The Nibbles - Space Apps Challenge

The Nibbles| The Memory-Maker

Project Details

The Challenge | The Memory-Maker

Traditional electronics do not work well on Venus, and memory is one of the biggest challenges. Your challenge is to develop mechanical approaches to accomplishing tasks normally done electronically within the context of space exploration.

The most promising solution for the Venus data storage problem we could think of was to use micro-scale nitinol wires in switches to create a write-once memory. We thought that, if we can significantly go above the 1MB specification, it could be ok to have write-once memory. Realistically, a lander on Venus wouldn't survive long regardless, so we imagined a mission infrastructure where a lander would rapidly collect data in its write-once memory while it descends or while it is on the surface of Venus. This data then would be uploaded to an orbiter before the lander's systems fail from Venus's harsh environmental conditions.

Nitinol wires exhibit hysteresis, where a wire can be "programmed" into a shape. Once the wire is cooled down below a threshold temperature, it can be reshaped, and after being warmed above the threshold temperature, the wire will go back to the shape that i was programmed to. (https://www.youtube.com/watch?v=JKBM9my5eOA)

Using this property, we devised a write-once memory. Initially the memory contacts are in "1" state. After applying a modest amount of current (we calculated ~10mA, assuming that the surface of venus is ~450C, and the wires need to be heated by ~100C), the bits can be written to a 0 state.

for a memory cell that is about ~200um x 50um, we estimated that ~10GB of storage should be possible within the volume given to us in the challenge.

Things we didn't address:

Circuits for driving and controlling the memory. We assumed that a stopgap measure could be to expose the bulk storage to the conditions of Venus, whereas the controllers could be implemented in a smaller space that is refrigerated.
Precise details of manufacturing. We thought that MEMS manufacturing processes should be capable of manufacturing such a switch.

Further resources below:

Interesting articles on nitinol:

Properties and potential of two (Ni,Pt) Ti alloys for use as high-temperature actuator materials

Nitrinol yarns, ~5um

https://www.fwmetals.com/services/r-d/rd-update/previous-rd-updates/ultra-fine-shape-memory-alloy-yarn-for-textiles/