This pdf file contains the front matter associated with SPIE Proceedings Volume 7731, including Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The next generation of large space telescopes, including ATLAST, SAFIR, IXO and Generation-X will require the development of key technologies to enable their development at an affordable cost. This includes technologies for the rapid, low cost fabrication of ultra-light weight primary mirror segments, active figure control of primary mirror segments, high speed wavefront sensing and control, highly-packageable and scalable deployment techniques, and active vibration and thermal control for light weight structural elements to supply good pointing stability. In this paper we discuss the current state-of-the-art for these technologies and roadmaps for future development in these areas.

Following recommendations by the NRC, NASA's FY 2008 Authorization Act and the FY 2009 and 2010 Appropriations bills directed NASA to assess the use of the human spaceflight architecture to service existing/future observatory-class scientific spacecraft. This interest in satellite servicing, with astronauts and/or with robots, reflects the success that NASA achieved with the Shuttle program and HST on behalf of the astronomical community as well as the successful construction of ISS. This study, led by NASA GSFC, will last about a year, leading to a final report to NASA and Congress in autumn 2010. We will report on its status, results from our March satellite servicing workshop, and recent concepts for serviceable scientific missions.

Parametric cost models are routinely used to plan missions, compare concepts and justify technology investments. This paper reviews the methodology used to develop space telescope cost models; summarizes recently published single variable models; and presents preliminary results for two and three variable cost models. Some of the findings are that increasing mass reduces cost; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and technology development as a function of time reduces cost at the rate of 50% per 17 years.

The James Webb Space Telescope (JWST) is a large aperture, space telescope designed to provide imaging and spectroscopy from 1.0 μm to 28 μm. JWST will be launched to an orbit at L2 aboard an Ariane 5 launcher in 2013. The Goddard Space Flight Center (GSFC) is the lead center for the JWST program and manages the project for NASA. The prime contractor for JWST is Northrop Grumman Aerospace Systems (NGST). JWST is an international partnership with the European Space Agency (ESA), and the Canadian Space Agency (CSA). ESA will contribute the Ariane 5 launch, and a multi-object infrared spectrograph. CSA will contribute the Fine Guidance Sensor (FGS), which includes the Tunable Filter Imager (TFI). The European consortium, in collaboration with the Jet Propulsion Laboratory (JPL), builds the mid-infrared imager (MIRI). In this paper we present an overview of the JWST science program, and discuss recent progress in the development of the observatory.

The Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is discussed from a systems perspective with emphasis on development status and advanced technology aspects. The ISIM is one of three elements that comprise the JWST space vehicle and is the science instrument payload of the JWST. The major subsystems of this flight element and their build status are described.

The James Webb Space Telescope (JWST) Optical Telescope Element has completed its Critical Design Review and is well into fabrication. This paper will summarize efforts to date in the design, manufacturing and planning for integration and testing. This will include a top level summary of mirror performance to date, hardware results, and planning status for the integration and testing program. The future plans for manufacturing, assembly, alignment and testing will also be summarized at a top level.

The James Webb Space Telescope (JWST) is a large space based astronomical telescope that will operate at cryogenic temperatures. The telescope by virtue of its size must be stowed in an inoperable configuration for launch and remotely reconfigured in space to meet the operational requirements using active Wave Front Sensing and Control (WFSC). This paper will report on the optical budgeting process used to manage the performance of the active system. The current status of the design and verification of the optical hardware, the WFSC processes, and the total system verification modeling will be presented. More detailed discussions of the system verification by analysis will be presented in separate accompanying papers.

The Near Infrared Camera (NIRCam) is one of the four science instruments of the James Webb Space Telescope (JWST). Its high sensitivity, high spatial resolution images over the 0.6 - 5 μm wavelength region will be essential for making significant findings in many science areas as well as for aligning the JWST primary mirror segments and telescope. The NIRCam engineering test unit was recently assembled and has undergone successful cryogenic testing. The NIRCam collimator and camera optics and their mountings are also progressing, with a brass-board system demonstrating relatively low wavefront error across a wide field of view. The flight model's long-wavelength Si grisms have been fabricated, and its coronagraph masks are now being made. Both the short (0.6 - 2.3 μm) and long (2.4 - 5.0 μm) wavelength flight detectors show good performance and are undergoing final assembly and testing. The flight model subsystems should all be completed later this year through early 2011, and NIRCam will be cryogenically tested in the first half of 2011 before delivery to the JWST integrated science instrument module (ISIM).

The Near Infrared Spectrograph (NIRSpec) is one of the four science instruments aboard the James Webb Space Telescope (JWST) scheduled for launch in 2014. NIRSpec is sensitive in the wavelength range from ~ 0.6 to 5.0 μm and will be capable of obtaining spectra of more than a 100 objects simultaneously, as well as fixed slit high contrast spectroscopy of individual sources. It also features an integral field unit for 3D spectroscopy. The key scientific objectives of the instrument include studies of star formation and chemical abundances of young distant galaxies and tracing the creation of the chemical elements back in time. In this paper, we present the status of the NIRSpec instrument as it is currently being prepared for its extensive ground calibration campaign later in 2010.

MIRI is one of four instruments to be built for the James Webb Space Telescope. It provides imaging, coronography and integral field spectroscopy over the 5-28.5um wavelength range. MIRI is the only instrument which is cooled to 7K by a dedicated cooler, much lower than the passively cooled 40K of the rest of JWST, and consists of both an Optical System and a Cooler System. This paper will describe the key features of the overall instrument design and then concentrate on the status of the MIRI Optical System development. The flight model design and manufacture is complete, and final assembly and test of the integrated instrument is now underway. Prior to integration, all of the major subassemblies have undergone individual environmental qualification and performance tests and end-end testing of a flight representative model has been carried out. The paper will provide an overview of results from this testing and describe the current status of the flight model build and the plan for performance verification and ground calibration.

The Fine Guidance Sensor (FGS) of the James Webb Space Telescope (JWST) features a tunable filter imager (TFI) module covering the wavelength range from 1.5 to 5.0 μm at a resolving power of ~100 over a field of view of 2.2'×2.2'. TFI also features a set of occulting spots and a non-redundant mask for high-contrast imaging. This paper presents the current status of the TFI development. The instrument is currently under its final integration and test phase.

During 2009, Tinsley finished most of the Configuration 1 pre-cryo test Computer Controlled Optical Surfacing (CCOS) operations on the James Webb Space Telescope primary mirror segments and in mid-2009 we began the Configuration 2 post-cryo test CCOS operations. After completing the grinding and polishing operations, including final figuring to a cryo-null target, we delivered the finished Engineering Development Unit (EDU) to Ball Aerospace Technology Corporation on 4 December 2009. Achieving fabrication and metrology conditions to meet the specifications for this off-axis ~1.5 m hexagonal point-to-point segmented mirror required special methods. Achieving repeatable and accurate interferometric alignment of the off-axis aspherical mirror surface and stable thermal gradient control of the beryllium substructure during tests required rigorous component and system-level validation. Final optical wavefront measurements over the various spatial frequency ranges have demonstrated that all of the requirements are met. This success has validated our processes of fabrication and metrology and allows us to proceed with the production of the 18 flight mirror segments. The first finished flight mirror, the Tertiary Mirror, was shipped to BATC on 24 February, 2010. Performance of that mirror is reported here also.

The Mid Infra Red Instrument (MIRI) is one of the four instruments onboard the James Webb Space Telescope (JWST), providing imaging, coronagraphy and spectroscopy over the 5 - 28 μm band. To verify the optical performance of the instrument, extensive tests were performed at CEA on the flight model (FM) of the Mid-InfraRed IMager (MIRIM) at cryogenic temperatures and in the infrared. This paper reports on the point spread function (PSF) measurements at 5.6 μm, the shortest operating wavelength for imaging. At 5.6 μm, the PSF is not Nyquist-sampled, so we use am original technique that combines a microscanning measurement strategy with a deconvolution algorithm to obtain an over-resolved MIRIM PSF. The microscanning consists in a sub-pixel scan of a point source on the focal plane. A data inversion method is used to reconstruct PSF images that are over-resolved by a factor of 7 compared to the native resolution of MIRI. We show that the FWHM of the high-resolution PSFs were 5 - 10 % wider than that obtained with Zemax simulations. The main cause was identified as an out-of-specification tilt of the M4 mirror. After correction, two additional test campaigns were carried out, and we show that the shape of the PSF is conform to expectations. The FWHM of the PSFs are 0.18 - 0.20 arcsec, in agreement with simulations. 56.1 - 59.2% of the total encircled energy (normalized to a 5 arcsec radius) is contained within the first dark Airy ring, over the whole field of view. At longer wavelengths (7.7 - 25.5 μm), this percentage is 57 - 68 %. MIRIM is thus compliant with the optical quality requirements. This characterization of the MIRIM PSF, as well as the deconvolution method presented here, are of particular importance, not only for the verification of the optical quality and the MIRI calibration, but also for scientific applications.

