232 research outputs found
Modeling and Optimization of Aero-Ballistic Capture
No full textIn this paper a novel paradigm for Mars missions is modeled and optimized. This concept consists in a maneuver that combines aerocapture and ballistic capture upon Mars arrival, and is labelled aero-ballistic capture. The idea is reducing the final mass by exploiting the interaction with the planet atmosphere as well as the Sun-Mars gravitational field. The problem is stated by using optimal control theory, and optimal solutions are sought. An assessment of aero-ballistic capture shows the superiority compared to classical maneuvers when medium-to-high final orbits around Mars are wanted
Deep neural networks of Optimal Low-Thrust Orbit Raising
No full textGeostationary Earth orbit (GEO) satellites are of great significance in the space market. Low-thrust propulsion has been highly developed in the last decades because it is fuel saving. Therefore, the design of GEO satellites is rapidly changing from classic high-thrust propulsion more and more toward low-thrust propulsion. However, the transfer time will be quite long using low-thrust propulsion and it will be very expensive if the ground supports the whole orbit raising. Therefore, autonomous orbit raising is necessary. Deep neural networks are trained to learn the optimal control. Results show that DNNs can be applied in this long-duration optimal control problem and have excellent performance
Trajectory Design for LUMIO Cubesat in the Cislunar Space
No full textThe Lunar Meteoroid Impacts Observer, or LUMIO, is a CubeSat mission concept awarded ex-aequo winner of ESA’s SysNova Competition “Lunar Cu-beSats for Exploration” that shall observe, quantify, and characterize the meteoroid impacts by detecting their flashes on the lunar farside. After a study at the ESA/ESTEC concurrent design facility, LUMIO is now under consideration for future implementation by the Agency. In this paper, we propose the implementation of a sophisticated orbit design, concept of operations, and station-keeping strategy: LUMIO is placed on a quasi-halo orbit about Earth–Moon L2. The baseline solution is presented with evidence to support the orbit design
Dedicated Mission to the Sun-Earth Saddle Point: a Feasibility Assessment
No full textGravitational Saddle Points are points in space where the net gravitational acceleration of solar system bodies cancels. Certain gravitational theories, motivated by the still unresolved Dark Matter problem, predict potentially verifiable deviations from General Relativity around these points. A dedicated mission to one of these points may be an attractive proposition, if feasible. In this paper, a scientific test case is built to set the requirements for that mission, then periodic orbits through the Sun-Earth Saddle Point, necessary to collect relevant data, are sought. The periodic orbits survey is made using a systematic approach, firstly addressing it in the circular restricted three-body problem with the Sun and the Earth as main bodies: first attempt trajectories are sought through a grid search and then refined using a simple shooting, differential correction scheme. Stability is evaluated and a classification is made. Restricted four body problem adding the Moon is used as middle complexity model in order to find quasi-periodic orbits. These are refined in a full ephemeris high-fidelity n-body model. Results show different solutions with diverse characteristics and properties
Model Predictive Static Programming for Bang-off-Bang Low-Thrust Neighboring Control Law Design
No full textMars orbit insertion via ballistic capture and aerobraking
No full textA novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is presented. Mars ballistic capture orbits that neglect the aerodynamics are first generated, and are distilled from properly computed stable and unstable sets by using a pre-established method. A small periapsis maneuver is implemented at the first close encounter to better submit a post-capture orbit to the aerobraking process. An adhoc patching point marks the transition from ballistic capture to aerobraking, from which an exponential model simulating the Martian atmosphere and a box-wing satellite configuration are considered. A series of apoapsis trim maneuvers are then computed by targeting a prescribed pericenter dynamic pressure. The aerobraking duration is then estimated using a simplified two-body model. Yaw angle tuning cancels the inclination deflections owing to out-of-plane perturbation from the Sun. A philosophy combining in-plane and out-of-plane dynamics is proposed to simultaneously achieve the required semi-major axis and inclination. Numerical simulations indicate that the developed method is more efficient in terms of the fuel consumption, insertion safety, and flexibility when compared with other state-of-the-art insertion strategies
An optimal h6 scheme for solving TPBVP in astrodynamics
No full textThe present paper presents an accurate scheme for the solution of boundary value problems with two-point nonlinear boundary conditions. The proposed scheme is a linear multi-point method of sixth-order accuracy successfully used in uid dynamics and here implemented for the rst time in astrodynamics applications. It is an optimal scheme since a discretization molecule made up of just four grid points assures an h6 order of accuracy. This kind of discretization allows to attain an accuracy beyond the rst Dahlquist's stability barrier and simultaneously has a simple formulation and numerical e ciency. Astrodynamics applications concern the computation of libration point halo orbits, in the restricted three- and four-body models, and the design of an optimal control strategy for a low thrust libration point mission
Orbit Determination for X-Ray Pulsar Navigation with the Aid of Artificial Neural Networks
No full textA flow-informed strategy for ballistic capture orbit generation
No full textBallistic capture is a phenomenon by which a spacecraft approaches its target body, and performs a number of revolutions around it, without requiring manoeuvres in between. Capture orbits are characterized by specific dynamics, defining regions that guide transport phenomena. Because of the limitations associated with existing approaches, the development of heuristics informed by Lagrangian Coherent Structures appears desirable. In fact, such structures identify transport barriers in dynamical systems, separating regions with qualitatively different dynamics. In this work, different flow-informed approaches are presented, and their relations with ballistic capture are discussed. A new heuristic, the time-varying strainline, is introduced. This new tool is applied to compute ballistic capture orbits around Mars. Different degrees of model fidelity have been investigated, mainly in order to test the robustness of the proposed technique with respect to different features of the underlying dynamical model. We show that time-varying strainlines are useful in identifying ballistic capture orbits
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