The Design, Construction and Hypervelocity Impact Testing of a Prototype Orbital Debris and Interplanetary Dust Detector

The constant bombardment of millimeter and submillimeter interplanetary dust and orbital debris particles on spacecraft and other space assets leads to long term degradation of exposed surfaces and systems. In the past, post-flight surface analysis on the Space Shuttle provided regular data on these small particles in low Earth orbit. The accumulation of data provided by the characterisation of these particles is required for the development, and updating, of orbital debris environment models, which are essential to predict the conditions in space that can significantly a?ect the design, operation and cost of spacecraft.

Since the retirement of the Space Shuttle program in 2011, there has been very little new data generated. Consequently, there is now an increasing need for additional information on the characteristics of interplanetary dust and orbital debris for both commercial and research purposes. Dedicated dust detectors, rather than post-flight data collection from collision damage, have successfully demonstrated the potential for characterising particles in the past, and provide the most likely method of analysis going forward. However, current versions have a number of limitations and there is an opportunity to make significant advancements in the next generation of detectors. Designing, testing and analyzing improved detector systems was the primary focus of this research.

Interplanetary dust and orbital debris properties of specific interest include; flux, size, velocity, trajectory, kinetic energy, density and mass. Although previously flown detectors are capable of measuring a number of these parameters, no previous detector has integrated the capacity to measure all of them simultaneously. This thesis describes concepts for a detector capable of collecting, processing and transmitting back the data for all of the parameters listed above and in real time, which is a significant advancement on current state-of-the-art detectors.

Prototypes were designed incorporating selected adaptations of previous detectors, utilising the basic principle of sequential detection gates. Proof-of-concept experiments were conducted on the prototypes using the light gas gun at the University of Kent in order to replicate orbital impacts with simulated space particles in the laboratory. Algorithms written in Python were developed for the five subsystems to analyse data collected by PVDF sensors on each of the three detection gates, and to directly calcu- late the flux, velocity, trajectory, diameter and kinetic energy of particles interacting with the prototypes. In turn, these results were used to derive mass and density. The characteristics of particles calculated by the subsystems during the experiments were compared with their known properties in order to quantify the accuracy of each mea- surement. The velocity, trajectory and diameter calculations had an average confidence within 6.5%, 0.5% and 10.0%, respectively. Measurement of the kinetic energy was accurate to ?26.0 %, which is regarded as a significant step forward. Additionally, the experiments provided evidence that flux models can be accurately measured for par- ticles larger than 50?m. The prototypes designed and validated in this research can

be used as templates for future detectors capable of providing real-time data on the characteristics of interplanetary dust and orbital debris. These data will contribute directly to the design of future instrumentation and assist the development of more detailed environment models with both commercial and research applications.