Page 1 of 10 Paper presented at the 164th Xiangshan Science Conference. Beijing , P.R.China May 9-11, 2001 The World Space Observatory/Ultraviolet (WSO/UV) Project: Current Status. Willem Wamsteker ESA/VILSPA P.O.Box 50727 28080 Madrid, Spain I. Introduction. The World Space Observatory/Ultraviolet (WSO/UV) represents a new mission implementation model for large space missions for Astrophysics. The process has been brought up to enable a, fully scientific needs driven, logic to be applied to the demands for the large collection powers required to make space missions which are complementary to the continuously increasing sensitivity of ground based telescopes. One of the assumptions associated with the idea of a WSO is to avoid the excessive complexity required for multipurpose missions. Although there may exist purely technological or programmatic policy issues, which would suggest such more complex missions to be more attractive, many other aspects, which do not need to be explored here, may argue against such mission model. Following this precept and other reasons explained below, the first implementation model for a World Space Observatory has been done for the ultraviolet domain WSO/UV [2, 8]. For the purpose of this discussion we will refer to the wavelength domain from ll120 nm to ll320 nm as the Ultraviolet (UV) domain, the range from ll80 nm to ll120 nm as the Lyman range and from ll10 nm to ll80 nm as the extreme Ultraviolet (EUV). Even though the boundaries between these domains are somewhat fuzzy, it is convenient to maintain the concepts. In the early 1970’s the fist orbiting UV missions were launched with ESA’s TD-1 UV photometric mission, NASA’s Copernicus mission for high resolution spectroscopy in the UV and Lyman range and the Astronomical Netherlands Satellite (ANS). From 1978 through 1996 most of the Astrophysics in the Ultraviolet wavelength domain has been done with the highly successful International Ultraviolet Explorer satellite (IUE) [9], a joint project between NASA, ESA and PPARC. From 1984 through 1987 the Russian ASTRON mission was in orbit. In 1990 the (ESA/NASA) Hubble Space Telescope (HST) introduced a new capability for the UV community. This instrument was designed as a multiple purpose telescope, is in Low Earth Orbit (LEO) and the observing time is necessarily shared between the different instruments and wavelengths domains. Regular instrument exchanges have been taking as part of the HST Programme. When a full complement of instruments is available only about 30% of the schedule can be dedicated to the UV range. The UV capability of HST was originally with the Goddard High Resolution Spectrograph (GHRS), the Wide Field Planetary Camera (WF/PC2), the Faint Object spectrograph (FOS), and the Faint Object Camera (FOC). Some of these instruments have been replaced by others and at this moment the UV capability of HST is limited to WF/PC2 and the Space Telescope Imaging Spectrograph (STIS) [4], which will be replaced in the future by the Cosmic Origins Spectrograph (COS) [3], the Advanced Camera for Surveys (ACS) and WF/PC3. The expected results of the first dedicated Ultraviolet Sky Survey mission GALEX which will be launched in 2003 by NASA, supply a very strong impetus for Page 2 of 10 the need of more efficient follow-up instrumentation to address the many new results to be expected from such survey. The GALEX survey is expected to supply catalogues with e.g. 1 million QSO’s; 1000 Clusters of Galaxies; 300,000 White Dwarfs; 10,000 Cataclysmic Variables etc. [15]. Also the combination with the major ground-based 10-m class telescopes in operation (see also [5]) together with the capabilities of the current generation of powerful X-ray telescopes (CHANDRA and NEWTON_XMM) supply additional unique mission goals in multi-ll science for the WSO/UV. In the following sections we will outline the philosophical background of the World Space Observatory concept in section II. The current situation in Space Astrophysics through a short overview of the implementation plans of the major Space Agencies with a Basic Space Science Programme, will be addressed in section III. In section IV we will expand on the details and capabilities of WSO/UV as presently agreed by the scientists who have been collaborating in the early assessment of WSO/UV. And in section V the current status and implementation planning is expanded upon. In this article we will not address the scientific impact of the WSO/UV in detail, since the other speakers will address these issues. II. WSO Concept and Purpose. History has shown that development in a socially peaceful environment is extremely difficult to achieve and that revolutionary changes, driven by intellectually advanced (and at times extreme) ideas, can become dominant. Therefore sustainable development in the modern world needs a culturally appropriate and sociologically stable development. This can only be accomplished when the educational processes also supply professional outlets for those motivated to learning