Engineers have come up with an innovative "clockwork rover" concept designed to survive the hostile environment of Venus.
Fans of steampunk, rejoice: a mechanical rover might one day explore the surface of the planet Venus.
The recent proposal for the Automaton Rover for Extreme Environments (AREE) comes from NASA's Innovative Advanced Concepts (NIAC) program and is currently being evaluated at the Jet Propulsion Laboratory in Pasadena, California.
The rover's power source works on an old-fashioned yet innovative concept: A wind turbine would capture Venusian surface winds, winding up an internal spring that would in turn transfer power using shafts and clutches.
A Custom Rover for a Hellish World
Although Venus is often touted as a sister world roughly Earth's size, any similarities end there. Daytime surface temperatures reach 864°F, hot enough to melt lead, and the surface pressure is 90 times that of Earth's atmosphere at sea level, enough to crush most rovers like a tin can. Delicate electronics can't survive long in such conditions. Early Soviet Venera and Vega spacecraft only functioned for a few hours on the surface at most before succumbing to the extreme environment.
The harsh reality of Venus is one of the prime reasons NASA has instead focused on Mars exploration. The Russians landed 10 missions on Venus during the Soviet era, but NASA has never sent a dedicated lander to Venus, though atmospheric probes dispatched from Pioneer Venus 2 did briefly transmit from the surface.
Traditional Venus rover concepts envision exotic technology utilizing either expensive cooling mechanisms or electronics hardened against the environment. Solar power is out of the question, as direct sunlight can't penetrate to the surface, though the Venera missions found more sunlight filtered through the perpetual cloud cover than expected.
To get around these difficulties, JPL mechatronics engineer Jonathan Sauder came up with the idea of a clockwork rover back in 2015. He was inspired by early mechanical computers that predate the electronic era. If you still use a wind up wristwatch, you're already familiar with the idea of mechanical computers, which use cogs and gears to make calculations, powered by the release of tension from a wound-up spring.
The Greek Antikythera device used a series of gears to calculate eclipses. Swiss watch-maker Pierre Jaquet-Droz created an automaton known as “The Writer” which was able to produce letter combinations via crude programming. Charles Babbage also envisioned a “Difference Engine” using cogs and dials for solving algebraic equations. Babbage's Difference Engine No. 2 was finally built by the British Science Museum in 1991.
More recently, artist Theo Jansen created the kinetic sculptures known as Strandbeests. These wind-powered, spindle-legged mechanical creatures inspired the initial design for AREE. Later, the spindly legs were deemed too unstable and were replaced with treads reminiscent of early World War I tanks
This unorthodox rover would nevertheless face challenges surviving on Venus. For one, winds on the surface of Venus are light, blowing at just 0.3 to 1.3 meters per second (0.7 to 3 mph), but they're more powerful than Earth-based experience would have us think. "While that is pretty slow," says Jonathan Sauder (NASA-JPL), "the atmosphere is about 10 times denser than that of Earth, so it really helps."
Engineers will also have to construct the rover out of materials able to function under the high heat and terrific pressure on the surface of Venus. There is some precedent for this, as Soviet engineers designed the early Venera landers to take thermal expansion into account for optimal performance.
Communication without traditional electronics will require some creativity. AREE engineers are investigating an old-fashioned solution: Morse code. If an orbiter accompanies the rover to Venus, it could regularly ping the rover using radar. A rotating shutter in front of the rover's radar target could then be opened and closed to send a Morse code signal back to the orbiter. Of course, this would be a slow, one-way conversation, from the rover to the relay orbiter, and on to Earth — with no way to talk back to tell the rover what to do. Once on Venus, the rover would have to be on its own.
Science would likewise have limitations. The rover's potential suite of instruments might include a hybrid mechanical/electrical system, limited to drilling, soil sample analysis, and weather monitoring, with no imaging capabilities (limited electronics means no cameras).
"Mechanical instruments would be fairly crude," says Saunder. "There is currently a lot going on in the area of high-temperature electronic instruments. This has moved us to a hybrid rover, where the mobility and power systems are done mechanically, and then the instruments are run electrically."
For all its limitations, it's possible that the mechanical Venus rover, or part of its design, could make a future Planetary Decadal Survey wish list. The AREE project is now in the second phase of NIAC development, with the JPL team looking to select portions of the AREE design for refinement and prototyping. "We just received funding to perform two more years of work," says Sauder. "We plan to build a small scale prototype with limited functionality."
The era of steampunk robotic explorers may yet come to pass.