The End of Radio Astronomy?

In the last year or so I have noticed more and more articles talking about new types of wireless technology. As well as the traditional devices with fixed bands such as WiFi and Bluetooth, there is now more talk of an open radio spectrum, perhaps using something like Ultra-Wide Band (UWB). The idea of spread spectrum technologies like UWB, is to make full use of big swathes of the radio spectrum by transmitting over many frequencies at the same time. This approach is championed by people like Lawrence Lessig - the man behind the excellent Creative Commons license - as they say the spectrum should not be 'owned' by corporations like TV and radio companies but used more like a commons.

The idea with UWB is that there wouldn't be problems for existing users of the spectrum as it uses "a new band of spectrum in the noise floor". Indeed Lawrence Lessig also talks about picking signals out of the noise to point out how broadcasts could be distinguished from one another. This all sounds great; allowing more people to use the radio spectrum to transmit data and let each other know they are on the train. However, as you might have guessed, I am not too keen on the idea.

Radio astronomers spend their time trying to look at radio waves emitted by various objects in space such as clouds of hydrogen and ethanol, stars such as pulsars and energetic galaxies called quasars to name but a few. Of all the radiation emitted by these objects, only a small amount reaches us on the Earth and the job of a radio astronomer is to collect this tiny amount, measure it and try to work out as much as they can about the Universe. As I said these signals are extremely faint with the brightest radio sources coming in at about 10-23 Watts per Hertz per square metre (i.e. about 0.00000000000000000000001 Watt/Hz/m2) - in more straightforward terms, a mobile phone on the Moon would be considered 'bright'.

We already suffer from radio frequency interference (RFI), and it is easy to see the effects of 'spillover' transmission into radio astronomy bands by satellites already. It isn't just confined to satellites either; internet access, mobile phones, CCTV, balloon platforms and even garage door openers add to the problem. It isn't even as if radio astronomers can change their frequency bands. This isn't because they have build expensive receivers that they don't want to change but because the Universe only emits at specific freqencies so we have to use what we are given.

Radio astronomy bands shouldn't be thought of as equivalent to a commercial communications band and therefore open to anyone that wants to transmit in it. They already are open to all that want to 'listen' just not those that want to 'talk'. Radio astronomy bands should be treated in the same way as National Parks are, as a place to be protected from development so that anyone who wants to can listen to the Universe.

Posted in astro blog by Stuart on Saturday 25th Sep 2004 (22:36 UTC) | Permalink
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