Making a Non-Electric Rover For the Venus Planetary Surface
A rover which can see, move and communicate all without electricity. Sounds impossible? Turns out non-electric solutions exist for all these challenges.
We have sent several robotic missions to Mars, yet despite being closer there are no robotic rovers roaming around on the surface of Venus.
Why is that? For those who have followed my writing, you probably already know it is because the surface temperature of Venus is over 460 °C, and the pressure is 93 bars on average. Oh and by the way, it rains sulfuric acid. Under these conditions lead will melt and form pools.
However making the physical structures to withstand this is actually not that difficult. Steel melts at 1370 °C. And if we really wanted to be certain we could just use Tungsten which melts at 3422 °C.
The problem is that regular electronics is not made to operate at those temperatures. An AMD Ryzen microprocessor chip e.g. can’t handle temperatures above 95 °C.
Fluidics devices performing computations using fluids can operate at almost any temperature because you can make them out of any material:
My 3D printer story basically explain how to build and control machinery operating on air or some other fluid alone. So we got that part covered.
That leaves three major challenges:
- How can the rover figure out where it is, if you can’t use a a camera, laser or radar, which all require electrical circuits?
- How would you control it remotely. How would e.g. the humans in their aerostat habitats above the Venus cloud tops communicate with it and give it instructions?
- Where would the rover get energy to move from without a battery or solar cells?
Remote Communications Using Acoustic Signals
We do in fact have fluidics amplifiers for sounds. Meaning a fluid signal can be controlled by sound. That opens up the possibility of sending and receiving information using sound waves. This is not as crazy as it sounds. There are people who have already patented a communication system based on this principle.
That means our Venus rover instead of an antenna sending an electromagnetic signals we would have speakers broadcasting sounds to be received by our human colonists controlling the rover.
Seeing Like a Bat
Bats are essentially blind, but they can still “see” using echolocation:
Echolocation — the active use of sonar (SOund Navigation And Ranging) along with special morphological (physical features) and physiological adaptations — allows bats to “see” with sound. Most bats produce echolocation sounds by contracting their larynx (voice box).
The sounds bats emit are however ultrasound so we can’t hear it. The sound is so loud that bats have to close their ears when they emit the sound. Then they have to open them again to listen to the echo. Depending on whether the bat wants to scan a whole cave or just look at a prey close by it will alter the frequency of emitting sound and listening to the echo. If you send out sound too rapidly then there is no time to pick up the reflection of sound from further away places.
A Venus rover could use the same principles. It could broadcast sounds and listen for reflections at different frequencies depending on whether it is scanning the landscape or analyzing a rock or boulder close by.
We already have a lot of experience with sound based “seeing,” through the use of ultrasound for looking at a fetus to using seismic for looking at the rock layers in the ground. The granularity of these systems can vary a lot. E.g. there are ultrasound sensors, which are just used to measure the distance to the closes objects, but which doesn’t give you any details about the shape or orientation of the object.
However you could combine multiple ultrasound sensor or continuously rotate them to get a form of seeing. Here are some Arduino projects exploring that.
Dimitris Platis uses multiple ultrasonic sensors to scan observe his surroundings in this project.
Example of using a rotating ultrasonic sensor to detect surroundings. Yes I know these projects use electronics. But the point of showing them is about demonstrating what can be accomplished by using sound waves for seeing. However as we discussed earlier fluidics based amplifiers to amplify sounds exists. You don’t need electrical signals to amplify sound.
Unlike Mars, Venus actually has a very thick atmosphere which makes the utilization of wind power possible. The blades of say a windmill could power an air compressor. Compressed air thus serves the same function as a battery in traditional electrical rover.
The compressed air is used to power the pneumatic motors driving the belts or wheels of the rover. It is also used to drive the fluidics computational devices which controls the rover.
Existing Alternative Designs Proposals
When researching this topic, I came across some NASA ideas for Venus rovers, e.g. the AREE project.
These utilize wind power as my suggestion but base their design on a combination of electronic and mechanical computers for autonomy. The AREE project seems strongly wedded to the idea of using mechanical systems for computation, in the spirit of Charles Babbage’s Difference Engine. Sophisticated mechanical computation devices have been used all the way up to modern times. E.g. the Russians used the IMP Globus instrument to find the orientation of its spacecraft until 2002, which a very sophisticated mechanical device, as you can see from all the gears inside:
Reading through the AREE proposal I can’t find any ways of scanning the landscapes. They propose mechanical bumpers to avoid obstacles.
They also propose using many different systems. E.g. communications is done with some sort of radio signals using vacuum tubes. Vacuum tubes can handle high temperatures but the vacuum seal may eventually break in the high pressures and temperatures.