Saturday, October 21, 2017

Steampunk Computer Rover Heading for Venus?

Today's fun fact is that Mars is the only planet known to be inhabited entirely by robots.

It may be there's another planet that will soon share that title: Venus.  NASA is currently investigating a robotic explorer to land on Venus and explore. Unlike the rovers on Mars, this rover has decidedly steampunk character to it; it's all mechanical.

If there's any planet that seems like a good definition of hell, Venus is a strong candidate with a surface temperature of approximately, 450ºC or 850ºF, which is high enough for paper to spontaneously combust and melt lead. The atmosphere is a mix of carbon dioxide, nitrogen, and sulfur dioxide, while the surface pressure is 92 bar or 1,334 psi. The atmosphere is dense enough to crush a submarine.  Some data says Venus' atmosphere undergoes critical refraction and it's possible for light to circle the planet, above the surface.  Ray tracing computer modeling suggests that with a strong enough telescope, a hypothetical astronaut in the right place could see himself in the distance.  

The electronics geeks, hams and experimenters might have had the thought "hot enough to melt lead?  What about solder?" and it is.  Parts can be welded onto a substrate, but "hot enough to melt solder" is an important consideration.  The NASA lab planning the mission, NASA’s Innovative Advanced Concepts Program (NIAC) had developed a conceptual robot based on mechanical computers and WWI tanks because mechanical parts should survive the environment. Called AREE (Automaton Rover for Extreme Environments), the design has been referred to as a Steampunk Robot or Clockwork Rover.  Shades of Babbage's Analytical Engine
AREE was first proposed in 2015 by Jonathan Sauder, a mechatronics engineer at JPL. He was inspired by mechanical computers, which use levers and gears to make calculations rather than electronics.
Sauder said these analog technologies could help where electronics typically fail. In extreme environments like the surface of Venus, most electronics will melt in high temperatures or be corroded by sulfuric acid in the atmosphere.

"Venus is too inhospitable for kind of complex control systems you have on a Mars rover," Sauder said. "But with a fully mechanical rover, you might be able to survive as long as a year."
Venus has had only two robotic missions land on its surface, both from the former Soviet Union, the Venera and Vegas landers.  They were able to function only for minutes: specifically 23 and 127 minutes before the electronics failed in the oppressive environment.  To survive on Venus long enough to do any good science clearly requires thinking well outside the proverbial box.
AREE includes a number of other innovative design choices.

Mobility is one challenge, considering there are so many unknowns about the Venusian surface. Sauder's original idea was inspired by the "Strandbeests" created by Dutch artist Theo Jansen. These spider-like structures have spindly legs that can carry their bulk across beaches, powered solely by wind.

Ultimately, they seemed too unstable for rocky terrain. Sauder started looking at World War I tank treads as an alternative. These were built to roll over trenches and craters.

Another problem will be communications. Without electronics, how would you transmit science data? Current plans are inspired by another age-old technology: Morse code.

An orbiting spacecraft could ping the rover using radar. The rover would have a radar target, which if shaped correctly, would act like "stealth technology in reverse," Sauder said. Stealth planes have special shapes that disperse radar signals; Sauder is exploring how to shape these targets to brightly reflect signals instead. Adding a rotating shutter in front of the radar target would allow the rover to turn the bright, reflected spot on and off, communicating much like signal lamps on Navy ships.
To be clear, this isn't a mission that's on the calendar and being planned, it's one of a few options being discussed.  Mechanical computers are interesting, but incredibly slow compared to electronics for a general purpose computer.  Even a 1970s processor like an 8080 would be orders of magnitude more capable than rotating gears.  Perhaps there might be ways to customize the mechanical computer, but could they do mineral analysis, or some of the other science work Curiosity and the other Mars rovers do? 

A mission like this would be interesting from the technology-geek standpoint, but one has to wonder if there might be ways to cool electronics to get more science done.  NASA's Space Technologies Directorate talks about RTG-powered refrigerators (Radioisotope Thermal Generator - the type of power generator powering the Voyagers and some other deep space probes) has some high level summary. 
Two enabling technologies, RTG powered cooling systems and high temperature electronics, have been proposed to enable long duration in-situ Venus operations. The former is highly complex and requires billions in R&D to cool a small chamber of electronics, while the latter is not close to the integration level required for a rover....

...The automaton rover is designed to reduce requirements on electronics while requiring minimal human interaction and based on the subsumption architecture from robotics, where simple reactions of the rover lead to complex behavior. AREE combines steampunk with space exploration to enable science measurements unachievable with today’s space technology.

In Phase 1 purely mechanical rover technologies were compared to a high temperature electronics rover and a hybrid rover technologies. A purely mechanical rover, while feasible, was found to not be practical and a high temperature electronics rover is not possible with the current technology, but a hybrid rover is extremely compelling. Phase 1 mitigated our highest risks, demonstrating passive signaling was possible, the power budget balanced, and the rover fits within current EDL systems. Building on the design created in Phase 1, the objective of this proposed work is to finalize the trades with regards to implementation of locomotion and signaling systems, develop an end to end rover design, and perform Venus environmental testing of a representative prototype.
That last paragraph makes it sound like the mechanical AREE might be getting close to being approved to go to Venus.  For real.


  1. There is a lot of science that a rover could do on Venus if we can overcome the environment. And if we can do Venus, why not Io?

  2. The fire control systems on the four Iowa-class battleships is 100% electromechanical. When the ships were first modernized in the 1980's, HP, IBM, and Honywell were called in to see what it would take to retrofit them with modern digital computers.

    After about 6 months of study, the three companies came back to the Navy, and said that not only could they not do the task as well as the installed computers, they couldn't do it at all with the current state-of-the-art 1980's computers.

    I think the big issue was interfacing with all the servomechanisms, magnetic amplifiers, and other "obsolete" equipment, but the digital guys were stunned by how accurately those old "Clockwork Computers" could perform the required calculations.

    Sometimes the old stuff "that just works" is good enough.

    1. I'm sure that electromechanical systems (the current buzzword is "mechatronic") would be just fine in that application. I'm thinking of doing something like analyzing a soil sample. How could they do that? As far as I can tell, the current systems use something like IR spectroscopy. They irradiate the sample with IR, look at the spectrum it gives off, find peak wavelengths and send the data back. How does one do spectroscopy with gears and levers? Alright, scratch soil analysis. What kind of science are they going to do that doesn't go better or faster with a processor of some sort?

      The articles were talking about sending data back with their radar-reflector-Morse Code system at a rate of 1000 bits per day. Curiosity rover sends back a megabit per day. I have a hard time envisioning how this whole thing would be useful.

      Which just means lots of new things to learn!

  3. I am still stuck on the thought of a heat transfer system that is going to be able to reject heat to an ambient temperature of 850 F and just what working fluid will they use.

    1. If I understand this, they don't use a heat transfer fluid. The rover has to endure that environment on its own. I don't know what sort of lubricant they could use; maybe some liquid metal of some kind. Hard to imagine a grease could survive 850 F, 90 bars of pressure, and sulfuric acid in the atmosphere.

    2. Hmmm. This is gonna take more envelope backs.