Space exploration has been one of the greatest adventures the human race has taken on since the second half of the twentieth century, clarifying important scientific and philosophical questions relevant to the history and evolution of the planets and solar system, while recent years have seen an ever greater interest and excitement about the presence of life away from Earth and the search for extrasolar planets similar to our own.
Embarking on long, difficult and expensive space missions over the last seven decades, including sending satellites into orbit, space probes and rovers to the planets of the solar system (Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune), towards Pluto, and to various comets and asteroids drifting through space, has helped contribute to the development of new technologies, the proliferation of scientific experiments which would be impossible to carry out here on Earth, and a greater integration of the international scientific community.
Naturally, mankind has been more than a mere spectator. Human beings have dreamt of leaving Planet Earth and journeying to other worlds since antiquity, and in 1961, thanks to advances in technology, physics and astronomy, a Russian cosmonaut, Yuri Gagarin, began the era of manned space exploration by completing an orbital flight around the planet inside a tiny capsule, just big enough for a human, before returning to Earth safe and sound. From there on, more than 500 astronauts have "set foot" in space, with some of them even getting the chance to walk on the surface of the moon and take a small part of our natural satellite home with them.
These lunar explorations are the only ones to have seen mankind step foot on a celestial body other from Earth, but significant progress has also been made to enable astronauts to reach Mars (experts say they will be people already alive today).
Before taking a look at the possible nature of future space missions, let's examine the most important events in space exploration so far, both manned flights and otherwise, which have enabled millions and millions of people to dream with their eyes wide open.
Manned space exploration would not have been so full of success and with so many incredible stories without the help of satellites, rovers, and even the sacrifice of some animals who, by being sent into space in the name of science, were able to provide essential data for future manned space missions. The Sputnik 1, in 1957, was the first object sent into orbit by man. In the same year, it was the turn of the famous dog Laika, the star of the first mission containing a living creature to leave the limits of the Earth's atmosphere and enter into orbit. Then, as we mentioned above, in 1961 the Russians also managed to be the first country to send a human being into space. Yuri Gagarin travelled once around the Earth in 1 hour and 48 minutes inside the Vostok 1 spacecraft, before returning to Earth. Then, two years later, in 1963, it was the turn of the first woman, Valentina Vladimirovna Tereshkova. It was an outstanding achievement for the Russian Tereshkova; especially if you consider that the first Italian woman to go into space (to the International Space Station) was the astronaut Samantha Cristoforetti, from 2014 to 2015, who was able to set the record for the longest amount of time spent in space by a woman, at 199 days.
A few years after the launch of the first man and first woman into orbit, the real race to put a man on the Moon began between the two great superpowers of the era, the United States of America and the Soviet Union. First, a series of satellites and probes launched by the two countries helped to map the Moon's surface and to study its characteristics, vital for a safe landing. Then in the end it was the United States, thanks to the Apollo program, to make it. There were a great number of Apollo missions, not all of them ending happily, but it wasApollo 11which, in July of 1969 and not without difficulty, finally brought the first human beings to the surface of the Moon: Neil Armstrong and Buzz Aldrin. The third member of the crew, Michael Collins, orbited around the Moon on board the command ship (the LEM), which had the task of bringing the three astronauts back to Earth. Another memorable mission was the unfortunate but heroic Apollo 13. The three astronauts in the crew were able to avoid a tragic end after, having almost arrived in the Moon's orbit, they had to deal with damage to an oxygen tank. Thanks to the assistance of NASA scientists communicating from the Kennedy Space Center in Houston and their own piloting abilities, they were able to return to Earth without assistance and limiting the engine starts of the lunar module in which they were travelling.
