US History/US History (Bureau Development Inc.)(1991).ISO/dp/0001/00018.txt

Text File | 1990-12-23 | 21KB | 441 lines

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$Pretitle{2}
$Title{NASA, The First 25 Years 1958-1983
Chapter 3  Applications Satellites}
$Subtitle{}
$Author{Thorne, Muriel M., Technical Monitor & Editor}
$Affiliation{NASA}
$Subject{satellites
satellite
earth
first
communications
weather
nasa
surface
landsat
resources}
$Volume{}
$Date{1983}
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Book:        NASA, The First 25 Years 1958-1983
Author:      Thorne, Muriel M., Technical Monitor & Editor
Affiliation: NASA
Date:        1983

Chapter 3  Applications Satellites

     When the first satellites were launched in the late 1950's, many people
were skeptical about the practical value of a space program.  In just three
years, however observations and measurements from Earth-orbiting satellites
were revolutionizing communications and weather forecasting and showing Earth
on a global scale.  These were the applications satellites, spacecraft with
experiments and instruments that provided unique, direct benefits to life on
Earth.  They and those that evolved from them have made it possible for people
on opposite sides of Earth to communicate instantaneously, for people in
remote areas of the world to learn by television, for ships to know where
storms and icebergs threaten passage, for forecasters to watch weather
develop, for oil companies to locate drilling sites, for environmentalists to
monitor the spread of pollutants.

     In both domestic and foreign applications satellite programs, NASA has
contributed research and development, launching capabilities, and evaluation
of spacecraft.  The technologies developed produced passive and active
communications satellites, the first synchronous and geostationary orbits, and
the cloud cover pictures that now are a regular feature of daily weather
reports.

     From Echo, the balloon that was the first satellite everyone could see,
and the scientific Explorer 6 that also took the first crude cloud cover
picture, the applications satellites have become complex multipurpose systems.

     Once NASA has developed the weather and communications satellites, the
responsibility for operating them falls to other government agencies or to
private industry.  NASA continues its research role, seeking and developing
advanced technologies.

     The following list introduces the major groups of these satellites, their
purposes, and the benefits they have contributed.

Communications

     In 1945 British scientist and science fiction writer, Arthur C. Clarke,
published a technical paper in which he suggested that communications
satellites were feasible.  Fifteen years later, NASA launched its first
communications satellite, Echo, a silvery balloon that orbited Earth every 114
minutes.

     Echo was a passive satellite that reflected radio signals back to Earth.
Two years later, Relay, the first active satellite was launched to receive
signals, amplify them, and transmit them back to Earth.

     Today's split-second global communications by voice, television, and
computer are such a part of daily life that the evolution from simple passive
reflectors to complex active transmitters is hardly remembered.  After NASA
completed research and development, private companies produced their own
communications satellites, and in 1962 Congress authorized the Communications
Satellite Corporation, Comsat, which is the U.S. representative in and manager
of Intelsat, the International Telecommunications Satellite Organization.  For
both industry and Intelsat, NASA launches and tracks satellites on a
cost-reimbursable basis.

Echo

     The Echos were inflated in space to spherical balloons of aluminized
Mylar, 30.5 and 40 meters (100 and 135 feet) in diameter, respectively.
Passive communications satellites, they reflected radio signals between ground
stations.  They also provided information about the density of the upper
atmosphere.  Echo 1 was launched August 12, 1960, Echo 2 in January 1964.

Relay

     Relay 1 was NASA's first active repeater experimental satellite; launched
December 13, 1962, it handled 12 simultaneous two-way telephone conversations
or one television channel and provided the first satellite communications link
between North and South America and Europe.  Relay 2, an improved version, was
launched in January 1964.

Syncom

     Three experimental, active satellites; the name, coined from the first
syllables of "synchronous communications," referred to their orbits.  Weight:
38.5 kg (about 85 lbs) each.

Syncom I
February 14, 1963
In nearly synchronous orbit, but communications failed.

Syncom II
July 26, 1963
First satellite placed in synchronous orbit.
Many successful intercontinental communication experiments.

Syncom III
August 19, 1964
First stationary Earth satellite.  Demonstrated the practicality and
effectiveness of stationary, active communication satellites.  In orbit near
the International Dateline, it was used to telecast the 1964 Olympic Games in
Tokyo to the United States, the first television program to cross the Pacific.

