What Jules Verne’s book From the Earth to the Moon recounted in 1865, the year of its publication, seemed nothing more than pure imagination. Yet it came true one century later with man setting foot on a different planet for the first time. Since the first moon-landing up till today, enormous progress has been made in our knowledge of space. 2015 has been a fundamental year vis-à-vis space exploration because the extreme boundary of our solar system has been reached by the American space probe New Horizons that, ten years after its departure, has been able to photograph Pluto. The sad aspect of this thrilling milestone is that, at least for now, the journey towards more distant planets stops here. In fact, it would take 70,000 years to reach Proxima Centauri, the star closest to the sun, which is the time equivalent of 3,000 human generations. This should not discourage us though. If anything, it should be an incentive to better investigate what we have within our own solar system.
In fact, for some time now, the various space agencies have reviewed their strategies, focusing on such less remote and possibly profitable goals as the search for rare elements in asteroids and the creation of a self- sufficient base on Mars. This base would have to rely only on materials recovered from the means of navigation and on those present on the planet. To this end also the soil will have to play its part, primarily for greenhouse cultivation, once freed of certain toxic substances, such as superoxide and perchlorates. In fact, from a chemical point of view, Martian soil appears to contain all the major plant nutrients except perhaps nitrogen. However, apart from its fertility potential, is Martian soil real soil? Space scientists use various and often inappropriate terms to define soil while those dealing specifically with the subject have rarely spoken about it. The concept of soil has always been associated with that of life, on our planet because the two are almost inseparable and the living organisms are one of the main factors in soil generation. Nonetheless, there also are practically lifeless soils – such as those of Antarctic’s Dry Valleys or Chile’s Atacama Desert – because of the unavailability of liquid water. So, why should those on Mars not also be considered soils, along with all the deposits of loose material on other rocky bodies in the solar system where clear signs of chemical alteration have been observed (such that it changed the composition of the original material) which for this author is the true essence of the concept of soil? on that basis, Venus, Mars and our moon have soils while other possible candidates in this sense are Mercury; the dwarf planet Ceres; the moons of Jupiter, Io and Europa; and of Mars, Phobos and Deimos as well as a plethora of asteroids.
The article has been taken from the report given by Prof. Certini at “The science of the soil: past, present and future” workshop, held at Venice’s Ca’ Foscari University last 28 September (see Georgofili INFO, http://www.georgofili.info/evento.aspx?id=2243
) where the entire life’s work and scientific contributions of emeritus member Prof. Fiorenzo Mancini
, who died in April 2015, were remembered. (see Georgofili INFO , http://www.georgofili.info/detail.aspx?id=2291
(Giacomo Certini, Università di Firenze - firstname.lastname@example.org)