Astra is 20 years old!

[Satsearching]

Astra Satellite is 20!

It doesn’t feel that long ago that I first saw the advert in a news paper for UK Satellite TV for £199, but now realise that was over 20 years ago! How time passes…..

Astra 1A was launched on 11th December 1988 aboard an Ariane 4 craft, from Kourou in French Guiana, flight Number V27. It arrived at it’s 19.2’ East Geostationary home on the 7th January 1989. The first channel to transmit from it was Filmnet on 1st February 1989.


Later other channels appeared such as Sky, Screensport, TV3, MTV, SAT1, RTL etc.

Astra 1A was SES’s first satellite and had 16 transponders (Analogue Channels), SES then pioneered "Co-Location", this enabled several Satellites to be located close to each other allowing multiple channels to appear from 1 orbital position, so was then joined by 1B, 1C, 1D etc.

After sky switched off Analogue at the end of 2001 to take up digital at 28'E, Astra 1A was moved to 5.2'E east to provide data services. Astra 1A was retired in December 2004 and moved to "Graveyard Orbit"

Who remembers the first Amstrad SRX100 and 200 boxes for Astra 1A in the UK?

[humforce]

ooohh those free 16 chnls .

[PaphosAL]

I'd like to know how they 'move' a satellite along it's geostationary orbit, which is around 23,000 miles up, directly above Earth's equator??

Have these things got little solar-powered retro rockets, or summat? Still working after 20 years in space? Just wondering, as I've seen a few references to this 'moving' Satellites mullarky lately...

This orbit is waaaaay beyond the reach of the Space Shuttle, remember...

[Satsearching]

When a Satellite is put into geostationary orbit, they are "Thrown" and accelarated into this position using a sling shot method.

Imagine thowing a tennis ball so hard and fast, it just keeps orbiting the world!

But certain things like irregular pull of gravity from the world does knock them off the equator line, so they are equipt with "apogee boosters" to keep nudging them back into place. Eventually after many years, the stored fuel will run out causing satellites to be retired even though electronically they could carry on.

This method was mathematically designed by Authur C Clarke (hence the geostationary area called the "Clarke Belt"). Many years later it was found his theory was correct and the method was used!

A method used by companies like SIS (I got a grand tour of that place and should upload the pics I took!) is to allow the satellite to move a bit offline, saving fuel (known as inclined orbit) but needs a dish capable of the inclined tracking. This method is used on old satellites running out of fuel to add a few more years for cheaper broadcast links. When they go inclined, they appear to move about in a figure of "8" (wobble).

Get a dish fitted AL

SS

Originally Posted by PaphosAL

I'd like to know how they 'move' a satellite along it's geostationary orbit, which is around 23,000 miles up, directly above Earth's equator??

Have these things got little solar-powered retro rockets, or summat? Still working after 20 years in space? Just wondering, as I've seen a few references to this 'moving' Satellites mullarky lately...

This orbit is waaaaay beyond the reach of the Space Shuttle, remember...

[PaphosAL]

Yeah- but only a few weeks ago, Astra were talking about 'moving' a Satellite along it's orbit, so it covers E. Europe better. The few degrees they mentioned eastwards equated to a start - go - stop trip of about 56,000 miles (I calculated)...

As for the 'wobble'- yep, I've seen time-lapse pix in Astronomy mags of the Sun doing the same apparent figure of eight in the sky throughout the year. It's Earth (pulled to and fro by the Moon) that's actually doing the wobble. The Sun, and all the Satellites in orbit around the earth, just stay put, LOL!

Not many people know this, but the concept of orbiting Geostationary comms satellites was first put foward by Arthur C Clarke (also a brilliant mathematician) in a Sci-Fi novel he wrote in 1947!! Years before the Russians put Sputnik into orbit...

[Satsearching]

Yup, common for satellite operators to move satellites around, I'm guessing they lift orbit to move back, or drop orbit to move forward. Either way, they will use up more of the limited fuel onboard to get back into the clarke belt?

SS

Originally Posted by PaphosAL

Yeah- but only a few weeks ago, Astra were talking about 'moving' a Satellite along it's orbit, so it covers E. Europe better. The few degrees they mentioned eastwards equated to a start - go - stop trip of about 56,000 miles (I calculated)...