Projected Near-Earth Object Discovery Performance of the Large Synoptic Survey Telescope

This report describes the methodology and results of an assessment study of the performance of the Large Synoptic Survey Telescope (LSST) in its planned efforts to detect and catalog near-Earth objects (NEOs). The baseline LSST survey approach is designed to make only two visits to a given field in a given night, leading to two possible NEO detections per night. These nightly pairs must be linked across nights to derive orbits of moving objects. However, the presence of false detections in the data stream leads to the possibility of high rates of false tracklets, and the ensuing risk that the resulting orbit catalog may be contaminated by false orbits. To understand the challenges stemming from a two-visit-per-night cadence, we conducted high-fidelity linkage tests on a full-density simulated LSST detection stream. We also sought to quantify the overall performance of LSST as an NEO discovery system under the hypothesis that detections from the baseline cadence can be successfully linked. Our simulations revealed that in 10 years LSST would catalog ~60% of NEOs with absolute magnitude H<22, which is a proxy for 140m and larger objects. This results neglects linking losses and the contribution of any other NEO surveys. Including our worst-case linking efficiency we reach a overall performance assessment of 55% completeness of NEOs with H<22. We estimate that survey mis-modeling could account for systematic errors of up to 5%. We find that restricting the evaluation metric to so-called Potentially Hazardous Asteroids (PHAs) increases the completeness by 3-4%, and that including the benefits of past and expected future NEO survey activity increases completeness at the end of the baseline LSST survey by 15-20%. Assembling these results leads to a projection that by the end of the baseline LSST survey the NEO catalog will be 80+/-5% complete for PHAs with H < 22.