Birth of Venus

https://drive.google.com/drive/folders/1h0KMZucE2Au9M6F8yWGqee_97ziz0teW?usp=sharing

https://drive.google.com/drive/folders/17nfzB3B0Opfh6JpHxtlnwvO0cZVmcVUx?usp=sharing

Introduction:

In popular culture, Venus is usually called Earth’s twin sister for many reasons. The two planets exert a very similar gravitational force, for example. But if Venus is to be considered a twin of our home planet, it has to be an evil one. With its atmospheric pressure of 93 bar, high temperatures of 460°C, highly corrosive gases and dense winds on its surface, Venus is far from being a human-friendly environment. And if our race won’t be able to revert climate change issues before the end of this century, Earth might become just like its evil sister: a living hell.

It is, then, a very challenging problem to design a rover capable to survive for a long time in this environment. This is why our team, named “Birth of Venus” after the all-time famous painting by Italian artist Sandro Botticelli, decided to accept the challenge proposed by NASA, and design HADES: an High-temperature Advanced Energy Storage system for a possible rover to be sent on Venus.

The batteries:

First, we did some brainstorming to figure out what primary sources of power would suit best this kind of hostile environment. As we excluded RTGs (Radioisotopes Thermal Generator) and turbine systems for several reasons (safety, necessary specific energy…) we moved on to high-temperature electrochemical batteries.

HadES Batteries are different from precedent proposals, as they aim to gain high power and performance using the planet's own resources for an extended life cycle, thanks also to the high resistance offered by the titanium reinforcements.

The batteries calculations have been done with MATLAB starting from an initial power estimate, taking into consideration the operative modes of a medium scientific rover.

Estimating the duration of the operative phases, we can compute the required energy.

The mass is obtained from the specific energy and then the volume (supposing the batteries as cylinder-shaped) is determined. Supposing a typical height to diameter ratio, the height of the single battery is computed.

In the end, the battery system proves to be endurable for a minimum of 2 years, with a relatively low mass impact.

We compared two different types of batteries, but only the first one is based on CO2.

Final results are illustrated in the following table:

The CO2 conduct:

As far as the convoy channel is concerned, the external gases are pushed in the duct using a motor driven Inconel fan, particularly adapt in high-temperature high-pressure applications in an acid environment. The conduct is wrapped on a cylinder at the base of which is located the battery pack. The duct is placed between the aforementioned cylinder and a second one, and in the vane a controlled atmosphere is required, preferably near-void, in order to mitigate the impact of external heat sources and to dissipate heat through irradiation. In fact, the duct is covered in a high absorbivity-high emissivity Multi Insulation Layer, with a view to absorb heat from the gases and reject it towards the external cylinder. The length of the duct is sized in order to obtain a substantial drop of temperature and to let the gases lose total pressure, so that the impact on the battery is smoother.

The last portion of the duct is then insered in the internal cylinder to reach the battery pack vain. At the end of the duct a molecular filter is set, which aim is to passivate acid gases (like SO2, HCl and HF) using highly basic molecules (calcium hydroxide, for instance). This is important in order to avoid chemical contamination and corrosion of the batteries.

The material chosen for the design of the duct is a high performance titanium alloys, preferably with the highest conductivity possible. The robustness of the system is granted using four independent set of fan-duct-filter-battery, this way, the batteries are placed along the cylinder circumference, while the internal part is used for cables and electric systems. The duct sizing process have been based on a unitary gas mass flow, knowing the maximum gas speed at which the filter can efficiently work and the atmospheric density the area and the diameter has been determined. As far as the thickness is concerned, an analytical shell theory allowed to estimate it and the mass per length. Basing the heat rejection calculations on a pure irradiation exchange, the length has been obtained as well.

The fan calculations have been done using a simple actuator disk theory, in order to obtain a first impression of the dimension and the mass.

Conclusion:

In the end, thanks to the different types of engineers present in our team, we were able to analyze the problem from several points of view, not just limiting ourselves to the battery cell itself but trying to make it fit inside a proper context. It was important to design an original solution that would make use of Venus’ atmosphere, in other words, discovering something good right at the core of its infernal environment. On the other hand, it was also important to maintain our project as balanced as possible, always checking the feasibility of our solutions through calculations. With this in mind, we figured out both the dimensions for the battery cells, and the dimensions for the recharging system, and thus we proved that the solution proposed is, indeed, completely viable. As a last thing, we made an example timeline of what is expected to be done for future years of development, considering the long time of R&D still needed for the types of batteries we chose. All of this can be found in our presentation, and in fact, we believe that HADeS batteries would be a strong, cost-effective, efficient solution, whether it will be implemented in a future application, or not.

