Tuesday, June 5, 2007

Mysterious Radio Waves

The Huygens Atmosphere Structure Instrument (HASI) scored a first in 2005 by measuring the electrical conductivity of Titan’s atmosphere. The results hint at a new way to investigate the subsurface layers of Titan and could provide insight into whether or not Titan has a subsurface ocean.

The Permittivity, Waves and Altimetry (PWA) sensor on Huygens detected an extremely low frequency (ELF) radio wave during the descent. It was oscillating very slowly for a radio wave, just 36 times a second, and increased slightly in frequency as the probe reached lower altitudes.
If the PWA team confirms that the signal is a natural phenomenon and not an artefact of the way the instrument worked, they will have discovered a powerful new way to probe not just the atmosphere of Titan but its subsurface as well.

The only other world on which ELF waves were detected before was Earth. They are reflected by both the surface of the Earth and its ionosphere, the rarefied region of the atmosphere where most particles are electrically charged. This turns the atmosphere into a giant ‘sound box’ where certain frequencies of ELF waves resonate and are reinforced, whilst other die away.

On Titan, however, the surface is a poor reflector because of its low conductivity and so these waves penetrate the interior. “The wave could have been reflected by the liquid-ice boundary of a subsurface ocean of water and ammonia predicted by theoretical models,” says Fernando Simões, CETP/IPSL-CNRS, France, and a member of the PWA team.
More at:http://www.scientificblogging.com/news/mysterious_radio_waves_on_titan
Posted by Ajay :: 9:47 AM :: 0 comments

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