Dr Alexander Wittig

• Astrodynamics and Orbital Mechanics
• Mission Design and Analysis
• Numerical Methods including Differential Algebra and High Order Automatic Differentiation
• Dynamical Systems
• High Performance Computing

Alexander's research interests focus on the study of complex, non-linear dynamical systems in various interdisciplinary fields such as astronautics, engineering, and physics.

He does so through the application of modern numerical methods, such as high-order differential algebra techniques and HPC, together with mathematical concepts from modern dynamical systems theory.

He has successfully applied these methods to problems in the fields of Applied Mission Design and Analysis, Solar System Dynamics, Gravitational Physics, and even Computer Science. 

Selected current and past research projects in various research areas include:

Numerical and Dynamical Systems Methods in Astronautics

• Understanding the dynamical structure of phase space in astrodynamics problems to automatically identify qualitatively different orbits for novel mission design. Efficient and accurate computation of Lagrangian Coherent Structures using Differential Algebra methods. Application to planetary Ballistic Capture orbits.
• Improving Differential Algebra based Orbital Propagators for application to space debris clouds (supported by the Royal Society).
• Asteroid retrieval missions using manifold dynamics in three body problem. HPC on Soton’s IRIDIS cluster with numerical optimization using the MIDACO multi-objective global optimizer.

Applied Mission Design and Analysis

• Cube-de-ALPS project on development of an all-printed electric propulsion system to deorbit cubesats. Applied mission design and analysis for coupled orbital and attitude motion of under-actuated systems with high degrees of control uncertainty and limited state knowledge (supported by ESA).
• XR Orbital Visualization Toolkit development for visualization of orbital data using Microsoft HoloLens technology (supported by UK Space Agency).
• On-board high order state estimation for relative satellite attitude using high-order DA Kalman filter. Implementation on a breadboard model (Beaglebone Black) to demonstrate feasibility of real-time performance on restricted computing platforms.
• Guaranteed robust low-thrust trajectory design and on-board closed-loop autonomous control under large state uncertainties using Lyapunov guidance laws.

Astronomy

• Planetary system formation simulation via direct n-body gravitational dynamics modelling and propagation for very long term integrations (109 orbits) at machine precision. Development of Terrestial Exoplanet Simulator (TES) solar system simulator, integration into several standard software packages in the field such as REBOUND (Prof Hanno Rein, University of Toronto) and AMUSE (Prof Simon Portegies Zwart, Leiden Observatory).

Gravitational Physics

• Black hole raytracing around black holes / wormholes using GPUs to predict what looking at a black hole would look like. Development of the ESA ACT Black Hole Simulator for public outreach.
• Study of underlying dynamical system to describe black hole shadows as the shadow of the invariant manifolds.

Computer Science

• Implementation and maintenance of a modern Differential Algebra library (DA Core Engine, DACE), available as open source on GitHub.
• Reliable computing hardware through fuzzing applied to European space rated LEON-3 CPUs to identify un-documented behaviour in the CPU instruction set.