MODELING THE PERFORMANCE OF THE LSST IN SURVEYING THE NEAR-EARTH OBJECT POPULATION

Abstract

We have performed a detailed survey simulation of the LSST performance with regards to near-Earth objects (NEOs) using the project’s current baseline cadence. The survey shows that if the project is able to reliably generate linked sets of positions and times (a so-called “tracklet”) using two detections of a given object per night and can link these tracklets into a track with a minimum of three tracklets covering more than a ∼12 day length-of-arc, then they would be able to discover 62% of the potentially hazardous asteroids (PHAs) larger than 140 m in its projected 10 year survey lifetime. This completeness would be reduced to 58% if the project is unable to implement a pipeline using the two detection cadence and has to adopt the four detection cadence more commonly used by existing NEO surveys. When including the estimated performance from the current operating surveys, assuming these would continue running until the start of LSST and perhaps beyond, the completeness fraction for PHAs larger than 140 m would be 73% for the baseline cadence and 71% for the four detection cadence. This result is a lower completeness than the estimate of Ivezić et al.; however, the result is quite close to that of Jones et al., who show ∼70% completeness using the identical survey cadence as used here. We show that the traditional method of using absolute magnitude H < 22 mag as a proxy for the population with diameters larger than 140 m results in completeness values that are too high by ∼5%. Our simulation makes use of the most recent models of the physical and orbital properties of the NEO and PHA populations, as well as simulated cadences and telescope performance estimates provided by the LSST project. The consistency of the results presented here when compared to those of Jones et al. demonstrates the robustness of these survey modeling approaches. We also show that while neither LSST nor a space-based IR platform like NEOCam individually can complete the survey for 140 m diameter NEOs, the combination of these systems can achieve that goal after a decade of observation.