Astra 1D
Astra 1D is a geostationary communications satellite launched in 1994 by the Société Européenne des Satellites.
, the craft remains in service for occasional use.
Astra 1D was the fourth, and under original plans, last Astra communications satellite from SES. It was launched to SES' original solitary operational position at 19.2° east, and was intended as an in-orbit spare for Astra's 1A, 1B and 1C and to carry digital TV transmissions. However, development of digital reception equipment in Europe was not sufficiently advanced for Astra 1D to be SES' first digital satellite and demand for additional capacity for both British and German television channels led to 12 of the satellite's transponders being leased to broadcast analogue TV channels before the satellite had been launched.
History
After launch to 19.2° east, Astra 1D served two periods as a spare at the Astra 28.2°E position colocated with Astra 2A, for seven months in 1998 and for 13 months from December 1999. In between these two periods, it returned to the Astra 19.2°E position. During this time, some small numbers of transponders were used for regular service. After other Astra craft either arrived or were ordered for the slot, it moved to 24.2° east where it spent over two years carrying little more than test cards or feeds, until a move to 23° east and then 23.5° east where Euro1080 began to use it as their main transmitting craft.When the satellite originally went on air in January 1995, several of its transponders were used by British Sky Broadcasting for new channels such as Granada Talk TV. These transponders broadcast on frequencies outside the tuning range offered by the original Sky set-top-box receiver and a standard Astra LNB so Sky produced a frequency shifter, comprising a small box connected between the LNB and the receiver with a single manual switch to select between Astra 1A and Astra 1D reception. Switched to Astra 1D reception, this shifted up the IF signal from the LNB by 250 MHz to bring the new frequencies within the receiver's tuning range. Subsequent Sky receivers had an 'extended' 950-2150 MHz IF tuning range and were used with an 'Enhanced LNB' with a 9.75 GHz local oscillator to enable reception of all the transponders used on the Astra 1A-1D satellites.
In November 2007, Astra 1D was replaced at the Astra 23.5°E position by Astra 1E, and was moved to 31.5° east, where it operated in inclined orbit, to replace Optus A3, and was joined in April 2008 by Astra 5A to officially open the Astra 31.5°E position.
On January 16, 2009 Astra 5A suffered a technical failure and all traffic ceased. Much of it transferred to Astra 23.5°E as Astra 1D was not suitable for the transmission of these services because it was in an inclined orbit. In May 2009, Astra 2C was moved from the 28.2° east position to Astra 31.5°E to take over Astra 5A's mission with Astra 1D as ultimate backup. In June 2010, Astra 1G was moved from Astra 23.5°E to Astra 31.5°E, where it could take over all broadcasting activity from Astra 2C, releasing Astra 2C for backup, and releasing Astra 1D for use elsewhere. Astra 1D then commenced movement westwards and in August 2010 arrived at 1.8°E where, with Astra 1C at 2.0°E it was used for occasional traffic such as outside broadcast news feeds. Astra 1D returned 23.5° east in 2012 with two transponders active for several months.
In June 2013 the satellite moved east from 23.5°E to 52.2°E. In February 2014 Astra 1D began moving westward, reaching its destination of 67.5°W in June 2014, where it was joined by Astra 1H in August 2014, moved from 19.2°E. Both Astra 1D and Astra 1H were moved close to NSS806 at 47.5°W in the Spring/Summer of 2015. In 2017 1D was moved to 73°W.