There are a few 'pesky' rules to follow, and to succeed is decidedly non-trivial, but could be interesting for some people.
Note that the ESA is the European Space Agency - NASA is not not the only Western organization associated with Space Exploration.
Mission Analysis and Design
This yearly competition aims at advancing the automation of the trajectory design process. The competition has been taken up by the community after its first edition organized by the Advanced Concepts Team.
To organise the first international competition to find the global optimal of an interplanetary trajectory was a risky idea. We saw it, a bit romantically perhaps, as a sort of "sailing challenge", with our galaxy as the racing waters and mathematical tools as the competing boats. In keeping with this idea, we hoped each successive winner would become the host (and referee) for the next event. The competition was opened to the widest international community including industry, academia and research groups. Still it was far from certain that any of these specialists and researchers would be willing to devote their (usually scarce) free time to such a contest. As it turned out, luck was indeed on the side of those who dare, and not only seventeen different groups participated to the first contest, but the winner also accepted to carry on and organise the next event, thereby fully supporting the original vision.