April 12 was a very special day in the history of space exploration. On that date, two very separate events occurred that were major milestones in man's journey to the stars.

The first was the flight that started man's journey, and the other was the first flight of the world's first reusable spacecraft.

Since the launch of Sputnik 1 on Oct. 4, 1957, the Soviet Union and the United States had begun ambitious space programs, each seeking to put a man into orbit around the Earth. While the U.S. program was having difficulty getting off the ground, the U.S.S.R. racked up success after success. Finally, the U.S. program got on firm footing and was preparing to launch their first astronaut into space for a sub-orbital flight.

However, unknown to the folks at NASA, the Soviets were already ready for such a mission. On that fateful morning, Yuri Gagarin and his backup pilot, Gherman Titov, were awakened, aided in donning their spacesuits, and then were driven to the launch pad. Back then, the Soviets had the backup pilot ready to go and suited up to the last moment, in case he was needed.

Upon arrival, Gagarin boarded his craft and, while the process of sealing the hatch and testing the craft was being accomplished, Gagarin was the picture of grace under pressure. He even requested music to be playing on the communication channel while he waited.

Finally, after all of the tests and preparations were completed, the countdown reached zero and the powerful rocket fired and lifted off. Ten minutes after launch, the rocket shut down and Vostok 1 had reached past the atmosphere. This first flight was just for one orbit, as it was for two purposes: to test the systems and make sure everything worked fine and to beat the United States into orbit.

Both goals were accomplished, and after two hours in flight, Gagarin and Vostok 1 landed back on Earth. Gagarin instantly became a hero of the Soviet Union. Sadly, due to the fears of the government leaders of possibly losing such a national hero, Gagarin was banned from ever flying into space again. This was done after Gagarin was backup pilot for the tragic Soyuz 1 flight which ended in the death of Cosmonaut Vladimir Komarov.

In his later years, Gagarin worked as a designer, seeking to create the world's first reusable spacecraft. He rose in rank in the Soviet Air Force and begin working on re-qualifying to be a fighter pilot. Sadly, this would be the decision that caused Gagarin's death. Gagarin died in a fighter jet crash on March 27, 1968. He was laid to rest in a state funeral, with his ashes being interred into the Kremlin Wall.

Twenty years later, Gagarin's vision for a reusable spacecraft became a reality, thanks to the efforts of NASA with the first successful launch of Space Shuttle Columbia, with astronauts John Young and Robert Crippen at the controls. After a successful two-day test flight, the shuttle glided to its first landing at what was then Edwards Air Force Base in California.

Thirty years later, on April 12, 2011, NASA announced the retirement homes for the shuttle fleet as they finish their 30-year missions. The final destinations of the shuttles are as follows:

Shuttle Enterprise, the first shuttle that was unveiled at a ceremony attended by the cast of "Star Trek," will leave the Smithsonian Institution's National Air and Space Museum and be taken to the Intrepid Sea, Air and Space Museum in New York.

Shuttle Discovery, which completed its 39th mission in March, will replace Enterprise at the National Air and Space Museum's Steven F. Udvar-Hazy Center.

Shuttle Endeavour, which will make its final flight into space at the end of this month, will be retired to the California Science Center in Los Angeles.

Shuttle Atlantis will become part of the Kennedy Space Center's Visitor's Center after its final flight in June of this year.

From the one orbit flight of a lone man in a round capsule, to 30 years of space shuttle flights, and the creation of the International Space Station, space exploration has come a very long way. Quite literally only man's imagination, and the sky, is the only limits to what the future holds.