NASA Experimental Communications Satellites 1958-1995
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NASA Experimental Communications Satellites
Contents
NASA has been active in the development of the communications satellite from the founding of the agency in 1958 to the present day. Communications has been the most successful commercial enterprise in space. Of the hundreds of communications satellites sent into orbit, around 150 are operational today. To enable this success, NASA has launched several experimental satellites to develop the technology needed for commercial applications.
This document presents a short history of experimental communications satellites developed by NASA.
The projects are covered in chronological order:
- Introduction
- Echo
- Telstar
- Relay
- Syncom
- Applications Technology Satellites (ATS) 1 through 6
- NASA Quits
- Communications Technology Satellite (CTS)
- Advanced Communications Technology Satellite (ACTS)
- Other related projects , such as the Tracking and Data Relay Satellite (TDRS), are also covered.
- Concluding Remarks
- Some NASA Links
Click on the headings below (satellite names) for more detail.
···
INTRODUCTION
This picture shows the latest NASA experimental communications spacecraft, the Advanced Communications Technology Satellite (ACTS), after deployment from the Space Shuttle Discovery on mission STS-51 on September 12, 1993. NASA has been active in the development of the communications satellite from the founding of the agency in 1958 to the present day. Communication is the most successful commercial enterprise in space. Of the hundreds of communications satellites sent into orbit, approximately 150 are operational today. To enable this success, NASA has launched several experimental satellites to develop the technology needed for commercial applications.
ECHO
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The Echo satellites were large metallized balloons that served as passive reflectors of radio signals. Passive satellites were not attractive for commercial use because the reflected signal is so weak.
(83K) Technicians check-out the Echo satellite payload. The 26 inch diameter magnesium sphere contains the balloon into orbit where it is released and inflated.
Launch dates:
Echo 1 - August 12, 1960
Echo 2 - January 25,1964.
TELSTAR
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AT&T's Telstar I and II were not really NASA spacecraft, but NASA was able to claim participation in the program because of its involvement in launching them. AT&T designed, built, and payed for the launches with its own funds. The Telstar I and II spacecraft were prototypes for a constellation of 50 medium orbit satellites that AT&T was working to put in place. When the Kennedy Administration decided to give the monopoly on satellite communications to Comsat, AT&T's satellite project was halted.
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The Telstar spacecraft awaits mating with its Delta launch vehicle.
Launch dates:
Telstar 1 - July 10, 1962
Telstar 2 - May 7, 1963.
RELAY
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Relay was an active satellite (like all the following) that received a radio transmission from the ground and retransmitted it back to another location on Earth. The 172 pound spacecraft is 33 inches high and 29 inches in diameter at its broad end.
Launch dates:
Relay 1 - December 13, 1962
Relay 2 - January 21, 1964.
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The NASA Relay 1 experimental active communication satellite in assembly at the Astro-Electronics Division of RCA at Princeton, NJ.
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The travelling-wave tube (TWT) is the key power amplifying device in the Relay transponder. This 3.5 pound tube produced a minimum rf output of 11 Watts at a gain of 33 dB over the 4050-4250 MHz band with an overall efficiency of at least 21%.
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Brazilian electronics engineers check out a ground communications equipment van for Project Relay. The transportable space communications terminal was developed by ITT.
SYNCOM
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The first synchronous orbit satellite, Syncom led to the development of the Early Bird Intelsat I commercial communications spacecraft as well as the ATS series of NASA research satellites.
Launch dates:
Syncom 1 - February 14, 1963, but failed seconds after its apogee kick motor fired.
Syncom 2 - July 26, 1963
Syncom 3 - August 19, 1964.
Summary Chart of ATS Satellites
ATS - Applications Technology Satellites
ATS-1
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The Applications Technology Satellite program has launched six satellites so far. This picture of Earth was taken by ATS-1's meteorological camera. ATS spacecraft addressed both communications and weather applications. The spacecraft configuration was nearly identical to ATS-3 (below).
Launch date: December 7, 1966.
ATS-2
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Engineers check out the second Application Technology Satellite at Cape Kennedy, FL. Designed to transmit television (black-and-white and color) and narrow band traffic among stations located in the US, Japan, and Australia, ATS-2 was not successful due to the failure of the launch vehicle second stage.
