Humanity is a long way from being able to colonize a single star, let alone the entire Milky Way galaxy. NASA’s Jet Propulsion Laboratory (JPL) issued an interesting challenge to scientists around the world as part of the 10th Global Trajectory Optimisation Competition (GTOC X). Teams had to devise a process to colonize the galaxy in the most efficient way possible. It might take a few million years, but the simulations show how we could do it.
The contest, by its very nature, makes a lot of assumptions. While we’ve detected thousands of exoplanets, most of them are too large, hot, or cold for human life. We lack the technology to spot most Earth-like planets, so there aren’t any worlds we know to be colonizable. Therefore, the contest used a collection of 100,000 hypothetical habitable star systems spread around the Milky Way, all of which are identified by location and trajectory (known as ephemerides) in the contest rules. JPL judged submissions based on how many stars the team settled and how much energy was expended to do it.
All teams have to adhere to the same rules. The contest begins 10,000 years into the future in what JPL calls “Year Zero.” From that point, the teams have 10 million simulated years to launch their colonization efforts from Earth. Everyone also has to use the same initial colonization fleet. They start with three motherships, each one with 10 settlement pods that can colonize star systems as the ship passes through. The mothership can also only make three course changes at a total speed of 500 kilometers per second. Earth can also launch two “fast ships” that travel three times faster but can only colonize a single star. Each settled star can launch up to three settler ships with intermediate speed and the ability to colonize one other star.
There’s no hyper-advanced warp drive technology here — these are generational ships that may take thousands of years to reach their destination. Most submissions used the fast ships to launch missions toward the edge of the galaxy and work inward with settler ships. Meanwhile, the motherships lurched toward the denser star fields near Earth to release all their pods.
The winning solution came from China’s National University of Defence Technology and the Xi’an Satellite Control Center. Second place went to China’s Tsinghua University, and the ESA’s Advanced Concepts Team (ACT) came in third. ACT has also posted a video of its solution to YouTube (see above).
JPL found that it took around 90 million years for the teams to occupy large swaths of the Milky Way. The universe is billions of years old, so why hasn’t some other species done this already? That’s what we call the Fermi Paradox, and no one knows the answer. Maybe the universe is teeming with life, but traveling between stars is fundamentally impractical. Alternatively, there may be few if any advanced civilizations in the universe. It’s even possible aliens have colonized most of the galaxy, but they’re steering clear of Earth for some unknown reason. Whatever the case, these simulations are an interesting piece of the puzzle.