Tsiolkovskiy's Plan Of Space Exploration Nation: USSR. In this work he predicted the manned colonization of the universe in 16 phases:
1. Design of rocket-propelled airplanes with wings.
2. Progressively increasing the speeds and altitudes reached with these airplanes.
3. Designing of a pure rocket without wings.
4. Developing the ability to land on the ocean surface by rocket.
5. Reaching of escape velocity and first flight into space.
6. Lengthening of the rocket flight time into space.
7. Experimental use of plants to make an artificial atmosphere in spacecraft.
8. Using of pressurised space suits for activity outside spacecraft.
9. Making of orbital greenhouses for plants.
10. Building of the large orbital habitats around the earth.
11. Using solar radiation to grow food, to heat space quarters, and for transport needs throughout the solar system.
12. Colonization of the asteroid belt.
13. Colonisation of the entire solar system and beyond.
14. Achievement of individual and social perfection.
15. Overcrowding of the solar system and galaxy colonisation.
16. The sun begins to die and the people remaining in the solar system's population move to other solar systems.
Valier-Oberth Moon Gun Nation: 
Goddard test of liquid rocket. Nation: