9th IAA PLANETARY DEFENSE CONFERENCE 2025

The Pan-STARRS-1 telescope in Maui, Hawaii performed a multi-purpose survey of the of the sky north of -30° declination from 2010 to 2014. From 2014 onwards, the main focus of Pan-STARRS has been a survey of the sky for Near-Earth Objects (NEOs), funded by the NASA Planetary Defense Program. With the addition of the second telescope, Pan-STARRS has become one of the leading surveys for Near-Earth Objects. In 2024, Pan-STARRS achieved its highest number of NEO discoveries, and even higher discovery rates are expected in the future.

A major strength of the Pan-STARRS NEO survey has been discovery of larger NEOs. Pan-STARRS has consistently discovered more than half of all NEOs with diameter >140 meters each year. Another strength of Pan-STARRS is excellent astrometry, which assists in candidate recovery, helps produce better orbits, and can reveal curvature in tracklets that is a signature that an object is nearby. Pan-STARRS discovers more than half of its NEOs south of the celestial equator. As the Rubin Observatory begins surveying the southern sky, some complementarity with the Pan-STARRS survey is expected, with the telescopes likely providing follow up for each other’s discoveries.

The main characteristics of the Pan-STARRS survey will be summarized, and some of the recent improvements will be explained. Some of the systematics that arise from the survey will be described. Discovery highlights include the first interstellar object, `Oumuamua (also an NEO). A new detection-based discovery technique will be explained. This is expected to enable discovery of fainter NEOs, further increasing the discovery rate, and will also help in the discovery of potential impactors (such as the near-miss object 2019 OK) by helping discovery of slow moving objects that may be headed directly towards Earth. It is likely that this technique will also produce discoveries of more distant comets (that are moving very slowly) and other outer solar system objects. Follow up of fainter NEO candidates will continue to be challenging. Self-follow up is already important, and is expected to become more important.