Overview[]
The first radar contact with the moon was initiated in October 1951, and the received echo was of surprisingly high fidelity. Scientists found that despite the Moon being a diffuse optical reflector, it was also a quasi-smooth radio reflector, with a substantial part of the reflection coming from a specular "hot spot." The success of this and subsequent trials proved that the project’s potential was greater than originally anticipated.
The Communications Moon Relay (CMR) was established in 1956 for transmission of teletype and facsimile messages between Washington, D.C., and Hawaii. The inaugural test of CMR was conducted in January 1960. The CMR system offered very reliable communications and was resistant to jamming.
The National Security Agency and the Naval Security Group did not allow encrypted message traffic on the CMR link, arguing that anyone could intercept the link because "all the world could hear it" — despite the fact that encrypted messages had been transmitted on the Medium Frequency/High Frequency (MF/HF) broadcasts for years. The principal operational disadvantage of the CMR was simply the availability of the moon, which had to be within sight of both of the link terminals.
CMR was the only operational satellite communications relay system in the world until the Defense Satellite Communications System (DSCS) came on line on June 16, 1966. The CMR capability was disestablished in the mid-1960s.