Recent observational highlights from ESA’s Planetary Defence Office

The NEO Coordination Centre (NEOCC) is one of the key components of ESA’s Planetary Defence activities. Among its goals, it has a mandate to coordinate, collect and analyse telescopic observations of NEOs. To reach this objective, we developed a wide network of observational assets. In this contribution, we discuss some of the latest results obtained thanks to this unique global network.

In the recent years, ESA has strengthened its network of follow-up telescopes. It now has direct access to the Optical Ground Station (Tenerife, Spain) and the Calar Alto Schmidt telescope (fully dedicated to NEOCC activities - Spain). Via dedicated contracts, it also has allocated time in the LCO network, as well as telescopes in Australia (Zadko), Namibia (6ROADS), Reunion and India. Scientific collaboration & agreements granted time with ESO’s VLT and Korean’s BOAO and SOAO facilities.

Regarding future observational means, ESA is currently continuing the construction of the Flyeye telescope. This is a 1-meter class telescope with an ultra-wide field of 7º by 7º that will be installed on top of Monte Mufara (Italy). The Flyeye will be a remote-controlled telescope, while data will be automatically analysed by a dedicated pipeline, with the overall objective of reducing to a minimum the human intervention.

The mentioned observational assets available to our observers are used for a variety of observations. The main goal is of course the acquisition of follow-up observations, both on short notice and at the faint end of an object's observability window. We employ our smaller but geographically-distributed telescopes to quickly react to discoveries of possible new high-priority objects, such as imminent impactors. Larger assets, such as VLT, are instead routinely scheduled to obtain astrometry of risk list objects, down to magnitude ~27. With some specific telescopes we are also focusing on twilight and low-elongation observations, which are essential to track and characterize specific classes of objects, such as Atiras or Earth Trojans.

In addition to these regular observations, we also use some of the telescopes to attempt challenging or innovative observation techniques. For example, we are experimenting with the possibility to use modest sub-meter-size telescopes to obtain detections of important objects down to magnitude ~24, by observing the same target for an entire night and then stacking hundreds of frames on the motion of the object. These capabilities are made possible by recent advancements in GPU processing, which are also opening the way to new image analysis modes, such as synthetic tracking. We are also pioneering the so called "negative recovery" technique, using targeted non-detections of risk list objects to exclude their impact solutions, even without recovering the object itself.

Finally, we are active players in international campaigns dedicated to specific NEOs or observational challenges. This includes both our participation in internationally-led efforts, such as those managed by IAWN, and the organization of our own campaigns, such as a recent one dedicated to the astrometric coverage of the Earth fly-by of BepiColombo as a proxy to test the observational capabilities of our network on very close approachers.

All those observations are supplemented by the operations of our own orbit determination and impact monitoring software system (so-called AstOD) that allows constraining with the best possible accuracy the orbits of the observed objects and the possible impact chances with the Earth in the next 100 years. In what regards the threat monitoring over imminent impactors, we count on the Meerkat tool, which bases its automated operation on the use of systematic ranging and allows detecting and warning our staff of those cases, as recently occurred with 2022 EB5.