rastaman@ihdev.UUCP (Biding my time) (03/18/85)
The recent questions about SETI looking at the "Water Hole" prompted me to dig through some of my old literature. I quote from "Project Cyclops" NASA pub. CR114445, presumably still available from Ames Research Center at Moffett Field: Ch. 15, pg 170 "3. Of all communication means at our disposal, microwaves are the best. ...energy required at the wavelengths is least and the necessary stabilities and collecting areas are ... easier and cheaper... 4. The best part ... is the low frequency end of the 'micro- wave window' - frequencies from about 1 to 2 or 3 GHZ. Again this is because greater absolute frequency stability ..., Doppler rates are lower, beam widths are broader for a given gain, and collecting window is cheaper... 5. Nature has provided us with a rather narrow quiet band in this best part of the spectrum that seems especially marked for interstellar contact. It lies between the spectral lines of hydrogen (1420 MHz) and the hydroxyl radical (1662 MHz). Standing like the Om and Um on either side of a gate, these two emissions of the disassociation products of water beckon all water based life to search for its kind at ... the water hole." I gave up astro for CS money six years ago so things have certainly changed, but I presume the basic ideas still apply. ihnp4!ihdev!rastaman