The Verification Model (VM) of MIRI has recently completed an extensive programme of cryogenic testing, with the Flight Model (FM) now being assembled and made ready to begin performance testing in the next few months. By combining those VM test results which relate to MIRI's scientific performance with measurements made on FM components and sub-assemblies, we have been able to refine and develop the existing model of the instrument's throughput and sensitivity. We present the main components of the model, its correlation with the existing test results and its predictions for MIRI's performance on orbit.

The James Webb Space Telescope (JWST) requires cryogenic testing of a critical stray light path, named as the Rogue Path. Although blockage of this path is verified during fabrication and assembly of JWST, simple small light sources added to the test configuration provide an opportunity to check for successful blockage at the system level in the cryogenic environment. Although the test occurs in the largest environmental chamber at the NASA Johnson Space Center, the size of the chamber challenges this test by placing the origin of the Rogue Path within the collimated beam of the telescope. The design of the test overcomes this challenge with sufficient signal to noise ratio and without interference with the optical test of the system.

AKARI, the Japanese satellite mission dedicated for infrared astronomy launched in 2006 February, exhausted its 180 litter liquid helium (LHe) in 2007 August. After the LHe exhaustion, the telescope and focal plane of AKARI have still been kept less than 50K by the onboard cryocooler and near-infrared (NIR) observations with the Infrared Camera (IRC) are continuing. The data reduction software optimized for the warm mission enables us to carry out efficient and sensitive observations in the NIR despite the increase of hot pixels. In particular, the NIR spectroscopic capability of the IRC provides a unique opportunity to obtain spectra in 2.5-5μm with a high sensitivity, which will not be able to be carried out with any other facilities until JWST. An overview of the AKARI warm mission is given together with the performance and some observational results taken during the warm mission.

We present an overview of the calibration and properties of data from the IRAC instrument aboard the Spitzer Space Telescope taken after the depletion of cryogen. The cryogen depleted on 15 May 2009, and shortly afterward a two-month- long calibration and characterization campaign was conducted. The array temperature and bias setpoints were revised on 19 September 2009 to take advantage of lower than expected power dissipation by the instrument and to improve sensitivity. The final operating temperature of the arrays is 28.7 K, the applied bias across each detector is 500 mV and the equilibrium temperature of the instrument chamber is 27.55 K. The final sensitivities are essentially the same as the cryogenic mission with the 3.6 μm array being slightly less sensitive (10%) and the 4.5 μm array within 5% of the cryogenic sensitivity. The current absolute photometric uncertainties are 4% at 3.6 and 4.5 μm, and better than milli-mag photometry is achievable for long-stare photometric observations. With continued analysis, we expect the absolute calibration to improve to the cryogenic value of 3%. Warm IRAC operations fully support all science that was conducted in the cryogenic mission and all currently planned warm science projects (including Exploration Science programs). We expect that IRAC will continue to make ground-breaking discoveries in star formation, the nature of the early universe, and in our understanding of the properties of exoplanets.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3-m class (3.2 m in the current design) telescope. Its high spatial resolution and unprecedented sensitivity in the mid- and far-infrared will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3-m class cooled (6 K) telescope in space with moderate total weight (3.7t). SPICA is proposed as a Japanese-led mission together with extensive international collaboration. The most important international partner is ESA. The assessment study on the European contribution to the SPICA project has started under the framework of the ESA Cosmic Vision 2015-2025. US and Korean participations are also being discussed extensively. The target launch year of SPICA is FY2018.

SPICA is a next generation infrared astronomy mission to reveal the origin of planets and galaxies. The mission is led by Japan Aerospace Exploration Agency (JAXA) in collaboration with the European Space Agency (ESA) and international consortiums in Japan, Europe, USA, and the Republic of Korea. SPICA is an "observatory" based on the heritage of AKARI's "all sky survey". ESA provides a 3-m class telescope using technology heritage of Herschel. The SPICA will achieve superior sensitivity in the mid- to far- infrared astronomy to be launched into space. SPICA has a completely new cooling system, which utilizes efficient mechanical coolers. This system enables a large, cryogenically cooled telescope in space. SPICA system concept and requirements are clear, but it is not easy to design. SPICA spacecraft consists of the Payload Module (PLM) and the Bus Module (BM). The PLM includes mechanical coolers and passive thermal shields, which enable to cool down the telescope and scientific instruments below 6K. The PLM is connected to the BM with low thermal conductivity truss structure to keep the PLM cool and the BM warm. This paper describes how to meet the system requirements to establish the feasible design of SPICA spacecraft.

The Mid-Infrared Medium-Resolution Eschelle Spectrometer (MIRMES) is one of the focal-plane instrument onboard SPICA mission proposed in the pre-project phase. It is designed for measuring the strengths and the profiles of lines and bands emitted from various phases of materials including ionized gas, gas-phase molecules, solid-phase molecules and dust particles in the wavelengths from 10 to 40μm. The MIRMES provides a medium resolution (R=700-1500) spectroscopic capability in the mid-infrared spectral range (10-36μm) with integrated field units of a field-of-view of about 12"×6" for shorter wavelength range (10-20μm) and 12"×12".5 for longer wavelength range (20-36μm). The science targets of the MIRMES and the results of the concept study on its optical design and the expected performance are described.

We are developing the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) for SPICA to provide a breakthrough capability for far-IR survey spectroscopy. SPICAs large cold aperture allows mid-IR to submm observations which are limited only by the natural backgrounds, and BLISS is designed to operate near this fundamental limit. BLISS-SPICA is 6 orders of magnitude faster than the spectrometers on Herschel and SOFIA in obtaining full-band spectra. It enables spectroscopy of dust-obscured galaxies at all epochs back to the rst billion years after the Big Bang (redshift 6), and study of all stages of planet formation in circumstellar disks. BLISS covers 35 - 433 microns range in ve or six wavelength bands, and couples two 2 sky positions simultaneously. The instrument is cooled to 50 mK for optimal sensitivity with an on-board refrigerators. The detector package is 4224 silicon-nitride micro-mesh leg-isolated bolometers with superconducting transition-edge-sensed (TES) thermistors, read out with a cryogenic time-domain multiplexer. All technical elements of BLISS have heritage in mature scientic instruments, and many have own. We report on our design study in which we are optimizing performance while accommodating SPICAs constraints, including the stringent cryogenic mass budget. In particular, we present our progress in the optical design and waveguide spectrometer prototyping. A companion paper in Conference 7741 (Beyer et al.) discusses in greater detail the progress in the BLISS TES bolometer development.

We have undertaken a study of a far infrared imaging spectrometer based on a Fourier transform spectrometer that uses well-understood, high maturity optics, cryogenics, and detectors to further our knowledge of the chemical and astrophysical evolution of the Universe as it formed planets, stars, and the variety of galaxy morphologies that we observe today. The instrument, Wide-field Imaging Spectrometer for the InfraRed (WISPIR), would operate on the SPICA observatory, and will feature a spectral range from 34 - 210 microns and a spectral resolving power of R=1,000 to 6,000, depending on wavelength. WISPIR provides a choice of full-field spectral imaging over a 2'×2' field or longslit spectral imaging along a 2' slit for studies of astrophysical structures in the local and high-redshift Universe. WISPIR in long-slit mode will attain a sensitivity two orders of magnitude better than what is currently available.

