NASA has been trying to figure out how to send a rover to Venus for years, but Earth's sister planet is a harsh mistress. Although Venus is similar in size, mass, and overall composition to Earth, the similarities essentially end there. The closest planet to us would perhaps be more accurately described as Earth's evil twin rather than its sister.
On Venus, the surface pressure hovers around 92 bar, or 92 times the pressure on Earth's surface, equivalent to the pressure nearly a kilometer deep in our oceans, enough to crush most submarines. The average surface temperature is 864 degrees Fahrenheit (462 degrees Celsius), hot enough to melt lead. And the Venusian atmosphere is filled with clouds of sulfuric acid that rain down corrosive liquid on the surface. The longest a spacecraft has ever survived on the unforgiving planet is only 127 minutes—the Soviet Venera 13 lander that touched down in 1982.
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To overcome the immense challenges of exploring the surface of Venus, NASA engineers at JPL are studying designs for what they call a "clockwork" rover, which would be a rover that relies almost entirely on mechanical systems rather than electronics that would be vulnerable to the unforgiving environment. The project, known as Automaton Rover for Extreme Environments (AREE), was first proposed in 2015 by Jonathan Sauder, a mechatronics engineer at JPL who was inspired to build a mechanical Venus rover by the intricate levers and gears of mechanical computers.
"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."
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The AREE project recently received a second round of funding under NASA's Innovative Advanced Concepts program, which provides grants to engineers to develop early-stage concepts for future missions. The engineering team envisions a rover that is powered by wind turbines in the center of the craft and uses a tank-like tread to navigate the rugged Venusian surface. Additional mechanical constructions have also served as inspiration for the AREE project, including Dutch artist Theo Jansen's "Strandbeests," intricate mechanical walkers that can cross the beach just by catching the wind in their sales.
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While harnessing the thick winds of Venus in turbines to run a tank-like mechanical rover across the surface is encouraging, there are a few major challenges the AREE team needs to overcome. One of the biggest challenges for a rover with no electronics is communication. How is the AREE rover going to talk to an orbiting spacecraft that can relay information back to Earth? Once again, the JPL engineers are looking to a past technology for a solution: Morse code.
The idea under consideration is to build a radar-reflective surface, what Saunder calls "stealth technology in reverse," that would sit on top of the rover. An orbiting spacecraft could hit the rover with radio waves and the radar target, shaped to reflect the signals, would send back a bright, discernible spot. The rover could use its turbine-power system to run a rotating shutter that would cover the radar target at certain speeds, creating a blinking signal that could communicate with Morse code.
Using these mechanical processes, the AREE team believes they could build a rover that could conduct field geology on Venus and perhaps even drill out a few samples. The engineers are researching different materials and selecting certain components of the craft to build prototypes for testing.
NASA/JPL-Caltech
However, a mechanical rover like AREE could be augmented significantly if you were able to include a few simple electronics, like a camera, even if they don't last as long as the rover itself. Fortunately, NASA is working on computer chips and other electronics that could withstand the hellish environment of Venus. Earlier this year, NASA's Glenn Research Center tested a computer chip with heat-resistant silicon carbide (SiC) semiconductors that functioned in Venus-like conditions for an impressive 521 hours, almost 22 days. Even then, the experiment was shut down because the Glenn Extreme Environments Rig (GEER) had to be powered down after running for more than three weeks straight, not because the chip was beginning to fry.
Venus-hardened electronics will have trouble functioning for a full year, the amount of time the AREE team thinks a mechanical rover could roll around on its gears and tank tread, but it would still be worthwhile to outfit a Venus rover with some electronics. For one, it could take images of the surface and communicate more data to an orbiter while the electronics survive. There is also the possibility that a spectrometer could function long enough to determine the composition of Venusian soil, and a mechanical Venus rover would be the perfect test platform to see if our composite, heat-treated computer chips are really up to the task of functioning on the second-closest planet to the sun.
We have been roving on Mars since 1997. It's about time to leave the tire tracks of exploration on Venus.
Bagikan Berita Ini
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