Space Apps Challenge 2018

We're trying to find a solution for detecting damage caused by Micro-Meteoroids and Orbital Debris. So ours is to create an autonomous free-flyer to inspect the spacecraft from outside.

I present you "Puffer", inspired by the fish with the same name. It's a sphere-like drone that orbits around the spacecraft using micro-thrusters and makes use of multiple sensors to detect the damage.

Detection system

We decided to install four different sensors on Puffer:

• a LiDAR system that measures the distance to a target and creates a 3D image by illuminating it with a pulse laser.
• a plenoptics camera, for visual images with depth
• a thermal camera, for detecting leaks and breaches into the pressurized habitat zone
• an infrared sensor (similar to the face detection camera on the iPhone, or the Kinect). This is used for close range 3D mapping.

Navigation system

We designed Puffer to be autonomous, which means it will be deployed automatically when needed, scan the required surfaces for damage and then return to the base station.

Inside Puffer there is a rechargeable battery that powers all the sensors and the propulsion system. Once the battery level reaches 15%, Puffer will automatically return to its docking station for wireless charging.

The way Puffer scans the spacecraft for damage was inspired from nature by the way an eagle tracks its target. First it scans the ground surface from a distance and then gets closer to the location and dives in on its pray when it sees it moving.

The same way, Puffer scans are made in two separate passes, orbiting around the spacecraft:

• The first pass is from a distance of approximately 20 meters which uses the laser radar to map a 3D image of the spacecraft and then compares it with the internal 3D image stored inside Puffer. This will detect bigger damages and holes that are larger than a few centimeters by comparing the 3D image stored inside Puffer with the LiDAR scan.
• The second pass is from up close, at a distance of around one meter, which uses the infrared proximity sensor to look for really small damages that the LiDAR cannot see. This pass uses either the infrared proximity sensor or the plenoptics camera, depending on the amount of light or shadow in the image.

When a damage is detected, Puffer will use local communication to send an alert message to the spacecraft along with the 3D, thermal and optical images that it took.

Propulsion system

We designed the propulsion system to use water as an inexpensive propellant and to be adapted for zero gravity environments. The water is electrolyzed and stored as oxygen and hydrogen which are then used for combustion by the six micro-thrusters.

Puffer needs to have its sensors always facing the spacecraft for the scan to be successful. This is accomplished with the help of an internal gyroscope, which also rotates Puffer along its own axis for taking pictures and moving around the spacecraft.

We hope Puffer will help astronauts avoid unnecessary EVAs which may become dangerous because of the space debris.

Our hopes are that Puffer will also help with damage assessment before atmosphere reentries of Earth bound capsules.

This is our vision of Puffer and maybe some day it will become reality!