and development in a broad sense. For the post-industrial times this presents an important challenge to the world at large, as a consequence of the complex and fast information distribution capabilities. Economic globalization in the industrialized world is accompanied by a strong democratization drive, but regional cultural identity should not be ignored. The influence of these cultural factors defy quantitative analysis and the absence of proper consideration of them, has been one of the main problems associated with the implementation of sustainable development programmes. It appears now clear that the activation of sustainable development schemes will have to be based on original and innovative approaches to the development process, where sharing must be an integral part of the collaborative efforts of all countries involved The current development strategies in many developing countries, include a significant investment in education which does not appear to bear the desired fruits, because of strong emigration pressures on the best educated people. One reason for this may be that participation in advanced science can only function efficiently if also access to advanced investigation tools are accessible. Consequently, investment in education often results only in the creation of a consumer market, without the creation of the professionally well-formed, culturally and intellectually identifiable and academically oriented cadre of scientists that is necessary for sustainable development. In hindsight, it is very clear that the success of the western industrial revolution was based on a fruitful interplay between the academic community and the commercial sector of the population. Over the centuries, astronomy has played a major cultural role as the predecessor of all scientific and philosophical development. This is because it uses scientific method to approach a most fundamental question, basic to many religious as well as non-religious philosophical concepts: Page 3 of 10 What is the place of (the people of) planet Earth in the Universe? During the United Nations/ESA workshops on Basic Space Science [1], the concept of a World Space Observatory has been recognized as an important tool to bring about the necessary quantum leaps in development. The World Space Observatory embodies a twofold goal: a. To create opportunities for all countries of the world, to participate in the frontiers of space science, on a sustainable basis and at the national level, without the need for excessive investment. In doing so, a WSO will make an important contribution to the development of an academically mature and competitive cadre in many developing countries within 5 to 10 years after inception of the project by offering equal opportunities to highly trained scientists all over the world; b. To support worldwide collaboration and to assure that the study of the mysteries of the universe from space can be shared in a sustainable way by scientists from all countries. This will then, not only maintain the curiosity-driven spirit of discovery that is an integral part of sustainable development, but also make a reality in the scientific world of the visionary principle that “space is the province of all mankind”. For scientific reasons upon which we will expand below, the choice for the assessment study of a World Space Observatory [2] has been made to be the UV domain. The obvious reasons being that UV can only be reached from beyond the atmosphere and, that already considerable expertise exists in the developing world for the associated astrophysical problems. This will incorporate a direct application of the “headstart”principle. Thus it is possible to benefit greatly from a new space observatory to be launched in the 2nd half of the first decade of the 21st Century. Considering the combination of the WSO concept and the UV needs for a dynamic science program, the WSO/UV mission was conceived: Mission concept WSO/UV The driving principles behind the design of the mission are: a. Operation of a 1-2 meter-class telescope in Earth orbit with a spectroscopic and imaging capacity specific to the ultraviolet domain; b. High throughput and optimized operational and orbital efficiency; c. Optimum benefit to be derived from the fact that ultraviolet cosmic background radiation is at a minimum around 200 nm; d. Minimal operational costs without affecting the scientific excellence of mission products; e. Direct access to a front-line facility for basic space science for the international astrophysics and planetary science community; f. Limitation of the technological developments needed for a prime science mission; g. Data distribution and data rights established as in UN A/AC 105.723 [1] III. Photon Astrophysics from Space The astrophysical studies from space have been historically driven by the major Space Agencies from the United States, Europe, Russia, and Japan. The table below shows the past and future Astrophysics missions in the quarter century spanning the turn of the century.