Most of our information on celestial objects comes through the electromagnetic radiation that planets, stars and galaxies emit throughout the spectrum.They obviously do not care that on our planet only a small (frequency) window, the one to which our eyes became adapted, penetrates the atmosphere. Placing telescopes in orbit has provided astronomers with an immense leap in their powers of observation.The recent Nobel Prize to Riccardo Giacconi for the development of X-ray astronomy is but one example of the recognition of such a widening of horizons.
Huygens revealed a world previously unknown to science: first colour view of Titan's surface. (ESA/NASA/ JPL/Univ.Arizona)
There is another dimension of research in space that is more akin to traditional exploration: exploration in situ. Europe is currently present on many planets in the Solar System, including the Moon, Mars, the Saturn/Titan system,Venus and, tomorrow, Mercury. Europe is thus acquiring data on all the major solid-body atmospheres in the Solar System:Venus, Mars and Titan.The potential benefits for understanding the evolution and fate of the fourth solid-body atmosphere in the Solar System, that of our Earth, are apparent. Planetology helps us to put in context the particular planet on which we happen to live. On the other hand, participating in missions closing in on the Sun has given us a new view of our own star, which ultimately controls our lives.
There is more to space astronomy besides the electromagnetic spectrum and in situ exploration.We also receive information from the Universe through essentially untapped channels, such as gravitational waves - another of Einstein's predictions -that have so far only been indirectly observed.Through them, we expect to improve our understanding of a variety of phenomena, such as merging neutron stars, forming gigantic black holes in the centres of Galaxies, and the very first instants of the explosion that gave birth to the Universe.
Finally, the 'corpuscular'channel has been exploited from the very first cosmic-ray experiments aboard satellites for sampling the origin and composition of nuclei synthesised in stars, as well as for understanding their importance in the energy balance of our Galaxy, and their
significance for interplanetary space and indeed our Earth.To these now-traditional particle astronomy studies, new physics dimensions could be added that address exotic species or energy levels so far unexplored.
In this global panorama of science advances, rendered possible by access to space, Europe has contributed, through ESA, complemented by additional national efforts, in a major way. Through creativity, organisation and determination, Europe has achieved leadership in a number of research areas since ESA's foundation. However, ESA and its Member States have achieved successes in space science that are disproportionate to their relatively small budgets.They come from pursuing difficult and highly original projects in an unwavering fashion over many years. Like Aesop's tortoise competing with the hare, Europe gets there in the end -whether to the sludgy surface of Titan or into orbit with the world's most sensitive X-ray and gamma-ray telescopes, XMM-Newton and Integral.
Gaia will decipher the history of the entire Galaxy.
After proving its competence in space astronomy with COS-B for gamma-rays (1975) and Exosat for X-rays (1983), the scientific mission through which ESA 'came of age'was probably Giotto (1985-1986). Witness the breathtaking movie of Giotto's approach to within less than 600 km of comet Halley, much closer than any other space agency dared to go.The Rosetta mission, launched in 2004, will land on a comet in 2014, reinforcing the leading position achieved by Giotto.
In 1989, Hipparcos was launched, a unique satellite that gave unprecedented and, as yet, unmatched accuracy in measuring the positions and motions of stars within a range of hundreds of light-years in our Galaxy and, for the first time, solved the discrepancy between the age of the oldest stars in the Milky Way and the expansion age of the Universe.This mission will be followed in 2012 by Gaia, a much more powerful satellite, able to map one billion stars in six dimensions and decipher the history of the entire Galaxy. Space astrometry, by now an established European specialty, has given us direct access to the distance ladder, whose steps measure our Universe.
Both Giotto and Hipparcos were projects that NASA in principle might have done but did not.The scientific and political will came from Europe.Yet willpower on behalf of individual science projects was not enough. By the early 1980s, Europe's scientific institutes, aerospace companies and governments all realised that to create and preserve talented teams, as well as to be reliable partners in international collaborations, ESA needed long-term commitments in planning and funding.
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