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PROGRAMME INFO |
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Quentin Cooper reports on developments across the sciences. Each week scientists describe their work, conveying the excitement they feel for their research projects.
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Contact Material World |
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LISTEN AGAIN 听30 min |
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PRESENTER |
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"For me science isn't a subject, it's a perspective. There are fascinating scientific aspects to everything from ancient history to the latest gadgets, outer space to interior decorating; and each week on The Material World we try to reflect the excitement, ideas, uncertainties, collisions and collaborations as science continues its never-ending voyage into the unknown".
Quentin Cooper |
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PROGRAMME DETAILS |
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| Surface of Titan (courtesy of European Space Agency) |
鈥淚鈥檓 on the Plane!鈥
Those are words to sink the hearts of peace-loving travellers.
At present, mobile phone use is banned on planes on safety grounds, but surveillance equipment shows that many frequent fliers ignore the rule.
So are mobile phones a genuine threat to air safety or just to airlines鈥 income from their own in-flight phones? Surely it鈥檚 OK to leave your phone switched on if you don鈥檛 actually make a call?
No, says Bill Strauss, who researches electromagnetic compatibility in the USA.听 He points out that your mobile will send out stronger and stronger signals to try to stay in touch with phone masts on the ground.
If US and European phones on the same flight both do so, they produce interference on the same frequency as the plane uses for its GPS navigation equipment. There is circumstantial evidence of occasions where the GPS has been 150 miles off course, perhaps as a result.
Even electronic equipment not intended for communications, such as music players and games consoles can produce interference at critical frequencies, the research shows.
But there could be ways round these problems and some airlines have plans to introduce their own in-flight mobile phones systems using what are called picocells. Paul Guckian is working on them at Qualcomm in the USA, European companies are also developing the technology.
The idea is to keep the signals low, effectively by flying a mini phone mast in the plane. But each plane must pass stringent safety tests for electrical interference and quite a few passengers may have objections to the audio interference!
Landing on Titan
On January 14th 2005, after a journey of more than听seven years, the European Huygens spacecraft parachuted down onto the surface of Saturn's largest moon, Titan. With the American parent craft, Cassini, still in orbit around Saturn, this is possibly the most ambitious interplanetary mission ever attempted.
We hear the latest from Professor Marty Tomasko of the University of Arizona, who was in charge of Huygens' camera, and Professor John Zarnecki of听the Open University, whose team built the surface science package.
Such missions are always risky, and there was the possibility that the years of waiting would be for nothing.
The scientists hoped that there would be a stream of data from the parachute drop through Titan's hazy atmosphere. If they were lucky, they might get a few minutes of data from the ground. In fact Huygens was still transmitting several hours later, after Cassini had passed over the horizon and could no longer hear it.
The results reveal a strange world indeed. Titan is the only body we know, apart from Earth, to have a nitrogen atmosphere. In fact it is rather like a primitive, lifeless Earth, held in deep, deep freeze, far from the Sun.
Huygens detected a fine drizzle of liquid methane, and there's evidence in the landscape that methane rivers sometimes flow into lakes of liquid natural gas.听 |
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RELATED LINKS
h2g2: Mobile Phones and Aircraft
成人论坛 Science & Nature: Space - Cassini-Huygens
成人论坛 Radio 4 Science programmes
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