SSCIENTIFICCIENTIFIC SSTRATRATEGYTEGY PPLANNINGLANNING AATT ESOESO INTRODUCTION BY RALF BENDER, CHAIR OF THE SCIENTIFIC STRATEGY WORKING GROUP At its 100th meeting in June 2003, the ESO Bender (Chair), Tim de Zeeuw, Claes Frans- tific goals and objectives. To this end, current Council decided to install a Working Group son, Gerry Gilmore and Franco Pacini; Bruno and future developments and the possible to discuss ESO’s scientific strategy until Marano and members of the STC, the implications of further external collaboration 2020. The time appeared ripe to discuss VLTI Implementation Committee and the and enlarged membership may also be con- the future, as the VLT was now largely com- European ALMA Board: Jean-Loup Puget, sidered.” pleted, ALMA had just been approved, and Thomas Henning, and Simon Lilly. ESO was The Working Group met three times and the ESO community had been significant- represented by Bruno Leibundgut, Guy Mon- prepared a report accompanied by a set of ly strengthened by the recent accession of net and Peter Quinn. The Director General recommendations. After minor revisions, the the United Kingdom. Furthermore, the dis- and the Head of Administration attended all ESO Council adopted the recommendations cussions and concept studies for the next meetings as well. as a formal “Council Resolution on Scientific large facilities (notably the Extremely Large The charge to the Working Group was Strategy” in its last meeting in December Telescopes) were underway world-wide. Evi- defined by Council as follows: “Prepare and 2004. Both documents are printed below. dently, it was important to develop a strategy assess the options for ESO’s long term pro- I take this opportunity to thank all Work- for ESO’s future now. gramme, taking a broad view of ESO’s role ing Group members for very good and open The Scientific Strategy Working Group in world astronomy [...]. In doing so, the discussions, constructive contributions and was composed of members of Council: Ralf Group shall consider ESO’s long term scien- pleasant and efficient meetings. REPORT FROM THE WORKING GROUP ON SCIENTIFIC STRATEGY PLANNING INTRODUCTION and stars throughout 90 % of the age of the until today, (iv) extreme conditions of matter 1. ESO’s mission was stated in the Con- universe. We have found supermassive black and energy (e.g. black holes), (v) the forma- vention as to “establish and operate an holes in most galaxy centres and have probed tion of stars and planetary systems, and (vi) astronomical observatory in the southern their evolution to high redshifts. We have the characterization of extra-solar planets in- hemisphere, equipped with powerful instru- seen the seeds of galaxies and their large- cluding the search for extraterrestrial life. ments, with the aim of furthering and orga- scale distribution in the cosmic microwave 7. Addressing all of these questions re- nising collaboration in astronomy”. In the background. We have determined the cosmic quires a co-ordinated observational and ex- current world and in view of Europe’s and parameters with an order of magnitude better perimental approach, spanning all wave- ESO’s achievements in astronomy in the last accuracy. We have confirmed the existence lengths of the electromagnetic spectrum with decade, ESO’s mission could be stated more of dark matter which is 5 times more abun- facilities on the ground and in space but also ambitiously: ESO should provide European dant than ordinary matter, and we have found exploring new observing windows to the uni- astronomers world-class facilities to pursue that the universe is filled to 70% with the verse, like underground neutrino detectors, the most fundamental astronomical ques- so-called ‘dark energy’, a new state of ener- or space interferometers for gravitational tions. gy of hitherto unknown nature. And last, not wave detection. Ground-based astronomy 2. ESO cannot do this alone. A close least, we have, for the first time, found plan- with large aperture telescopes plays a pivotal partnership between ESO and the astronomi- ets around other stars. role in the overall concept because (a) most cal institutions in its member countries is cru- 5. It is evident that progress in astronomy sources we want to study emit a large frac- cial to the development and preservation is driven by both unexpected discoveries tion of their radiation between optical and of the scientific and technical excellence (e.g. dark matter, dark energy) as much as radio wavelengths, (b) this wavelength range of European Astronomy. This implies that by particular experiments designed to test provides crucial and detailed information the success of European Astronomy relies specific theories (like ongoing microwave about the physical nature of the sources, and equally on a world-class ESO and on strong background experiments). Astronomical dis- (c) the sources we want to study are general- and active research institutions throughout coveries are