European vision for space science

In 2000, amateur astronomer Mike Oates started to search the SOHO images, which had then recently became available via the internet. He soon revealed just how much potential SOHO had by quickly spotting over 100 comets in LASCO images. Almost all S O H O ' s comets are discovered using images from its L A S C O instrument the Large Angle and Spectrometric Coronagraph. LASCO is used to observe the corona - the faint, multimilliondegree outer atmosphere of the Sun. A disk in the instrument is used to make an artificial eclipse, blocking direct light from the Sun so that the much fainter corona can be seen. Sungrazing comets are discovered when they enter LASCO's field of view as they pass close by the Sun. As time passed, more professional astronomers, as well as amateur enthusiasts from all over the world, have joined the search for 'SOHO' comets. In August 2002, Rainer Kracht (now the leading comet discoverer using SOHO, with over 150 comets) spotted SOHO's 500th comet. This in itself was an achievement that none of those involved in planning the SOHO mission and its LASCO instrument ever imagined would, or could, happen. However, just three years later, SOHO, with 1000 comet discoveries, is responsible for almost half of all officially recorded comets in history! Add to this the fact that the SOHO mission has completely revolutionized solar physics and the understanding of the Sun, and it shows just how truly amazing the SOHO spacecraft has proved to be.

European Vision for Space Science [by Giovanni F, Bignami]

T

he 2004 Nobel prizewinner in Physics, David Gross, once commented that "Science is shaped by ignorance".

Space science is no exception: by going after our knowledge gaps (or 'ignorance chasms') in the universe around us, we focus on questions that both direct and motivate us. Identifying those questions has been the starting point of Cosmic Vision 2015-2025. Long-range plans for space science are vital to foster the development of space science missions, for which a development time of 10 to 15 years, preceded by long and intense preparatory work, is the rule. Such an investment of time and effort could not be sustained by scientists, technologists, national funding agencies, the space industry and international partners without the existence of long-term plans prepared by such major agencies as ESA or NASA. All these self-same scientists, technologists, national funding agencies, space industry companies and international partners rely very heavily on the existence of ESA's long-term plans to build confidence in the success of space projects. The missions in operation today were planned in the Horizon 2000 plan, prepared in 1984/85 and then in Horizon 2000+ which was formulated during 1994/95. Following on this highly successful tradition is Cosmic Vision 2015-25 that aims at furthering Europe's achievements in space science for the benefit of all mankind. The year 2005 is especially apt for taking stock of the new science done from space in the continent that was home to Ptolemy, Tycho, Kepler, Galileo, Newton and Einstein. One century after the 'annus mirabilis' of the theory of relativity, the photoelectric effect and Brownian motion, we celebrate thirty years of activity of the European Space Agency, itself emerging from the achievements of the European Space Research Organization (ESRO) over the previous decade. We European space scientists are proud to have given again a new contribution to mankind in its quest to

understand the universe. After about four thousand years of naked-eye astronomy, Galileo initiated a period of four hundred years of astronomy with ever more powerful telescopes, followed by forty years of astronomical studies from space-borne laboratories and with space-bome experiments. In each one of these historical periods, astronomers have gathered more information about the universe than in the previous one, in a spectacular example of the acceleration of science.

Why do astronomy? Astronomy, the understanding of our universe and of mankind's place within it, is the 'mother of all science'. Lack of interest in basic science, in addition to the devastating economic effects that such an omission has - no basic science means no applications - is always the symptom of a profound disease in any society. Why look at the heavens from Space? Most of our information on celestial objects comes courtesy of electromagnetic radiation, which planets, stars and galaxies emit throughout the spectrum. In the universe in which we find ourselves, our close and distant neighbours are oblivious and indifferent to the fact that our planet has only a small (frequency) window, the one to which our eyes have become adapted, to penetrate the atmosphere. Putting telescopes in orbit has provided astronomers with an immense leap in their power to open out the narrow window that confined observations of the heavens in previous centuries. The award, in 2002, of a Nobel Prize for Physics to Riccardo Giacconi for the development of X-ray astronomy is only one example of the recognition of such a widening of our observational horizons. There is another dimension of research in space that is more akin to traditional exploration, i.e. exploration in situ. European sensors are currently present on many planets (and their satellites) in the solar system, including the Moon, Mars, the Saturn/Titan system, Venus and, all being well, on Mercury

'tomorrow'. In this way, Europe is 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, namely that of the Earth, are apparent. Planetology helps to put the particular planet on which we happen to live in context. 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 all our lives. There is more to space astronomy than the electromagnetic spectrum and in situ exploration. We also receive information from the universe through essentially untapped channels, such as gravitational waves (another Einstein prediction) that have so far only been indirectly observed. Through them, we can expect to be able to improve our understanding of a variety of phenomena, such as neutron star mergers, the formation of gigantic black holes in the centre of galaxies, as well as the very first moments of the explosion which gave birth to the universe. Finally, the 'corpuscular' information channel has been exploited from the very first cosmic-ray experiments on board satellites until today for sampling the origin and composition of nuclei synthesized in stars, as well as for understanding their importance in the energy balance of our home galaxy, and their significance for interplanetary space and, indeed, for our Earth. To these, by 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 scientific advances, that have been rendered possible by access to space, Europe itself has contributed in a major way, through ESA, complementing the many individual national efforts. Through its creativity, organization and determination, ESA and its Member States have achieved