Applications Technology Satellites (ATS)

     A series of six multipurpose Applications Technology Satellites designed
to test new space instruments and demonstrate new satellite technologies,
particularly those used in synchronous orbit satellites.

ATS-1
December 6, 1966
Took first U.S. high-quality photographs of Earth from synchronous orbit,
showing changing cloud-cover patterns.  Also relayed color television across
the U.S. and was the first satellite to permit two-way VHF communication
between ground and aircraft in flight.

ATS-3
November 1967
Carried advanced communications, meteorology, and navigation experiments;
transmitted color images of one complete side of Earth.

ATS-6
May 1974
The first communications satellite with power to broadcast TV photos to small
local receivers; also used for a number of experimental public health and
education telecasts to remote rural areas in the U.S. and India. (See Chapter
IV, India.)

Communications Technology Satellite (CTS)
January 17, 1976
The CTS was a joint project with Canada.  A high-powered satellite, it used a
movable terminal to investigate the possibility of transmitting public service
information to small, inexpensive antennas in remote locations.

Earth Resources

     Earth observation satellites have brought us a new view of our planet.
Mountains, prairies, deserts, lakes, rivers, reservoirs, forests, farms,
cities, highways, have become infrared and ultraviolet scenes.  Millions of
these pictures have been distributed to users of Earth resources information
around the world.

     From the outset, the remote sensory devices of these spacecraft have
produced a continuous flow of data.  The results, including often dramatic
pictures, have been tangible and the satellites unique tools of enormous
practical value for a wide range of interests: urban development and land use
and water source management, agriculture, locating pollution, geology,
forestry, mapping and charting.

     Geologists use the data to locate drilling sites, to predict earthquakes,
and to study volcanoes.

     Skilled photointerpreters among agriculturists can readily distinguish
among a variety of crops in the satellite images.  With computers, maps can be
produced showing the precise location of each crop over large areas of land.
Using this technology, NASA participated in a three-year experiment to monitor
global wheat production beginning in 1974.  The Large Area Crop Inventory
Experiment (LACIE) successfully tested several techniques for predicting crop
production early in the growing season.

     Much of the everyday disposal of tons of garbage and trash and toxic
wastes dumped into the environment ends up in our rivers, lakes, and oceans.
The challenge to clean up polluted areas and to protect those areas yet
untouched requires information on a scale that was unavailable before
satellites.  Earth resources spacecraft have provided valuable surveys of
large areas of land, helping scientists and environmentalists trace the
sources of pollution and monitor the dissemination of waste.

     Wise management of the Earth's water resources is necessary for both
present and future generations.  Data from satellites has been helping
hydrologists to predict floods and estimate flood damage, as well as to
monitor water supplies.

     From the simple PAGEOS balloon of 1966 to the advanced Landsat 4 of 1982,
the Earth resources experiments have changed radically the way we see Earth,
collect information about it, and interpret the results.

Passive Geodetic Earth Orbiting Satellite (PAGEOS)
June 1966
A large metalized balloon, 30 meters (98.4 ft) in diameter similar to the Echo
satellites.  A passive satellite, it reflected sunlight and, photographed by
ground stations around the world, established a worldwide triangulation
network to map Earth's surface.

Landsat

     A series of satellites that have provided a wealth of observations which
have improved our ability to monitor and understand the dynamics and character
of the various features and materials covering the surface of the Earth.

Landsat 1, July 1972

Landsat 2, January 1975

Landsat 3, March 1978
The first Landsats (1 and 2 were originally called ERTS for Earth Resources
Technology Satellite) carried an Earth-viewing sensor called Multispectral
Scanner (MSS), a radiometer that obtains imagery of Earth's surface in four
discrete spectral bands.  The decade of their image-collecting showed the
unique types of data that MSS imagery could provide vegetation types, bare
soil and rock conditions, snow cover - on a highly repetitive basis.  The
images Landsats 1, 2, and 3 collected represent the first historical record of
Earth's global surface conditions.

     Landsat 1 was removed from service in 1978, Landsat 2 in 1982, and
Landsat 3 will be retired in 1983.

Landsat 4, July 1982
In addition to the MSS, Landsat 4 has a more sophisticated sensor, the
Thematic Mapper (TM) which measures the intensity of surface radiation in
seven discrete bands and has approximately twice the spectral resolution,
three times the spatial resolution, and four times the sensitivity of the MSS.
From a 695-kilometer (432-mi) orbit, it is providing extraordinary details,
and for the first time, natural color images, of Earth's surface features.

