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["Mauno Ritola" <mauno.ritola@xxxxxxxxx>]

US satellite plan 'will knock out Pacific radio links'

4.00pm Monday August 14, 2006
By Kent Atkinson


Pacific Island nations -- and airline pilots around the globe -- could lose 
high frequency radio links for up to a week if the US goes ahead with a plan 
to protect its satellite network, Otago University researchers said today.

They warned the Americans plan to protect its satellites from both natural 
radiation and "airbursts" of nuclear weapons posed a global communications 
threat.

The US Air Force and the US Defence Advanced Research Projects Agency 
(DARPA) have proposed using very low frequency radio waves to flush 
particles from radiation "belts" above Earth and dump them into the upper 
atmosphere over either one or several days.

This deluge of dumped charged particles would temporarily change the 
ionosphere from a "mirror" that bounced high frequency radio waves around 
the planet to a "sponge" that soaked them up, Dr Craig Rodger of Otago 
University's physics department, said today.

The ionosphere is one of the highest layers of the Earth's atmosphere, 
starting at about 70km and continuing out to about 640km, and contains ions 
created when solar radiation tears electrons off atoms in the atmosphere. It 
is important for reflection of some radio waves.

Dr Rodger, lead researcher on a multinational study also involving 
scientists from Finland and Britain, said plane pilots and ships would lose 
radio contact and some Pacific Island nations could be isolated for up to a 
week, depending on the system's design and how it was operated.

He said GPS services would also likely suffer large-scale disruptions, if 
signals between ground users and satellites were scrambled in the 
ionosphere.

The US "radiation belt remediation" was intended to protect hundreds of low 
earth-orbiting satellites from having their onboard electronics ruined by 
charged particles in unusually intense radiation belts "pumped up" by 
powerful solar storms -- or small nuclear weapons deliberately exploded in 
the atmosphere to disrupt communications.

"Earth's upper atmosphere would be dramatically affected by such a system, 
causing unusually intense high-frequency (radio) blackouts around most of 
the world," Dr Rodger said.

The researchers, whose work is published work in August edition of the 
international journal Annales Geophysicae, called for policymakers to 
carefully consider the implications of the US scheme.

"If the intense radiation belts resulted from a rogue state detonating a 
nuclear-tipped missile in the upper atmosphere, using such remediation 
technology would probably be acceptable to the international community," 
they said.

But the case for using the system to mitigate the lesser risk to satellites 
from charged particles injected by naturally-occurring solar storms needed 
to be considered more closely and weighed against the impact of the 
disruption to global communications.

Many developed countries use HF radio for communicating with aircraft and 
ships, international broadcasting, amateur radio, and fixed long-distance 
communications, and developing countries use it for domestic links - 
national broadcasters and both mobile and fixed point-to-point 
communications.

The researchers also considered whether the changes to atmospheric chemistry 
would harm the ozone layer, but found that ozone depletion would be 
short-lived.

- NZPA

http://www.nzherald.co.nz/section/story.cfm?c_id=1&ObjectID=10396164 

___________________________________________________________________________________
Ennakkotilaa WRTH 2006 nyt:
http://www.amazon.com/exec/obidos/ASIN/0823059367/hardcoredxcom/
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