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This paper presents a proof of concept for the application of artificial intelligence (AI) to the problem of efficient, catalogue-wide conjunction screening. Framed as a machine learning classification task, an ensemble of tabular models were trained and deployed on a realistic all vs. all dataset, generated using the CNES BAS3E space surveillance simulation framework, and consisting of 170 million object pairs over a 7-day screening period. The approach was found to outperform classical filters such as the apogee-perigee filter and the Minimum Orbital Intersection Distance (MOID) in terms of screening capability, with the number of missed detections of the approach controlled by the operator. It was also found to be computationally efficient, thus demonstrating the capability of AI algorithms to cope and aid with the scales required for current and future operational all vs. all scenarios.

A branch-and-bound-based algorithm for preliminary design of space debris removal missions has been devised. The proposed algorithm comprises two different levels. Upper level, modelled as an Integer Programming problem, selects a subset of a large pool of candidate objects to be removed so that removed threat value is maximised. Lower level, modelled as a Mixed Integer Nonlinear Programming problem, defines the trajectory that allows to rendezvous with them in an optimal order while a limit mission duration and a v budget are imposed as constraints. Performance of this algorithm is demonstrated for a pool of 1000 objects.

Regularized formulations provide a highly accurate description of the orbit as a geometric element, while the dynamical instabilities concentrate in the integration of the physical time. However, in highly perturbed problems, the geometric variables may also exhibit an important accumulation of propagation errors, where different formulations display distinctive error build-up patterns. To understand the error growth in each of the variables, in this paper interval arithmetic is used to perform a sensitivity analysis of the propagation error for various orbital formulations. The study considers a variety of orbital scenarios and conclusions are drawn based on the performed numerical tests.

Twelve years ago the Catalina Sky Survey discovered Earth's first known natural geocentric object other than the Moon, a few-meter diameter asteroid designated 2006 RH120. Despite significant improvements in ground-based telescope and detector technology in the past decade the asteroid surveys have not discovered another temporarily-captured orbiter (TCO; colloquially known as minimoons) but the all-sky fireball system operated in the Czech Republic as part of the European Fireball Network detected a bright natural meteor that was almost certainly in a geocentric orbit before it struck Earth's atmosphere. Within a few years the Large Synoptic Survey Telescope (LSST) will either begin to regularly detect TCOs or force a re-analysis of the creation and dynamical evolution of small asteroids in the inner solar system. The first studies of the provenance, properties, and dynamics of Earth's minimoons suggested that there should be a steady state population with about one 1- to 2-m diameter captured objects at any time, with the number of captured meteoroids increasing exponentially for smaller sizes. That model was then improved and extended to include the population of temporarily-captured flybys (TCFs), objects that fail to make an entire revolution around Earth while energetically bound to the Earth-Moon system. Several different techniques for discovering TCOs have been considered but their small diameters, proximity, and rapid motion make them challenging targets for existing ground-based optical, meteor, and radar surveys. However, the LSST's tremendous light gathering power and short exposure times could allow it to detect and discover many minimoons. We expect that if the TCO population is confirmed, and new objects are frequently discovered, they can provide new opportunities for (1) studying the dynamics of the Earth-Moon system, (2) testing models of the production and dynamical evolution of small asteroids from the asteroid belt, (3) rapid and frequent low delta-v missions to multiple minimoons, and (4) evaluating in-situ resource utilization techniques on asteroidal material. Here we review the past decade of minimoon studies in preparation for capitalizing on the scientific and commercial opportunities of TCOs in the first decade of LSST operations.

The characterization of the performance of numerical orbit propagation methods is addressed using performance curves. A systematized algorithmic approach is presented to compute the performance curves, identify the linear and non-linear regimes, and parameterize the linear zone. Also, the performance index concept is introduced, which aims to reduce the meaningful information of a performance curve (ultimately, the performance of the propagation method) into a single figure of merit. Several such performance indices are proposed.

The tight relationship between the stop-condition of a numerical integrator and the resulting accuracy of regularized orbit propagators is addressed. It is noted that the use of events as a means to halt the numerical orbit propagation introduces timing or phasing errors in formulations involving a Sundman transformation. The fundamentals of this timing error are described, along with the mechanisms that produce this apparent loss in the achievable accuracy. This behavior is linked to the dynamical instabilities of the orbital motion. Examples are provided to support that the purely geometrical description provided by regularized methods is typically orders of magnitude more accurate than when the timing error is taken into account.

A collection of test cases is proposed for the validation and testing of numerical orbit propagators. These test problems are designed to characterize the performance of the propagators and intended to highlight their possible deficiencies and expose their limitations. Every problem in the collection is accompanied by an accurate solution, and the performance of several orbit propagators is shown as examples to these problems.

There is evidence of past Near-Earth-Objects (NEOs) impacts on Earth and several studies indicating that even relatively small objects are capable of causing large local damage, either directly or in combination with other phenomena, e.g. tsunamis. This paper describes a space mission concept to demonstrate some of the key technologies to rendezvous with an asteroid and accurately measure its trajectory during and after a deflection maneuver. The mission, called SIROCO, makes use of the recently proposed ion beam shepherd (IBS) concept where a stream of accelerated plasma ions is directed against the surface of a small NEO resulting in a net transmitted deflection force. We show that by carefully selecting the target NEO a measurable deflection can be obtained in a few weeks of continuous thrust with a small spacecraft and state of the art electric propulsion hardware.

To calculate the force associated with the Yarkovsky effect the temperature distribution on the surface of the asteroid should be determined; it depends on the asteroid orbit, size and shape, spin axis orientation and period, mass, density of surface layers, albedo, thermal conductivity, capacity and IR emissivity of the material. The uncertainty of many of these parameters invites to develop simplified methods to calculate the influence of the Yarkovsky effect on long term dynamics of asteroids. In this paper we present one of this method based in a special perturbation procedure developed in our group.

The ion beam shepherd (IBS) is a recently proposed concept for modifying the orbit and/or attitude of a generic orbiting body in a contactless manner, which makes it a candidate technology for active space debris removal. In this paper we deal with the problem of controlling the relative position of a shepherd satellite coorbiting at small separation distance with a target debris. After deriving the orbit relative motion equations including the effect of the ion beam perturbation we study the system stability and propose different control strategies.

We present the concept of topological stability in the numerical propagation of orbits, and show how it results in a useful new method for measuring the global numerical error of an orbit propagation. The concept applies to any problem in orbital dynamics. Moreover, it can be extended to any three-dimensional system of differential equations of second order. In order to assess the topological stability of a given integration a special metric is introduced, which can be used to estimate the numerical errors robustly. The method is particularly well suited for dealing with strongly perturbed and chaotic systems. The construction is based on the constraint imposed by the Hopf map that supports the Kustaanheimo-Stiefel transformation. Generic concepts of stability are translated to KS space.