     NASA has transferred the operation and management of Landsat to the
National Oceanic and Atmospheric Administration (NCAA).  Management control
over the TM will be retained during the experimental research and development
phase of the new sensor system; NASA expects to transfer control of the TM to
NCAA in early 1985.

     Landsat imagery is available for a lab service charge.  For information
about ordering pictures, write to the EROS Data Center, Sioux Falls, SD 57198.

Earth Resources Experiment Package (EREP)
SKYLAB, May 1973-February 1974

     Objectives: To test the use of sensors operating in the visible and
infrared portions of the spectrum, to test a complex microwave sensor that
provided a space-based radar system for Earth resource studies, and to develop
data analysis techniques.

     Investigations: Agriculture, range, and forestry; land use and
cartography; geology and hydrology; oceans and atmosphere.

     Results: Demonstrated the potential and practicality of using quality
photos from orbiting spacecraft for large geographic as well as regional and
local areas and their usefulness as a tool for professionals concerned with
management of resources.

Laser Geodynamics Satellite (LAGEOS)
May 1976
A heavy sphere, 411 kg (906 lbs), 60 centimeters (2 ft) across and covered
with laser reflectors, designed to demonstrate the feasibility and utility of
a ground-to-satellite laser system to contribute to the study of solid Earth
dynamics; provided valuable data to scientists analyzing conditions leading to
earthquakes.

Heat Capacity, Mapping Mission (HCMM)
April 1978
First in a series of small experimental satellites designed for the
Applications Explorer Missions.  Later called AEM-1, it had one sensor for one
purpose, making thermal measurements of Earth's surface and atmosphere across
the U.S.  Its unique sensor could read daytime temperatures associated with
the Sun and nighttime temperatures associated with radiative cooling.

Meteorology

     Weather affects everyone - food supplies, travel, recreation - and along
with other applications satellites, the weather satellites have brought
special advantages to life on Earth.  They enable people to plan ahead, assist
meteorologists with forecasting, and help scientists to understand better the
air around us.

     Advance knowledge of weather systems that can be disastrous is the most
striking advantage; part of that knowledge comes from the ability to see the
sparsely populated regions of the world where weather is born, thus aiding
long-term prediction.  For local meteorologists, daily photographs show how
their local weather patterns fit into the overall picture.

     On April 1, 1960, TIROS 1, the first true weather satellite, was
launched.  With each succeeding generation of satellites, remote sensing
instruments became increasingly sophisticated and today's high quality
pictures are a far cry from the first tentative trials.

TIROS

     The Television and Infrared Observation Satellite (TIROS) was a simple
hatbox-shaped craft carrying special television cameras that viewed Earth's
cloud cover from a 725-km (450-mi) orbit.  The pictures radioed back to Earth
provided meteorologists with a new tool - a nephanalysis, or cloud chart.

     By 1965, nine more TIROS satellites were launched.  They had
progressively longer operational times, carried infrared radiometers to study
Earth's heat distribution, and several were placed in polar orbits to increase
picture coverage over the first TIROS in its near-equatorial orbit.

     TIROS 8 had the first Automatic Picture Transmission (APT) equipment that
allowed pictures to be sent back right after they were taken instead of having
to be stored for later transmission.  Eventually, APT pictures could be
received on fairly simple ground stations anywhere in the world, even in high
school classrooms.

     TIROS 9 and 10 were test satellites of improved configurations for the
Tiros Operational Satellite (TOS) system. (When it became part of another
acronym, TIROS was written Tiros.)

     Operational use started in 1966.  In orbit, the TOS satellites were
called ESSA for the Environmental Sciences Services Administration, the
government agency that financed and operated them.  TOS satellites were placed
in Sun-synchronous orbits, so they passed over the same position on Earth's
surface at exactly the same time each day; this allowed meteorologists to view
local cloud cover changes on a 24-hour basis.

     Several ITOS (for Improved TOS satellites) have been launched since 1970
and are the workhorses of the meteorologists.  In orbit they are called NOAA
for the National Oceanographic and Atmospheric Administration which is
responsible for their operation.

Nimbus

     More complex than TIROS, Nimbus was a second-generation research
satellite.  Each carried advanced cameras, an APT system, an advanced TV cloud
mapping camera system, and an infrared radiometer that allowed pictures at
night for the first time.

