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EDITIONS
Friday, 7 February, 2003, 08:59 GMT
New life for old spacecraft
Car dashboard, BBC
Cars could get news and music from satellites
Ageing television satellites could soon be providing European car drivers with a digital radio service.

The European Space Agency (Esa) is considering using the satellites as relay stations for radio signals carrying traffic information, weather forecasts as well as music and entertainment.

It believes that careful use of the satellites' dwindling fuel supplies could extend their useful life by five years to create a continent-wide digital radio network.

Esa has already sent test broadcasts via the old satellites and is now working on a design for a cheap car antenna that can track the satellites.

Higher plane

Most people who watch satellite TV get their signal via a fixed dish that picks up signals from spacecraft orbiting the Earth 35,000 kilometres up.

The satellites use their on-board fuel supplies to ensure they do not drift and can reliably relay signals to subscribers.

Once the fuel runs out, typically after 15 years, the satellites are abandoned and parked in a higher orbit.

Now Esa scientists are working on ways to use ageing satellites to provide European car drivers with news and entertainment via digital radio.

Instead of using fuel supplies to keep the satellites stationary, Esa proposes letting them drift north-south and only expending fuel to keep them in the same east-west axis.

Skyscraper front, Eyewire
Tall buildings could limit the service's reach
Satellites expend most of their fuel maintaining their north-south position, so letting them drift could add five years to their useful life, say Esa scientists.

The movement of the satellite over a few degrees could easily be accommodated by vehicular antenna. Such receivers already have to move to keep a satellite in view as the vehicles they are mounted on move around.

Tests with ageing Astra satellites have established that it would be possible to use such spacecraft to run a digital radio service with a one megabit per second datastream.

Cheap signals

Many US drivers already enjoy digital radio services in their cars beamed to them by a fleet of specially launched satellites.

Esa believes it could set up a similar service for European drivers using ageing satellites at a fraction of the cost and at comparable data rates.

Now Esa is embarking on further studies and is developing a flat patch antenna for cars that can constantly track the satellites.

The radio system could provide weather forecasts, traffic information, music and news to drivers.

The only disadvantage of using satellites is the fact that signals can be lost in built-up areas where tall buildings block signals.

Esa tests have shown that in some areas signals can be lost for minutes at a time. This means that any radio service would have to be cached and downloaded regularly to subscribers' cars.

See also:

22 Nov 02 | Health
12 Jul 02 | Science/Nature
12 Jan 03 | Technology
10 Dec 02 | Science/Nature
19 Aug 02 | Entertainment
24 Jul 02 | England
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