Orbite preliminari di asteroidi e satelliti artificiali

Vengono discusse e analizzate le tecniche classiche e moderne di determinazione orbitale applicate agli asteroidi e ai satelliti artificiali

Interstellar Object Uncertainty Evolution and Effect on Fast Flyby Delivery and Required Delta-V

Interstellar objects (ISOs) are small bodies that can travel through our solar system from other star systems. When present in our solar system, they represent an opportunity to study the properties and origins of these objects, as well as the potential for cross-pollination of material between star systems. With current propulsion technology, rendezvous with these objects is likely infeasible, and thus the maximum science return results from a rapid response flyby and impactor. However, while trajectories to ISOs may be feasible, their potentially high ephemeris uncertainties and high-speed hyperbolic orbits present significant challenges to navigation. In this paper we assess these challenges by modeling the uncertainties of reachable synthetic ISOs as a function of time, as derived by measurements from ground observatories and an approaching spacecraft. From these uncertainties we derive the final delivery accuracy of fast flyby spacecraft to the ISO and required statistical delta-v for navigation. We find that these two challenges can lead to hundreds of meters-per-second or even kilometers-per-second of required statistical delta-v for navigation, reduce delivery accuracy to hundreds of kilometers, and make autonomous navigation a requirement

Population orbit determination: Algorithms and Simulations

The thesis deals with the problem of population orbit determination for uncollaborative objects, when observations are a scarce resource. In this case we not only have to find an orbit compatible with the observations, but also to solve the identification problem, i.e., finding among independent detections of celestial bodies those belonging to the same physical object. After reviewing classical methods, we describe a full sequence of algorithms allowing build-up and maintenance of a catalog of objects starting from a database of observations. The most difficult step is the linkage, when two or more separate sets of observations are used to assess whether they can belong to the same object and an orbit exists to fit the data. We present two algorithms capable of dealing with the linkage and of keeping the computational load within acceptable limits. The first algorithm is based on the admissible region, which bounds the set of possible orbits by reasonable hypotheses on the dynamics of the object. The second algorithm relies on the conservation of the integrals of motion of the Kepler problem. To test these algorithms we applied them to different classes of objects: 1) we showed that it is possible to build up a catalog of Geosynchronous debris from scratch starting from sparse real data; 2) we performed catalog build-up and maintenance for Low Earth orbit debris starting from simulated data and keeping the orbit accuracy within the collision avoidance requirements; 3) we simulated the discovery and risk assessment process for a population of small impacting Near Earth Objects; 4) we successfully attributed Pan-STARRS PS1 data to numbered and multi-apparition asteroids, and performed a statistical analysis of the postfit residuals. The performed simulations validated not only the algorithms, but also hypothetical optical networks proposed in the Space Situational Awareness framework

Detectability of the Yarkovsky Effect in the Main Belt

We attempt to a detect signal of Yarkovsky-related acceleration in the orbits of 134 main belt asteroids (MBAs) we observed with the University of Hawai'i 88 inch telescope, supplemented with observations publicly available from the Minor Planet Center and Gaia Data Release 3. We estimated expected Yarkovsky acceleration values based on parameters derived through thermophysical modeling, but we were not able to find any reliable detections of Yarkovsky in our sample. Through tests with synthetic observations however, we estimated the minimum observational arc length needed to detect the Yarkovsky effect for all of our sample MBAs, which in nearly every case exceeded the current arc length of the existing observations. We find that the Yarkovsky effect could be detectable within a couple of decades of discovery for a 100 m MBA assuming 0.1" astrometric accuracy, which is at the size range detectable by the upcoming Vera Rubin Observatory Legacy Survey of Space and Time.Comment: 28 pages, 6 figures, 6 tables, accepted by PS