Cornell Caltech Atacama Telescope (CCAT) Feasibility/Concept Design Study Final Report January 2006 Cornell University California Institute of Technology Jet Propulsion Laboratory Table of Contents Contributors 1.0 Executive Summary 2.0 The CCAT Vision 3.0 Introduction 4.0 CCAT Science 5.0 Top-Level Requirements 6.0 Instrumentation 7.0 CCAT Concept Design Overview 8.0 CCAT Baseline Optical Design 9.0 Systems Engineering 10.0 Site Selection 10.2 Geotechnical Report, GEO Consultores 11.0 Site, Architecture, and Civil Engineering 11.2 M3 Engineering and Technology Corporation Report 12.0 Enclosure Dome 12.2 AMEC Dynamic Structures Ltd. Report 13.0 Telescope Mount 13.2 VertexRSI Report 14.0 Primary Mirror 14.2 Molded Borosilicate Panels, ITT Industries 14.3 CFRP Al Panels, Composite Mirror Applications 14.4 Mandrel Manufacturing, Goodrich 15.0 CCAT Telescope Alignment and Guiding 15.2 Calibration and Wavefront Sensing 15.3 Laser Metrology 15.4 Shack Hartmann Alignment System, Adaptive Optics Associates 15.5 Optical Guiding with CCAT 16.0 Secondary and Tertiary Mirror Systems 16.2 CSA Engineering Report 17.0 Observatory Control System 18.0 Integration Plan 19.0 Operations Concept 20.0 Project Plan 21.0 Summary Acronyms CCAT Project Management Director: Ricccardo Giovanelli Project Manager: Thomas Sebring Deputy Project Manager: Simon Radford Project Scientists: Terry Herter, Jonas Zmuidzinas Instrument Committee Chair: Gordon Stacey JPL Lead: Paul Goldsmith Contributors Contractors Andrew Blain, Caltech Adaptive Optics Associates Matt Bradford, JPL Ten Wilson Road Cambridge, MA 02138-1128 Robert Brown, Cornell University Don Campbell, Cornell University AMEC Dynamic Structures Ltd. German Cortes, Cornell University 1515 Kingsway Ave. British Columbia, V3C1S2 Darren Dowell, JPL Mark Dragovan, JPL CSA Engineering 2565 Leghorn Street Neal Evans, Univ. of Texas Mountain View, CA 94043-1613 Duncan Farrah, Cornell University Composite Mirror Applications Sunil Golwala, Caltech 1638 S. Research Loop, #100 Paul Harvey, Univ. of Texas Tucson, AZ 85710 Chuck Henderson, Cornell University General Dynamics/Vertex RSI Shardha Jogee, Univ. of Texas 1217 Digital Drive Teresa Jordan, Cornell University Richardson, TX 75081 William Langer, JPL GEO Consultores James Lloyd, Cornell University 6 1/2 Oriente 169 Jean-Luc Margot, Cornell University Viña del Mar, Chile Thomas Nikola, Cornell University Goodrich Optical and Space Systems Thomas Phillips, Caltech 100 Wooster Heights Shanti Rao, JPL Danbury, CT 06810-7589 Anthony Readhead, Caltech ITT Industries Eugene Serabyn, JPL Space Systems Division Michael Werner, JPL 800 Lee Road Rochester, NY 14606-0488 Harold Yorke, JPL David Woody, Caltech M3 Engineering & Technology Corp. 2440 W. Ruthrauff Rd., Suite 170 Feng Zhao, JPL Tucson, AZ 85705 Polytec PI 16 Albert Street Auburn, MA 01501 1 Executive Summary Cornell University, the California Institute of Technology (Caltech), and Caltech’s Jet Propulsion Laboratory have joined to study the development of a 25 meter telescope to be built above 5000 meters in the Atacama region of northern Chile. The Cornell-Caltech Atacama Telescope (CCAT), operating to the shortest submillimeter wavelengths at which the atmosphere is transparent, will enable astronomical research that no other telescope on earth or in space can perform. Compared to currently existing single-aperture submillimeter telescopes, CCAT will: • Be substantially larger (25 m vs. 10-15 m) to yield images more quickly and see deeper into space • Have a more accurate surface (rms. error of 10 μm vs. 15-25 μm) to provide high resolution images • Employ a site with better atmospheric transmission (Above 5000 meters altitude) • Employ larger, more capable instruments capable of imaging larger areas of the sky. The CCAT will enable the partner institutions to maintain and enhance their positions at the forefront of astronomical research and will substantially advance our understanding of the universe. Over the past year astronomers at Cornell and Caltech have worked to identify the most significant areas of submillimeter research and derive the requirements these programs place on the telescope and instrumentation. The research programs proposed include surveys of galaxy formation in the early universe, galaxy clusters, planetary origins, and the regions within molecular clouds where stars form. The wide field of view of the telescope will make it the best instrument in the world to survey large areas of the sky at submillimeter wavelengths, providing an excellent scientific complement to the Atacama Large Millimeter Array, an interferometer array being built by the US and Europe in the same region of Chile. During the course of this study we have used the resources of the partner