Maybe one of the smart people who posts here can figure it out. Is there anything similar on Earth?

Here's just one example of the narrow dune channeling:

The scale of these dunes and channels is vast. They look so small, but they are enormous.

The channels begin at the tops of the dunes... does water migrate upwards through the dunes via capillary action? Differences in pressure between surface and subsurface would tend to force water (at least vapor) to migrate to the surface. But why, if it did, would water only begin to flow down the surface of the dunes from the dune crest? And how would this flowing material maintain such narrow channels for such a surprising length? 2-3km it looks like.

The dunes are routinely referred to as "sand dunes," but their composition is unknown. It is not even certain that there is sand as such on Mars. Dark dunes like these tend to be much larger than their light toned counterparts. Is that due to a difference in grain size? I have yet to see channeling on light-colored dunes.

Do these dense, narrow channel networks appear anywhere else on Mars? Or are they unique to Russel Crater?

Could the dunes be substantially icy? Let's say frozen CO2. Would water at a warmer temperature (whatever the melting temperature is on Mars -- and we don't know what that is) be able to carve these channels in a mostly icy dune? Note, the channels end abruptly. There is no deposit at the ends of the channels. What happened to the material the channels were carved from and what happened to the material that caused the channels? Could something be flowing internally in the dunes?

Just throwing out questions here.

Very intriguing.

Cheers, B R Felix