Sonar could probably be implemented using fluidics for navigation on Venus. Now a big problem is that it has traditionally been difficult to make fluidics opera

Sonar could probably be implemented using fluidics for navigation on Venus. Now a big problem is that it has traditionally been difficult to make fluidics operate at ultrasonic frequencies. There have been fluidic ultrasonic beam break sensors that worked on the principle of ultrasound disrupting a laminar jet to turbulence, but these can't 'directly' sense ultrasound. The response rate is also somewhat slow and not that sensitive. There are also means of heterodyning ultrasonic frequencies, but the method relies on a transitional jet so it's not reliable. However, if you do the math it appears that fluidic amplifiers with dimensions that do not require semiconductor processing to make using a working fluid of helium should have flat gain to about 26 KHz, which is in the ultrasonic range. What really makes this work is the fact that helium becomes less viscous as it gets much hotter. In fact power requirements for fluidic amplifiers may be about the same as their electronic counterparts(~0.2 mW per amplifier). In addition, laminar fluidic amplifiers have very low internal noise, meaning we should be able to amplify the fairly weak sonar return signals. A simple sonar sensor which reports back range should be possible, but a more interesting possibility is using acoustic metamaterials to do 'image recognition' to steer the rover away from obstacles. A couple problems are how to couple sound from the fluidic circuits to Venus' atmosphere and keeping the helium contained. Having the entire circuit encased in metal and using metal would ensure that the leakage rate is insignificant. The issue is that making a reliable metal bellows pump could end up being a boondoggle. NASA tried to make an RTG that used a stirling engine rather than a Seebeck generator, but it stopped working reliably within a month or so, which may have been due to fatigue in the metal bellows. Another is it's difficult to determine sonar system performance due to the difficulty of calculating return strength