
own satellites, INMARSAT II F-1. The third generation,
INMARSAT III, has already been launched.
An aeronautical satellite was proposed
in the mid-1970s. A contract was awarded to General
Electric to build the satellite, but it was canceled--INMARSAT
now provides this service. Although INMARSAT was initially
conceived as a method of providing telephone service
and traffic-monitoring services on ships at sea, it
has provided much more. The journalist with a briefcase
phone has been ubiquitous for some time, but the Gulf
War brought this technology to the public eye.
The United States and Canada discussed
a North American Mobile Satellite for some time. In
the next year the first MSAT satellite, in which AMSC
(U.S.) and TMI (Canada) cooperate, will be launched
providing mobile telephone service via satellite to
all of North America.
Competition
In 1965, when EARLY BIRD was launched,
the satellite provided almost 10 times the capacity
of the submarine telephone cables for almost 1/10th
the price. This price-differential was maintained until
the laying of TAT-8 in the late 1980s. TAT-8 was the
first fiber-optic cable laid across the Atlantic. Satellites
are still competitive with cable for point-to-point
communications, but the future advantage may lie with
fiber-optic cable. Satellites still maintain two advantages
over cable: they are more reliable and they can be used
point-to-multi-point (broadcasting).
Cellular telphone systems have risen as
challenges to all other types of telephony. It is possible
to place a cellular system in a developing country at
a very reasonable price. Long-distance calls require
some other technology, but this can be either satellites
or fiber-optic cable.
The LEO Systems
Cellular telephony has brought us a new
technological "system"-- the personal communications
system (PCS). In the fully developed PCS, the individual
would carry his telephone with him. This telephone could
be used for voice or data and would be usable anywhere.
Several companies have committed themselves to providing
a version of this system using satellites in low earth
orbits (LEO). These orbits are significantly lower than
the TELSTAR/RELAY orbits of the early 1960s. The early
"low-orbit" satellites were in elliptical
orbits that took them through the lower van Allen radiation
belt. The new systems will be in orbits at about 500
miles, below the belt.
The most ambitious of these LEO systems
is Iridium, sponsored by Motorola. Iridium plans to
launch 66 satellite into polar orbit at altitudes of
about 400 miles. Each of six orbital planes, separated
by 30 degrees around the equator, will contain eleven
satellites. Iridium originally planned to have 77 satellites--
hence its name. Element 66 has the less pleasant name
Dysprosium. Iridium expects to be providing communications
services to hand- held telephones in 1998. The total
cost of the Iridium system is well in excess of three
billion dollars.
In addition to the "Big LEOS"
such as Iridium and Globalstar, there are several "little
leos." These companies plan to offer more limited
services, typically data and radiodetermination. Typical
of these is ORBCOM which has already launched an experimental
satellite and expects to offer limited service in the
very near future.
Prospect and Retrospect
Arthur C. Clarke's 1945 vision was of
a system of three "manned" satellites located
over the major land masses of the earth and providing
direct-broadcase television. The inherent "broadcast"
nature of satellite communications has made direct-broadcast
a recurrent theme--yet one never brought to fruition.
The problems are not technical--they are political,
social, and artistic. What will people be willing to
pay for? This is the question-- especially with the
availability of 120-channel cable systems. Hughes is
apparently about to enter this field and may encourage
others to do the same. Only then will Clarke's prophetic
vision be fulfilled.
There are currently six companies providing
fixed satellite service to the U.S.: GE Americom, Alascom,
AT&T, COMSAT, GTE, and Hughes Communications. They
operate 36 satellites with a net worth of over four
billion dollars. The gound stations which communicate
with these satellites are innumerable and may have a
similar net worth. INTELSAT has had competition in the
international market from Pan American Satellite since
1986. Orion Satellite is expected to begin international
service in 1994. Since Canada began domestic satellite
service in 1972, that country has been joined by the
United States (1974), Indonesia (1976), Japan (1978),
India (1982), Australia (1985), Brazil (1985), Mexico
(1985), and many others. Each year from 10-20 communications
satellites are launched valued at about $75 million
each. The launch vehicles placing them in orbit have
similar values. Both satellites and launch vehicles
are multi-billion dollar businesses. The earth station
business is equally large. Finally the communications
services themselves are multi-billion dollar businesses.
John R. Pierce was right--it would be worth a billion
dollars.
A Selective Communications Satellite Chronology
- 1945 Arthur C. Clarke Article: "Extra-Terrestrial
Relays"
- 1955 John R. Pierce Article: "Orbital Radio
Relays"
- 1956 First Trans-Atlantic Telephone Cable: TAT-1
- 1957 Sputnik: Russia launches the first earth satellite.
- 1960 1st Successful DELTA Launch Vehicle
- 1960 AT&T applies to FCC for experimental satellite
communications license
- 1961 Formal start of TELSTAR, RELAY, and SYNCOM
Programs
- 1962 TELSTAR and RELAY launched
- 1962 Communications Satellite Act (U.S.)
- 1963 SYNCOM launched
- 1964 INTELSAT formed
- 1965 COMSAT's EARLY BIRD: 1st commercial communications
satellite
- 1969 INTELSAT-III series provides global coverage
- 1972 ANIK: 1st Domestic Communications Satellite
(Canada)
- 1974 WESTAR: 1st U.S. Domestic Communications Satellite
- 1975 INTELSAT-IVA: 1st use of dual-polarization
- 1975 RCA SATCOM: 1st operational body-stabilized
comm. satellite
- 1976 MARISAT: 1st mobile communications satellite
- 1976 PALAPA: 3rd country (Indonesia) to launch domestic
comm. satellite
- 1979 INMARSAT formed.
- 1988 TAT-8: 1st Fiber-Optic Trans-Atlantic telephone
cable
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