THE PHYSICAL PERFORMANCE OF TELSTAR IN ORBIT
Determination of the choice of the telstar orbit, how well it was realized, the effectiveness of its spin stabilization, and the temperature of the satellite in space
SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Determination of the choice of the telstar orbit, how well it was realized, the effectiveness of its spin stabilization, and the temperature of the satellite in space
This papers that follow describe in depth the satellite and ground systems designed for the Telstar experiment and give the results to date. The purpose of this introduction is to set the scene in which the project was undertaken and to state some general conclusions.
The Goonhilly satellite-communication aerial uses an 85-ft. diameter paraboloidal reflector with waveguide feed at the focus. The aerial is movable in azimuth and elevation, and is provided with independent feedback control systems for these two motions. During a satellite pass, the aerial must be steered so that its axis points continuously, and with high accuracy, in the direction of the satellite. Of the various possible methods of achieving this result, that based on prediction of satellite position has been adopted for the first transatlantic communication experiments using the Telstar and Relay satellites. The process by which orbital predictions originating in the USA are converted to substantially continuous real-time azimuth and elevation pointing instructions at Goonhilly is described herein.
NASA Special Publication SP-32 is being published in accordance with the cooperative agreement executed on July 27, 1961 between the National Aeronautics and Space Administration and the American Telephone and Telegraph Company for the development and experimental testing of active communications satellites. This report consists of four volumes. The first three are composed of papers originally published together as a regular issue of the Bell System Technical Journal. The fourth volume, to be published at a later date, will contain pertinent papers contributed by various authors at the NASA Goddard Space Flight Center; the General Post Office of the United Kingdom; the Centre National d'Etudes des Telecommunications, France; and Telespazio, Italy.
The facility for satellite communication studies at Holmdel, New Jersey, was originally established to take part in Project Echo. This paper describes the modifications required to participate in the Telstar experiments and the results obtained during operations from July 10 to November 9, 1962. Reception of television from the satellite was successfully accomplished, studies were made of the signal levels, and the changes with time of the satellite spin rate and spin axis orientation were determined.
Telstar is the project of the American Telephone and Telegraph Company to demonstrate the relaying of transoceanic telephone service and live television via satellites. It is really much more than that. It will be a calibration of the space environment. We expect that it will tell us a great deal about how to achieve long-life reliable operations in space. This information should be of value to the designers of other kinds of satellites as well as communication satellites. Most of all, we hope that through our cooperative efforts with NASA the Telstar experiment will be a significant step towards the creation of a commercially operable satellite communication system.
The STS-51G flight crew, Commander Daniel C. Brandenstein, Pilot John O. Creighton, Mission Specialists Shannon W. Lucid, John M. Fabian, and Steven R Nagel, and Payload Specialists Patrick, Baudry, and Sultan Salman Al-Saud are seen performing pre-launch activities such as eating of the traditional breakfast, ride out to the launch pad, and crew suit-up for an early morning launch. Also, included are various panoramic views of Discovery on the pad. The main objective of this mission is to deploy three communication satellites. The satellites being deployed are MORE LOS-A, for Mexico; ARABSAT-A, for the Arab Satellite Communications Organization; and TELSTAR-3D, for AT&T. The crew also retrieve the SPARTAN-1 satellite. Scenes include the crew in the mess deck via video link with Mission Control Center in celebration of the 100th American in space. Al-Saud also spoke with his father in Saudi Arabia via video link. Views of certain experiments are also seen. Al-Saud is seen conducting the postural experiment, and Baudry is seen conducting the equilibrium experiments. Panoramic views of the Hawaiian Island Archipelago, and Wadi Habawnah, Saudi Arabia are also visible from the shuttle. Live footage ends with the re-entry of the vehicle into the Earth's Atmosphere, an early morning touchdown at Edwards Air Force Base and crew departure from the craft.
NASA Special Publication SP-32 is being published in accordance with the cooperative agreement executed on July 27, 1961 between the National Aeronautics and Space Administration and the American Telephone and Telegraph Company for the development and experimental testing of active communications satellites. This report consists of four volumes. The first three are composed of papers originally published together as a regular issue of the Bell System Technical Journal. The fourth volume, to be published at a later date, will contain pertinent papers contributed by various authors at the NASA Goddard Space Flight Center; the General Post Office of the United Kingdom; the Centre National d'Etudes des Telecommunications, France; and Telespazio, Italy.
A comprehensive review is presented of worldwide communication programs that range in time from the inception of satellite communications to August 1971. The programs included are: Echo, Courier, West Ford, Telstar, Relay, Syncom, Lincoln experimental satellites, Intelsat, Tacsat, Skynet, Nato system, and Telesat.