institutions, science and instrumentation committees, and experienced commercial vendors to define a baseline telescope concept design and to evaluate the feasibility and risks associated with its development. Building on technologies developed for the most recent optical and radio telescopes, approaches have been identified which can make the CCAT cost effective, reliable, and robust in operation. This report presents details of architectural and mechanical design of the telescope buildings, dome, and telescope mount together with studies of two possible approaches to mirror panel fabrication and testing. Analysis to assess the first order risks associated with development of the telescope is provided and these risks have been found to be manageable. The total Project has been designed to a target of $100m and detailed cost estimates developed during the study show that this is a reasonable project budget. This study constitutes the first phase of development of the Project. The next phase, Engineering Concept Design, is scheduled to begin in June of 2006 and to last one year. This work will significantly advance the design and provide a more detailed assessment of the approaches chosen. When completed, the majority of technical issues will have been thoroughly analyzed, the configuration of all the subsystems chosen, and the cost for construction and operations known to a high degree of accuracy. Detailed design, manufacturing, and construction will follow over a six year Development Phase. First Light is planned in 2012, to be followed by a one year Commissioning Phase to optimize performance of the telescope. The results to date show the development of CCAT is strategically important and technically feasible. The concept developed is viable, the cost is within expectations, and the scientific goals are compelling. CCAT has the potential to substantially advance astronomical science and significantly enhance the stature of the partner institutions. Executive Summary 1-1 2 The CCAT Vision The Cornell-Caltech Atacama Telescope, CCAT, is specifically designed as a surveyor of cosmic origins. Operating at the far infrared and submillimeter wavelengths at which radiation from distant sites of cosmic birth reaches us, it will be the prime instrument to provide large scale surveys of primeval galaxies, of forming stars, and of the circumstellar disks within which planets aggregate and which may, eventually, lead to the development of life. The detection and study of cosmic radiation at far infrared and submillimeter wavelengths presents some of the hardest challenges of any region of the electromagnetic spectrum. The Earth’s atmosphere absorbs and emits profusely at those wavelengths, both removing valuable photons from the line of sight to cosmic sources and adding unwanted noise. That and the rapidly varying conditions of our dynamic atmosphere make the treatment of data a difficult exercise. In order to minimize the difficulty of that task, the CCAT will be built on a site at which the atmosphere will be minimally intruding: a desert location as high as we can drive a truck. Many good reasons can explain why telescopes of previous generations were not built at extreme elevations, not last being the desire to breathe and think clearly while observing. Advances in communications technology do make it now possible to operate complex facilities remotely and we can dare to place our telescope as high as it is practical to build it. Moreover, advances in forecasting of atmospheric conditions, possible with increasing accuracy and look-ahead times, will make it possible for CCAT to be scheduled in a dynamic manner to optimize the match between science and observing conditions. The technology of far infrared and submillimeter detectors is undergoing a rapid development. Only a few years ago the most advanced bolometer array cameras had no more than a few dozen pixels. The first light camera intended for CCAT will have several tens of thousands pixels and the telescope is being designed to accommodate megapixel cameras in its field of view. Size, site, and a design that will take advantage of the fast-moving technological wave will make the combination of CCAT's sensitivity, resolution, and survey speed unmatched in its wavelength range by any other telescope on Earth. CCAT will have a primary mirror 25 m in diameter. That size is determined by the desire to avoid confusion limits for integration times of practical interest, a goal impossible to achieve with the smaller telescope sizes imposed by deployment in the atmosphere-free environment of outer space. Sites under consideration for the CCAT are all located in the vicinity of the Chajnantor Plateau in the Atacama Desert of northern Chile. Geography, meteorology, availability