Sending a lander to Venus has some huge engineering challenges. Of course, we could go through the process of re-entry, descent, and landing of a spacecraft, because Venus’s atmosphere is so dense that a lander would gently land on its surface, like a rock sinking into water.
Photos from open sources
However, the rest of the project is fraught with difficulties. The average surface temperature is 455 degrees Celsius, hot enough to melt lead. The mixture of chemicals that make up the atmosphere, such as sulfuric acid, is corrosive to most metals. And the crushing atmospheric pressure is roughly equivalent to being at a depth of 1500 meters under water.
Under these extreme environmental conditions, metals and electronics are destroyed. Therefore, several Venus lander missions that made it to the surface, such as the Soviet Venera missions, lasted only two hours or less. Future landers or rovers will need to have superhero-like performance in order to survive on the surface of a second planet from the Sun.
But there’s another problem that may be close to being solved: building batteries that can last long enough in Venus’ hellish conditions to make a lander mission worth the effort.
NASA scientists partnered with Advanced Thermal Batteries, Inc. (ATB) created the first battery that demonstrated the ability to operate at the temperatures of Venus for an entire solar day, which is approximately 120 Earth days.
Photos from open sources / High Temperature Batteries Adapted for the Surface of Venus / Advanced Thermal Batteries, Inc.
The battery is based on short-life thermal battery systems used to power smart missiles. The battery contains 17 individual cells and uses specially formulated chemistry and construction materials.
While this battery is still in development, engineers are encouraged that tests have shown that these types of batteries are capable of operating in harsh environments, such as on Venus. In addition, this advanced type of battery technology could provide a novel energy storage device for future exploration in harsh environments throughout the solar system.
“This recent demonstration of battery technology with improved architecture and low self-discharge electrochemistry is a huge achievement that many did not consider possible,” said ATB engineer Kevin Vepasnik.
Batteries appear to be the only solution to power a Venus lander. Solar panels are not viable due to the fact that the level of illumination on the surface is comparable to an overcast day on Earth, and current solar panel designs cannot withstand the high pressure on the surface. A radioisotope thermoelectric generator (RTG) requires a heat source to be delivered to the surface of Venus, and since heat management is already a major mission issue, this method is not a good option.
But on Venus, thermal batteries can use the surrounding atmospheric conditions to heat a special high-temperature electrolyte. In addition, they can remain functional without the use of thermal insulation.
NASA says this new battery approach has been demonstrated to operate at high temperatures for unprecedented periods of time and lays the foundation for new battery technologies and for Venus landers.
Work on the new type of thermal battery is part of ongoing work at NASA’s Glenn Research Center to develop a small Venus lander called the Long-Lived In situ Solar System Explorer (LLISSE). The program uses the latest advances in high-temperature systems and a new concept of operations to enable operations on the Venusian surface for 60 days or longer while the lander collects science data and transfers it to the Venus orbiter.
The LLISSE is expected to weigh about 10 kg and be equipped with a set of small sensors to measure wind, brightness, temperature, pressure and key atmospheric chemical constituents. LLISSE will be a complete system with electronics, communications and instrumentation – all of which will require a battery to operate.
ATB says they expect a complete battery system prototype to be unveiled within the next 18 months.