Ten thousand years from now, humanity decides to settle 100,000 stars in the galaxy, and the race is on to see who can spread through our cosmic neighbourhood the fastest. That鈥檚 the premise of the 10th Global Trajectory Optimisation Competition (GTOCX) currently being run by NASA, in which teams of astrophysicists and engineers attempt to plot out a course for the human race to populate the stars.
In this imagined future, humans have access to large spacecraft that can support life long enough to travel to other stars, but still can鈥檛 travel at the near instantaneous speeds seen in science fiction. 鈥淚 guess you can imagine these vessels to be like the spaceships shown in [the Disney film] WALL-E,鈥� says Nathalie Hager, a member of a team聽from Columbia University. They are one of 73 teams from four continents competing in the challenge.
There are a few rules. The first settlers must depart from our solar system within 10 million years and they have up to 90 million years to fan out across the galaxy, with a bonus for answers submitted earliest in the month-long challenge聽to account for humanity鈥檚 supposed dwindling resources in the scenario.
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They can have up to three mother ships, which each carry up to 10 settlement pods that may be released when passing a star. Teams also have up to two fast ships that fly directly to a single star system to settle it. And up to three settler ships can depart each star, so long as 2 million years have passed since the star was settled 鈥� a limitation that mimics the need to rebuild resources, but also makes the game more manageable.
鈥淚f we let them depart immediately, it would make the problem more complex. Instead of having 30 generations of ships, you could have two or three times that number, and they only have a month to solve this,鈥� says Anastassios Petropoulos, one of the organizers of the competition at NASA鈥檚 Jet Propulsion Laboratory.
The game is聽a bit like solving the mathematics puzzle known as the travelling salesman problem, in which you must find the shortest route that visits several cities, but on a galactic scale. 鈥淗ere you have multiple salesmen and the targets are all moving,鈥� says Petropoulos.
Jacob Irwin, also on the team at Columbia University, says they started with an animated simulation of all 100,000 stars on their orbits, and then broke up into smaller teams to solve each part of the problem 鈥� the number of ships to send out, the speed at which they should travel, and the next star they鈥檇 visit.
鈥淓arly on in the competition, there was one team on the leaderboard that had about 6000 stars settled, but they didn鈥檛 score so well because their settlements were clumped. Other teams had only about 1000 stars, but they were more evenly spread out,鈥� Petropoulos says.
So why do this? First, because it鈥檚 fun, says Petropoulos. Irwin agrees, and adds that 鈥渆veryone on the team thrives on tackling difficult, if not previously unsolved problems.鈥�
But it鈥檚 also a chance to learn something, even if the scenario is far-fetched right now. 鈥淲hile I think it is possible that we reach the technological level needed for building this kind of vessel at some point, I don鈥檛 think that settling other stars is something we鈥檒l need to seriously plan in the next centuries,鈥� says Hager. 鈥淭hat being said, many technological advances have often existed in people鈥檚 imagination long before they have been implemented in reality.鈥�
