High-Level Project Summary
We designed a rover which will be able to survive on Venus for 60 Earth Days. Our goal was creating a lightweight design that sufficiently fulfilled the power needs of the rover. To achieve this, we based the design around Low Temperature Solid Oxide Fuel Cells, which were able to generate power in Venus' scorching temperatures. The main inputs of the Low Temperature Solid Oxide Fuel Cell is Oxygen and Hydrogen, which we will create using Chemical reactions and Venus' natural atmospheric composition. A Stirling Cooler will also be used to maintain temperatures in parts of the rover containing electronics which cannot handle the high temperatures of Venus like the battery of the Rover.
Link to Final Project
Link to Project "Demo"
Detailed Project Description
The rover that we designed is based around the Low Temperature Solid Oxide Fuel Cell. The Low Temperature Solid Oxide Fuel Cell requires Oxygen and Hydrogen as the inputs, which are created in separate processes.
To create the Oxygen needed for the Solid Oxide Fuel Cell, the team decided on using taking advantage of the natural abundance of CO2 in the Venusian atmosphere. The abundance of CO2 is "sucked" in and goes through a canister of Sodium Peroxide which acts as an oxidizing agent. The oxygen is then transported to the Solid Oxide Fuel Cell to start the process of producing energy. In the future, we plan on taking inspiration from the MOXIE machine that NASA has created for the Mars space mission. We might use the design and replace the Sodium Peroxide storage with the MOXIE machine to make the process more sustainable and not consumable based.
The Hydrogen will be created by reacting sodium metal with the Sulfuric Acid to create Hydrogen. The sulfuric acid will be absorbed through the same filter as the carbon dioxide, and will be separated and treated with the sodium metal to create the product Hydrogen. The sodium metal is one of the lightest metals, even lighter than water. What this means is that the sodium metal will not contribute to the mass as much as the other components.
The Solid Oxide Fuel Cells are individually 4cm x 4cm in area, and 1 cm in thickness. The model Low Temperature SOFC that we based our model off of was able to produce 8W per 500 hours at 450 C . Using this figure, that means that per approximately 20 days, we are able to create 8W of power. If the CO2 producer and the Hydrogen reactor require 10 W per day in total, then it'll require 200 W in 20 days. The Martian rover required 100 W per day to drive, so factoring that into our calculations, we'll need 2200 W per 20 days. Our design also includes a Stirling Cooler based on NASA designs, which will need 240 W per day in order to maintain a temperature under 300 C in order to prevent the battery from overheating. In total, we'll require approximately 7000 W of power to produce energy and drive around. Dividing the figure by 8, we'll get that we'll need 875 Low Temperature SOFC to generate that much energy. Assuming a worst case scenario, and that the density of the SOFC was similar to that of Tungsten, that means that the 16 cubic cm cell would weigh 0.31 kg. The whole power system which contains 875 cells would weigh approximately 271.25 kg.
The Stirling Cooler's main job is to cool the battery so it doesn't overheat. The Stirling cooler is estimated to have a mass of 1.6 kg, and consume 240 watts of power. The Stirling Cooler only requires electrical energy to work, and is able to cool the electronics to maintain a temperature under 300 C. This is directly sufficient for electronics to work long durations with breaking down.
Space Agency Data
https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/
https://rps.nasa.gov/news/39/high-efficiency-stirling-convertor-demonstrates-long-term-performance/
https://ntrs.nasa.gov/api/citations/20050192311/downloads/20050192311.pdf
https://www.nasa.gov/content/cooling-system-keeps-space-station-safe-productive
Hackathon Journey
Space Apps was a fun short project. I learned a lot about myself while working on Space Apps, and met two new friends as a result of it. What inspired the team to choose "Exploring Venus Together" as a challenge was our similar interest in engineering and design. Overanalyzing small details while discussing novel solutions was one of the best parts of Space Apps for me. It truly was amazing being able to meet two likeminded individuals and work with them on making a design. I'm really proud of what we created and I'll definitely be participating in Space Apps next year.
Our teams approach to developing this project was to have an open discussion about what ideas we thought might've worked well, and then we would discuss and present a case for which idea was the best. Once a majority of us agreed, we would implement the idea into our design. Our team faced many setbacks, but we always tried to continue on and fix our mistakes. One example of a setback that our team faced was when we discovered that our original idea of using wind power to power our rover wasn't possible because of the windspeeds on the surface of Venus. In the atmosphere, the wind speeds reaches a terrifying 360 KPH, but what we failed to consider was that on the ground, the wind speeds were a measly 8 KPH, not even close to how much speed we needed to power our wind turbine design. Once we noticed the error in our design, we had to rush to find a new method of generating power, and remodel everything as well. It was truly difficult, but we persevered and made it through.
I'd like to thank my Mom for always believing in me, and my Dad for his helpful suggestions. I'd also like to thank my teacher, who helped guide the team. Finally, I'd like to thank NASA for offering this contest. Without it, I might've never met Ray or Evan.
References
cooling
https://www.1-act.com/resources/tech-papers/24-hour-consumable-based-cooling-system-for-venus-lander/
https://www.newscientist.com/article/dn12905-antique-fridge-could-keep-venus-rover-cool/
http://beyondearthlyskies.blogspot.com/2013/05/cooling-venus-rover.html
Energy
https://www.rsc.org/suppdata/d0/ee/d0ee00870b/d0ee00870b1.pdf
https://pubs.rsc.org/image/article/2020/EE/d0ee00870b/d0ee00870b-f2_hi-res.gif
https://arpa-e.energy.gov/sites/default/files/documents/files/1_Low%20Temperature%20SOFC%20-%20Wachsman.pdf
https://www.researchgate.net/post/Why_humidified_hydrogen_is_used_for_SOFC_solid_oxide_fuel_cell_anode_materials
https://www.cambridge.org/core/journals/mrs-bulletin/article/lowtemperature-solidoxide-fuel-cells/3DB2E7054578B3C4BC0E3E19673FBB56
https://pubs.rsc.org/en/content/articlelanding/2016/ee/c5ee03858h
https://pubs.rsc.org/en/content/articlelanding/2020/ee/d0ee00870b#:~:text=Low%2Dtemperature%20solid%20oxide%20fuel%20cells%20(LT%2DSOFC),as%20power%20output%20and%20durability.
https://www.rsc.org/suppdata/d0/ee/d0ee00870b/d0ee00870b1.pdf
https://www.energymaterj.com/article/view/4371
Background Photo
https://www.labnol.org/reverse/
Background Audio for Demo