Application of Intelligent Spacecraft Structures for Impact Detection

Operating spacecraft in Earth orbit is an increasingly important element in nearly all business segments of the U.S. and most world economies. It is essential for national defense, communications, and remote monitoring of the Earth and the Universe around us. As our dependency on these assets exponentially grows, many Earth orbits are becoming more populated. Commercial and government entities are deploying proliferated ‘mega-constellations” of hundreds or even thousands of spacecraft. The number of spacecraft, especially in low Earth orbit, has resulted in increased risks from these vehicle's orbital debris or collisions. The unknown, and potentially significant risks posed by space debris are a major concern to both commercial and government spacecraft operators. While agencies track these spacecraft and the larger pieces of debris on a regular basis, it is limited by both the size of the debris and the quantity of objects. Objects <5cm are difficult, if not impossible, to track from Earth. The small size and large volume of such debris requires statistical risk characterization with respect to orbit, rather than tracking the individual objects. Accurate modeling requires accurate in-situ data sampling. The distribution of space debris is anticipated to increase exponentially over time, thereby requiring persistent surveillance to understand and update the magnitude of the danger. Technologies that provide in-situ characterization of the Micrometeoroid and Orbital Debris (MMOD) environment are not currently available. Southwest Research Institute® (SwRI®) is developing technology to detect, localize, and characterize MMOD impacts on spacecraft. The technology employs an array of sensitive sensors mounted to spacecraft structures. On-board processing use signals from these sensors to detect and characterize the impacts. The resulting data supports estimating the size and frequency distribution of impacts in the spacecraft's orbit, monitoring changes in this distribution over time, and even enable a rapid mitigation response to protect the vehicle or alert other vehicles within the constellation. Reliably detect and charactering spacecraft impacts allows the rejection of a vast majority of nominal spacecraft structural “noise,” in order to reduce the computational burden and data demands. The onboard processor derives information about the size of a detected impactor by analyzing the magnitude and spectral content of impact data. It also monitors differences in the arrival time of signals at the spatially distributed sensors, which provide the location of the impact and its velocity. This paper describes SwRI's ongoing efforts to develop the MMOD detection and characterization capability. It addresses the electronics design for sampling and processing sensor signals; developing processing algorithms to detect, localize, and characterize impacts; design considerations for distribution of the sensor network; testing and simulations to develop training data; and system level design considerations for applying this technology.