Cosmic Vision 2015-25 is therefore aiming boldly at furthering Europe' s achievements in space science, for the benefit of all mankind. As with its predecessors, the plan has been created 'by scientists, for both science and industry'. It is based on a massive response by the scientific community to ESA's call for themes that was issued in April 2004. A total of 151 novel ideas were submitted, more than twice as many as for the equivalent exercise in 1984-85.

leadership in a number of research areas since the foundation of ESA, successes in space science that are disproportionate to their relatively small budgets. These successes have come to fruition as a result of 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.

Science in the 21 st century seeks answers to profound questions about mankind's existence, and survival in a tumultuous cosmos. What has emerged as being of particular importance is the rate of increase of our knowledge. We can now pose questions that seemed beyond our reach less than a generation ago. Many of the answers can be sought and found only with space projects of ever-increasing ingenuity. ESA is not alone in recognizing the scientific challenges, and it embraces collaboration with other agencies whenever that is opportune. However, Europe has made its most distinctive contributions to space science by giving its own scientists every opportunity to prioritize their goals.

At the time of writing, celebrations are ongoing for ESA's thirtieth anniversary. It is a different organization from what it was 30 years ago and reflects a different environment. The evolution of our space science community deserves special attention (Bignami 2005). It is the one on which ESA's Science Programme 'insists' and that is served by the programme. It represents the future for Europe, first of all in terms of new ideas and work, but also for the Programme's governance that is constantly effected through ESA's advisory bodies. In the time-honoured fashion, the space research community was called upon to express its new ideas in 2004, and did so with unprecedented enthusiasm. The community was patently conscious of the responsibility it had to take to build its own future by responding to the need for tackling new frontiers in space science in a new Europe. The number of responses more than doubled in comparison with the first such exercise undertaken by ESA, while the number of participants per proposal also significantly increased, together covering the whole space scientific community within Europe. In some countries, such as Spain, the increase has been dramatic. Decision and policy makers are today aware of and becoming engaged in an important sector of society's aspirations and needs. Cosmic Vision 2015-2025 is an attempt to do justice to all such aspirations.

Cosmic Vision 2015-2025 addresses four main questions that are high on the agenda of research all across Europe (and indeed world-wide) concerning the universe and our place in it. 9 W h a t a r e the c o n d i t i o n s for life a n d planetary formation? 9 How does the solar system work? 9 W h a t are the f u n d a m e n t a l l a w s o f the universe? 9 H o w did the u n i v e r s e o r i g i n a t e a n d w h a t is it m a d e of?.

The team preparing Cosmic Visions

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flexibility. The White Paper calls for urgent "corrective action".

2015-25 has subdivided these four main questions by selecting areas where substantial progress can be expected in the next two decades (see the figures on the following pages). Under each of the resulting subheadings, one, two or three appropriate space techniques (or tools) have been nominated. It is here that technical progress in the next ten years is required and the targets finally chosen; the progress made will then determine what we can confidently expect to do scientifically maybe 20 years from now. In some cases the same technique or tool appears in more than one context, thanks to its cross-disciplinary character. Above all, Cosmic Visions 20152025 is being put forward to the newly-formed European Space Council, in the context of the institutional European Union presence in space activities, tn the European Commission's White Paper Space: a new European frontier for an expanding Union (November 2003), space science is described as "essential to Europe's identity and leadership as a knowledge-based society", society".

Cosmic Vision 2015-2025 is also an act of confidence of a vast and multi-faceted community, the members of which have gladly collected together within it their best ideas and confidently expect to obtain the necessary support for the timely implementation of an exciting programme aimed at responding to the call expressed in the European Commission's White Paper. Moreover, ESA's successes in space science can be expected to encourage students to pursue studies and careers in science and engineering. The programme also helps to stem a potentially disastrous brain drain of scientific and engineering talent to the USA and other parts of the world with active space programmes. By being more visible than some of ESA's other activities, space science does secure attention from the media that benefits space research as a whole, along with the national space agencies from which Europe's citizens can get a well-deserved sense of where their taxes are going.

The Commission also has noted that the recent erosion of funding for ESA's space science programme has reached a point where it disrupts the balance of the programme and misses the chance to optimize costs and

References Bignami G.F. 2005 Nature, Lond., 435, 563. Cosmic Vision." Space Science for Europe 2015-2025. 2005 ESA BR 247.

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