ARRL

ARRL Propagation Bulletin ARLP033 (2006)

SB PROP @ ARL $ARLP033
ARLP033 Propagation de K7RA

ZCZC AP33
QST de W1AW  
Propagation Forecast Bulletin 33  ARLP033
From Tad Cook, K7RA
Seattle, WA  August 15, 2006
To all radio amateurs 

SB PROP ARL ARLP033
ARLP033 Propagation de K7RA

This is a special early edition of the propagation bulletin, three
days before the regular Friday publication schedule.  The regular
bulletin will appear on Friday, August 18.

A newspaper article on Monday out of New Zealand reported a proposed
Defense Advanced Research Projects Agency (DARPA) project that could
cause major worldwide disruptions to HF radio communication and GPS
navigation.  The ''Radiation Belt Remediation'' (RBR) system is
envisaged as a method for protecting low earth orbit (LEO)
satellites from damage caused by high altitude nuclear detonations
or severe solar storms.  Testing the system would use extremely high
intensity very low frequency (VLF) radio waves to flush particles
from radiation belts and dump them into the upper atmosphere.

When I first heard of this on Monday morning, I thought it must be
something from a fringe web site peddling dark conspiracy theories.
But the newspaper reporting the news is real, and so is the team of
scientists from New Zealand, the UK and Finland whose study of
possible effects of the scheme is reported in a recent edition of
Annales Geophysicae.

You can find the article here:

http://www.physics.otago.ac.nz/research/space/ag-24-2025.pdf

A web page from the University of Otago describing the research is
here:

http://www.physics.otago.ac.nz/research/space/RBR_Media_release_8Aug06.htm

I contacted the lead researcher on the team reporting the possible
effects of the project, Dr. Craig Rodger of the Physics Department
at the University of Otago in Dunedin, New Zealand.  He proved very
cooperative, accessible and helpful, and told me RBR is a serious
project, ''money is starting to appear to investigate it in more
detail'', and ''U.S. scientists with military connections are treating
it seriously''.

It is feared that testing the system could shut down worldwide HF
communications for several days to a week, rendering the ionosphere
a giant sponge for RF.

I sent Dr. Rodger a comment from Ward Silver, N0AX, who speculated
''the sheer energy needed to accomplish it would tend to rule it out
from the start, and I don't know where they would erect the
necessary antennas.''

Dr. Rodger responded, ''This would be true, but they are hoping to
rely on some of the non-linear processes in space plasmas, stealing
the energy from the radiation belts to get the wave-amplitudes high
enough.  We know this is possible (in theory), as it happens
naturally already.  We don't know how easy it will be to get it
happening under our control''.

''Also, as for erecting the antenna, there are two plans.  One is to
fly VLF antenna in space.  This could be a power problem.  But for
ground-based systems, you probably already know that most major
naval powers have big VLF transmitters dotted over the globe.  (Two
of the US Navy transmitters radiate one megawatt).  While these are
designed to keep the signals mostly under the ionosphere, it shows
the possibility for building big powerful antenna''.

You can read Monday's article from the New Zealand Herald, here:

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

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://www.arrl.org/tis/info/propagation.html.  For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past
propagation bulletins is at http://www.arrl.org/w1aw/prop/.

Sunspot numbers for August 3 through 9 were 23, 0, 0, 0, 0, 12 and
25 with a mean of 8.6. 10.7 cm flux was 71.3, 69.6, 69.5, 69.5,
69.8, 71.4, and 74.1, with a mean of 70.7.  Estimated planetary A
indices were 6, 3, 4, 4, 32, 12 and 9 with a mean of 10.  Estimated
mid-latitude A indices were 5, 2, 2, 2, 19, 10 and 9, with a mean of
7.
NNNN
/EX