Relay (satellite)

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Artist's impression of NASA's Relay 1 & Relay 2 satellites

Relay was an early American experimental communications satellite program that consisted of the two satellites Relay 1 and Relay 2 . The program was financed by NASA , and the two satellites were built by RCA . In 2018, both satellites were still in orbits so high that they can remain in space for decades to come.

Relay 1

Relay 1 was launched into Earth orbit on December 13, 1962 at the head of a Delta B missile from the LC-17A launch complex at Cape Canaveral Air Force Station .

Technical information

The satellite was about 83 cm (33 inches) high and weighed about 78 kg (172 pounds). The spin-stabilized satellite initially rotated around its own axis at a speed of 167.3 revolutions per minute, the position of which in space is determined by a declination of −68.3 ° and a right ascension of −56 °. The orbital period of the satellite around the Earth was 185.09 minutes initially orbit had a perigee of about 1,320 kilometers (820 Miles) and an apogee of about 7,450 kilometers (4,630 Miles) on.

For payload included radiation experiments by which the location and extent of today as Van Allen radiation belt known radiation belt of the earth should be included. The satellite could via the antenna mast in the extension of the satellite axis with each of the two alternatively usable transponder in with a transmission power of 10 W is either a TV channel or twelve telephone calls duplexing transmitted. In the satellite there was a transmitter for the transmission of the orbit data of the satellite and another for the transmission of telemetry data . The telemetry system used pulse code modulation with a transmission rate of 1152 bit / s. Of the 128 data words of a telemetry data set transmitted in each time window of 1 s, 113 data words were used to transmit data for the radiation experiment.

Two fundamental problems arose shortly after the start. The first was the response of the satellite to falsified control commands, the second a faulty charging behavior of one of the electrical power packs fed by solar cells for the nickel-cadmium batteries used in the satellite . Due to this undervoltage in the on-board network, the satellite could not be used in the first two weeks of its orbit, but could then be used largely as intended. For Relay 1 an automatic shutdown was planned for the end of 1963, but the electronics installed in the satellite for this purpose failed. Due to the incorrect charging behavior of the energy supply , the satellite was placed in an undervoltage status at the beginning of 1965. Up to February 10, 1965, data was still transmitted sporadically, after which no scientifically usable information could be received.

use

In April 1963, an electroencephalogram from Bristol, England was transmitted via satellite to the Mayo Clinic and the diagnosis made there was transmitted back to the doctor in England via satellite.

Relay 1 was the first satellite used to transmit signals from a television broadcast between the United States and Japan. This broadcast took place in orbit 2677 on November 22, 1963 from 2027: 42 to 2048 (GMT) (1:27 pm Dallas time). A pre-recorded greeting from John F. Kennedy to the people of Japan was planned for the transmission , instead the message of the assassination attempt on him about an hour before was sent. On the next orbit in 2678, the satellite broadcast the first simultaneous broadcast in the United States and Japan, entitled "Record, Life of the Late John F. Kennedy". With later rounds, NBC broadcast the funeral procession from the White House to the Church. In the three days following the murder, Relay 1 broadcast eleven television reports, eight in Europe and three in Japan. All overflight phases of the satellite that could be used for the transmission were used to enable the transmission of current reports on the tragic events.

In August 1964, the satellite relay 1 was to transfer the Olympic Games used from Tokyo by the United States to Europe. The reports had previously been transmitted from Japan to the United States via the Syncom 3 satellite . This was the first time that two satellites were used simultaneously for the transmission of a television program. Relay 1 was the first satellite transmission between North and South America, as well as from the United States to Japan, Scandinavia and Germany. This satellite transmitted a total of 81 television programs and thus more than doubled its planned service life of one year.

Reception possibilities

Horn antenna for communicating with Relay 1 in Andover, Maine

For the experiments with the satellites of the Telstar (1 and 2), Syncom ( 1 , 2 and 3 ) and Relay (1 and 2) series, which were taking place around the same time , several satellite receiving stations, some of them mobile, were in Andover (Maine) , Goonhilly (Cornwall) ) and Pleumeur-Bodou (France). An antenna 10 m in diameter proved to be sufficient.

COSPAR name of Relay 1: 1962-068A

Relay 2

Relay 2 was launched on January 21, 1964 at the tip of a Delta B rocket from the LC-17B launch complex at Cape Canaveral Air Force Station and its physical structure was largely similar to the Relay 1 that was already in circulation. Various changes made its behavior possible however, it should be improved to the effect that, in contrast to Relay 1, it reacted correctly to the control commands. The first of the two transponders in the satellite worked properly until November 20, 1966. From this point on, the time until it was ready for operation was extended, and on January 20, 1967, it finally failed. The second transponder worked until June 9, 1967.

Relay 2 COSPAR name: 1964-003A

Web links

Commons : Relay satellite program  - collection of pictures, videos and audio files

Individual evidence

  1. ^ A b Donald H. Martin: Communications Satellites , fourth. Edition, The Aerospace Press, El Segundo, CA 2000, ISBN 1-884989-09-8 , pp. 8-9 (accessed October 31, 2009).
  2. ↑ a b c d Significant Achievements in Space Communications and Navigation, 1958-1964 (PDF; 15.0 MB) In: NASA-SP-93 . NASA. Pp. 20 ff. 1966. Retrieved November 15, 2010.
  3. ↑ In contrast to the document NASA-SP-93, p. 20, NASA currently states a satellite weight of 170 kg on the website for Relay 1 .
  4. ↑ Final Report on the Relay 1 Program (PDF; 341 MB) In: NASA-SP-93 . NASA. 63, 1966. Retrieved October 31, 2009.
  5. ↑ Final Report on the Relay 1 Program (PDF; 341 MB) In: NASA-SP-93 . NASA. P. 663. 1966. Retrieved October 31, 2009 (list of actual orbit dates and times)
  6. ↑ NBC News : There Was a President . Random House, New York 1966.
  7. ↑ Richard F. Shepard: TELEVISION POOLS CAMERA COVERAGE . In: The New York Times , Nov. 26, 1963, p. 11. 
  8. ↑ a b c Significant Achievements in Space Communications and Navigation, 1958-1964 (PDF; 15.0 MB) In: NASA-SP-93 . NASA. Pp. 30-32. 1966. Retrieved October 31, 2009.