Dr. John G. Rather

John D. G. Rather

Assistant Director

Space Technology

Programme Development OACT

Dr. John Rather of NASA HQ
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by Dr. John Rather of NASA Headquarters, entitled "LASERS REVISITED: Their
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Here now is a summary of Dr. Rather's
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2. Dr. Rather bases his system on the assumption that the Signal-To-Noise Ratio (SNR) is always limited by Planckian starlight.In my rationale,
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3. Because Dr. Rather assumes large optical transmission arrays, and when I say large I mean large - many kilometers in diameter - sort of Optical Cyclops, he can arrange things so that targeted star systems
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Dr. Rather's near-field beams result in the Planckian starlight background becoming negligible at large distances, even with wide optical bandwidth detection.
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Because Dr. Rather is proposing the use of extremely large
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4. Dr. Rather also doesn't think that interstellar absorption in many regions of the Galaxy is much of a problem in the optical regime.So he considers that optical communications may be feasible over tens of thousands of light years, even in the visible part of the spectrum.
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In line with this rationale, Dr. Rather also doesn't feel
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7. Although Dr. Rather did not use the expression "Signpost SETI", he believes it possible that we might detect low-bandwidth microwave ETI signals directing us to the optical regime.

8. Dr. Rather doesn't stop at considering a 1 GW transmitter as being too powerful.He considers 100+ GW laser transmitters are quite possible.
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presumption for Dr. Rather of knowing where the planets are in their orbits!

10. He also feels that a large optical array is ideally suited for spatial multiplexing many beams at many target star systems.

11. Dr. Rather suggests that a small scale optical receiving system could be constructed with today's technology.

In my earlier brief conversation with Dr. Rather, I had obtained the wrong impression as to how he was targeting stellar biospheres.He was not assuming fan-shaped or annular-ring beams just to increase the SNR by a few dB, but as stated above, he was assuming near-field transmission systems. This mistaken notion of mine was featured as a question (No. 6) in the recently uploaded OPTICAL SETI SURVEY (RADOBS.7C).This will be corrected in later versions.

In conclusion, I would like to say how impressed I am by the scope of Dr. Rather's imagination.As I have indicated previously to members of
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"small is beautiful", Dr. Rather's rationale is "large is beautiful so long

John D. G. Rather, Ph.D.: Assistant Director for Space Technology (Program Development): National Aeronautics and Space Administration

A practical way to pump juice to the elevator cars materialized in the early 1990s, when optical physicist Hal Bennett and NASA scientist John Rather began developing technology to beam megawatts of energy to a point thousands of miles away with free electron lasers, which use some of the same components as atom-smashing supercolliders.

A Fascinating Paper on Optical SETI by Dr. John Rather of NASA HQ

It was named SELENE, a name first suggested by Dr. John Rather of the National Aeronautics and Space Administration.