Project Ideas
The GTOP database (Global trajectory optimization Problem database) was established by the Advanced Concepts Team (ACT) with the goal to provide ongoing challenges for trajectory optimization and track progress. Given an easy interface to selected mission concepts, participants were able to search and submit solutions for various trajectory challenges which were ranked according to their accumulative Delta-V. The GTOP database inspired researchers from Europe and the rest of the world to improve their algorithms for getting a place in the leaderboard, but has been discontinued as the necessary software is no longer maintained.
This project is the first step to re-establish the GTOP in a new and modern online format of high interactivity which will enable users to publish trajectory problems and solutions online, further increasing collaboration, competition and open exchange. Pykep (and the related pagmo open source project) are the key enablers for this ambition.
The goal of this project is to make pykep ready to handle the new GTOP trajectory problems, i.e. functionality that allows a reliable verification and ranking of submitted solution. In particular, new features for multi-objective optimization are needed, to rank submitted solution along multiple dimensions (Delta-V, time of flight, maximum thrust, etc.).
Constructing the set of optimal trade-offs ("Pareto-front") is of mayor importance in mission design, as it allows to select fly-by sequences or deep space maneuvers according to flexible decision criteria. However, advanced search methods are needed to conquer the massive design space of possible trajectories. Consequently, performance evaluation metrics from the field of multi-objective optimization need to be accessible. These may include but are not limited to:
Furthermore, several evolutionary multi-objective optimization algorithms suitable for trajectory optimization need to be made available via the pagmo interface, i.e.:
- SPEA-2
- IBEA
- Multi-objective PSO (MOPSO)
While the implementation of this functionality is a precondition for the establishment of the GTOP portal, pykep would already benefit from a stronger interface to pagmo to provide a multi-dimensional and more detailed perspective on trajectories.
Accuracy and reproducibility are essential and have to be ensured by extensive tests.
To conclude this project, the multi-objective enhancements will be showcased on a mission concept to be added and documented as one (or more) examples to the list of advanced research topics to the pykep documentation.