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Research Project

SPACE SHOES: FOOTWEAR FOR ZERO-GRAVITY ENVIRONMENT

What's the Problem ?


On earth, the skin on bottom of our feet is tough because we use it every day to walk, run, stand. Whereas top of our feet are hardly used so it has soft skin. Feet are used very differently in space than on earth. Astronauts hardly use bottom of their feet, so the calluses (rough skin) on bottom of feet falls off leaving soft pink baby skin. Astronauts often use top of their feet to grip on foot rails. Friction with foot rails due to frequent anchoring can cause painful blisters, calluses and corns as the foot slides back and forth. The blisters may also become infected and cause greater complications. This can be painful, annoying and might distract astronauts from completing their work in long duration space flights.

We selected this problem because it is unique, it’s small but it affects every astronaut during long duration space travel. Shoes are probably the most used piece of apparel (3000+ hrs per year).

“If your feet hurt, you hurt all over”. It is true the comfort of your feet greatly influences the comfort of your whole body and your disposition.



Our Solution

“Made of the very finest materials to exacting specifications the SPACE SHOES will be unique and remarkable in fit, function, comfort and craftsmanship”

We made a crocs based footwear prototype with the bottom hollowed out and covered with soft breathable fabric. The goal was to provide comfort to the newly exposed soft skin when the thick skin sheds off. Top of this footwear is rigid with extra support to handle rough use. There’s also a strap at ankle and bottom of the foot for a firm grip on the foot.

The shoe also has an Arduino controlled servo-motor claw to grip on foot rails allowing the astronaut to put minimal efforts. The claw can be easily actuated by pressing a toe switch. There is an ultrasonic sensor on the shoe. In case of emergency, the claw will anchor the astronaut automatically using the ultrasonic distance measurement. This will prevent astronaut from drifting away or bumping into objects. This concept can be generalized to ensure safety during space-walk.


The shoe also has a light sensor and LEDs. When the light level goes down the LEDs light up.
The top of shoe is hard so it protects astronauts feet in case the ultrasonic claw does not work for specific kind of foot rails.


What solutions do we have so far and how did we get here?
The foot problems became more visible when astronauts started spending months on International Space Station. Astronaut Scott Kelly and Don Petit were the first ones to spend an entire year on space station in zero-gravity environment. They wrote various articles about effects of zero-gravity on human body.

Currently, Astronauts also use regular sneakers while exercising. Astronauts use socks inside space station. Don Petit accidently got his wife's ankle socks but it worked perfectly because it protected his toe but keeping the heel open. He called it toe coozies. However, it does not protect top of feet.
NASA HUNCH in partnership with Madison high school developed soft fabric foot pads for astronauts on ISS. They were helpful but it became hard for astronauts to grip on them without any straps. They are now trying to modify to have straps

Our solution develops from this idea but, instead of foot pads, we started with better structure to support foot like crocs. We made a reverse shoe … like current shoes have breathable top, our shoes have breathable bottom, but a tough top.

Our footwear design includes an arduino claw to help astronaut grip on foot rails. This should help reduce the friction and irritation of foot.
We also used an ultrasonic sensor which will help automatically anchor in case of emergency.
Mr. Glenn Johnson from NASA HUNCH was impressed with this idea and would like us to think about using such claw for space walk activity also.

Here’s how we developed our solution:

  • We hollowed the bottom of crocs- heel and toe portions. We added breathable fabric to bottom of the crocs. We read about NASA HUNCH foot pads solution, we thought that a strap at bottom and a strap at the ankle to help grip on the shoes 

  • We ordered the basic pieces for an claw and we assembled the claw. The claw is made of 2 pieces of aluminum which join together using gears. It requires a servo motor to close and open the claw. We tested our claw with HummingBird Duo Arduino based platform using Scratch coding. We found that servo motor cannot be moved beyond 180deg. To test the claw we used elderly assist bathroom hand-rail. We cut off one side of the croc to insert motor shaft and then we used few small screws to attach the servo motor to the crocs. This provided a pretty stable arrangement for further testing. 

  • We used a 9V battery pack for power. 
  • After testing, we figured the claw should be moved forward in order to be able to grip the foot rail. We changed program in Scratch to operate the claw when a button(toe-switch) is pressed. 
  • We thought of adding LEDs to this shoe to give it a cool factor.We used light sensor (Light Detecting Resistor) from HummingBird kit. We made Scratch program to turn on lights when LDR <= 10, else turn off.  We used Arduino Ultrasonic sensor to trigger claw automatically. 
  • We tested Ultrasonic sensor, unlike EV3 sensor which gives directly the distance in cm, Ultrasonic sensor gives a number between 3-50. We compared those numbers with actual distance in cm and found when number is < 4, it means Ultrasonic sensor is closer to foot rail. 
  • For turning LEDs on/off, we made program to automatically adjust light intensity when LDR records value less than 30 using formula: LED intensity = (30 - LDR) * 5
Can this be a product?
We have a Provisional Utility Patent  Application Number 62/822180 filled at USPTO for SPACE SHOES footwear design for zero gravity environment as a micro-entity.



  • Our mentor from NASA Mr. Glenn Johnson gave us a feedback that this design is feasible, he said the design meets the criteria of support of astronauts feet in space and is a good enhancement over current solution. Also he liked the strap at bottom and back of the crocs but the croc plastic is considered flammable in space. We looked at several alternative material, especially leather and coating of Nomax. 
  • Mr. Glenn Johnson suggested the possibility of using such arrangement even on outside of spaceship or for safety during space walk. He also mentioned about adding a button somewhere within the shoe like on the toe to allow closing or opening the claw.
  • We would like to keep working on this solution further and also create a miniaturize Arduino board with wires and batteries. Then, we would like to embed that inside the shoe so it won't be visible at all. 
  • We would like to work on an idea that the claw will be retractable so it won't be a problem when moving around normally in the spaceship and it will come out when astronauts wants to grip on foot rail. 
  • We are researching on different materials for the breathable bottom which will ease the calluses falling and will trap the dead skin without littering the space ship.