We've been watching this subject for some time in ITU-R Study Group 1
(spectrum management). As I'll be traveling this week, I've asked Jon
Siverling to review the relevant ITU documents and advise.
At 01:59 AM 11/11/2006 -0500, Tom Clark, K3IO wrote:
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/m.
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/(mHz) . 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
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 1 weeks
<fontfamily><param>Helvetica,</param>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.
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</fontfamily>
Dave Woodie (CalTech), the current USNC Commission J chairman, appended
these notes from last January's submission by the Radio Astronomers:
<fontfamily><param>Helvetica,</param>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
Attachment Converted: "c:\eudora\attach\URSI white paper on solar