Marcopolo (satellite)

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The satellites Marcopolo 1 and Marcopolo 2 were two television satellites for direct television reception. They used the five frequencies allocated to the United Kingdom for its radio satellites at the WARC-77 radio administration conference , for one television program or several radio programs per frequency, at the orbital position 31 ° West .

prehistory

For broadcast satellites, the WARC-77 radio administration conference decided to assign the BSS band from 11.7–12.5 GHz. This in turn was divided into a lower (11.7-12.1 GHz) and an upper half-band (12.1-12.5 GHz). Normally, as here, a state was allocated its five frequencies in a half-band. Because the United Kingdom is a Western European country, it and four other Western European countries (Ireland, Iceland, Portugal, Spain) were given the five channels 4, 8, 12, 16 for its broadcast satellites on the orbital position 31 ° West on the WARC-77 and 20 left-handed polarized assigned. This means that only 25 of the 40 frequencies with a bandwidth of 27 MHz available at this orbital position had been assigned to European countries. The 40 frequencies, each with a width of 27 MHz, only fit in the 11.7–12.5 GHz range because successive channels were polarized in opposite directions and thus could move together to 19.18 MHz.

Tender

In the United Kingdom, the direct broadcast television satellites were not - as in the Federal Republic of Germany and France - built on behalf of the state and operated by the competent authorities, but a license for the operation of satellites on the frequencies assigned to the United Kingdom at position 31 was issued ° West advertised by the responsible Independent Broadcasting Authority (IBA). One of the license conditions was the use of the new D-MAC television standard . The licensee, on the other hand, had to choose and buy the satellite himself.

This tender was not issued until 1986-87 (while the TV-SAT and TDF satellites had been developed since 1979) and was won by British Satellite Broadcasting . Rupert Murdoch had also applied . This then started its Sky Television with four channels on Astra 1A even before the Marcopolo satellites went into operation .

technical description

Satellite Broadcasting ordered two satellites based on the proven spin-stabilized HS 376 satellite bus from Hughes (now Boeing Defense, Space and Security ). These were significantly smaller and lighter than the TV-SAT , TDF and Tele-X based on the Spacebus 300 . In the launch configuration, each of the two satellites was 2.16 m in diameter and 2.7 m high. In geostationary orbit, when the antenna was unfolded and the outer cylindrical solar cell-covered mantle was lowered, the satellites were 7.2 m high. The satellites weighed approx. 1220 kg at launch and approx. 660 kg in geostationary orbit.

For course corrections and attitude control, Marcopolo had 2,220 liters of hydrazine for the correction engines on board. Both satellites used a Star 30BP solid propulsion engine as an apogee motor . The solar cells of the two satellites generated around 1100 watts at the beginning of their life. The elliptical transmitting antenna was extended 2.54 m × 1.73 m and generated a signal level of 59 dBW in the footprint. By connecting two normal traveling wave tubes with 55 watts of power in parallel , the Marcopolo satellites were able to transmit with the transponder power of 110 watts, which was unusually high at the time. This also made it possible to choose whether a transponder should work with 110 or only 55 watt transmission power. However, the electrical power was not sufficient to operate all five transponders at full power; a maximum of three transponders could be used at a time with maximum transmission power. In order to be able to continue transmitting during the eclipses that occur twice a year, Hughes developed a new, very powerful "Super Nickel-Cadmium Battery". The alignment accuracy of the parabolic antenna was 0.05 °.

The manufacturer Hughes was not only responsible for the development and production of the satellites, but for the first time also for the launch (Marcopolo 1 was the first purely commercial launch of a US rocket) and the first tests in orbit before the satellites were handed over to the operator .

Names of satellites

Most of the time the satellites are referred to as Marcopolo 1 and 2. In the NSSDC Master Catalog , however, the two satellites are registered under the names BSB-R1 and BSB-R2 . Boeing uses BSB or Marcopolo as the name. BSB also seemed to use the term Marcopolo. The spellings MarcoPolo and Marco Polo are also used.

Operation at BSB

The two satellites were launched on August 27, 1989 and August 17, 1990, respectively, and were co-positioned at 31 ° West . Together they broadcast television programs in the D-MAC television standard on five channels, which could be received with 35 cm antennas in the British Isles. In addition, a sister company of BSB marketed the bandwidth for data transmissions that was not used by the television program at D-MAC.

End of BSB and whereabouts of the satellites

BSB lost the competition with Sky Television , which did not broadcast in D-MAC, but PAL via Astra, and was taken over by the latter at the end of 1991. The merged company British Sky Broadcasting (BSkyB) continued to transmit five programs in parallel via the Marcopolo satellites in addition to Astra until the beginning of 1992. Then the transmissions stopped. The satellites were sold to Telenor and Nordiska Satellitaktiebolaget .

Web links

Individual evidence

  1. ^ Ross Lockley: The DBS satellite frequencies. June 20, 2004, archived from the original on November 18, 2012 ; accessed on November 8, 2012 (English, frequency assignments for the DBS satellites of the European countries).
  2. ↑ a b c Chris Wathan: The BSB / Sky Merger. October 4, 2004, archived from the original on November 21, 2009 ; accessed on November 8, 2012 .
  3. ↑ Wilfried Ahrens: ASTRA - television without borders: Eine Chronik , ECON Verlag, Düsseldorf, Vienna, New York, Moscow 1993, ISBN 3-430-11008-4 , pp. 92–93
  4. ↑ Section through a typical HS-376 (BSS 376) satellite with the lower jacket extended ( Memento from February 6, 2010 in the Internet Archive )
  5. ↑ Ross Lockley: Thor 1 retired. May 3, 2003, archived from the original on September 1, 2009 ; Retrieved November 8, 2012 (copy of a Telenor press release).
  6. ↑ a b BSB-R1 in the NSSDCA Master Catalog , accessed on November 8, 2012 (English). "It was the first commercial launch for a US launch vehicle and also heralded a new industry trend wherein the satellite maker must certify that the vehicle is safely in orbit before transferring control to the operator."
  7. ↑ BSB-R2 in the NSSDCA Master Catalog, accessed on November 8, 2012 (English).
  8. ↑ Boeing Satellites. Boeing, archived from the original on August 27, 2006 ; accessed on November 8, 2012 .