Astounding Stories of Super-Science, December 1930

  A SIGNAL TO THE MOON

  The idea of a radio signal to the moon may sound fantastic, but iseasily within the range of possibility, says Dr. A. Hoyt Taylor, Chiefof the Radio Division of the United States Naval Research Laboratoriesat Washington, who plans such an attempt in the near future.

  "We have reason to expect a good chance of getting the signal back in atime interval of slightly less than three seconds," said Dr. Taylor.

  To be exact, a radio signal should be reflected back to earth in a timeinterval of 2.8 seconds, this being the necessary elapsed time for it tocarry the 250,000 miles to the moon and return at its speed of 300,000kilometers, or 186,000 miles per second.

  The signal would be very weak, Dr. Taylor points out, but not impossibleof detection with the present refinement of receiving instruments,provided no great absorption took place in interstellar space.

  A high frequency wave will be used, as such a wave penetrates readilythe earth's atmosphere and probably goes far beyond. The frequency ofthe wave will range between 20,000 and 30,000 kilocycles. Twentykilowats of power will be used, enough to furnish current for aboutforty flatirons.

  The value of a radio signal to the moon lies in the confirmation ofwhether there is or not heavy absorption of waves in the upper levels ofour own atmosphere. If successful it would indicate a reasonably goodreflection coefficient at the surface of the moon--the power of themoon's surface to act as a joint agent in the perfection of the signal.

  The signal might have some bearing also on whether the moon has anatmosphere--something pretty much settled already by astronomicalobservation. It would also lead to the possibility of fairly accuratedetermination of wave velocity in free space, all of interest toscience, either confirming existing theories or establishing new ones.