LArID: Initial testing of a large area low resource integrated impact detector

The measurement of space debris in orbit has been a subject of study since the beginning of the space age. The high speeds in orbit give even small debris enough energy to pose a risk to spacecraft. The smaller end of the space debris population can only be assessed with either returned objects or in-situ measurements. Ground-based detection systems are currently unable to observe sizes below a few millimeters. In-situ systems offer the potential to give a fuller picture of the space debris environment and help improve particle models. The previous in-situ detectors, however, have seen challenges with system noise clouding the measurements and reducing the observable range of impactors. This paper describes the Large Area low Resource integrated Impact Detector, LArID, being developed at Fraunhofer EMI and the testing performed to characterize the limits of the sensors and establish the accuracy that the detector can measure. The LArID detector combines different physical measurements to assess the properties of impact events starting at 0.1 mm in size. Acoustic waves of the impact through a thin foil are triangulated, providing a location and time of impact. This is then followed by an impact on a second foil that has thousands of 100 µm wide copper traces running through it in an orthogonal pattern; giving a second location, the size of the impactor, and the time of impact. The flash of the impact is also measured, giving a second independent physical measurement of both times of impact. Combining these measurements of size and velocity with the spacecraft's orbital location and attitude will allow for a much more detailed picture of the space debris environment. The hypervelocity impact test series described here focuses on the smaller debris sizes covering impactors under 1 mm in diameter. With this information, the limits for the detector's measurement capabilities can be established. This will allow the detector to increase confidence in the results taking advantage of the multi-physics nature of the impact measurements.