Space exploration had been limited to just gazing up at the heavens until the invention of the telescope. Man always thought we needed more information, and in the late 20th century, we started doing things that many thought would be impossible, exploring extra-terrestrial bodies by landing spacecraft directly on the surface of planets and moons. Here are some astonishing planets and moons that we have explored up till now.
Image Captured By Venera 13(1982). Courtesy: USSR/NASA
As Venus is our closest neighbor, as near as 38 million kilometres at times, it was the first to be ‘probed.’ On March 1, 1966, the Venera 3, a Soviet-controlled space probe, crash-landed on Venus. It was not until 3 years later, however, that the Venera 7 landed on Venus, the first spacecraft to successfully land on another planet and send back data.
Moon –Â USSR 1959, Â And USA 1969 (first manned landing)Apollo 11 Lunar Module Pilot Buzz Aldrin’s bootprint. Image Courtesy: NASA
The Moon is the closest extraterrestrial body to Earth, and therefore is the most explored. The first ever mission to the Moon was the Soviet Luna 1(1959), It only took 36 hours to make the trip to moon, travelling an average speed of 10,500 km/hr. The Apollo 11 mission in 1969 brought the first human, Neil Armstrong, to walk on the moon, one of the most memorable events in mankind’s history.
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Mars – NASA, Mars Curiosity Rover(6 August 2012)The first color image taken by the Viking 1 lander (July 21, 1976). Courtesy: NASA/JPL
Mars 2 Lander (27 November 1971) became the first man-made object to reach the surface of Mars, but we could not sustain contact after its crash landing. The most successful exploring mission is The ‘Curiosity‘ Rover. It landed on Mars in August 2012, and has been thoroughly exploring Mar’s surface recently due to the possibility of evidence of its life-sustaining capabilities. It has been performing geological research ever since it landed.
First Use of Mars Rover Curiosity’s Dust Removal Tool, Image Courtesy: NASA
Titan – NASA-ESA-ASI, Cassini-Huygens (July 1, 2004)Image courtesy : NASA
One of Saturn’s largest moons, Titan, was explored by the Cassini-Huygens spacecraft in July 2004, It was a joint mission by NASA, ESA and ASI. It has been said that many of Titan’s landscapes had been formed by flowing waterways, a feat that is so far unique in outer space.
Mariner 10 was the first probe to look at Mercury, passing by using the gravitational ‘slingshotting’ effect in 1974. At first it was obvious that it had been struck by thousands of objects, evident from the multiple impact craters. As it is the closest planet to our sun, it is also very hot, with the surface regularly reaching 400 degrees Celsius.
Among the most successful exploring missions, Messenger was the second NASA mission to Mercury,  was launched on August 3, 2004. Most of Mercury’s hemisphere not imaged by Mariner 10 has been mapped by Messenger. Also it took the first orbital image of Mercury on March 29, 2011, and Messenger is still active.
Galilean moons (Io, Europa, Ganymede, and Callisto.)
The Galilean moons are the four largest moons of Jupiter discovered by Galileo Galilei in January 1610. They are Io, Europa, Ganymede, and Callisto. To explore these celestial bodies further, on October 18, 1989 NASA sent the Galileo (spacecraft), also various space probes, from Pioneers 10 and 11 to Cassini, have studied these Galilean Moons.
Io is the innermost of the four Galilean moons of the planet Jupiter. In 1979, two Voyager spacecraft (NASA) revealed Io to be a geologically active world, with numerous volcanic features, large mountains, and a young surface with no obvious impact craters.The Galileo spacecraft (NASA) performed several close flybys in the 1990’s and early 2000’s, obtaining data about Io’s interior structure and surface composition.
Jupiter’s moon Io, Taken by Galileo spacecraft. Image Courtesy: NASA
Most of the information collected on Europa, another one of Jupiter’s moons, was taken by the Galileo mission (NASA), launched in 1989, that flew by Europa to gather data. It was concluded that there may be a liquid water ocean beneath the silica rock surface, and extra-terrestrial life may be possible.
Europa, as viewed from NASA’s Galileo spacecraft. Image Credit: NASA
Ganymede is a satellite of Jupiter and the largest moon in the Solar System. There have been various flybys (Voyager and Galileo by NASA in 1996 and 2000 ) to Ganymede, but no avail. There has been very little information collected about this moon, with some suggesting that a salt water ocean exists beneath its surface.
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Image Of Ganymede taken by Galileo Orbiter, Image courtesy: NASA/JPL/DLR
Callisto is another moon of the planet Jupiter. Conditions to sustain life on Callisto are less favorable than its neighbor, Europa, due to its cold temperatures. However, Callisto is the third largest moon in our solar system, a similar size to Mercury, but only a third of its mass. Various space probes from Pioneers 10 and 11 to Galileo (NASA in 1994 to 2003) and Cassini (NASA,ESA,ASI) have studied Callisto.
Image of Callisto taken by Galileo Orbiter, Courtesy: NASA/JPL/DLR
Enceladus-Â NASA-ESA-ASI, Cassini-Huygens (2005)
Saturn’s icy moon Enceladus is hiding a large body of water under its surface,  it has a sub-crustal liquid ocean and also contains traces of hydrocarbon compounds. From this data they speculate that Enceladus might be yet another abode of life beyond the earth. In 2005 the Cassini spacecraft (NASA, ESA, ASI) performed several close flybys of Enceladus, revealing the moon’s surface and environment in greater detail.
Enceladus as viewed from Cassini spacecraft. Image courtesy: NASA,ESA,ASI
Mimas – NASA-ESA-ASI, Cassini-Huygens (February 13, 2010)Â Mimas as viewed from Cassini spacecraft. Image courtesy: NASA, ESA, ASI
Less than 400 km in diameter, crater-covered Mimas is the smallest and innermost of Saturn’s major moons. It is the smallest astronomical body that is known to be rounded in shape because of self-gravitation. Mimas has been imaged several times by the Cassini orbiter (NASA, ESA, ASI), which entered into orbit around Saturn in 2004. A close flyby occurred on February 13, 2010, when Cassini passed by Mimas at 9,500 km.
