SME - Space Missions Engineering

ONGOING ACTIVITIES

Non-Keplerian orbits. The research that has been conducted at SME Lab is aimed to analyze and explore the dynamics of both natural and artificial non-Keplerian orbits. In the former subclass, effort has been put to study the dynamics of the ballistic capture. A systematic method to derive ballistic capture orbits about a given body has been formulated. In the field of artificial non-Keplerian orbits, a design method based on the concept of attainable sets has been formulated. With this approach it is possible to merge low-thrust orbits and invariant manifolds of the restricted three-body problem. The concept relies on a simple definition of attainable orbit, and can be generalized to any n-body model.
Optimal control and space trajectory optimization. At SME Lab, research on both optimal control and space trajectory design is being conducted. In optimal control, iterative methods based on successive approximations have been implemented for control-affine dynamics. In the field of space trajectory design, numerical methods for solving both the direct and indirect problems have been developed. These involve the application of a number numerical integration schemes coupled with different nonlinear programming solvers in both the two- and n-body problems.
High-order methods for guidance, control, and uncertainty management. People at SME Lab have good records in the field of high order methods applied to astrodynamics. In particular, algorithms for the robust solution of two-point boundary value problems have been developed, as well as techniques for the high order sensitivity analysis and uncertainty mapping. Moreover, methods for deriving high-order optimal control about a reference solution have also been developed.
Dynamics of space debris and NEOs. In this field the main achievements involve the development of a high-order nonlinear method for the accurate orbit determination; the development of a DA-based method for the accurate estimation of the Minimum Orbit Intersection Distance (MOID); the validate integration of Solar System Dynamics; the implementation of highly accurate dynamic models; the development of high-order nonlinear filtering techniques.
Methodologies to support the system design: attention focused on multi-objective global optimizers comparison and selection; on multi-disciplines models tuning, selection and MDO results validation for the complex scenario of launchers and manned re-entry vehicles sizing. Testing of distributed architectures for multidisciplinary multicriteria design of human bases infrastructures such as greenhouses sizing.
Advanced technologies: attention focused on the uncooperative orbiting proximity maneuvering and interaction tailoring, with a strong effort in developing the numerical simulators to: deal with nets dynamics during deployment and impact and to deal with tethers and flexible systems, dynamics and control synthesis; deal with the momentum and angular momentum exchange under no-contact scenarios, between plume particles and impinging surface. A breadboard to run experiments on net deployment has been implemented and test campaign has been performed.
Algorithms for hazard maps generation during landing have been implemented and tested on artificial images, and input, still in open loop, to the landing adaptive guidance profile generator, implemented in the last year.
Progresses towards the experimental testing of wireless sensors during environmental tests have been achieved. The testing campaign is almost ready to be run.
Intelligent operations: harmonization of the already implemented tools for failure detection and identification has been performed, to prepare future activities related to critically compare different theoretical approach to the problem. Multi-agents techniques started to be applied to the complex scenario of the data management at ground stations to test their benefit in enhancing the data exploitation and the ground timely reaction to unpredictable events.
Concerning robotic devices, the most recent studies on the SD2 drill have proven the existence of a correlation between the drill behavior during perforation and the mechanical characteristics of the cometary soil. This outlines the possibility of using SD2 not only as a tool to support other instruments, but also as a scientific instrument itself. The possibility of using the drill as a quasi-static penetrator has been studied. Within this approach, laboratory tests on glass-foam specimens of different porosity show that penetration failures can be exploited for cometary soil characterization.

FUTURE PLANS

Non-Keplerian orbits. The future research in the field of non-Kepelrian orbits will be mainly focused on: a) the analysis of ballistic capture orbits in the real n-body problem; b) the refinement of the attainable set concept and its potential applications; c) the development of numerical methods to approximate the invariant manifolds; d) the implementation of n-body models and their analysis; e) the development of algorithm to optimize low-energy, low-thrust orbits.
Optimal control and space trajectory optimization. In this field the future research will deal with: a) the analysis and improvement of the approximate methods for solving nonlinear optimal control and their possible application to other context; b) the development of trajectory optimization schemes for treating the low-thrust orbits in n-body models; c) the search for shape-based solutions in n-body models; d) the refinement of the existing methods for solving the indirect problems.
High-order methods for guidance, control, and uncertainty management. In this field the future research will deal with: a) the application of the existing methods to models not yet studied to perform uncertainty analysis; b) the derivation of high order algorithms able to include control saturation; c) the implementation of high-order methods for the fast computation of Poincarè sections in generic dynamical systems; d) the development of novel methods for the high order expansion of invariant manifolds.
Dynamics of space debris and NEOs. The planned activities in this field of the SME Lab are: a) to improve the existing high-order methods for orbit determination; b) to develop highly accurate models for dynamics of space debris and NEOs; c) to improve the current techniques for the high-order propagation of space debris and NEOs; d) to develop a system for combining observations of objects, orbit determination, and propagation.
Methodologies to support the system design: refinement of the current distributed MDO architecture to support complex mission scenarios alternative pruning.
Advanced technologies: refinement of the numerical simulator for the flexible systems GNC design. Breadboarding and testing of the critical hw\sw components in the navigation and control chain. Numerical simulator validation through experimental tests, potentially in flight.
Experiment set up, and models characterization for the angular momentum exchange with no contact between orbiting vehicles.
Improvement of the GNC tool for landing, experimental testing and navigation algorithms validation with hardware in the loop.
Intelligent operations: multi-agents architectures exploitation to increase robustness in autonomous failure identification.
Automatic acquisition of knowledge related to causal dependencies between symptoms and faults, fundamental to increase the identification process robustness.
In the domain of planetary sampling, the group will continue the activities undertaken on the SD2 system for the Rosetta mission and, considering the activity closed by the end of 2015, will start studying mechanisms suitable for the planned future exploration missions to low gravity bodies (e.g. a Mars moon or a near-Earth asteroid), where it is planned to collect more than 100 grams of regolith (dust plus cm-sized pebbles) and return them to Earth for further ground-based analysis. So far, there is no single sampling technology for low-gravity bodies that has undergone a rigorous engineering assessment, aiming at proving the ability of the sampler to collect material in any envisaged situation. This will be done by using the Discrete Element Methods (DEM), implemented to realize an affordable and reliable tool useful to investigate the sampling device dynamics in soil sampling activities in order to support the sampling tool concepts identification, trade off and selection.

ERC KEYWORDS

PE9-15 Space Sciences
PE7-10 Robotics
PE7-4 Systems engineering, sensorics, actorics, automation
PE8-1 Aerospace Engineering

FREE KEYWORDS

Orbital dynamics
Optimization and control

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