A QUICK LOOK AT THE HISTORY OF HUMAN'S SPACE EXPLORATION

“That’s one small step for a man, one giant leap for mankind.”

I think we can all agree that moon landing is the most popular and most remembered space event in the history of mankind. Looking back, all of my classmates know who Neil Armstrong is, and that probably sparked everyone’s interest, including mine, to be an astronaut.  

In reality, space exploration started even before the moon landing on 1969. As early as thousands of years ago, Egyptians and Babylonians carefully observed heavens for practical and religious applications such as planning religious festivals and controlling agriculture. Later, philosophers such as Aristotle, then Ptolemy, developed complex theories on heavenly bodies. What became a tradition and the reigning school of thought during that era is the Earth-centered (geocentric) universe. 

Natural philosophers entered from 1500s onward with revolutionary concepts. Copernicus came in with his sun-centered (heliocentric) universe – a system quickly denied by the Church, with some asserting that Copernicus is challenging humanity’s view of itself and the world, and is reversing the entire science of astronomy. Brahe presented an alternative model where the Moon and Sun revolved about Earth, with everything else revolving around the Sun. The preservation of Earth at the center of the universe while keeping many of the merits of the Copernican system became more acceptable to many scholars. Kepler further pushed the revolution of concepts with his laws of motion – the first of which claims that the orbits of the planets are ellipses with the Sun as one of the foci. 

Galileo ushered humanity to a new era of space exploration with his telescope. Galileo’s telescopic observations solidly disproved several of Aristotle’s claim such as that all heavenly bodies revolve around the Earth. Newton unified the terrestrial and heavenly realms with his laws of motion and the law of universal gravitation. With his laws, scientist back then could predict the motion both in Earth and in space, and was able to locate Neptune. However, it was Einstein’s general theory of relativity that accurately predicted Mercury’s orbital changes over time. Einstein’s concepts also has profound implications for satellites such as Global Positioning System. 

In 1955, the Soviet Union (USSR) and the United States (US) announced their intent to launch artificial satellites. This marked the so-called Space Race – a fight for technological superiority with space as the new high ground. In 1957, USSR launched the first artificial Earth satellite, Sputnik 1, into an elliptical low earth orbit. Sputnik is a 58 cm diameter polished metal sphere with four external radio antenna to broadcast radio pulses. It lasted three months gathering information on Earth’s atmosphere. 

Replica of Sputnik 1 [Source: Wikipedia]

USSR got its hero on 1961 in the name of Yuri Gagarin, the first human to get into space. And just when we thought that US is losing the race, Neil Armstrong left his foot print on the surface of the moon eight years later. Fast forward and here we are in an era with several artificial satellites in orbit, and humans living in space. What used to be a space race is now a collaboration of several countries that joined forces to explore space for the benefit of mankind.

References:

Understanding Space: An Introduction to Astronautics, 2nd edition, Jerry Jon Sellers, McGraw Hill, USA 2004

Elements of Space Technology by Rudolf X. Meyer

Space Technology by Joseph A. Angelo Jr.

Handbook of Space Technology by Wilfried Ley, Klaus Wittmann, Willi Hallmann