Astra 1D
From Wikipedia, the free encyclopedia
| General information | |
|---|---|
| Launch Date | November 1, 1994 |
| Launch Mass | 2924 KG |
| Orbit Mass | |
| Manufacturer | Hughes Space Systems |
| Model | HS 601 |
| Launcher / Flight Number |
Ariane 4 |
| Lifetime | 12 years |
| Transponder Information | |
| Transponder Capacity | 24 (18 main, 6 backup) Ku band |
| Twta output power | 63W |
| Bandwidth | 18 x 26 MHz |
| EIRP | 50 dBW |
| Sundries | |
| Expendable Energy | 3300W |
| Location | |
| Former location | 19.2, 28.2, 24.2, 23.0°E |
| Current location | 23.5°E |
| List of broadcast satellites | |
Astra 1D was the fourth, and under original plans, last Société Européenne des Satellites (SES), now SES Astra satellite. It was launched to Astra's original solitary operational position at 19.2E, and was intended as an in-orbit spare for Astra's 1A, 1B and 1C. However, demand for additional capacity for both British and German television channels, plus the extension of the receivable segment of the Ku band beyond 250 MHz on most consumer equipment led to the satellite becoming regularly used, and the launch of a further 4 Astra 1 satellites. The launch of these later craft returned 1D to a role as a "troubleshooter" for the Astra fleet.
It later served two periods as a spare at 28.2E for Astra 2A, during mid-1998 and for most of 2000. In between these two periods, it returned to 19.2E. During this time, some small numbers of transponders were used for regular service. After other Astra craft (Astra 2B, Astra 2D) either arrived or were ordered for the slot, it moved to 24.2E where it spent almost two years carrying little more than test cards or feeds, until a move to 23E where Euro1080 began to use it as their main transmitting craft.
The satellite is currently operational at 23.5E, with only three active transponders. It currently carries feeds, internet, high-definition television and (as of November 10, 2006) 10 Dutch provincial stations, and is approaching the end of its life. Astra 1Es impending replacement at 19.2E is likely to see it replacing 1D as the in-orbit spare.
When the satellite went on air several of its transponders were used by British Sky Broadcasting for new channels such as Granada Plus. Since these channels used frequencies that were not available on the original Sky receivers due to being outside the original BSS band, Sky issued viewers with frequency shifters ("ADX Plus Channel Expanders"), comprising small boxes the size of cigarette packets with a single switch and an on/off LED. When connected between the dish and the receiver (and powered by the receiver) these allowed viewers to switch manually between the Astra 1A and Astra 1D frequency bands - precisely 250 MHz - although there were a few minor complaints because the units could not be operated by remote control.
