To give an idea of the magnitude of the signal loss, let's consider a hypothetical example. Suppose a signal is transmitted from the moon using a Ka-band transmitter with a power output of 1 kilowatt and an antenna with a gain of 40 decibels. If the signal travels a distance of 384,400 km to reach the Earth, the signal would experience an attenuation of approximately 285 decibels due to the inverse square law.
In addition to this, atmospheric and ionospheric effects can cause further attenuation, which can range from a few decibels to several hundred decibels depending on the conditions. For example, if we assume an additional attenuation of 100 decibels due to atmospheric and ionospheric effects, the total signal loss would be around 385 decibels.
To put this into perspective, a signal loss of 385 decibels is equivalent to a loss of about 1 trillion times the original signal strength. So, in practice, a signal loss of this magnitude would result in complete loss of communication between the moon and the Earth.