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OU on the BBC: Digital Planet: Learning Zone - Fighting For Space

Updated Tuesday, 8th May 2007

Will our increasing desire to communicate with each other stop us from hearing from intelligent life beyond the Earth?

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It's a little over one hundred years since Marconi transmitted his first "wireless" message. In a lonely lighthouse on the coast of Dover, he transmitted a simple Christmas greeting off shore. That radio signal is still being transmitted to this day. It has travelled over one hundred light years so far and may have reached about one thousand stars. And if someone was out there listening, it would take them another hundred years to reply.

In October 1997, a space craft took off for Saturn. It was the beginning of an epic journey that would take seven years and cover 1,300,000,000 km. Its earth-bound creators need to be able to talk to it, control and to receive the 2 trillion bits of data that it is capable of collecting. But how does it get here and how do we send back the vital software that the computers on Cassini need to run the mission? The answer is radio waves. Cassini has on board a small transmitter, with the power of a 20watt lightbulb.

Communicating with space is scary. Distances, time delays and data transfer are inherent problems. But how do you handle data when you can only transfer about one tenth of what you have collected? That takes intelligent systems that are able to select and compress what is available. But the problems begin even closer to home.

In the hundred years since Marconi's invention we have expanded our communications base so many times over. In 1969 the first men set foot on the moon. Thanks to Marconi's wireless communication they were able to tell us about it first hand and we were able to see them do it. But that was thirty years ago and things have moved on since then.

The biggest problem of all however comes when these systems overlap. How can you know if it's a call from an alien civilisation or data download from a satellite? Was it light green aliens or a conference delegate on her mobile phone?

But there's an irony. Communication technology might make the search impossible. Just as light from cities destroyed optical astronomy in urban areas, today the proliferation of mobile phones is causing radio pollution which is disrupting the sensitive equipment trying to make contact with aliens. And things can only get worse for the scientists as mobile phones are about to step into space themselves communicating directly with a web of satellites circling the earth.

To find out more about the Fighting For Space programme, you can read the script and the contributor biographies





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