Mid-InfRAred Camera w/o LEns (MIRACLE) is a focal plane instrument for the future JAXA/ESA infrared astronomical mission, SPICA. MIRACLE is designed for wide field imaging (5' × 5') and low-resolution spectroscopic observations (R~100) over a wide spectral range in the mid-infrared wavelengths (5-38μm). Thanks to the SPICA's large aperture (3-m class) and cold (<6K) telescope, MIRACLE has a better sensitivity than JWST/MIRI at the wavelength over 20μm (3.5 μJy at 20μm, R=5, S/N=5, 3600 seconds) and its wider field of view (FOV) provides a faster mapping speed in its full spectral range for point sources. Confocal off-axis reflective imaging system provides a wide FOV with diffraction limited image quality over wide spectral range. MIRACLE consists of two channels: MIRACLE-S and MIRACLE-L, which are optimized for 5-26μm and 20- 38μm, respectively. Each of them consists of a fore-optics and a rear-optics, each of which has a pupil position equipped with a filter wheel and a grating wheel, respectively. A field stop wheel, which provides optimal slits in the spectroscopic mode and a wide FOV in the imaging mode, is installed at the focal plane of the fore-optics. A large format array detector (Si:As 2K×2K for MIRACLE-S and Si:Sb 1K×1K for MIRACLE-L) is installed at the focal plane of the rear-optics in order to achieve Nyquist sampling of the point spread function. Contiguous wavelength coverage is considered in choice of the filter bands from the experiences in the Spitzer and AKARI observations. We will present the results of conceptual design study including sensitivity analysis.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is a Japan-led infrared astronomical satellite project with a 3-m-class telescope in collaboration with Europe. The telescope is cooled down to temperature below 6 K in space by a combination of mechanical coolers with radiative cooling in space. The telescope has requirements for its total weight to be lighter than 700 kg and for the imaging performance to be diffraction-limited at 5 μm at 6 K. The mirrors will be made of silicon carbide (SiC) or its related material, which has large heritages of the AKARI and Herschel telescopes. The design of the telescope system has been studied by the Europe-Japan telescope working group led by ESA with European industries to meet the requirements. As for optical testing, responsibilities will be split between Europe and Japan so that final optical verification at temperatures below 10 K will be executed in Japan. We present our recent optical testing activities in Japan for the SPICA telescope, which include the numerical and experimental studies of stitching interferometry as well as modifications of the 6-m-diameter radiometer space chamber facility at Tsukuba Space Center in JAXA. We also show results of cryogenic optical testing of the 160-mm and 800-mm lightweight mirrors made of a C/SiC material called HBCesic, which is a candidate mirror material for the SPICA telescope.

The Wide-field Infrared Survey Explorer (WISE), launched in December 2009, is a NASA-funded Explorer mission that is providing an all-sky survey in the mid-infrared with far greater sensitivity and resolution than any previous IR survey mission. The Utah State University Space Dynamics Laboratory designed, fabricated, and characterized the science payload, which is a cryogenically cooled infrared telescope with four 1024x1024 infrared focal plane arrays covering from 2.8 to 26 μm. Pre-launch characterization included measuring focus, image quality, repeatability, response nonlinearity, saturation, latency, absolute response, flatfield, point response function, scanner linearity, and relative spectral response. This paper provides a brief overview of the payload, discusses pre-launch characterization methods, and presents key performance results from ground characterization and early on-orbit performance.

On December 14, 2009 NASA launched the Wide-field Infrared Survey Explorer (WISE), a NASA MIDEX mission within the Explorers program that is currently performing an all-sky survey in four infrared bands. L-3 Integrated Optical Systems/SSG designed, built, and tested the telescope, scanner, and aft imaging optical system for WISE under contract to the Space Dynamics Laboratory. Hardware and test results for those subsystems are presented, as well as an on-orbit status of their imaging performance. The WISE payload includes a 40 cm afocal telescope, a scan mirror for back-scan during integration, and an aft optics imager assembly. All modules operate below 17 Kelvin. The allreflective system uses aluminum mirrors and metering structures. The afocal telescope provides distortion control to better than two parts in a thousand to prevent image blur during internal scanning. The one-axis scan mirror at the exit pupil scans the detectors' field-of-view across the telescope field-of-regard, countering the orbital motion and freezing the line of sight during the multi-second exposure period. The five-mirror imaging optics module follows the scan mirror and feeds dichroic beamsplitters that separate the energy into four channels between 2.8 and 26 microns. Once initial on-orbit checkout and calibration was completed, WISE began a 6-month mission performing an all-sky survey in the four infrared bands, which is over 80% complete as of June 2010.

The Wide Field Camera 3 (WFC3) was installed into the Hubble Space Telescope during Servicing Mission 4 in May 2009. This panchromatic camera considerably improves the ultraviolet, visible, and infrared imaging capabilities of HST. Commissioned over the summer of 2009, WFC3 is now fully functional and responsible for approximately half of the Cycle 17 HST Science Program. This paper will review the scientific performance of WFC3 including its sensitivity in absolute terms and relative to other HST instruments. The paper will also discuss the calibration programs for WFC3 and the achieved photometric and astrometric calibration accuracies. Lessons learned from the ground calibration and in-flight commissioning will also be considered.

Herein we report on a preliminary study to assess the use of the Hubble Space Telescope (HST) for the direct detection and spectroscopic characterization of exoplanets and debris disks - an application for which HST was not originally designed. Coronagraphic advances may enable the design of a science instrument that could achieve limiting contrasts ~10⁹ beyond 275 milli-arcseconds (4 λ/D at 800 nm) inner working angle, thereby enabling detection and characterization of several known jovian planets and imaging of debris disks. Advantages of using HST are that it already exists in orbit, it's primary mirror is thermally stable and it is the most characterized space telescope yet flown. However there is drift of the HST telescope, likely due to thermal effects crossing the terminator. The drift, however, is well characterized and consists of a larger deterministic components and a smaller stochastic component. It is the effect of this drift versus the sensing and control bandwidth of the instrument that would likely limit HST coronagraphic performance. Herein we discuss the science case, quantify the limiting factors and assess the feasibility of using HST for exoplanet discovery using a hypothetical new instrument.

The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments onboard the European Space Agency's Herschel Space Observatory launched on 14 May 2009. The low to medium resolution spectroscopic capability of SPIRE is provided by an imaging Fourier transform spectrometer of the Mach-Zehnder configuration. Results from the in flight performance verification phase of the SPIRE spectrometer are presented and conformance with the instrument design specifications is reviewed.

The Kepler Mission is designed to detect the 80 parts per million (ppm) signal from an Earth-Sun equivalent transit. Such precision requires superb instrument stability on time scales up to 2 days and systematic error removal to better than 20 ppm. The sole scientific instrument is the Photometer, a 0.95 m aperture Schmidt telescope that feeds the 94.6 million pixel CCD detector array, which contains both Science and Fine Guidance Sensor (FGS) CCDs. Since Kepler's launch in March 2009, we have been using the commissioning and science operations data to characterize the instrument and monitor its performance. We find that the in-flight detector properties of the focal plane, including bias levels, read noise, gain, linearity, saturation, FGS to Science crosstalk, and video crosstalk between Science CCDs, are essentially unchanged from their pre-launch values. Kepler's unprecedented sensitivity and stability in space have allowed us to measure both short- and long- term effects from cosmic rays, see interactions of previously known image artifacts with starlight, and uncover several unexpected systematics that affect photometric precision. Based on these results, we expect to attain Kepler's planned photometric precision over 90% of the field of view.

Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observations of the white light corona inside typically 2-2.5 solar radii. Formation flying offers an elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at a distance of hundred meters. Such an instrument, ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire), has just been selected by the European Space Agency (ESA) to fly (launch expected in 2014) on its third PROBA (Project for On-Board Autonomy) mission of formation flying demonstration which is presently in phase B. It will perform both high spatial resolution imaging of the solar corona as well as 2- dimensional spectroscopy of several emission lines (in particular the forbidden line of FeXIV at 530.285 nm) from the coronal base out to 3 solar radii. For this, it will use filters, polarisers and a solid Fabry-Perot interferometer ("étalon"). The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.04-0.05 solar radii (40-50 arcsec) from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to reach the chromosphere and the upper part of the spicules.

