The Universe is a vast, wondrous place and the myriad of celestial objects it nestles, in full display in our night sky, has awed humans since the dawn of mankind. From the early Babylonians, who viewed the Universe as a flat disk floating in the ocean; the great Greek philosophers, who modeled the motion of the heavenly bodies; to the modern astronomers, including Galileo Galilei and Isaac Newton, the nature of our Universe has been a topic of utmost fascination.
Several masterpieces of modern literature, from the works of H.G. Wells to Arthur C. Clarke, as well as cinema, most notably “2001: A Space Odyssey” and “Interstellar” delve deep into the possibilities space travel brings and have captured the imagination of the people with their gripping tales of space adventure.
But it was only around the middle of the Twentieth Century that men were able to send a spacecraft into outer space, when Sputnik 1 was launched by the Soviets in 1957 to orbit the earth. This iconic journey paved the way for a flurry of other probes to stretch further and explore the rest of the solar system, including the Apollo 11 mission, which saw Man land on the Moon for the first time. The initial space missions were dominated by a developing competition between the USA and the Soviet Union, and both sides sent out several spacecrafts in this period, including the Explorer and Apollo missions of the US Space Program, and the Sputnik mission of the Soviets.
The probes sent out to explore can be broadly classified as Flyby’s, which fly past astronomical bodies; Orbiters that orbit a body; Landers that descend to a celestial body’s surface; and Rovers to move on their surface. The first successful interplanetary flyby was the 1962 Mariner 2 flyby of Venus. Subsequently, flyby’s of all the planets of the Solar System has been accomplished.
Rovers have been sent to the Moon and Mars, where they have been used to find out valuable information and collect samples from the body’s surface. Lunakhod 1 was the first successful rover which landed on the moon in 1970. More recently, the rovers Opportunity and Curiosity were sent by NASA to explore the planet Mars, and also to help determine whether the Red planet could have once supported life.
Only five probes have ever gone beyond the realms of our Solar System, namely Voyager 1, Voyager 2, Pioneer 10, Pioneer 11 and New Horizons. Of these, Voyager 1 is farthest from the Earth, and is still operational and returns data. Its initial objective was the flyby of Saturn, Jupiter and Titan, which it accomplished successfully. It has now crossed the Heliopause, which is the boundary of the region of space dominated by the Sun, and is now hurtling away from the Earth and the Sun at a relatively faster speed than any other probe.
Interestingly, The Voyager space probes contain a phonograph record in case the spacecraft should encounter intelligent beings from another planetary system. The disc contains several photographs of the Earth, greetings in over 55 languages and a wide collection of music, from the works of Mozart to Chuck Berry.
Another instrument that plays an important role in observing and discovering new objects in our Universe, albeit at a distance, is the Space Telescope. These gigantic optical devices are located in outer space, most orbiting the Earth, and serve as observatories which receive electromagnetic radiations of a certain frequency range, and provide valuable information regarding distant astronomical phenomenon.
The Hubble Space Telescope is one of the largest and most versatile of space telescopes. With a 2.4-meter mirror, Hubble has recorded some of the most detailed visible light images ever. It has also led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.