often made by pushing the lim- ly very faint. In addition, large telescopes like Europe. its of observation with the most powerful tele- Keck and VLT have not only made important 3. The granting of access to ESO facilities, scopes on the ground and the most advanced discoveries by themselves but also have participation in ESO programmes, and even satellites in space (e.g. high redshift galax- provided crucial complementary information membership of ESO are based primarily on ies, black holes, gamma ray bursts etc), but to discoveries made with satellites (e.g. scientific excellence. ESO will continue to be smaller workhorse telescopes and instru- the Hubble Space Telescope, ISO, Chandra open to new members and collaborations, fol- ments used in a new mode of operation can etc.) which otherwise could often not be inter- lowing the principles of furthering excellence also produce very exciting discoveries (e.g. preted comprehensively and would remain and scientific cooperation. MACHOS, planets etc.). inconclusive. And finally, beyond their 6. Key scientific questions in astronomy large light collecting power, the additional THE ASTRONOMICAL FRAMEWORK and astrophysics over the next 20 years will strengths of ground-based telescopes are 4. Over the past two decades, Astronomy include (i) the nature of dark matter, (ii) the their high versatility and the possibility to has entered its golden age. A few examples nature of dark energy, (iii) the formation of explore new technologies rapidly. of what has been achieved are: We have now the very first stars and galaxies and follow- 8. Astronomy has from its very beginning direct evidence for the evolution of galaxies ing their evolution from the highest redshifts been a technology-enabled science and is 2 The Messenger 119 View of La Silla from THE EXTREMELY LARGE TELESCOPE the 3.6 m telescope. 15. The unique capabilities of an Extreme- ly Large Telescope (30 m and larger) are (i) its 16 to 160 times larger light collecting power than a VLT UT and (ii) its potentially 10 to 40 times higher spatial resolution than the Hubble Space Telescope. The combina- tion of these two features will enable imag- ing and especially spectroscopy of sources up to a factor 50 fainter than currently possi- ble. Considering the enormous progress the Hubble Space telescope brought with its fac- tor 10 improvement in spatial resolution, and the 8 m class telescopes with their factor 5 in light collecting power, the discovery power and impact of an ELT can hardly be overes- now progressing more rapidly than ever to be reconsidered and more specialization timated. With an appropriate choice of the site before, with its technology feedback benefit- may be required. an ELT should also offer unique imaging ing industry. In ground-based astronomy, 12. The VLTI is acknowledged to be the capabilities in the sub-mm range comple- improving the performance of existing tele- most advanced interferometer in the world menting ALMA. scopes and the construction of the next gen- in almost all aspects (except nulling interfer- 16. The case for an ELT alone is compel- eration of telescopes and instruments will ometry with Keck). It will be the best sys- ing; in the context of other facilities it is over- require investment in several critical tech- tem to enable faint science (e.g. structure of whelming. An ELTwill be an important com- nologies. Important over the next 10+ years Active Galactic Nuclei) and ground-based plement to ALMA, the James Webb Space will be, e.g., the development of multi-con- astrometry, because it is the only system Telescope (JWST), future space missions like jugate adaptive optics, laser guide stars, that can potentially combine four 8 m tele- DARWIN and XEUS, and to other space and the mastering of increasingly complex tele- scopes interferometrically. The VLTI is still ground observatories. It is important to real- scope/instrument systems and the handling being constructed, with new instruments to ize that, because of their intrinsically differ- and exploration of Petabytes of data. be added and four Auxiliary Telescopes to be ent capabilities, ELTs on the one hand and completed. space missions like DARWIN or JWST on ESO’S FACILITIES 13. ALMA will open a new window to the the other hand, will not compete but rather 9. ESO and its collaborating institutes universe and provide unprecedented access support each other by providing complemen- have a highly skilled and very motivated staff to the gaseous medium and the star formation tary information about planets, stars and gal- specialized in the design, construction and processes both in our Galaxy and in the most axies. In combination, these facilities will operation of large optical/IR telescopes and distant galaxies in the universe. ALMA will produce the next revolution in our under- their instruments. Another major strength of discover vast numbers of faint sources that standing of the universe and its constituents.