Launch date: April 6, 1967
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Technicians at NASA's Goddard Space Flight Center in Greenbelt, MD demagnetize the second ATS spacecraft. Permanent magnetism in a spacecraft interacts with the Earth's magnetic field that can torque the spacecraft out of the desired orientation with respect to the Sun.
ATS-3
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The third ATS spacecraft is readied for encapsulation in the launch vehicle fairing at Cape Kennedy, FL. ATS-3 was designed to provide color and black-and-white weather pictures of Earth using a spin scan camera as well as to relay radio voice traffic.
Launch date: November 8, 1967.
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The ATS-3 spacecraft is suspended during an antenna pattern test. The spacecraft was built by Hughes for NASA.
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This picture of Earth was taken by the ATS-3 Multicolor Spin Scan Camera. ATS-3 addressed both communications and weather applications. It is the oldest active communications satellite and is still being used today.
ATS-4
Technicians inspect the fourth ATS spacecraft at Cape Kennedy, FL. Built by Hughes for NASA, this satellite had a gravity-gradient stabilization system, ion engines, weather and communications payloads. ATS-4 did not reach the proper orbit due to failure of the launch vehicle.
Launch date: August 10, 1968
ATS-5
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The fifth ATS spacecraft is being prepared for mating with the Atlas-Centaur launch vehicle. ATS-5 failed to deploy properly.
Launch date: August 12, 1969
ATS-6
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The sixth ATS spacecraft is shown in final systems test and checkout at the Fairchild Industries Plant, Germantown, MD. The spacecraft was built by Fairchild Industries for NASA.
Launch date: May 30, 1974.
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A test model of the sixth ATS spacecraft is seen during checkout activity at NASA's Johnson Space Center in Houston, TX to see if the 30 foot diameter, umbrella-shaped antenna would unfold properly in a space vacuum.
NASA Quits the Program (for a while)
In 1973, as a result of the Nixon Administration's "Open Skies" policy and budget pressures, NASA ended its commercial satellite communications research and development program. The ATS 6 and CTS projects were already started and it was decided to continue those until finished. The ATS G and ATS H/I efforts were cancelled. The program was reinstated in 1978 with NASA's Lewis Research Center taking the lead role.
CTS
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The Communications Technology Satellite (CTS, also called Hermes) was a joint project by the Canadian Department of Communications and NASA. The synchronous satellite carried a 200 Watt TWT amplifier and operated at 14 up/12 down GHz.
Launch date: January 17, 1976.
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Solar panel deployment is being tested on the CTS spacecraft.
ACTS
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Mating of the Advanced Communications Technology Satellite (ACTS) with the Transfer Orbit Stage (TOS) booster is under way at Kennedy Space Center, FL. Martin Marietta (formerly GE) Astro-Space built the spacecraft and Orbital Sciences Corp. developed the TOS.
Launch date: September 12, 1993
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The Space Shuttle Discovery lifts off from Kennedy Space Center Pad 39B on Mission STS-51 carrying the ACTS spacecraft in the cargo bay.
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The last view of the ACTS spacecraft before it is rocketed to geosynchronous orbit.
RELATED SATELLITES
TDRSS
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The sixth Tracking and Data Relay Satellite (TDRS) is about to be released from its cradle/tilt table device in Endeavour's cargo bay during mission STS-54. TDRS 1 was launched on April 5, 1983 and TDRS 6 was launched on January 13, 1993. The second TDRS was in the Space Shuttle Challenger's payload bay for mission STS-51L and was lost in the tragic explosion on January 28, 1986 that claimed the lives of seven astronauts. The TDRS System is an operational communications system for NASA missions and does not fit the classification of "experimental communications satellites," but is included here as an example of the result of experimental projects like ATS-6.
Additional sites:
NASA's Tracking and Data Relay Satellite System (TDRSS) On-line Information Center
JPL's Mission and Spacecraft Library
GOES
The Geosynchronous Operational Environmental Satellite (GOES) included some data communications capabilities.
For more information check the links at the bottom of the page or
The EXPLORES! page.
NIMBUS
NASA's Nimbus weather satellites also served as data relays.
Concluding Remarks
Chronology
Bibliography
About the Author
Daniel R. Glover is a technical manager at NASA's Glenn Research Center in Cleveland, Ohio.
Links to Unmanned Spacecraft and Satellite Pages
Satellites on NASA's Spacelink
JPL's Mission and Spacecraft Library: Program Index
March 30, 2000