Possible optical designs of a Narrow Angle Camera (NAC) suitable for being the high resolution channel of the MarcoPolo Camera System for the MarcoPolo ESA mission are presented. The MarcoPolo mission objective is the rendezvous with a Near Earth Asteroid in order to fully characterize the body, to land on the surface and to return to Earth a sample of the asteroid soil. Science goals for the NAC are global mapping of the object, detailed investigations of the surface at high spatial resolution (order of millimeters), and deep examination of possible landing sites from a close distance. The instrument has a 3"/pixel scale factor, corresponding to 80 mm/px at 5 km from the surface, on a 1.75° × 1.75° FoV; imaging in 5 to 8 different spectral bands (panchromatic and broadband), in the range between 400 and 900 nm, is foreseen. Since the target is an extended low contrast object, to avoid image contrast degradation, only off-axis unobstructed optical layouts have been considered. Solutions with two mirrors plus a refractive corrector, or all-reflective three mirrors ones, have been studied, both allowing to reach good aberration balancing over all the field of view: the diffraction Ensquared Energy inside one pixel of the detector is of the order of 70%. To cope with the hazardous radiation environment in which the spacecraft will be immersed in during the mission, all the glasses selected for the design are rad-hard type.

The LOng-Range Reconnaissance Imager (LORRI) is the high resolution imager for the New Horizons mission to the Pluto system and the Kuiper Belt, which is the vast region of icy bodies extending roughly from 30 to 50 astronomical units (AU). LORRI is a monolithic SiC, Ritchey-Chrétien telescope with a 20.8 cm diameter primary mirror and with an 0.29° field of view. The detector is a thinned, backside-illuminated charge-coupled device (CCD) operated in frame transfer mode to obtain 1024 × 1024 pixel, panchromatic images over a bandpass of approximately 350 nm to 850 nm with 4.96 μrad pixels. LORRI operated successfully at the New Horizons Jupiter encounter in Feb-Mar 2007 and made challenging observations of faint sources, such as the Jovian rings within a few degrees of sunlit Jupiter and the nightside of Io illuminated by Jupiter shine. Ambitious observations are planned at Pluto encounter including some with LORRI pointed within 15° of the Sun. A unique program of inflight calibrations has measured LORRI's stray light rejection using Jupiter and the Sun. The measured point source transmittance (PST) function for LORRI decreases from 145 on axis to 4×10^-10 at 75° off-axis.

SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact instrument for spectropolarimetry, and in particular for detecting and characterizing aerosols in planetary atmospheres. With its ~1-liter volume it is capable of full linear spectropolarimetry, without moving parts. The degree and angle of linear polarization of the incoming light is encoded in a sinusoidal modulation of the intensity spectrum by an achromatic quarter-wave retarder, an athermal multiple-order retarder and a polarizing beam-splitter in the entrance pupil. A single intensity spectrum thus provides the spectral dependence of the degree and angle of linear polarization. Polarimetry has proven to be an excellent tool to study microphysical properties (size, shape, composition) of atmospheric particles. Such information is essential to better understand the weather and climate of a planet. The current design of SPEX is tailored to study Martian dust and ice clouds from an orbiting platform: a compact module with 9 entrance pupils to simultaneously measure intensity spectra from 400 to 800 nm, in different directions along the flight direction (including two limb viewing directions). This way, both the intensity and polarization scattering phase functions of dust and cloud particles within a ground pixel are sampled while flying over it. We describe the optical and mechanical design of SPEX, and present performance simulations and initial breadboard measurements. Several flight opportunities exist for SPEX throughout the solar system: in orbit around Mars, Jupiter and its moons, Saturn and Titan, and the Earth.

Gaia is the next space-astrometry mission of the European Space Agency, following up on the success of the Hipparcos mission. With a focal plane containing more than 100 large-area CCD detectors, Gaia will survey the sky and repeatedly observe the brightest 1,000 million (one billion) objects, down to 20th magnitude, during its 5-year nominal lifetime. Gaia's science data will comprise absolute astrometry, broad-band photometry, and low-resolution spectro-photometry. Medium-resolution spectroscopic data (resolving power 11,500) will be obtained for the brightest 150 million sources, down to 17th magnitude. The extreme thermo-mechanical stability of the spacecraft, combined with the selection of the L2 Lissajous point of the Sun-Earth/Moon system for operations, allows stellar parallaxes (distances) to be measured with standard errors less than 10 micro-arcsecond (μas) for stars brighter than 13th magnitude, 20-30 μas for stars at 15th magnitude, and around 300 μas at magnitude 20. Photometric standard errors are in the milli-magnitude regime. The spectroscopic data will allow the measurement of radial velocities with errors at the level of 15 km s-1 at magnitude 17. Gaia's primary science goal is to unravel the kinematical, dynamical, and chemical structure and evolution of the Milky Way. In addition, Gaia's data will touch many other areas of research, for instance stellar physics, solar-system bodies, fundamental physics, and exo-planets. The Gaia spacecraft is currently undergoing its critical design review (CDR). With a launch foreseen in the second half of 2012, the final catalogue is expected in 2020. The science community in Europe, organized in the Gaia Data Processing and Analysis Consortium (DPAC), is responsible for the processing of the Gaia data. This formidable task is in full preparation. The calibration of the data presents exciting challenges, in particular in the area of radiation-damage-induced charge-transfer inefficiency (CTI).

We present the latest optical design concepts for the Joint Dark Energy Mission (JDEM). This mission will tightly constrain the cosmological parameters describing the accelerating expansion of the universe. The current candidate designs are based on extensive examination of the interplay of requirements for the leading techniques being considered for space borne observation: Baryon Acoustic Oscillation (BAO), Type Ia Supernovae (SN), and gravitational Weak Lensing (WL). All techniques require very large fields of view across the visible/near infrared spectrum; BAO uniquely requires a moderate dispersion wide field spectroscopy capability. Weak lensing requires very good stability and knowledge of the point spread function in order to enable detection of local variations in galaxy ellipticities caused by the intervening dark matter. SN imaging spectroscopy should be done to high photometric signal to noise in order to make best use of these 'standard candles.' We have studied medium class and smaller, "Probe" class implementations enabling from one to three of these techniques. We describe two concepts that were submitted to the 2010 Astrophysics Decadal review as well as current concepts.

Weak gravitational lensing of galaxies is a versatile probe of the distribution of gravitating matter, both visible and invisible, and the influence of cosmological dark energy on that distribution for z<1.5. The weak lensing method is under consideration as an element of NASA-DOE Joint Dark Energy Mission (JDEM). The measurements are challenging, because of an ambitious goal for sensitivity to feeble gravitational shear and a competing goal for an extremely large statistical sample of galaxies. This motivates an instrument design which has very few pixels across each galaxy image and yet must extract galaxy shape information with very high precision and accuracy. This in turn places stiff requirements on calibration during observations and on instrument stability. We present a tool for estimating the impact of telescope and detector physics on the estimated lensing shear, in a way that permits us to propagate the instrument performance allocations all the way to bias uncertainties in gravitational shear. This tool can be validated against integrated modeling, and would allow powerful capability for system engineering trades.

The key enabling element of the Joint Dark Energy Mission (JDEM)^1,2,3 is a wide-field, high-magnification mixed spectroscopic and imaging telescope intended to study dark energy via measurement of the expansion history of the universe and the growth of large-scale structure. It is designed to provide tight constraints on the equation of state of dark energy and test the validity of general relativity. Complementary observation of Baryon Acoustic Oscillations (BAO), Type 1a Supernovae (SNe) and Gravitational Weak Lensing (WL) are under consideration for the mission. The science goals of this mission call for a high-resolution imaging survey and a spectroscopic survey of at least 10,000 square degrees. Signal to noise requirements of the Baryon Acoustic Oscillation (BAO) survey favor a prism disperser with a λ • d θ /d λ of roughly 200 arcsec and a coarse plate scale (~0.45arsec/pixel). The WL imaging survey seeks the shapes of galaxies, and therefore prefers a finer plate scale of ~0.1-0.23 arcsec/pixel. Accommodation all of these goals may be accomplished with an afocal telescope but the results of this study suggest that a focal telescope is also capable of achieving these goals. Discussed herein are several novel prism concepts designed for use in a focal three mirror anastigmat telescope (TMA). Multiple elements are used for aberration balancing and tailoring resolving power over the observational band. Several options for simultaneous or staggered imaging and spectroscopy as well as the required plate scale change with a focal TMA are presented.

