Astronomy

Little is known about the physical properties of the smallest NEOs with diameters of less than 10 meters. Due to their small sizes, they are usually very faint and hard to observe. Hence, only a small number of asteroids in this size regime are known and for only very few of those physical properties like diameter and albedo have been measured. However, small NEOs are much more frequent than larger NEOs, making some of these objects easily accessible spacecraft targets and potential impactors. Traditionally, people believed that these small NEOs have formed through collisions and that they are individual slabs of rock, i.e,. monolithic bodies. ...

Part of the NEO population is considered to consist of so-called dead comets. Dead comets are comets that have spent a long time as NEOs and have been depleted their volatile inventories in numerous, close encounters with the Sun, i.e., they are extinct comets. They can be identified through their distinctive comet-like orbits and their low, comet-like albedos. The dead comet archetype is NEO (3552) Don Quixote. We observed Don Quixote as part of the ExploreNEOs program, in which ~600 NEOs were observed to derive the diameters and albedos of these objects. Our observations at 3.6 and 4.5 µm were saturated because the target was brighter than expect, revealing something rather unexpected. ...

Plutinos are a subpopulation of the Trans-Neptunian Objects (TNOs), which are pristine and icy objects on the outskirts of the Solar System. The orbits of Plutinos - which are named after their prototype, Pluto - are in 2:3 resonance with Neptune, meaning that by the time a Plutino performs 2 full orbits around the Sun, Neptune performs 3. This “mean motion resonance” provides a high degree of stability to the orbits of Plutinos. Hence, Plutinos are dynamically and physically pristine objects. ...