In the 1970s the splendid adventure of the space programmes with robotic probes launched towards the planets of the solar system began. 2 March, 1972 saw the start of the long journey of the Pioneer 10, and around a year later the Pioneer 11 was launched, making stop-offs at the gas giants Jupiter and Saturn before immersing itself in deep, unknown space. Being the first probes to pass the asteroid belt near Jupiter and then Saturn, there was enormous enthusiasm when they began sending the first images to our planet of worlds which were until then almost totally unknown. Because of their reduced energy, the two Pioneer probes no longer communicate with Earth (Pioneer 10 since 2003, Pioneer 11 since 1993), but they continue their journey beyond the solar system regardless. In 1976-1977 there were two more probes, the Voyagers, which after years of travelling were able to send spectacular images of the outer planets back to Earth, along with the impressive discovery of various new satellites. Unlike the Pioneers, the Voyager probes are still sending us data, as well as carrying a recorded disc, hopefully towards a new world, containing images and sounds of our planet, along with a musical playlist.
The 1970s also saw the beginning of the space stations era, the first genuine permanent locations outside of the Earth's atmosphere, essential for the enrichment of various branches of knowledge and the health of human beings in the absence of gravity. The Russian Salyut 1 was the first space station outside of the Earth's atmosphere to host cosmonauts in history, followed by other projects such as the American Skylab, Mir and the International Space Station (ISS), still orbiting the Earth, and built with the help of the legendary "recyclable" spaceships, as well as the jewels of American astronautics, the Space Shuttles, and the Chinese Tiangong.
And we mustn't forget the exploration of the planets of the solar system by space probes and rovers. In 1966, Venera 3 became the first probe to land on another planet when it touched down on Venus. Other Venera probes followed, managing to land, send photos of their surroundings and take radar scans in order to analyse the geographical structure.
There have also been several visits to Mars. From the Russian missions in the 1970s with Mars 2 and Mars 3, to the NASA Viking probes, as well as Phobos 1 and 2, Mars Pathfinder and the small Sojourner rover, before the famous Spirit, Opportunity and Curiosity, the three rovers sent in the 21st century and which are still active, despite the fact that they were only programmed to be able resist the extreme temperature and conditions for just a few Martian years (one Martian year is equivalent to around two Earth years). So the red planet has always attracted the interests of human beings, hoping to find the first lifeforms outside of Planet Earth or the presence of water in its liquid state.
The situation is different for the giant giants beyond the asteroid belt, Jupiter, Saturn, Uranus and Neptune. Though their characteristics, colours and atmosphere are a feast for the eyes of astronomy enthusiasts, and whoever simply enjoys viewing the photos of space taken by the Hubble Telescope, no rover could ever land on the surface of these planets: none of these worlds possesses a solid surface like that of the rocky planets, and their environmental conditions are decidedly harsh. There is still a lot of scientifically valuable and important work being carried out by super-tech probes such as Juno (Jupiter) and Cassini-Huygens (Saturn). The New Horizons probe was launched towards Pluto (and its main satellite Charon), the former ninth planet of the solar system, now declassified to a nano planet, and arrived at its destination in July 2015 after nine years of travel and orbits (fly-bys) of the various planets of the solar system (to increase its speed and reduce travel time), aiming to study Pluto's geology and morphology, create a map of its surface for the first time and analyse its atmosphere.
Since mankind first began making serious and concrete investments in scientific space research and creating technologies to begin exploring its extraterrestial surroundings (protection systems and the strengthening of the primary rocket and liquid propellant, products based on solar energy, more accurate analysis of the position of the stars), increasingly ambitious new objectives have been added to the various programmes developed by the world powers.
In recent years, international cooperation has been essential for lowering costs and finding improved solutions, especially regarding manned space exploration to other planets in the solar system.
The first step to going beyond the "limits of the Moon" will be reaching the Moon itself once again. A return to the past to refresh our memories in order to prepare for journeys which promise to be much longer and more complicated. The new spaceship Orion will replace the Space Shuttles and the Soyuz spacecrafts, at least for the return to the Moon, while for the journey to Mars, which is not expected before 2020, the various global organisations are still studying the possible effects of radiation on human beings and perfecting the technology needed to make a safe journey (a spaceship capable of housing astronauts and space research systems for several months) and for a stay on the planet for a considerable amount of time.
In the next few years we can also expect to see further studies on the origins and the structure of the universe (dark matter is one of the most important topics in this area), research on extraterrestial life and the discovery of extrasolar planets, the colonisation (and the use) of minor celestial bodies (comets and asteroids) and the development of new technologies which would then find much wider application in other fields.