It is well known that a telescope with an unobstructed circular pupil delivers a smaller diffraction pattern than one centrally obstructed by its secondary mirror. Spaceborne dark energy investigations require measuring targets over a wide range of redshifts, with the most distant galaxies being the reddest, faintest, and smallest. For any given signal-to-noise (SNR) requirement, these highest redshift targets are the most demanding in terms of mission cost (time, aperture, etc), not only because they are faint but also because the diffraction pattern is largest at the longest wavelengths being observed. At the same time, a telescope's field of view must be large -- the order of a square degree -- to survey the entire extragalactic sky in reasonable time. The large field of view imposes a minimum requirement on the size of the secondary mirror baffle. For a centrally obstructed telescope, an enlarged secondary mirror baffle further enlarges the diffraction pattern. Previously published JDEM telescopes were centrally obstructed. Here, we explore unobstructed telescope designs because these can have a nearly ideal Airy diffraction pattern, avoiding both the central obstruction and the supporting spider legs, limited only by optical manufacturing and alignment errors. They therefore can deliver the best possible SNR for a given aperture. Simulations show that a 1.1m unobstructed aperture can deliver about the same cosmological constraints as a 1.4m aperture that has a 50% linear central obstruction.

Euclid is a high precision survey mission under development by the European Space Agency to investigate the properties of Dark Energy and Dark Matter by means of a weak lensing and baryon acoustic oscillations experiments. The technical capabilities of Euclid are such that it also addresses other cosmological and astronomical topics, providing an unprecedented science legacy. The survey mission will carry out an imaging and spectroscopic survey of the entire extragalactic sky (20,000 deg²). Euclid carries a meter class telescope which feeds two instruments: a visible imager (VIS), a near-infrared photometer combined with a medium resolution spectrometer (NISP). The two instruments have identical sized field of views (0.5 deg²) and will operate simultaneously in step-and-stare mode. The nominal mission period is 5 years. We describe the mission, the satellite, and the payload concepts, which we have adopted at the start of the definition phase.

Euclid is an ESA Cosmic Vision wide-field space mission concept dedicated to the high-precision study of Dark Energy and Dark Matter. The mission relies on two primary cosmological probes: Weak gravitational Lensing (WL) and Baryon Acoustic Oscillations (BAO). The first probe requires the measurement of the shape and photometric redshifts of distant galaxies. The second probe is based on the 3-dimensional distribution of galaxies through spectroscopic redshifts. Additional cosmological probes are also used and include cluster counts, redshift space distortions, the integrated Sachs-Wolfe effect (ISW) and galaxy clustering, which can all be derived from a combination of imaging and spectroscopy. Euclid Imaging Channels Instrument of the Euclid mission is designed to study the weak gravitational lensing cosmological probe. The combined Visible and Near InfraRed imaging channels form the basis of the weak lensing measurements. The VIS channel provides high-precision galaxy shape measurements for the measurement of weak lensing shear. The NIP channel provides the deep NIR multi-band photometry necessary to derive the photometric redshifts and thus a distance estimate for the lensed galaxies. This paper describes the Imaging Channels design driver requirements to reach the challenging science goals and the design that has been studied during the Cosmic Vision Assessment Phase.

Euclid-VIS is a large format visible imager under investigation for the ESA Euclid space mission in their Cosmic Vision program. Together with the near infrared photometer (NIP) it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-920 nm over a field of view of ~0.5 deg². Over 4 exposures totalling 1800 sec, VIS will reach to V=24.9 (10σ) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable PSF over a wide surcey area of of 20000 deg² to measure the cosmic shear from over 2 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy deep imaging dataset of unprecedented spatial resolution over the entire extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Imaging Consortium during the Euclid Assessment Phase.

The NIP is a near infrared imaging photometer that is currently under investigation for the Euclid space mission in context of ESA's 2015 Cosmic Vision program. Together with the visible camera (VIS) it will form the basis of the weak lensing measurements for Euclid. The NIP channel will perform photometric imaging in 3 near infrared bands (Y, J, H) covering a wavelength range from ~ 0.9 to 2 μm over a field of view (FoV) of ~ 0.5 deg². With the required limiting point source magnitude of 24 mAB (5 sigma) the NIP channel will be used to determine the photometric redshifts of over 2 billion galaxies collected over a wide survey area of 20 000 deg². In addition to the photometric measurements, the NIP channel will deliver unique near infrared (NIR) imaging data over the entire extragalactic sky, enabling a wide variety of ancillary astrophysical and cosmological studies. In this paper we will present the results of the study carried out by the Euclid Imaging Consortium (EIC) during the Euclid assessment phase.

The Euclid Near-Infrared Spectrometer (E-NIS) Instrument was conceived as the spectroscopic probe on-board the ESA Dark Energy Mission Euclid. Together with the Euclid Imaging Channel (EIC) in its Visible (VIS) and Near Infrared (NIP) declinations, NIS formed part of the Euclid Mission Concept derived in assessment phase and submitted to the Cosmic Vision Down-selection process from which emerged selected and with extremely high ranking. The Definition phase, started a few months ago, is currently examining a substantial re-arrangement of the payload configuration due to technical and programmatic aspects. This paper presents the general lines of the assessment phase payload concept on which the positive down-selection judgments have been based.

PLATO - PLAnetary Transits and Oscillations of stars - is a Cosmic Vision 2015-2025 M-class mission candidate of ESA's future Science and Robotic Exploration programme. The scientific goals are to detect exoplanetary transits and to characterize the parent stars using astero-seismology. This is achieved through high-accuracy, high time-resolution photometry in the visible waveband. Assessment studies were carried out for all M-class missions during 2008-2009 in order to design a basic spacecraft configuration and identify critical areas. Following the down-selection in the beginning of 2010, PLATO will enter into the Definition Phase, in which the spacecraft design will be consolidated and optimized. The proposed payload will use a multi-aperture approach in which the combined observations of 34 telescopes with individual pupil sizes of ~120 mm will produce highly accurate light curves of the target stars. Since the orbits of the exoplanets should preferably be in or close to their habitable zone, an observation period of several years per sky field is required to detect repeated transits of the exoplanets around the parent stars. This requires a stable spacecraft with a high pointing accuracy and a benign operating environment. It is foreseen to launch PLATO using a Soyuz 2-1b via a direct insertion into a large amplitude orbit around Sun-Earth L2. This paper will give an overview of the PLATO mission and the planned activities during the Definition Phase.

The Wide Field Coronagraph Telescope (WFCT) is a 4-meter space telescope for general astrophysics and exoplanet observations that meets the 2000 Decadal Committee requirements. This paper presents a design for a 4-m diameter, off-axis space telescope that offers high performance in both wide field and coronagraphic imaging modes. A 3.8 x 3.3-m unobstructed elliptical pupil is provided for direct coronagraphic imaging of exoplanets and a 4-m diameter pupil for wide-field imaging from far-ultraviolet (UV) to near-infrared (IR). The off-axis wide-field optics are all reflective and designed to deliver an average of 12 nm wavefront aberrations over a 6 x 24 arcminute field of view (FOV), therefore providing diffraction-limited images down to 300 nm wavelength and 15 mas images down to a wavelength limit set only by the mirror coatings. The coronagraph with phase-induced amplitude apodization (PIAA) provides diffraction suppression around a 360-degree field with high Strehl and sensitivity at the 1e-10 level to an inner working angle of 2 λ/D (or 50 mas at 500 nm wavelength). This paper focuses on the optical design that allows the above imaging features to be combined in single telescope, and gives a preliminary spacecraft design and costing, assuming a distant trailing orbit.

Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500 km circular orbit and provide reliable imagery at NIIRS 7-8. An analysis of such an imager based on a lightweight, high-performance, structured 4m primary mirror cast from borosilicate glass is described. The relatively high CTE of this glass is used to advantage by maintaining mirror shape quality with a thermal figuring method. Placed in a 290 K thermal shroud (similar to the Hubble Space Telescope), the orbit averaged figure surface error is 6nm rms when earth-looking. Space-looking optical performance shows that a similar thermal conditioning scheme combined with a 270 K shroud achieves primary mirror distortion of 10 nm rms surface. Analysis shows that a 3-point bipod mount will provide launch survivability with ample margin. The primary mirror naturally maintains its shape at 1g allowing excellent end-to-end pre-launch testing with e.g. the LOTIS 6.5m Collimator. The telescope includes simple systems to measure and correct mirror shape and alignment errors incorporating technologies already proven on the LOTIS Collimator. We have sketched a notional earth-looking 4m telescope concept combined with a wide field TMA concept into a DELTA IV or ATLAS 552 EELV fairing. We have combined an initial analysis of launch and space performance of a special light-weighted honeycomb borosilicate mirror (areal density 95 kg/m²) with public domain information on the existing launch vehicles.

