Twelve people have walked on the Moon, and quite a few more have gone into orbit around Earth, but in terms of the universe human space exploration has not gone so far. Nonetheless, most of us who remember the Apollo programme felt we went vicariously to the Moon with the astronauts. Even today, as we enter an era where lots of people have put down deposits for tourist trips to the edge of space with Virgin Galactic, many feel that there is something special about getting off our planet. I think that it is visceral. Could humans eventually live out there? Space is the final frontier of our world and it calls to be explored and understood.
In a real sense we (or at least, the stuff we are made of) came out of the universe. At the most extreme, all the material in us came out of the Big Bang. However between the Big Bang and today much more has happened. The idea of the Big Bang was derived from astrophysics but today we also have new sciences such as astrochemistry and astrobiology. These are emerging to allow us to trace the way in which, from the original chaos, the order that we see in life on our planet developed. How did the Cosmos come to create the stars and the planets? How did environments form that allowed something as complicated as us to evolve? How did the teeming life we see on our planet come together? We can ask these questions today as our technology now allows it. Moreover these questions give rise to even more intriguing questions. The surprise discovery of planets outside our solar system about a decade and a half ago has now led us to realise that planets are common. Could there be life elsewhere?
At the same time, the ability to get to some of the nearest celestial bodies allows us to ask why the siblings of our Earth now have environments very different to Earth and in many respects quite inimical to life. Was there once life on Mars? How or why did it fail? Why did the greenhouse effect occur on Venus so catastrophically that metal can melt on the surface? Could life eventually come to exist on Mars? The strange Moons of the outer solar system - Europa, Ganymede, Enceladus and perhaps Titan - seem to be likely to contain liquid water. Are there some nascent processes even now slowly developing in the subsurface ocean of one of these objects that will lead to life in the future? We can even fantasize that in the far distant future, when the Sun becomes a red giant as we know it must, that one day these places may seem more hospitable than our Earth.
The technology of the space age has expanded our horizons over the last half century. It has pushed back the final frontiers of our universe and it is not over. What a great age to be living in!
Prof. David Southwood is president of the Royal Astronomical Society and Senior Research Investigator at Imperial College London, and former Director of Science and Robotic Exploration at the European Space Agency (ESA).