Building Electronics That Can Work on Venus

The weather on Venus is like something out of Dante’s Inferno. The average surface temperature – 737 K (462 °C; 864 °F) – is hot enough to melt lead and the atmospheric pressure is 92 times that of Earth’s at sea level (9.2 MPa). For this reason, very few robotic missions have ever made it to the surface of Venus, and those that have did not last long – ranging from about 20 minutes to just over two hours.

Hence why NASA, with an eye to future missions, is looking to create robotic missions and components that can survive inside Venus’ atmosphere for prolonged periods of time. These include the next-generation electronics that researchers from NASA Glenn Research Center (GRC) recently unveiled. These electronics would allow a lander to explore Venus surface for weeks, months, or even years.

In the past, landers developed by the Soviets and NASA to explore Venus – as part of the Venera and Mariner programs, respectively – relied on standard electronics, which were based on silicon semiconductors. These are simply not capable of operating in the temperature and pressure conditions that exist on the surface of Venus, and therefore required that they have protective casings and cooling systems.

Naturally, it was only a matter of time before these protections failed and the probes stopped transmitting. The record was achieved by the Soviets with their Venera 13 probe, which transmitted for 127 minutes between its descent and landing. Looking ahead, NASA and other space agencies want to develop probes that can gather as much information as they can on Venus’s atmosphere, surface, and geological history before they time out.

To do this, a team from NASA’s GRC has been working to develop electronics that rely on silcon carbide (SiC) semiconductors, which would be capable of operating at or above Venus’ temperatures. Recently, the team conducted a demonstration using the world’s first moderately-complex SiC-based microcircuits, which consisted of tens or more transistors in the form of core digital logic circuits and analog operation amplifiers.

These circuits, which would be used throughout the electronic systems of a future mission, were able to operate for up to 4000 hours at temperatures of 500 °C (932 °F) – effectively demonstrated that they could survive in Venus-like conditions for prolonged periods. These tests took place in the Glenn Extreme Environments Rig (GEER), which simulated Venus’ surface conditions, including both the extreme temperature and high pressure.

Back in April of 2016, the GRC team tested a SiC 12-transistor ring oscillator using the GEER for a period of 521 hours (21.7 days). During the test, they raised they subjected the circuits to temperatures of up to 460 °C (860 °F), atmospheric pressures of 9.3 MPa and supercritical levels of CO² (and other trace gases). Throughout the entire process, the SiC oscillator showed good stability and kept functioning.

SiC high-temperature electronics before and after testing in Venus surface conditions (rugged operation for extended durations). Credits: Marvin Smith/David Spry/NASA GRC

This test was ended after 21 days due to scheduling reasons, and could have gone on much longer. Nevertheless, the duration constituted a significant world record, being orders of magnitude longer than any other demonstration or mission that has been conducted. Similar tests have shown that ring oscillator circuits can survive for thousands of hours at temperatures of 500 °C (932 °F) in Earth-air ambient conditions.

Such electronics constitute a major shift for NASA and space exploration, and would enable missions that were previously impossible. NASA’s Science Mission Direction (SMD) plans to incorporate SiC electronics on their Long-Life In-situ Solar System Explorer (LLISSE). A prototype is currently being developed for this low-cost concept, which would provide basic, but highly valuable scientific measures from the surface of Venus for months or longer.

Other plans to build a survivable Venus explorer include the Automaton Rover for Extreme Environments (AREE), a “steampunk rover” concept that relies on analog components rather than complex electronic systems. Whereas this concepts seeks to do away with electronics entirely to ensure a Venus mission could operate indefinitely, the new SiC electronics would allow more complex rovers to continue operating in extreme conditions.

Beyond Venus, this new technology could also lead to new classes of probes capable of exploring within gas giants – i.e. Jupiter, Saturn, Uranus and Neptune – where temperature and pressure conditions have been prohibitive in the past. But a probe that relies on a hardened shell and SiC electronic circuits could very well penetrate deep into the interior of these planets and reveal startling new things about their atmospheres and magnetic fields.

AREE is a clockwork rover inspired by mechanical computers. A JPL team is studying how this kind of rover could explore extreme environments, like the surface of Venus. Credit: NASA/JPL-Caltech

The surface of Mercury could also be accessible to rovers and landers using this new technology – even the day-side, where temperatures reach a high of 700 K (427 °C; 800 °F). Here on Earth, there are plenty of extreme environments that could now be explored with the help of SiC circuits. For example, drones equipped with SiC electronics could monitor deep-sea oil drilling or explore deep into the Earth’s interior.

There are also commercial applications involving aeronautical engines and industrial processors, where extreme heat or pressure traditionally made electronic monitoring impossible. Now such systems could be made “smart”, where they are capable of monitoring themselves instead of relying on operators or human oversight.

With extreme circuits and (someday) extreme materials, just about any environment could be explored. Maybe even the interior of a star!