The General Purpose Astronomy - Small Satellite (GPA-SS) project studied the feasibility of developing a useful space telescope with a cost to launch below $100 million. An optical telescope assembly (OTA) designed for ground use is proposed for use in a space mission in order to take advantage of the economies of scale in existing mirror fabrication processes. This paper details the additional design, manufacture and test tasks required to flight-qualify the ground telescope. A near-infrared imaging space telescope was costed as a potential mission. Key subsystems were designed at a conceptual level. This design was used both to estimate subsystem costs and to inform the science achievable from a given telescope design. Subsystem costs were estimated from the design through a combination of previously published cost estimating relationships and vendor quotes. This paper concludes that the space-qualification of an existing ground telescope is a potential approach for making significant cost savings when designing a low cost space telescope. Additional work on design and cost estimation around the framework presented in this paper could be undertaken to add certainty to the cost estimate.

WISH is a new space science mission concept whose primary goal is to study the first galaxies in the early universe. We will launch a 1.5m telescope equipped with 1000 arcmin2 wide-field NIR camera by late 2010's in order to conduct unique ultra-deep and wide-area sky surveys at 1-5 micron. The primary science goal of WISH mission is pushing the high-redshift frontier beyond the epoch of reionization by utilizing its unique imaging capability and the dedicated survey strategy. We expect to detect ~10⁴ galaxies at z=8-9, ~3-6x10³ galaxies at z=11-12, and ~50-100 galaxies at z=14-17 within about 5 years of the planned mission life time. It is worth mentioning that a large fraction of these objects may be bright enough for the spectroscopic observations with the extremely large telescopes. By adopting the optimized strategy for the recurrent observations to reach the depth, we also use the surveys to detect transient objects. Type Ia Supernova cosmology is thus another important primary goal of WISH. A unique optical layout has been developed to achieve the diffraction-limited imaging at 1-5micron over the required large area. Cooling the mirror and telescope to ~100K is needed to achieve the zodiacal light limited imaging and WISH will achieve the required temperature by passive cooling in the stable thermal environment at the orbit near Sun-Earth L2. We are conducting the conceptual studies and development for the important components of WISH including the exchange mechanism for the wide-field filters as well as the primary mirror fixation.

The Experimental Probe of Inflationary Cosmology - Intermediate Mission (EPIC-IM) is a concept for the NASA Einstein Inflation Probe satellite. EPIC-IM is designed to characterize the polarization properties of the Cosmic Microwave Background to search for the B-mode polarization signal characteristic of gravitational waves generated during the epoch of Inflation in the early universe. EPIC-IM employs a large focal plane with 11,000 detectors operating in 9 wavelength bands to provide 30 times higher sensitivity than the currently operating Planck satellite. The optical design is based on a wide-field 1.4 m crossed-Dragone telescope, an aperture that allows not only comprehensive measurements of Inflationary B-mode polarization, but also measurements of the E-mode and lensing polarization signals to cosmological limits, as well as all-sky maps of Galactic polarization with unmatched sensitivity and angular resolution. The optics are critical to measuring these extremely faint polarization signals, and any design must meet demanding requirements on systematic error control. We describe the EPIC-IM crossed Dragone optical design, its polarization properties, and far-sidelobe response.

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from frequencies 30 GHz to 6 THz (1 cm to 50 μm wavelength). PIXIE uses a polarizing Michelson interferometer with 2.7 K optics to measure the difference spectrum between two orthogonal linear polarizations from two co-aligned beams. Either input can view either the sky or a temperature-controlled absolute reference blackbody calibrator. The multimoded optics and high etendu provide sensitivity comparable to kilo-pixel focal plane arrays, but with greatly expanded frequency coverage while using only 4 detectors total. PIXIE builds on the highly successful COBE/FIRAS design by adding large-area polarization-sensitive detectors whose fully symmetric optics are maintained in thermal equilibrium with the CMB. The highly symmetric nulled design provides redundant rejection of major sources of systematic uncertainty. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r << 10^-3. PIXIE will also return a rich data set constraining physical processes ranging from Big Bang cosmology, reionization, and large-scale structure to the local interstellar medium.

Improvement of our understanding of Fundamental Physics is more and more based on high precision measurements over significant fractions of our Universe. Among the crucial tests of General Relativity and competing theories is the detection of gravitational waves, which is the subject of advanced modern experiments (LISA, VIRGO, LIGO). Our investigation is focused on a novel concept for pointed observations of selected astronomical objects in our Galaxy, like compact binary systems, neutron stars and compact white dwarf binaries, which are expected to be sources of gravitational waves in the Very Low Frequency range, i.e 10^-4 Hz < fg < 10^-1 Hz. The detection mechanism is based on indirect astrometric observations by a spaceborne dedicated instrument, monitoring the astrometric light deflection of the photons crossing the buffer zone of the gravitational source at the microarcsecond level accuracy. We discuss the class of potential candidates, the mission concept and its high level specifications; furthermore, we present an implementation concept including basic instrument characteristics (system configuration, telescope size and constraints, operating wavelength, detector, operation).

We present a new design of a four mirrors telescope for astrometric measurement to be used in the GAME mission, currently under study at the Astronomical Observatory of Turin, Italy. The main aim of GAME - Gamma Astrometric Measurement Experiment - is to measure the γ parameter of the Parameterized Post- Newtonian formulation by looking at the deflection of light produced by the Sun's gravitational curvature, as in the Dyson, Eddington et al. 1919 experiment, using a dedicated, space based dual-field telescope. A first design has been presented in recent years, based on a Cassegrain scheme with a mask in front of the primary mirror to realize multiple aperture Fizeau interferometry. The new design still implements a Fizeau interferometer, but the telescope layout is based on a Korsch-like scheme with four conical mirrors, long focal length, and without the use of exotic surfaces (aspheric or polynomial) as adopted in other long focal astrometric instruments. A different combination scheme of the two lines of sight makes the dimensioning of the primary mirror more relaxed allowing us to work with smaller surfaces and therefore to achieve a more compact payload configuration. The design of the instrument and the masked interferometry approach allow us to maximize the astrometric performances and at the same time to improve the baffling, minimizing the amount of stray light from the Sun. In this paper we describe the mission profile, the observation principle, the new instrument layout and the expected performances.

ExoplanetSat is a proposed three-unit CubeSat designed to detect down to Earth-sized exoplanets in an orbit out to the habitable zone of Sun-like stars via the transit method. To achieve the required photometric precision to make these measurements, the target star must remain within the same fraction of a pixel, which is equivalent to controlling the pointing of the satellite to the arcsecond level. The satellite will use a two-stage control system: coarse control will be performed by a set of reaction wheels, desaturated by magnetic torque coils, and fine control will be performed by a piezoelectric translation stage. Since no satellite of this size has previously demonstrated this high level of pointing precision, a simulation has been developed to prove the feasibility of realizing such a system. The current baseline simulation has demonstrated the ability to hold the target star to within 0.05 pixels or 1.8 arcseconds (with an 85 mm lens and 15 μm pixels), in the presence of large reaction wheel disturbances as well as external environmental disturbances. This meets the current requirement of holding the target star to 0.14 pixels or 5.0 arcseconds. Other high-risk aspects of the design have been analyzed such as the effect of changing the guide star centroiding error, changing the CMOS sampling frequency, and reaction wheel selection on the slew performance of the satellite. While these results are promising as an initial feasibility analysis, further model improvements and hardware-in-the-loop tests are currently underway.

