Space Exploration

This high-resolution image of the Hubble Ultra Deep Field includes galaxies of various ages, sizes, shapes, and colors. The smallest, reddest galaxies are some of the most distant galaxies to have been imaged by an optical telescope.

Space exploration is the use of astronomy and space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft. While the observation of objects in space, known as astronomy, predates reliable recorded history, it was the development of large liquid-fueled rocket engines during the early 20th century that allowed physical space exploration to become a reality. Common rationales for exploring space include advancing scientific research, uniting different nations, ensuring the future survival of humanity and developing military and strategic advantages against other countries. Various criticisms of space exploration are sometimes made, generally on cost or safety grounds.
Space exploration has often been used as a proxy competition for geopolitical rivalries such as the Cold War. The early era of space exploration was driven by a "Space Race" between the Soviet Union and the United States; the launch of the first man-made object to orbit the Earth, the USSR's Sputnik 1, on October 4, 1957, and the first Moon landing by the American Apollo 11 craft on July 20, 1969 are often taken as the boundaries for this initial period. The Soviet space program achieved many of the first milestones, including the first living being in orbit in 1957, the first human spaceflight (Yuri Gagarin aboard Vostok 1) in 1961, the first spacewalk (by Aleksei Leonov) in 1965, the first automatic landing on another celestial body in 1966, and the launch of the first space station (Salyut 1) in 1971.

After the first 20 years of exploration, focus shifted from one-off flights to renewable hardware, such as the Space Shuttle program, and from competition to cooperation as with the International Space Station.

From the 1990s onwards, private interests began promoting space tourism and then private space exploration of the Moon (see GLXP).

In the 2000s, China initiated a successful manned spaceflight program, while Japan and India have also planned future manned space missions. Larger government programs have advocated manned missions to the Moon and possibly Mars sometime after 2010.

Source: Wikipedia