Further Reading: NASA

Time To Build A Venus Rover

The planet Venus, as imaged by the Magellan 10 mission. Credit: NASA/JPL

Venus is often described as being hell itself, because of its crushing pressure, acidic atmosphere, and extremely high temperatures. Dealing with any one of these is a significant challenge when it comes to exploring Venus. Dealing with all three is extremely daunting, as the Soviet Union discovered with their Venera landers.

Actually, dealing with the sulphuric rain is not too difficult, but the heat and the pressure on the surface of Venus are huge hurdles to exploring the planet. NASA has been working on the Venus problem, trying to develop electronics that can survive long enough to do useful science. And it looks like they’re making huge progress.

Scientists at the NASA Glenn Research Centre have demonstrated electronic circuitry that should help open up the surface of Venus to exploration.

The first color pictures taken of the surface of Venus by the Venera-13 space probe. Credit: NASA
The first color pictures taken of the surface of Venus by the Venera-13 space probe. The Venera 13 probe lasted only 127 minutes before succumbing to Venus’s extreme surface environment. Credit: NASA

“With further technology development, such electronics could drastically improve Venus lander designs and mission concepts, enabling the first long-duration missions to the surface of Venus,” said Phil Neudeck, lead electronics engineer for this work.

With our current technology, landers can only withstand surface conditions on Venus for a few hours. You can’t do much science in a few hours, especially when weighed against the mission cost. So increasing the survivability of a Venus lander is crucial.

With a temperature of 460 degrees Celsius (860 degrees Fahrenheit), Venus is almost twice as hot as most ovens. It’s hot enough to melt lead, in fact. Not only that, but the surface pressure on Venus is about 90 times greater than Earth’s, because the atmosphere is so dense.

To protect the electronics on previous Venus landers, they have been contained inside special vessels designed to withstand the pressure and temperature. But these vessels add a lot of mass to the mission, and make sending landers to Venus a very expensive proposition. So NASA’s work on robust electronics is super important when it comes to exploring Venus.

The team at the Glenn Research Centre has developed silicon carbide semiconductor integrated circuits (Si C IC) that are extremely robust. Two of the circuits were tested inside a special chamber designed to precisely reproduce the conditions on Venus. This chamber is called the Glenn Extreme Environments Rig (GEER.)

The GEER (Glenn Extreme Environments Rig) facility can recreate the conditions of any body in our Solar System. (No, not the Sun, obviously.) Image: NASA/Glenn Research Centre
The GEER (Glenn Extreme Environments Rig) facility can recreate the conditions of any body in our Solar System. (No, not the Sun, obviously.) Image: NASA/Glenn Research Centre

GEER is a special chamber that can recreate the conditions on any body in our Solar System. It’s an 800 Litre (28 cubic foot) chamber that can simulate temperatures up to 500° C (932° F), and pressures from near-vacuum to over 90 times the surface pressure of Earth. GEER can also simulate exotic atmospheres with its precision gas-mixing capabilities. It can mix very specific quantities of gases down to parts per million accuracy. For these tests, that means the unit had to reproduce an accurate recipe of CO2, N2, SO2, HF, HCl, CO, OCS, H2S, and H2O, down to very tiny quantities. And the tests were a success.

“We demonstrated vastly longer electrical operation with chips directly exposed — no cooling and no protective chip packaging — to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere,” Neudeck said. “And both integrated circuits still worked after the end of the test.”

In fact, the two circuits not only functioned after the test was completed, but they withstood Venus-like conditions for 521 hours. That’s more than 100 times longer than previous demonstrations of electronics designed for Venus missions.

A before (top) and after (bottom) image of the electronics after being tested in Venus atmospheric conditions. Image: NASA
A before (top) and after (bottom) image of the electronics after being tested in Venus atmospheric conditions. Image: NASA

The circuits themselves were originally designed to operate in the extremely high temperatures inside aircraft engines. “This work not only enables the potential for new science in extended Venus surface and other planetary exploration, but it also has potentially significant impact for a range of Earth relevant applications, such as in aircraft engines to enable new capabilities, improve operations, and reduce emissions,” said Gary Hunter, principle investigator for Venus surface electronics development.”

The chips themselves were very simple. They weren’t prototypes of any specific electronics that would be equipped on a Venus lander. What these tests showed is that the new Silicon Carbide Integrated Circuits (Si C IC) can withstand the conditions on Venus.

A host of other challenges remains when it comes to the overall success of a Venus lander. All of the equipment that has to operate there, like sensors, drills, and atmospheric samplers, still has to survive the thermal expansion from exposure to extremely high temperature. Robust new designs will be required in many cases. But this successful test of electronics that can survive without bulky, heavy, protective enclosures is definitely a leap forward.

If you’re interested in what a Venus lander might look like, check out the Venus Sail Rover concept.