Multi-purpose Infra-Red Imaging System (MIRIS) is the main payload of the Korea Science and Technology Satellite-3 (STSAT-3), which is being developed by Korea Astronomy & Space Science Institute (KASI). MIRIS is a small space telescope mainly for astronomical survey observations in the near infrared wavelengths of 0.9~2 μm. A compact wide field (3.67 x 3.67 degree) optical design has been studied using a 256 x 256 Teledyne PICNIC FPA IR sensor with a pixel scale of 51.6 arcsec. The passive cooling technique is applied to maintain telescope temperature below 200 K with a cold shutter in the filter wheel for accurate dark calibration and to reach required sensitivity, and a micro stirling cooler is employed to cool down the IR detector array below 100K in a cold box. The science mission of the MIRIS is to survey the Galactic plane in the emission line of Paschen-α (Paα, 1.88 μ;m) and to detect the cosmic infrared background (CIB) radiation. Comparing the Paα map with the Hα data from ground-based surveys, we can probe the origin of the warm-ionized medium (WIM) of the Galaxy. The CIB is being suspected to be originated from the first generation stars of the Universe and we will test this hypothesis by comparing the fluctuations in I (0.9~1.2 um) and H (1.2~2.0 um) bands to search the red shifted Lyman cutoff signature. Recent progress of the MIRIS imaging system design will be presented.

Multi-purpose Infra-Red Imaging System (MIRIS) is a near-infrared camera onboard on the Korea Science and Technology Satellite 3 (STSAT-3). The MIRIS is a wide-field (3.67° × 3.67°) infrared imaging system which employs a fast (F/2) refractive optics with 80 mm diameter aperture. The MIRIS optics consists of five lenses, among which the rear surface of the fifth lens is aspheric. By passive cooling on a Sun-synchronous orbit, the telescope will be cooled down below 200 K in order to deliver the designed performance. As the fabrication and assembly should be carried out at room temperature, however, we convert all the lens data of cold temperature to that of room temperature. The sophisticated opto-mechanical design accommodates the effects of thermal contraction after the launch, and the optical elements are protected by flexure structures from the shock (10 G) during the launch. The MIRIS incorporates the wide-band filters, I (1.05 μm) and H (1.6 μm), for the Cosmic Infrared Background observations, and also the narrow-band filters, Paα (1.876 μm) and a specially designed dual-band continuum, for the emission line mapping of the Galactic interstellar medium. We present the optical design, fabrication of components, assembly procedure, and the performance test results of the qualification model of MIRIS near-infrared camera.

MIRIS is a compact near-infrared camera with a wide field of view of 3.67°×3.67° in the Korea Science and Technology Satellite 3 (STSAT-3). MIRIS will be launched warm and cool the telescope optics below 200K by pointing to the deep space on Sun-synchronous orbit. In order to realize the passive cooling, the mechanical structure was designed to consider thermal analysis results on orbit. Structural analysis was also conducted to ensure safety and stability in launching environments. To achieve structural and thermal requirements, we fabricated the thermal shielding parts such as Glass Fiber Reinforced Plastic (GFRP) pipe supports, a Winston cone baffle, aluminum-shield plates, a sunshade, a radiator and 30 layers of Multi Layer Insulation (MLI). These structures prevent the heat load from the spacecraft and the earth effectively, and maintain the temperature of the telescope optics within operating range. A micro cooler was installed in a cold box including a PICNIC detector and a filter-wheel, and cooled the detector down to a operating temperature range. We tested the passive cooling in the simulated space environment and confirmed that the required temperature of telescope can be achieved. Driving mechanism of the filter-wheel and the cold box structure were also developed for the compact space IR camera. Finally, we present the assembly procedures and the test result for the mechanical parts of MIRIS.

The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (≥6) gamma ray reaching to the epoque of reionization. The photometric and spectral capabilities of the IRT will allow to use GRB afterglow as probes of the composition and ionization state of the intergalactic medium of the young universe. A prompt follow up (within three minutes) of the transient discovered by the EXIST makes IRT a unique tool for detection and study of these events in the infrared and optical wavelength, which is particularly valuable at wavelengths unavailable to the ground based observatories. We present the results of the mission study development on the IRT as part of the EXIST observatory.

This paper describes new, large, ultra-lightweight, replicated, actively controlled mirrors, for use in space telescopes. These mirrors utilize SiC substrates, with embedded solid-state actuators, bonded to Nanolaminate metal foil reflective surfaces. Called Actuated Hybrid Mirrors (AHMs), they use replication techniques for high optical quality as well as rapid, low cost manufacturing. They enable an Active Optics space telescope architecture that uses periodic image-based wavefront sensing and control to assure diffraction-limited performance, while relaxing optical system fabrication, integration and test requirements.

In order to facilitate the construction of future large space telescopes, the development of low cost, low mass mirrors is necessary. However, such mirrors suffer from a lack of structural stability, stiffness, and shape accuracy. Active materials and actuators can be used to alleviate this deficiency. For observations in the visible wavelengths, the mirror surface must be controlled to an accuracy on the order of tens of nanometers. This paper presents an exploration of several mirror design concepts and compares their effectiveness at providing accurate shape control. The comparison test is the adjustment of a generic mirror from its manufactured spherical shape to the shape required by various off-axis mirrors in a segmented primary mirror array. A study of thermal effects is also presented and, from these results, a recommended design is chosen.

The trend in future space telescopes points toward increased primary mirror diameter, which improves resolution and sensitivity. However, given the constraints on mass and volume deliverable to orbit by current launch vehicles, creative design solutions are needed to enable increased mirror size while keeping mass and volume within acceptable limits. Lightweight, segmented, rib-stiffened, actively controlled primary mirrors have emerged as a potential solution. Embedded surface-parallel actuators can be used to change the mirror prescription onorbit, lowering mirror mass overall by enabling lighter substrate materials such as silicon carbide (SiC) and relaxing manufacturing constraints. However, the discrete nature of the actuators causes high spatial frequency residual errors when commanding low-order prescription changes. A parameterized finite element model is used to simulate actuator-induced residual error and investigate design solutions that mitigate this error source. Judicious specification of mirror substrate geometry and actuator length is shown to reduce actuator-induced residual while keeping areal density constant. Specifically, a sinusoidally-varying rib shaping function is found to increase actuator influence functions and decrease residual. Likewise, longer actuators are found to offer reduced residual. Other options for geometric shaping are discussed, such as rib-to-facesheet blending and the use of two dimensional patch actuators.

We are investigating new technologies for creating ultra-large apertures (>20m) for space-based imagery. Our approach has been to create diffractive primaries in flat membranes to be deployed from compact payloads. This research has led us to the development of photon sieves in which millions of holes of a well-determined size are positioned over an otherwise opaque background. High resolution focusing is obtained for transmitted light. We have analyzed the theoretical performance of several types of photon sieves to improve both efficiency and bandwidth. We have also created several prototype devices in both rigid and flexible substrates.

The project PLAnetary Transits and Oscillations of stars (PLATO) is one of the three medium class (M class) missions selected in 2010 for definition study in the framework of the ESA Cosmic Vision 2015-2025 program. The main scientific goals of PLATO are the i) discovery and study of extra-solar planetary systems, (including those hosting Earth-like planets in their habitable zone) by means of planetary transits detection from space and radial velocity follow-up from ground, and ii) the characterization of the hosting stars through seismic analysis, in order to determine with high accuracy planetary masses and ages. According to the study made by the PLATO Payload Consortium (PPLC) during the PLATO assessment phase, the scientific payload consists of 34 all refractive telescopes having small aperture (120 mm) and wide field of view (greater than 1000 degree²) observing over 0.5-1 micron wavelength band. The telescopes are mounted on a common optical bench and are divided in four families with an overlapping line-of-sight in order to maximize the science return. In this paper, we will describe the detailed design of the Telescope Optical Units (TOUs) focusing on the selected optical configuration and the expected performances.

THESIS, the Transiting Habitable-zone Exoplanet Spectroscopy Infrared Spacecraft, is a concept for a medium/Probe class exoplanet mission. Building on the recent Spitzer successes in exoplanet characterization, THESIS would extend these types of measurements to super-Earth-like planets. A strength of the THESIS concept is simplicity, low technical risk, and modest cost. The mission concept has the potential to dramatically advance our understanding of conditions on extrasolar worlds and could serve as a stepping stone to more ambitious future missions. We envision this mission as a joint US-European effort with science objectives that resonate with both the traditional astronomy and planetary science communities.

