I love electronics, but there may be some meaningful alternatives when applications have extreme conditions. Enter a ‘Steampunk’ Rover for Venus exploration.
Meet the Automation Rover for Extreme Environments (AREE), a mechanical design that was influenced by classic mechanical clockwork computers and a WW I tank design. NASA’s Jet Propulsion Labs (JPL) at Caltech in Pasadena, CA (The Mars Rover was designed here) is looking into the possibilities of such a design for Venus exploration.
AREE on a hostile-environment planet such as Mercury and Venus with extreme heat, a corrosive atmosphere composed of Sulfuric Acid, and crushing atmospheric pressure (Image courtesy of NASA JPL)
The Russians tested the Venus environment back in the 1960s on through to the early 1980s and their 14 attempts yielded only 23 to 127 minutes before their robust crafts became inoperative.
Why not electronics?
We know that there are cooling techniques and high temperature semiconductors that may be a possible solution, but the problem is that even with a Radioisotope Thermal Generator (RTG) as a cooler engine for a tiny enclosure housing the electronics, the design would be quite complex and the cost would require billions of dollars in research. The high temperature Integrated circuit technology today is not small enough to fit what is needed in a small rover.
Using an all-mechanical, high temperature alloy design such as Inconel 625, Haynes R-41, and Aktiebolag 253, a rover might survive on the Venus surface for weeks to months.
What will power this beast?
A turbine, powered by wind energy, could store that energy in a constant force spring mechanism since the atmospheric density of 65 kg/m3 is much higher than we have on Earth and this will provide more energy for the harvester. Companies like GE Renewable Energy know how to make good wind turbines. A design with 50% average efficiency should work on Venus for a small rover.
The energy is collected through the wind turbine and then would be transferred through a transmission to increase the amount of torque. That energy would be distributed throughout the rest of the rover. Energy not used by the rover would be stored in clock springs. The clock springs would be designed such that energy could be drawn by the system and gained from the turbine at the same time. Further, some additional energy could be used to run a gas compressor, which would compress Venus atmosphere for later use in in signaling and pneumatic computers1 .
But it still would need a brain
A design for a mechanical computer and logic system that could be programmed for this particular mission to examine wind speed (using a rotating wind turbine), temperature (by material displacement due to thermal expansion), pressure (measure the expansion and contraction of a control volume as atmospheric pressure changes) and seismic activity (using a cantilevered mass that will vibrate under seismic activity and be mechanically amplified). Computing and Control methods need to be re-thought for this mission.
Examining chemical composition can be done by the use of rods that react to certain chemicals. If the rod is placed under a load as well, the chemical concentration of the material sensed could be determined by recording the time it takes for the rod to break. This is because higher concentrations of a chemical would cause the rod to break more quickly.
The ancient Greeks did something like this over 2,200 years ago with the Antikythera Mechanical Computer for astronomical events. Charles Babbage, an early computer pioneer also created the Babbage Engine.
An Analog Computer is also an idea being considered. An example of Analog computing mechanisms is shown below.
An example of mechanical Analog mechanisms that serve as traditional logic gates: (a) An adder; (b) A multiplier, and (c) An integrator (Image courtesy of Reference 1)
By using 3D printers and today’s advanced MEMS technology, the compute and control system may be able to be built small enough to fit into a Rover.
How can the rover communicate its findings back to Earth?
Possibilities for communication being explored are:
- A relatively simple high temperature transponder
- A retroreflector target or inscribing phonograph-style records that can be launched via a balloon to a high-altitude drone that can transmit to Earth (We saw such a type of record sent with the Voyager but this one may have to be more robust)
Roving mechanism on Venus
Some possibilities for mobility of the Rover would be similar to the ones previously deployed with wheels. Other ideas are a track or tread system which may be more stable, especially over rough terrain. Challenges with these two methods would be sealing the mechanical system to avoid dust on Venus and also how to transfer energy from the body of the Rover to the wheels. A walking mechanism has also been discussed because it may have advantages of not stirring up too much dust since the legs would keep the dusty ground contact far below the Rover and help minimize dust during movement. A Jansen mechanism is one idea for this. See the following video.
(Video image courtesy of Scott Allen Burns on Project Docs)
Basic design idea
A possible systems level flow chart showing all major components of design needed for this mission (Image courtesy of NASA JPL/Reference 1)
AREE concept for sensor instrument integration on the rover (Image courtesy of NASA JPL)
Although I am an electronics engineer, I have great respect for what other engineering disciplines can do better under different conditions, but with a great deal of ingenuity and pushing the engineering envelope to extremes.
What are your thoughts about this?
1 An Automaton Rover Enabling Long Duration In-Situ Science in Extreme Environments, J. Sauder, E. Hilgemann, B. Bienstock, A. Parness, JPL Caltech, IEEE 2017