Imagine I put a floating probe inside the subglacial ocean of Encelado or Europa: how much power should my radio have to be able to communicate from external surface with the probe? Or, in different words, how much attenuation do 100 km of solid ice cause to a radio signal at, say, UHF frequency?
Electronic – How much power do I need to transmit a radio signal through a solid ice crust 100 km thick
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Best Answer
I can't answer that directly but Nasa are probing Greenland's ice sheets with aeroplane radar to find the depth of the bedrock. Here's what they say about ice and radio waves: -
This came from here and it's interesting to note that this is radar and requires a reflection from the bedrock to pass back through the ice to the receiving aeroplane. I would imagine that the reflected power is a fraction of the incident power reaching the rock so maybe you might get 10x this distance thru a solid ice sheet with a one-way transmission.
Here's the sort of image they are getting: -
It looks to me that +3km is possible with radar. I don't know what the radar beam angle is so it's impossible to calculate what the incident power at the surface of the ice is - the transmission from the aeroplane might be a 1MW pulsed radar with a very tight beam angle producing an incident power at the top surface of the ice of hundreds of watts. Also, the reflection from the bedrock will not be a tight beam - this means the power reflected back will be spread thinly as distance increases (see Friis equations). Also the power received at the aeroplane will be much smaller than that emitting from the surface of the ice - again see the Friis equations.
Addendum
I had a think about the link loss for the radar application: -
These losses won't be encountered by a simple transmission thru ice - transmitting and receiving antennas are sited either in the ice or at its surface. This all bodes well for being able to transmit in a single direction through large distances of ice.