Galactic Colonisation: General Relativistic Interstellar Trajectory Optimisation

Abstract

A vast wealth of literature exists on the topic of rocket trajectory optimisation, particularly in the area of interplanetary trajectories due to its relevance today. However, a large proportion of the research is focused on using a specific propulsion system, and is almost exclusively conducted using Newtonian mechanics. Studies on optimising interstellar and intergalactic trajectories are usually performed in flat spacetime using an analytical approach, with very little focus on optimising interstellar trajectories in a general relativistic framework. This thesis examines the use of low-acceleration rockets to reach galactic destinations in the least possible time, with a genetic algorithm being employed for the optimisation process. The fuel required for each journey was calculated for various types of propulsion systems to determine the viability of low-acceleration rockets to colonise the Milky Way. To limit the amount of fuel carried on board, it was found that an antimatter propulsion system would likely be the minimum technological requirement to reach star systems tens of thousands of light years away. However, using a low-acceleration rocket would require several hundreds of thousands of years to reach these star systems, with minimal time dilation effects since maximum velocities only reached about 0.2c. Such transit times are clearly impractical, and it was concluded that low-acceleration rockets are not a viable candidate for galactic colonisation. High accelerations, on the order of 1g, are likely required to complete interstellar journeys within a reasonable time frame. To minimise fuel consumption, the propulsion system would likely need to be more advanced than an antimatter drive, though such a claim would require further research.