Background

Space explorers need to see the outside of their spacecraft. Remember how the Apollo 13 crew was almost lost when they had no cameras to image the spacecraft’s exterior for damage? The Columbia crew was lost after an impact put a hole in its wing’s leading edge thermal protection system (TPS) – there was no way to see that damage had occurred.

For all post-Columbia missions, astronauts controlled robotic manipulator arms containing 3D sensors for hours to survey most of the Orbiter’s external TPS surfaces. As a result, the process of survey for damage detection and characterization of damages was perfected for the Space Shuttle. Today, International Space Station (ISS) remote manipulator arms are used to inspect the ISS and visiting vehicles for Micro-Meteoroid and Orbital Debris (MMOD).

The TPS for future spacecraft that will travel to and beyond the moon faces a high risk from MMOD impacts. Also, the remoteness of the journey demands a high degree of autonomy. Limited communication to Earth and limited image downlink means ground control of inspection tools is challenging. Analysis of all inspection images on Earth means more ground crews and longer timelines to reach decisions. Control from in-space crews on future spacecraft or space stations use precious crew time and robotic manipulator time as well.

Currently there are several small satellite spacecraft projects that are investigating technologies for inspection. When commanded/scheduled, the designated free-flyer surveys the area assigned, identifies and maps real damage sites, and— for those damages that are assessed to exceed the threshold or do not meet decision criteria confidence factors— performs damage characterization of individual damage sites.

Mother Nature’s elegant solutions for this problem are unexplored! What aspects of Nature could help you design an efficient and effective autonomous operations sequence for imaging and controlling a free-flyer in order to detect and characterize MMOD impact damage? Would you scan for damage like a farmer plowing a field, or like an eagle looking for prey? Results of your efforts could have broad implications for a number of spacefaring entities, including commercial industry, and could have applications on an international scale.

Potential Considerations

What components, structures, or patterns of Nature (or inspired by Nature) are your machine and/or operations sequence based on?

What types of sensors will your flyer use? Visual? Electromagnetic? Sensors based on sound?

In your designs, you may consider the following (this is not an exhaustive list):

• Dimensions of the damage: The width of the MMOD entry hole is usually small compared to the depth; angle of impact is not known
• Lighting and shadows: light sources/shadows, surface reflections, view angles, camera/sensors
• Inspection surface: Cone-shaped inspection surface geometry; distance of free-flyer from inspection surface
• Zero-g, vacuum of space, orbital mechanics/relative motion (would capsule be made to spin to support survey, or not spin to support damage site characterization?)
• Flight plan optimization for reliable results, free-flyer efficiency, and/or spacecraft efficiency (e.g., propellant/power used, inspection time, etc.)
• Autonomy and minimum crew time (In-space or on-ground? Would you use local or remote communications? On-board imaging and processing? What type of decision logic would you use to direct the free-flyer operations?)