Who are We?

We are a group of young aerospace engineers, who share a common passion for space. During our studies, we have worked alongside each other in numerous projects. Combining this with the incredible opportunity NASA Spaceapps has provided us, we have been able to work together to present our best solution for this problem. Our aim is to help NASA to the best of our abilities to push humanity forward in terms of space exploration.

How does our solution work?

The memory mechanism was designed around the concept of an odometer, which consists of a series of coaxial gears, each with a certain number of angular positions, in which a set of resistors is placed. The idea behind this mechanism is that after one disk has completed an entire revolution, the next disk will advance one position. This meant that information could be stored in a compact and completely mechanical way.

The number of disks would be equivalent to the number of digits of the data stored and the number of angular positions would represent the numerical base of these digits. The unit considered for the Hackathon had four disks with eight angular positions each, therefore this unit would store four octal digits.

The process for reading data begins when a measurement is taken. At that moment, the gear connected to the measuring system turns a certain number of degrees, rotating the whole system sequentially. Once the reading process is complete, the mechanical input would be disengaged to maintain a particular configuration of resistors as a way to store the data. Following this, the stored data would be read by closing the circuit along the face in which the set of four resistors for the final configuration is and measuring the current for a certain voltage. Lastly, resetting the memory could be done by applying a reverse torque on the input and rewriting by re-engaging the mechanical measuring equipment.

Video of the single unit mechanism:
https://github.com/idelafuentef/SpaceAppsMnemosyne/blob/master/SingleUnit.mp4

Exploding view of the single unit:
https://github.com/idelafuentef/SpaceAppsMnemosyne/blob/master/ExplodedView.avi

In the image below, the memory design achieved given the parameters of the challenge can be observed:

How Were the Resistors Selected?

When facing this design, one possible question could be: couldn’t there be different combinations of resistors that resulted in the same output current? This was indeed an important problem to solve, but it also allowed us to come up with a really powerful solution.

To solve this problem, our team implemented an optimization system based on concepts of digital signal modulation, such as QPSK (Quadrature Phase Shift Keying). Using this method allows designing a system for a limited and known set of states. If the measurement taken is equal to one of the already known sets, it is considered as correct. However, if it does not match with any of the known configurations, this method eliminates the noise in the measurement by taking the closest state. This method is more reliable as the differences between the points of the set increase.

But, how does this method apply to our set of resistances? Whereas QPSK is defined in terms of phase shifts, our design defines the constellation of points based on current values. For a data module, there is a limited and known amount of resistor arrays, and each of the configurations gives a different value in the current measured. An optimization code was developed to solve this multi-variable problem and provide a set of possible resistor values that would produce the set of currents defined by the designers.

For more information regarding the mechanism’s functioning and the way, data is stored and read, go to the Report Document in our GitHub repository.

Besides, the resistor configuration algorithm can be found in the following link. It was written in Octave, but could be easily moved to open-source, being one of our first future steps.

Sizing and Performance

Considering the model already described, estimations regarding memory and weight parameters were made. However, these are preliminary calculations, based on accessible industry data and with a highly conservative viewpoint.

Our final unit design is composed of 4 disks with 8 resistances each, which would result in a total of 2^12 possible states, or an equivalent 1.5 Bytes of binary memory. Combining the mechanisms and electrical circuit, the total volume of the unit was considered equivalent to that of a prism of 18mm x 18mm x 14mm. Taking into account that the total volume provided was 0.25 cubic meters, the overall total capacity was about 181.65kB.

Future Development

As has been stated, this preliminary study had the goal to find out the feasibility of this design. Once it was validated, the next steps would consist of finding new materials and machining techniques that could minimize the size and weight of this system, while withstanding the extreme conditions of Venus. This opens many fields of research, such as the one of Micro-Electro-Mechanical Systems, 3D printing, and Microfabrication, that would provide solutions to this sizing optimization problem.

When developing this project, we discovered that this design’s applications would not be limited to the surface of Venus, but could be extended to many other areas. For example, due to the high resistance of this unit to extreme conditions, it could be implemented in systems on Earth that operate at high temperatures, like for example in volcanic areas. Besides, as the limits of space exploration expand with the discovery of new planets, this solution could be of use in all those zones where electronics are not an option. Therefore, this would allow humankind to explore strange new worlds and seek out new life and new civilizations. To boldly go where no man has gone before.

Reference Links

Automaton Rover For Extreme Environments https://www.nasa.gov/sites/default/files/atoms/fil...

White Paper to the NRC Decadal Survey Inner Planets Sub-Panel on Technologies for Future Venus Exploration
https://www.lpi.usra.edu/decadal/vexag/techWhitePa...

Reports on Venera-D Mission

Phase 1 https://www.lpi.usra.edu/vexag/reports/Venera-D-ST...
Phase 2 https://www.lpi.usra.edu/vexag/reports/GOI-Space-P...
Technology Plan https://www.lpi.usra.edu/vexag/reports/Venus-Techn...
Seismic and Atmospheric Exploration of Venus https://www.lpi.usra.edu/vexag/reports/SAEVe-6-25-...

Our Github Complete Repository