High-Level Project Summary
SPACEBREAD team selected the challenge: Exploring Venus Together where we designed energy storage that allows power a surface lander or rover on the surface of Venus for at least 60 days. Many options were considered by our team - starting from obvious electrical batteries to generators that should work on the temperature difference. But finally, we selected an option with a mechanical bimetallic spiral spring. Lander can use the energy from the unwinding spring either directly or via the electric generator. Using an adiabatic process (here we will use some chemical elements delivered from Earth) this spring will be cooled and winded again. So cycle could be repeated many times
Link to Final Project
Link to Project "Demo"
Detailed Project Description
The main idea of our solution is to use this principle :
What exactly does it do?
We propose to use a bimetallic spiral spring in order to store and provide energy. So it will be a mechanical energy source!
Why mechanical energy source?
We considered different options starting from obvious electrical batteries to generators that should work on the temperature difference. But all of them have different limitations which bring us Venus with its climate and atmosphere.
When challenge conditions require that the lander should be powered for 60 days.
Our solution was inspired by NASA resource materials related to Automatons - definitely, you shouldn't protect mechanical solution in the same way as usual electronic components so it could survive for more than 60 days!
How does it work?
Everyone knows that energy could be extracted from the spiral spring. In everyday life, we can see this in our clocks or children's mechanical toys: 
So we will use a similar spiral spring which will provide energy during unwind process:
But who will wind the spring on Venus once it is unwinded? And that's why we decided to use the bimetallic spring which will wind itself after a temperature change. Initially winded in space during travel to Venus spring will start unwinding once the temperature will increase.
But how it will be winded again? For this purpose, we will use the well-known adiabatic process when the working camera volume will be rapidly expanded and the temperature inside will drop again: 
In order to push the piston and expand the volume of the main camera, we will use a chemical reaction with chemical reagents delivered from Earth. They should be stable during all flight and landing process and other components for the beginning of this chemical reaction will be taken directly from the acid atmosphere of Venus.
Concept schema and working principle of the solution
The main chamber will contain our bimetallic spiral spring and nitrogen. Since all isolations will not be ideal this spring will start taking heat from the Venus surface. During the heating process spring will be also uncoiling and produce energy:
Once spring will be heated and uncoiled we propose to use the adiabatic cooling process that could be initiated in another chamber with reagents brought from Earth. So the piston will be pushed, the volume of the main chamber will be rapidly increased and the temperature will be dropped there.
As a result - the main chamber with the spring will be cooled and the spring will be coiled again:
Energy from the coiling process could be used in order to return the piston back as close as possible to the initial state but much more slowly:
What benefits does it have?
All known solutions till now that were able to reach the surface of Venus were able to survive there for a maximum of several hours (if not minutes) only. Taking into account the relative simplicity and cheapness of our solution as well as the required duration of being in working condition, our solution looks really interesting.
According to preliminary calculations, our solution should satisfy the following conditions:
our system has an output power of 158 W, and the efficiency of its conversion to electricity is 85%, so we will get an output of 134.3 W, which would fully cover the costs of the Zephyr lander (given in the table).
The spring is made of two metals, Magnesium and Tungsten, due to the huge difference in heat transfer coefficients (at a temperature of 400°C, a1 = 29.8, a2 = 4.6), the range of untwisting/twisting will be huge. The temperature difference is achieved due to the reverse adiabatic process, nitrogen is taken as gas, and under pressure, the temperature difference that can be achieved will be 250K.
Thanks to this system, we will be able to not only meet the device's energy needs but also store part of it with the help of a sodium-sulfur accumulator, which has the advantage of not requiring cooling for stable operation.
What do you hope to achieve?
We hope that our idea if not implemented exactly as we described here then will at least inspire other people and they will continue to think in this direction. The main idea here is to show that well-known technologies used for centuries still could be useful in cutting-edge Solar system exploration approaches.
What tools, coding languages, hardware, or software did you use to develop your project?
Taking into account that this is an online hackathon our solution is mostly theoretical and rather conceptual than something close to a prototype.
Despite this fact, we used some software in order to work with graphics, and audio, or in order to perform our calculations:
YouCut - Video Editor & Maker - for video processing and creation;
Ibis paint X - for image creation;
Standard Windows Voice Recorder in order to record the presentation,
In order to perform our calculations, we write the related program in C++ (source code provided under the link to Final Project)
Space Agency Data
We were inspired by provided additional resources for the challenge, especially about Automaton.
So we actively used all these additional materials before our brainstorming phase and even after it in order to finalize our vision. Data obtained from NASA provided us with valuable information about conditions on the Venus surface as well as in the Venus atmosphere.
We use this information during our internal discussions as arguments for estimating all pros and cons of discussed ideas.
For example, we realized that in some cases mechanical energy could be used directly by a lander or rover instead of transforming into electrical energy. We were really expired by materials from NASA's Venus Rover Challenge.
Another example is the information provided by the DAVINCI Mission to Venus - especially about details of Venus's atmosphere.
For sure we used information from other open sources as well but the majority of required for our challenge information was available on the NASA pages.
Hackathon Journey
Our experience in this challenge was really great! We learned a lot about the past and future missions to Venus, and the difficulties and challenges that they are going to encounter.
What inspired us to choose this challenge was the desire to bring a fresh perspective to an old problem and try to find a non-standard solution. This topic immediately surprised us with its optimism, since, as people interested in science, we knew about not too long missions to the planet, most of which were there for much less than an hour. Then it became a challenge to come up with a way to conquer such a treacherous place. So we got down to business.
The approach we used was to brainstorm in order to generate all possible ideas, and quickly analyze them in order to select the most unobvious and less costly at the first glance.
The online format of the challenge brings for sure its own limitations like it was not possible to work together with some potential prototype of the solution but at the same time opens new possibilities - like international collaboration.
We are really grateful to all our mentors for their feedback, ideas, and suggestions and for sure to the organizers in our location for all the process and support.
References
https://www.nasa.gov/feature/automaton-rover-for-extreme-environments-aree/
https://www.nasa.gov/feature/jpl/nasas-venus-rover-challenge-winners-announced
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150000879.pdf
https://solarsystem.nasa.gov/news/1519/venus-resources/?page=0&per_page=40&order=created_at+desc&search=&tags=Venus&category=324
https://en.wikipedia.org/wiki/Bimetallic_strip#/media/File:Bimetal_coil_reacts_to_lighter.gif
https://geography.name/the-adiabatic-process/
https://www.inverse.com/article/12163-report-nasa-will-launch-a-venus-rover-in-2023
https://www.nasa.gov/offices/oct/early_stage_innovation/niac/2012_phase_I_fellows_landis.html
https://www.nationalgeographic.com/science/article/venus-1
https://youtu.be/mSLuJYtl89Y
https://solarsystem.nasa.gov/planets/venus/exploration/?page=0&per_page=10&order=launch_date+desc%2Ctitle+asc&search=&tags=Venus&category=33#ancient-observers
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-106D
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-128E
Tags
#Venus, #energysource, #mechanical, #adiabatic, #lander