I am creating a history for my galactic civilization, and was thinking that the first colonization ship might be launched around the year 2200.
World War Three
Just a few years from now, a third world war breaks out. It lasts for about 5 years. Afterward, all counties end up joining the GU (Global Union). Those that don't do so willingly are forced into submission.
With the GU uniting everybody, far more effort can be put into scientific advances. The mars landing takes place in the early 2030s, and the first probes to Alpha Centauri are launched (Breakthrough Starshot).
The space discoveries actually happen decades after the war.
In the 2050s, humans begin to colonize the solar system. Mars, as well as many moons, are soon being inhabited, both on the ground and with space stations.
The colonization of the solar system continues through 2100. The GU is still working, but corporations are becoming more and more powerful. Eventually, in 2140, a war breaks out between them. It lasts for about 20 years, until it is stopped by the GU.
Launch of Colonization Ship
In 2200, the first colonization ship is launched heading to Alpha Centauri. It will arrive 40 years later, and mark the human race becoming interstellar.
The ship would be capable of going 0.1 times the speed of light. It would have more than enough room for 40,000 people, as well as plenty of supplies for establishing a colony upon arrival.
Would it be possible to have such a ship ready for launch by 2200 under the circumstances described? When would construction have to begin? And if the proposed time frame is not long enough, how much time would be required?
The ship will be a metal construct assembled in space, using materials acquired with relatively advanced mining equipment from various planets in our solar system. It will likely be more or less a generation ship, but since the journey will only take 40 years, the original crew will still be alive during arrival.