I am a member of URSI (International Scientific Radio Union)
Commission J (Radio Astronomy). The US National Committee of URSI has
asked its members to review the attached document on Orbiting Solar
Power Stations. I send it along to you for information. You will see
that the concepts might involve Microwave Power transmission at S-Band
(2.45 GHz) and/or C-band (5.8 GHz). In the main footprint of the beam,
the power flux density might reach (near fatal!) levels of ~300W/m².
The orbiting antenna will certainly have sidelobes likely would wipe
out many services. You will note comments indicating that that this
worries many radio astronomers who routinely make measurements as
sources with flux densities of 1 mJy (1 Jansky =s a power flux density
of 1x10e-26 w/(m²Hz) . In the event of a failure of
just one active element, the beam-forming properties of the orbiting
antenna would certainly degrade. Inside the report you will note a
statement that even with a MTBF of ~30 years for magnetrons, this
implies a failure of one element/day for the array!
It is interesting to note that the report indicates current launch
costs of ~$10,000/kg (this is about the going rate for a Dnepr launch
to LEO), decreasing significantly by 2025 (good news for us, if true).
It is also interesting to note that the report still indicates the use
of (relatively) low efficiency solar cells and doesn't even note the
~28% cells that we have been using.
I have no idea of the reality of these systems. I presume that
AMSAT/ARRL/IARU could make comments to URSI. The following is the
"charge" given to URSI members which calls for responses a scan 1½
weeks hence:
Dear
USNC-URSI Colleagues:
The past president of URSI, Professor Kristian Schlegel, has asked me
for
the USNC opinion on the proposed URSI white paper on solar power, copy
of
which is attached. Even though it appears that the conclusion is
foregone
because a majority of URSI member countries are in favor of the
proposal,
it is important that the US opinion be registered and our objections,
if
any, be forwarded to URSI and remain a matter of record. I am therefore
asking that you let me have your reactions by e-mail on or before
Monday,
November 20. I will collate them into a memorandum that I will send to
Prof. Schlegel by his deadline of November 22. It is especially
important
that I hear from the Commission Chairs, and crucial that I receive the
opinion of Commission J.
I apologize for the short notice. I was hoping that we could discuss
this
matter at the USNC business meeting in Ottawa next summer, but it now
appears that URSI is in a hurry to decide the issue soon, and is not
willing to wait.
Best regards,
George Uslenghi
Chair of USNC-URSI.
_________________________________________
Piergiorgio L. E. Uslenghi, Ph.D.
Professor and Associate Dean
Department of ECE, College of Engineering
University of Illinois at Chicago
851 South Morgan Street, Chicago, IL 60607, USA
Dave Woodie (CalTech), the current USNC Commission J chairman,
appended these notes from last January's submission by the Radio
Astronomers:
Discussion
of the solar satellite white paper: Commission J members are concerned
about the process for producing such a white paper and whether there is
an implied approval by each commission. Many of the issues with this
project are beyond the technical scope of the URSI commissions and
hence it is inappropriate for URSI to take a strong position on this
project. Individual commission J members expressed strong reservations
about this project and do not want to be associated with a white paper
supporting solar satellites for beam power to earth. (The commission J
chair, David Woody, expressed these concerns to the URSI executives
during the Saturday morning executive session.)
Comments?
73, Tom