The United Nations General Assembly has declared the 12th April 2017 as the International day of Human Space Flight. On this same date in the year 1961 Yuri Gagarin became the first person to reach Earth orbit, when he was launched aboard the Vostok 1 spacecraft. He completed one orbit of Earth and during the final descent of his spacecraft he ejected whilst still some 7 km above the ground, parachuting to a safe landing. So he also became the first person to return from space, without a spacecraft.
In the 56 years since that time, how far have we gone?
In literal terms the greatest distance from Earth to which any human has thus far travelled is lunar orbit. The current record holders are Jim Lovell, Jack Swigert, and Fred Haise, on the ill fated Apollo 13 mission, who set a distance-to-Earth record of 400 171 km when they passed around the far side of the Moon on 15th. April 1971. In long duration flight terms, the record belongs to Valery Polyakov who spent 437 days aboard the Mir space station. And since the year 2000 there has been at least one person in space continuously, aboard the International Space Station (ISS).
Image credit: Encyclopedia Britannica
But what about in a more fundamental sense? Where are we today, as compared to 1961? What have we learned since 1961 which we did not know then? Since Gagarin's historic flight (and landing!) it has been demonstrated that the human body can survive long duration spaceflight, of the order of a year or more. We have demonstrated that we can function in low Earth orbit, on the surface of the Moon, in lunar orbit and most likely beyond. However the survival requirements of the human body are such that robotic spacecraft are considerably easier and less expensive to deploy to Earth orbit and deep space.
The current distance-to-Earth robotic record holder is the Voyager 1 spacecraft which, at the time of writing, is approximately 20 600 000 000 km from Earth. At this immense distance radio messages transmitted from the spacecraft take about 38 hours to reach home.
We have mapped the far side of our own Moon and, for the first time, discovered oceans on worlds beyond ours, namely Saturn's moon Titan, and most likely beneath the vast ice fields of Jupiter's moon Europa, and Enceladus at Saturn.
Voyager 1 has also become the first spacecraft to leave the heliosphere, a region in space created by the Sun's magnetic field and solar wind, and which, in physical terms, is dominated by the Sun. By leaving the heliosphere, arguably Voyager 1 has become the first spacecraft to reach interstellar space. We have also placed spacecraft into orbit around 6 of the major worlds in the solar system and flown passed many others, most recently Pluto. We have mapped the far side of our own Moon and, for the first time, discovered oceans on worlds beyond ours, namely Saturn's moon Titan, and most likely beneath the vast ice fields of Jupiter's moon Europa, and Enceladus at Saturn. Subterranean oceans may in fact be common throughout the solar system and their existence drastically improves the chances of finding extra-terrestrial habitats for alien life.
So what of the future? In addition to national governments, several private companies, particularly in the US, are actively developing their own human rated spacecraft and habitats, including Boeing, Space X, and Bigelow Aerospace. Very recently Space X have successfully demonstrated the concept of re-useable core stage orbital class rockets which has the potential to drastically reduce the cost of reaching space. Boeing are scheduled to make their first commercial spaceflight to the ISS this year, and Bigelow already have an inflatable module attached to the ISS.
Rather like the medieval explorers of the New World, one only really gets to know a place by going there in person.
I am quite convinced that both humans and robots have a fundamental role in space exploration. Space exploration is not wholly justified as a scientific endeavour, although that is certainly reason enough to undertake it. What our robotic scouts have revealed to us are tantalizing hints of what awaits future human explorers of the solar system, and ultimately civilization itself. Rather like the medieval explorers of the New World, one only really gets to know a place by going there in person. In order to protect the legacy of human civilization we need to demonstrate that we can exist beyond Earth indefinitely, and independently. Ultimately, it is a quest to discover who we are, where we came from, and, as Carl Sagan eloquently put it "what our fate maybe".