20th Century
- 1903: Konstantin Tsiolkovsky, Russian scientist, pioneers rocketry theory.
- 1926: Robert Goddard launches the first liquid-fueled rocket in the United States.
- 1957: Sputnik 1 becomes the first artificial satellite, launched by the Soviet Union.
- 1961: Yuri Gagarin completes the first human spaceflight aboard Vostok 1.
- 1969: Apollo 11 lands the first humans (Neil Armstrong and Buzz Aldrin) on the Moon.
- 1970s: Pioneer and Voyager missions explore the outer planets (Jupiter, Saturn, Uranus, Neptune).
- 1981: Space Shuttle program begins with the launch of STS-1 Columbia, marking reusable space transportation.
- 1990: Hubble Space Telescope (HST) is deployed, revolutionizing astronomy with high-resolution images.
- 1997: Mars Pathfinder lands on Mars, deploying the first rover, Sojourner, to explore the Martian surface.
