Speakers
Description
It typically takes a few days for a newly discovered near-Earth asteroid to be officially recognized as a real object and designated by the Minor Planet Center. During this time, the tentative discovery is published on the Near-Earth Object Confirmation Page until additional observations confirm that the object is in fact a real asteroid rather than an observational artifact or an artificial object. Among these candidate discoveries there can be short-term impactors, as was the case for 2008 TC3 and 2014 AA, the first two objects discovered prior to reaching the Earth. Both objects were a few meters in size and were first detected 20 hours before impact. Given the potentially short time interval between discovery and impact for small asteroids, we developed Scout, an automated system that provides an orbital and hazard assessment for newly discovered asteroids within minutes after the observations are available. Scout overcomes the orbit determination degeneracies typical of short observation arcs using systematic ranging, a technique that scans a grid in the poorly constrained space of topocentric range and range rate, while the plane-of-sky position and motion are directly tied to the recorded observations. This scan allows us to derive a distribution of the possible orbits and in turn identify the objects that have a significant chance of impact, in which case Scout also estimates the possible impact locations. The results of the analysis and ephemerides are readily publicly available on the JPL Center for Near-Earth Object Studies website to guide follow-up efforts by the observing community. Two of the main highlights since Scout started operating in late 2016 were the impacts of 2018 LA and 2022 EB5, both a few meters in size. Despite being discovered within hours of impact, Scout successfully predicted their atmospheric entry above Botswana and the Norwegian Sea, respectively.
This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration, USA (80NM0018D0004).
