Astra 2E in Spain – News Update –

  2 Responses to “Astra 2E in Spain – News Update –”

1. 

   Johnlagos says:

   January 15, 2014 at 11:11 am

   Looks like its moved about a degree, if it is on the move it will still take about 2 weeks to reach its target destination. They will be using a minimum burn path to preserve as much fuel as possible as this will help with the overall operational lifetime of the satellite.

   Just for fun: The electrical systems on-board satellites can operate for many decades, they just run out of fuel that maintains their geostationary orbit. There are satellites launched in the early days of space communications that still have functional electrical systems (from the 60’s and 70’s). Typically they are drifted up into Graveyard orbit (mostly Geostationary platforms) and others are crashed into the ocean (typically LEO satellites Low Earth Orbit).

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2. 

   Jon says:

   January 16, 2014 at 11:45 am

   If you are tracking the Astra 2E and it looks like it’s gone back to the start,it is still on course

   Still on track
   Satellites in orbit are not stationary at all, far from it they usually are following an elongated figure of 8 path that is confined within a 1 km station keeping box. This is because of the need to counteract the Earth’s gravity (which is not uniform) and the moons gravitational effect along with other influences such as solar pressure etc. As long as they keep within the 1 km box their orbital slot is sustained and the downlink footprint coverage can be calculated with a reasonable degree of accuracy (which also is influenced by the wave guides and the shape of the reflecting surface of the antenna and the forward power of the high power amplifiers. Most satellites are separated by about 3° from the view point of the Earth’s surface (inclined orbits allow for a safe drift into the allocated slot).

   It is most likely that Astra-2E performed a station keeping manoeuvre that took it to the edge of its 1 Km box and this may have resulted in the reported 1° shift. Also remember that the satellite is operating in 3 dimensional space x, y and z axis (so it’s floating around within cube)

   The path has no discernible affect to an observer of signal levels on the ground under beam centre, however those on the fringes of reception will find that the signal washes in and out like the tide and this corresponds to the figure of 8 station keeping pattern exactly. Very large uplink antennas (5.6M diameter and greater) typically have devices call step tracker positioners that are linked to beacon receivers so that the antenna can follow this movement to optimise reception and uplink.
   During a drift to a new position the satellite path is not as linear as one would expect its actually more like this… 888

   We will only really see what the situation will be when Astra-2E arrives at it designated orbital slot of 28.2° east and its transponders are switched from load to transmit

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