Laboratory testing of LArID: Paving the way for in-situ quantification of millimeter-sized space debris

The Earth's orbital environment is becoming increasingly crowded, with the rising probability of collisional fragmentation events aggravating the threat of Micrometeoroids and Space Debris (MMSD) impacts. While ground tracking networks allow for the observation of larger debris, their ability to measure components under 1 cm is significantly limited. Debris has a high energy density, posing a significant risk to spacecraft, and has been historically difficult to measure. Despite a long history of in-situ MMSD detectors, challenges in availability and reliability have left a gap in our knowledge of this crucial regime in the space environment.This work details the testing of the Large Area Low Resource Integrated Impact Detector (LArID). This technology has demonstrated the ability to measure MMSD velocity and size for particles between 0.2 mm and 5 mm in diameter at hypervelocity impact speeds of 6.5 km/s. LArID builds upon previous concepts by integrating multi-physical sensors, allowing for both precise and noise-robust measurements. The detector features a multi-layered design with two active layers that, when penetrated by debris, produce diverse physical effects measured by arrays of photodiodes, acoustic sensors, and a resistive grid. By leveraging different types of physical events, the detector can self-confirm impact events while utilizing the most precise measurements available.The testing campaign explored various material types, impact angles, and impactor sizes to observe their effects on measurements at the breadboard level. Two detector configurations were studied: the first featuring a thin membrane with acoustic sensors as the first layer and a resistive grid made of flexible printed circuit board material as the second; the second configuration employed two resistive grid layers. Confidence intervals for different methods of measuring distance traveled and time of flight through the detector are compared and discussed. Through rigorous testing, the advantages and disadvantages of different configurations and measurement methods were evaluated, informing recommendations for a flight model.With the conclusion of this testing phase, the LArID technology has demonstrated its ability to generate measurement data in a poorly explored area of the space debris environment. The best methods were able to estimate the velocity of the 6.5 km/s impactors to an average error of 0.1 km/s for individual measurement method and the full system had an average velocity error of 1.2 km/s. The detector was able to measure the size of the impactor with an error of 0.12 mm for impactors ranging from 0.2 mm to 5.6 mm.Further performance improvements have been identified for a Flight Model, enabling future missions to provide the scientific community with a more comprehensive understanding of debris risk in this challenging measurement regime.