The data provided by the space agency are central to our project work.

In particular, we referred to the following information shared by NASA:

• https://www.nasa.gov/feature/automaton-rover-for-extreme-environments-aree/
• https://solarsystem.nasa.gov/resources/549/energy-storage-technologies-for-future-planetary-science-missions/
• https://sbir.nasa.gov/SBIR/abstracts/21/sbir/phase1/SBIR-21-1-S3.03-3308.html

The first link deals with the challenges of using autonomous rovers in extreme environments, just like Venus. Throughout the discussion we focused on Table 4 in page 14, inherent to the Power Estimation List (PEL), since through this data it was possible to create a roughly realistic design of the batteries to be used for our goals, knowing the electrical energy expended by the system and, therefore, what the battery pack must supply.

The second (Table 4.1 in page 44) and the third link refer to the information and characteristics of high-temperature and long cycle life batteries for applications and missions on the surface of Venus. Among the various solutions we have placed our attention on two in particular:

1. LiAl-CO2, which are still in development;
2. Na-NiCl2, which have been tested extensively;

These batteries offer relatively high specific energy compared to the aqueous rechargeable batteries and also good specific power outputs. On this basis, the batteries are well suited for long-term Venus surface missions.

We used many of the informations in these articles for the MATLAB scripts we made.

Space Apps is AMAZING!

Not only because it allows us to touch innovative and constructive challenges first-hand, but above all because they give us the opportunity to meet new people, share ideas and become together!

But let's start from the beginning ...

Our team is made up of people who were initially unknown, but who got involved in order to participate together. We come from different places and we are each studied in a different sector, so this mix seemed for us a great base to start from.

Some in presence, some at a distance, we have developed a nice bond and we have been able to design something!

The first point common to all was the choice of the challenge: the idea of designing an energy storage system that could possibly be used on Venus for long-term operations has greatly excited us.

Then, when the hackathon started, we discussed and identified the best idea for us to deepen and implement. Subsequently we decided to divide the work according to the needs required by the challenge and to our skills: in particular, there are those:

• who took care of the electrical part of the system, calculating all the information necessary for the sizing of the batteries;
• who took care of the digital design of the actual batteries and the enclosure that contains them;
• who designed the apparatus and gasdynamic to support the innovation of recharging the batteries thanks to the resources of the planet;
• who created and shared with others the presentation of our work.

In the end it was a wonderful experience, in which two days flew by in an instant between chatting, discussions and a lot of work. We learned new concepts and new problems to be solved, we shared and understood the other points of view, improving together.

Thank you for giving us this great opportunity!

Landis G. A., Mellott K. C. 2007, "Venus surface power and cooling systems", Acta Astronautica, 61(11-12): 995-1001

Landis G. A., Harrison L. 2010, "Batteries for Venus surface operation", Journal of Propulsion and Power, 26(4): 649-654

Landis G. A. 2021, "Power System for Venus surface mission: A review", Acta Astronautica, 187: 492-497

NASA/Jet Propulsion Laboratory-Caltech 2017, "Energy Storage Technologies for Future Planetary Science Missions", JPL D-101146

Sauder J. 2017, "Automaton Rover for extreme environments", NASA Innovative Advanced Concepts (NIAC) Phase I Final Report  

Jet Propulsion Laboratory of California Institue of Technology, Presentation at ECS PRiME Pacific Rim Meeting 2020, "High Temperature Primary Batteries for Venus Surface Missions"

Bri DeMattia amd Cody O’Meara, Presentation at Sandia Power Sources Technology Group University Seminar 2021, "NASA Battery Research & Development Overview"

NASA SBIR 2021-I Solicitation, "High Temperature All Solid-State LiAl-CO2 Batteries for Venus Missions"

Wikipedia Page: Atmosphere of Venus (https://en.wikipedia.org/wiki/Atmosphere_of_Venus)

Tools

SolidWorks (https://www.solidworks.com/it), used for the battery package CAD representation

AutoDesk Inventor (https://www.autodesk.it/), used for modeling and assembling the rover

Matlab (https://it.mathworks.com/products/matlab.html), used for batteries performance and gasdynamics calculations

#hardware #venus #battery #resources #original #project #engineer #matlab #cool