In a recent letter, arXiv:1509.00021, it was shown that the lensing of light around rotating boson stars and Kerr black holes with scalar hair can exhibit chaotic patterns. Since no separation variables is known (or expected) for geodesic motion on these backgrounds, we examine 2D effective potentials photon trajectories, to obtain deeper understanding this phenomenon. We find emergence stable rings background spacetimes, allows formation "pockets" in one potentials, open sets impact...

Utilizing concepts from dynamical systems theory, we demonstrate how the existence of light rings, or fixed points, in a spacetime will give rise to families periodic orbits and invariant manifolds phase space. It is shown that these structures define shape black hole shadow as well number salient features lensing. We illustrate this through analysis lensing by hairy hole.

We present the operation of CubeSat De-orbiting All-Printed Propulsion System (Cube-de-ALPS), a thin-film Vacuum Arc Thruster being developed at University Southampton in collaboration with European Space Agency to provide robust de-orbiting capability sub-3U CubeSats. It comprises flexible substrate on which coplanar arrays vacuum arc micro-thrusters (micro-VAT) are printed alongside small supporting electronic subsystems. In particular, we focus application Cube-de-ALPS End-Of-Life...

We study the local shadow of Schwarzschild black hole with a quadrupole distortion and influence external gravitational field on photon dynamics. The matter sources modify light ring structure lead to appearance multiple images. In case negative moments we identify most prominent mechanism causing formation. Furthermore, obtain condition under which this can be realized. This depends moment, but also position observer celestial sphere.

Differential Algebra (DA) techniques have become increasingly popular in various aerospace engineering applications over the past 5-10 years. They allow computing polynomial expansions of functions representing a dynamical system terms initial conditions or parameters. The calculation these polynomials is computationally expensive, but can often replace many iterations pointwise computation provide valuable higher order information otherwise not readily available. DA will reducing...

Abstract This paper presents a novel method to obtain the solution initial orbit determination problem for optical observations as continuum of orbits—namely set—that fits set acquired within prescribed accuracy. Differential algebra is exploited analytically link uncertainty in state orbiting body with truncated power series, thus allowing compact analytical description set. The automatic domain splitting tool controls truncation error polynomial approximation by patching different...

Abstract The increasing demand for CubeSat missions with limited budgets and constrained timelines necessitates the development of innovative propulsion systems. This paper focuses on vacuum arc thrusters (VATs) investigates implementation battery-driven discharge triggerless firing. VATs offer a promising alternative propulsion, generating thrust through pulsed ejection plasma in cathode discharge. study explores feasibility direct demonstrates stable variable-duration pulses. Experimental...

In this paper we study space debris removal from a game-theoretic perspective. particular focus on the question whether and how self-interested agents can cooperate in dilemma, which resembles tragedy of commons scenario. We compare centralised decentralised solutions corresponding price anarchy, measures extent to competition approximates cooperation. addition investigate learn optimal strategies by reinforcement learning. To end, improve an existing high fidelity orbital simulator, use...

Active debris removal (ADR) missions have gained increasing importance in the space community due to necessity of reducing number jeopardizing operative satellites. In this context, autonomous guidance, navigation and control (GNC) plays a fundamental role problem rendezvous with an uncooperative target. Especially, estimation relative pose prediction target attitude are crucial for safe proximity operations. Therefore, key point success ADR is development efficient algorithms capable...

A differential algebra based importance sampling method for uncertainty propagation and impact probability computation on the first resonant returns of Near Earth Objects is presented in this paper. Starting from results an orbit determination process, we use a automatic domain pruning to estimate resonances automatically propagate time regions initial set that include return interest. The result list polynomial state vectors, each mapping specific observation epoch return. Then, employ...

A massively parallel method for the identification of optimal sequences targets in multiple-rendezvous low-thrust missions is presented. Given a list possible targets, global search compatible with mission requirements performed. To estimate feasibility each transfer, heuristic model based on Lambert's transfers evaluated target, making use commonly available general-purpose graphics processing units such as Nvidia Tesla cards. The resulting are ranked by user-specified criteria length or...

In dynamical systems, it is advantageous to identify regions of flow which can exhibit maximal influence on nearby behaviour. Hyperbolic Lagrangian Coherent Structures have been introduced obtain two-dimensional surfaces maximise repulsion or attraction in three-dimensional systems with arbitrary time-dependence. However, the numerical method compute them requires obtaining derivatives associated system, often performed through approximation divided differences, lead significant error and...