     Seven were placed in orbit between 1964 and 1978.  Nimbus 3, launched in
April 1969, provided data for the U.S. portion of the Global Atmospheric
Research Program (GARP), an international program formulating and coordinating
research for achieving long-range global weather forecasting.

     The Nimbus satellites tested space-borne meteorological equipment and
their experiments led to operational, 24-hour satellite weather coverage.

Applications Technology Satellites (ATS)

     Intended primarily for communications technology, these multipurpose
spacecraft contributed much to advance weather forecasting.

ATS-1
December 1966
Took repetitive photographs of the same area, greatly aiding in the early
detection of severe storms.

ATS-3
November 1967
Recorded the first color images of the full Earth disc.  Took photos every 20
minutes enabling meteorologists to put them together in a sequence and make a
motion picture of cloud movements; until 1975, the cloud cover pictures seen
on TV came from this satellite.

Synchronous Meteorological Satellites (SMS-1 and 2)

     May 1974 and February 1975 First experimental craft for a geosynchronous
satellite system designed specifically to provide weather data and to serve as
prototypes for later operational satellites funded by NOAA.  Following launch
and check out by NASA, SMS-1 and SMS-2 were transferred to NOAA for use in the
National Operational Meteorological Satellite System.  Successive satellites,
designated GOES (Geostationary Operational Environmental Satellite), were
constructed and launched by NASA, funded and operated by NOAA.

Oceanography

     Seventy percent of Earth is covered by oceans.  These vast areas of water
are a source of energy in the form of weather the home of great schools of
fish, a mechanism for the disposal of waste products, and the major means of
transporting the goods of the world by ship.

     Precise knowledge of the oceans resources and dynamics has potential
application in many scientific and commercial pursuits - ship design and port
development, fishing, weather forecasting, environmental science, shipping,
selection of sites for off-shore drilling.  Satellite observations have
contributed to our understanding with accurate measurements of surface wind
speeds and directions, temperatures, wave heights, and tides and currents; the
data have helped to detect storms, map the ocean floor, and monitor the
movement of icebergs.

Earth Resources Experiment Package (EREP)
Skylab, May 1973-February 1974

     A collection of instruments with relatively low-resolution,
middle-spectrum imaging sensors, EREP proved the feasibility of remote-sensing
of wind conditions, surface temperatures and roughness, and the recording of
visible phenomena, and advanced the study of the interaction of the atmosphere
and land and ocean surfaces.  Improved versions of the instruments were built
for GEOS-3 and Seasat.

Geodynamic Experimental Ocean Satellite (GEOS-3)
April 1975

     Measured the changing shape of the oceans surface, tides, and currents to
improve the geodetic model of Earth and knowledge of Earth-sea interactions.
Third in the series of Geodetic Earth Orbiting Satellites (GEOS), GEOS-3 was
renamed Geodynamic Experimental Ocean Satellite to emphasize its specific
mission in NASA's ocean physics program while retaining the GEOS acronym.

Seasat (Specialized Experimental Applications Satellite)
June 26, 1978

     First satellite for sole study of the oceans in a proof-of-concept
mission. Objectives: To demonstrate techniques for monitoring Earth's
oceanographic phenomena and features from space on a global scale; to provide
oceanographic data in a timely fashion to scientists and commercial users; and
to determine the key features of an operational ocean monitoring system.

     With all-weather and day-night capability, it circled Earth 14 times a
day and crossed 95 percent of the ocean's surface every 36 hours giving
oceanographers their first worldwide observation of the seas.

     Although contact was lost in October 1978 and the mission terminated in
November, the objectives were largely met.

For The Classroom

     1.   Research topics:
          History of communications
          Commercial satellites
          The development of Earth resources satellites
          Sources of pollution in the at mosphere

     2.  What advantage does geological study from space have over study from
Earth's surface? from Earth over study from space?

     3.   Why is a study of the atmosphere important?

     4.  Secondary school teachers may obtain a copy of Teachers' Guide for
Building and Operating Weather Satellite Ground Stations from the Educational
Programs Officer NASA Goddard Space Flight Center (202.3), Greenbelt, MD
20771.  The publication gives the information needed to construct, modify, and
operate a weather satellite recording station.

     5.  Have your students list the possible benefits of Earth resources
satellites; which are apparent in their local community? their state?