The initial purpose of the Post Office satellite system earth station at Goonhilly Downs, Cornwall, is to obtain information on the performance of experimental communication satellite systems; such information will be of great importance to the designers of systems for commercial operation. To facilitate this dissemination the UK and USA Governments prepared and signed, in February 1961, a Memorandum of Understanding regarding collaboration between the British Post Office and the United States National Aeronautics and Space Administration (NASA) on the testing of experimental communication satellites to be launched by NASA. The first phase of the tests covered Projects Telstar and Relay, both active satellites.
Components for a high-reliability system such as the Telstar project are obtained by: (a) design of the component for the required environment, (b) careful control of manufacturing processes, (c) elimination of potential early failures by screening tests, and (d) selection of the most stable components. For passive components, these methods could be applied by using design parameters, suppliers and screening techniques established in the earlier submarine cable program, with consideration being given to the additional effects of the satellite launch and orbit environments. Semiconductor component designs were selected by qualification tests using accelerated electrical and environmental stress conditions. Screening tests were applied to eliminate early failures, and resulting components were aged from two to six months before selection for the satellite. The recognition of the effect of ionizing radiation on transistors caused the addition of a radiation qualification test, or a screening to assure selection of the least sensitive devices. Tests have shown this screening to be effective for the radiation intensity expected. Experience with the passive components, and evaluation of the accelerated test results and aging data of the semiconductor devices, indicate that the reliability objective was obtained.
A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method of the satellite This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3psec for integration times ranging from 1 to 2000 seconds. For integration times greater then 500 seconds, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since substantially and the performance of various components has improved. An important factor is the leasing of small amounts of satellite communication bandwidth. We lease three 100kHz bands at approximately one hundredth the cost of a full 36 MHz transponder. Further tests of the system using terminal separated by large distances and comparison tests with two hydrogen masers and radio interferometry is needed.
The choice of the basic type of aerial for a satellite communication ground station is of major importance in view of its influence on the overall performance, cost and time to complete the installation. In the case of the Post Office satellite communication earth station at Goonhilly Downs, Cornwall, a decision was made early in 1961 to use an 85-ft diameter steerable paraboloidal dish aerial, without a radome for tests with the Telstar and Relay, and other communication satellites. Tests with smaller paraboloidal dish aerials with the feed in the aperture plane had shown that a satisfactory electrical performance could be obtained, and experience with the 250-ft diameter radio telescope at Jodrell Bank had shown that the mechanical problems could be overcome. An important factor in the present case was the limited time--less than one year--available for the design, manufacture, construction and testing of the aerial.
The power supply system in the Telstar spacecraft consists of a solar cell plant to convert solar radiation to electrical energy when the satellite is illuminated by the sun, a 19-cell nickel-cadmium battery to store energy, and a regulation circuit to supply constant output voltages over a wide variation in input voltages. Additionally, the power supply system provides switching to conserve power and allow battery recharging during periods between communications experiments.
Book on communications satellites design, testing, operation and power systems for Echo, Telstar, Relay, Syncom, ground stations, etc
The radiation experiments on the Telstar spacecraft were designed to measure the electron and proton particle distributions in the region of space explored by the satellite orbit and to give information on the integral semiconductor radiation damage produced by these particles. A solar aspect experiment is included with the radiation experiments because of its direct importance to solar cell damage results. The design and the hardware for these experiments are described in the present paper. Results of the experiments are included in a companion paper in this issue.
The command and telemetry portions of the Telstar system provide necessary support functions for the basic communications experiment and the radiation experiment. By means of the command system, the states of 9 magnetic latching relays in the satellite are controlled from the ground. Commands are sent to the satellite by coded signals modulated on a carrier in the VHF band. The telemetry system also uses a VHF carrier to transmit encoded information from the satellite. Data on 112 items are provided once each minute. This paper discusses the over-all command and telemetry systems and considers the general objectives, system aspects and detailed implementation.
NASA Special Publication SP-32 is being published in accordance with the cooperative agreement executed on July 27, 1961 between the National Aeronautics and Space Administration and the American Telephone and Telegraph Company for the development and experimental testing of active communications satellites. This report consists of four volumes. The first three are composed of papers originally published together as a regular issue of the Bell System Technical Journal. The fourth volume, to be published at a later date, will contain pertinent papers contributed by various authors at the NASA Goddard Space Flight Center; the General Post Office of the United Kingdom; the Centre National d'Etudes des Telecommunications, France; and Telespazio, Italy.