Mars Exploration: Surface
& Orbital Reconnaissance

Introduction: Is There Life On Mars? continued

common chemical origin of the planets, suggested the plausibility of life on other planets in the solar system. The discovery of life beyond Earth would also give biological theory a long-sought universality, whilst biology itself would at last be placed on a par with the physical sciences, which were known to be applicable to the rest of the universe and not to the Earth alone. The space age promised biology a "leg-up" in this direction. A panel of biologists commissioned by the US National Academy of Sciences (1964-1965) to evaluate the problem of life on Mars stated, "...The existence and accessibility of Martian life would mark the beginning of a true general biology, of which the terrestrial is a special case."

So far we have considered our estimate for the probability of life on other worlds in terms of the probability of the formation of planetary systems and how the prospect of that life in our own solar system has varied considerably from one observer to another, which, at the boundaries of human knowledge, is a common experience when speculation far outweighs the available data. As I suggested at the beginning, however, our view of the probability of life not only beyond our world or our solar system, but even beyond our galaxy depends upon how we view our Cosmos: what is the origin of the matter that forms the gas and dust from which stars and planets coalesce and from which life too might form? On what grounds do we assert that the same laws of physics apply universally rather than locally?

For some decades now the answers to these questions have been furnished by the ‘Big Bang’ theory of cosmogenesis according to which our universe began its emergence about 13 billion years ago: more precisely this was the emergence of space and time and the four fundamental forces that underpin the behaviour of all the material in the universe, both at the subatomic and macrocosmic levels (people, planets etc); I say in the whole universe because this is an expanding universe and so the physical laws established at its emergence preside in its farthest reaches too. The first atoms, from hydrogen to lithium – and perhaps beryllium - formed when our Cosmos was about 100 seconds old; heavier elements had to await the formation of stars that could provide the necessary temperatures and pressures to create these elements. Stars of sufficient size would explode at the end of their lives as supernovae and make available to a new generation of stars these heavier elements that might one day be used to form planets and even life, like you and me – and even perhaps life on Mars.

Whether or not Mars proves to harbour life the likelihood of our detecting it on another world is greater now than ever before: we have to date identified 3059 planetary systems around other stars amounting to a total of 4112 extra-solar planets (Extrasolar Planet Encyclopaedia), the closest being only 4.24 light years away in Alpha Centauri, the nearest star system beyond our Sun. This world, announced in Nature on August 24th, 2016, is called Proxima Centauri b after the star it orbits; it is of 1.3 Earth masses and at just the right distance from its star to support water - if it has an atmosphere and a magnetic field.