Space Exploration

Space exploration is the physical exploration of outer space, both by human spaceflights and by robotic spacecraft. While the observation of objects in space -- known as astronomy -- pre-dates reliable recorded history, it was the development of large liquid-fueled rocket engines during the early 20th century that allowed space exploration to become a practical possibility. Common rationales for exploring space include advancing scientific research, uniting different nations and ensuring the future survival of humanity.


FIRST ORBITAL FLIGHTS:

The first successful orbital launch was of the Soviet unmanned Sputnik I (Satellite I) mission on October 4, 1957. The satellite weighed about 83 kg (184 pounds), and is believed to have orbited Earth at a height of about 250 km (150 miles). It had two radio transmitters (20 and 40 MHz), which emitted "beeps" that could be heard by any radio around the globe. Analysis of the radio signals was used to gather information about the electron density of the ionosphere, while temperature and pressure data was encoded in the duration of radio beeps. The results indicated that the satellite was not punctured by a meteoroid. Sputnik 1 was launched by an R-7 rocket. It incinerated upon re-entry on January 3, 1958.

This success led to an escalation of the American space program, which unsuccessfully attempted to launch Vanguard 1 into orbit two months later. On January 31, 1958, the US successfully orbited Explorer I on a Juno rocket. In the meantime, the Soviet dog Laika became the first animal in orbit on November 3, 1957

FIRST HUMAN IN SPACE

Yuri Gagarin
The first human spaceflight was Vostok 1 (Sunrise 1) , carrying 27 year old cosmonaut Yuri Gagarin on April 12, 1961. The spacecraft completed one orbit around the globe, lasting about 1 hour and 48 minutes. Gagarin's flight resonated around the world; it was a demonstration of the superior Soviet space program and it opened an entirely new era in space exploration - manned space flights. The U.S. launched its first man into space within a month of Gagarin's flight with the first Mercury flight, by Alan Shepard. However, orbital flight was not achieved by the United States until John Glenn's flight nearly a year later. China launched its first taikonaut into space 42 years later, with the flight of Colonel Yang Liwei aboard the Shenzhou 5 (Spaceboat 5) spacecraft.

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. Larger government programs have advocated manned missions to the Moon and possibly Mars sometime after 2010.