To characterize orbits and atmospheres of exoplanets with large orbits (≥ a few AU), direct imaging is nowadays the sole way. From space, this involves high contrast imaging techniques as coronagraphy, differential imaging or wavefront control. Several methods exist or are under development and several small (~1.5m) space telescope missions are proposed. One of them is See-coast (super-Earth explorer coronagraphic off-axis space telescope) which will be proposed to the next ESA Cosmic Vision call. It will provide polarimetric and spectral characterization of giant gazeous planets and possibly Super-Earths in visible light. In this paper, we first detail science cases of this mission. We then describe the foreseen telescope design and its instrumentation. We finally derive performance for a particular instrumental configuration from numerical simulation and we show how See-coast can retrieve planet spectra.

Nanosatellites, i.e. spacecraft that weigh between 1 and 10 kg, are drawing increasing interest as platforms for conducting on-orbit science. This trend is primarily driven by the ability to piggyback nanosatellites on the launch of large spacecraft and hence achieve orbit at greatly reduced cost. The CubeSat platform is a standardized nanosatellite configuration, consisting of one, two, or three 10 cm x 10 cm x 10 cm units (1, 2, or 3 "U"s) arranged in a row. We present a CubeSat-based concept for the discovery of transiting exoplanets around the nearest and brightest Sun-like stars. The spacecraft prototype - termed ExoplanetSat - is a 3U space telescope capable of monitoring a single target star from low Earth orbit. Given the volume limitations of the CubeSat form factor, designing a capable spacecraft requires overcoming significant challenges. This work presents the initial satellite configuration along with several subsystem-specific solutions to the aforementioned constraints. An optical design based on a modified commercial off-the-shelf camera lens is given. We also describe a novel two-stage attitude control architecture that combines 3-axis reaction wheels for coarse pointing with a piezoelectric translation stage at the focal plane for fine pointing. Modeling and simulation results are used to demonstrate feasibility by quantifying ExoplanetSat pointing precision, signal-to-noise ratio, guide star magnitude, and additional design parameters which determine system performance.

ACCESS is one of four medium-class mission concepts selected for study in 2008-9 by NASA's Astrophysics Strategic Mission Concepts Study program. ACCESS evaluates a space observatory designed for extreme high-contrast imaging and spectroscopy of exoplanetary systems. An actively-corrected coronagraph is used to suppress the glare of diffracted and scattered starlight to contrast levels required for exoplanet imaging. The ACCESS study considered the relative merits and readiness of four major coronagraph types, and modeled their performance with a NASA medium-class space telescope. The ACCESS study asks: What is the most capable medium-class coronagraphic mission that is possible with telescope, instrument, and spacecraft technologies available today? Using demonstrated high-TRL technologies, the ACCESS science program surveys the nearest 120+ AFGK stars for exoplanet systems, and surveys the majority of those for exozodiacal dust to the level of 1 zodi at 3 AU. Coronagraph technology developments in the coming year are expected to further enhance the science reach of the ACCESS mission concept.

The Pupil-mapping Exoplanet Coronagraphic Observer (PECO) mission concept is a 1.4-m space-based coronagraphic telescope optimized to image exoplanets and disks at optical wavelengths and characterize them through low resolution spectroscopy and polarimetry. Thanks to a high efficiency Phase-Induced Amplitude Apodization (PIAA) coronagraph, PECO can deliver 1e-10 contrast at 2 λ/D separation (0.15") with no loss in angular resolution or throughput due to the coronagraph. PECO acquires narrow field images simultaneously in 16 spectral bands over wavelengths from 0.4 to 0.9 μm , utilizing all available photons for maximum wavefront sensing efficiency and optimal sensitivity for imaging and spectroscopy. PECO can detect and characterize potentially habitable planets around 20 known F, G, K type stars, and map exozodiacal clouds to a fraction of our own own zodiacal dust content. PECO's key technologies are currently under active development at several testbeds, and will enable efficient exoplanet imaging missions across a wide range of telescope sizes, from a sub-meter debris disk and giant planet imager to a ~4-m life-finding mission.

This paper presents the optical design of the Dilute Aperture Visible Nulling Coronagraph Imaging (DAViNCI). DAViNCI's dilute aperture approach to the TPF-C extra-solar earth-like detection mission reduces cost and technical risk compared to other filled aperture approaches. DAViNCI has been studied in an ASMCS (Astrophysics Strategic Mission Concept Study) and is included within the ASTRO2010 Decadal review [1]. The DAViNCI team is led by Michael Shao (PI) of JPL.

Three of the recently completed NASA Astrophysics Strategic Mission Concept (ASMC) studies addressed the feasibility of using a Visible Nulling Coronagraph (VNC) as the prime instrument for exoplanet science. The VNC approach is one of the few approaches that works with filled, segmented and sparse or diluted aperture telescope systems and thus spans the space of potential ASMC exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies and has developed an incremental sequence of VNC testbeds to advance the this approach and the technologies associated with it. Herein we report on the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under high bandwidth closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible light nulling milestones of sequentially higher contrasts of 10⁸, 10⁹ and 10¹⁰ at an inner working angle of 2*λ/D and ultimately culminate in spectrally broadband (>20%) high contrast imaging. Each of the milestones, one per year, is traceable to one or more of the ASMC studies. The VNT uses a modified Mach-Zehnder nulling interferometer, modified with a modified "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. Discussed will be the optical configuration laboratory results, critical technologies and the null sensing and control approach.

High precision astrometry of nearby bright stars is theoretically (in the photon noise limit) possible with a space coronagraph using a wide field diffraction limited camera imaging an annulus of background stars around the central coronagraphic field. With the sub-micro arcsecond accuracy theoretically achievable on a 1.4-m telescope, the mass of all planets that can be imaged by the coronagraph would be estimated. Simultaneous imaging and astrometric measurements would reduce the number of astrometric measurements necessary for mass determination, and reduce confusion between multiple planets and possible exozodiacal clouds in the coronagraphic image. While scientifically attractive, this measurement is technically very challenging, and must overcome astrometric distortions, which, in conventional telescopes, are several orders of magnitude above the photon noise limit. In this paper, we propose a new approach to calibrating astrometric distortions in the wide field imaging camera. The astrometric measurement is performed by simultaneously imaging background stars and diffraction spikes from the much brighter coronagraphic target on the same focal plane array. The diffraction spikes are generated by a series of small dark spots on the primary mirror to reduce sensitivity to optical and mechanical distortions. Small scale distortions and detector errors are averaged down to sub-micro arcsecond by rolling the telescope around the line of sight. A preliminary error budget is shown and discussed to identify major sources of error for a 1.4-m telescope imaging a 0.25 squaredeg field of view at the galactic pole.

Direct imaging of extrasolar planets in visible light, and Earth-like planets in particular, is an exciting but difficult problem requiring a telescope imaging system with 10^-10 contrast at separations of 100mas and less. Furthermore, only a small 1-2m space telescope may be realistic for a mission in the foreseeable future, which puts strong demands on the performance of the imaging instrument. Fortunately, an efficient coronagraph called the Phase Induced Amplitude Apodization (PIAA) coronagraph may enable Earth-like planet imaging for such small telescopes if any exist around the nearest stars. In this paper, we report on the latest results from a testbed at the NASA Ames Research Center focused on testing the PIAA coronagraph. This laboratory facility was built in 2008 and is designed to be flexible, operated in a highly stabilized air environment, and to complement efforts at NASA JPL's High Contrast Imaging Testbed. For our wavefront control we are focusing on using small Micro-Electro-Mechanical-System deformable mirrors (MEMS DMs), which promises to reduce the size of the beam and overall instrument, a consideration that becomes very important for small telescopes. In this paper, we briefly describe our lab and methods, including the new active thermal control system, and report the demonstration of 5.4×10^-8 average raw contrast in a dark zone from 2.0 - 5.2 λ/D. In addition, we present an analysis of our current limits and solutions to overcome them.

The New Worlds Observer is a flagship-scale terrestrial planet finding and characterizing mission using an external occulter known as a starshade. The starshade is a separate space vehicle from the observing telescope; the starshade performs all the necessary starlight suppression to enable high contrast imaging of terrestrial exo-planets. While effective as a flagship-scale mission designed to fulfill and exceed the requirements of the Terrestrial Planet Finder (TPF) mission, the starshade architecture is flexible and can accommodate a variety of design and cost categories, including working with an existing telescope. We present in this paper an architecture using a starshade with the James Web Space Telescope (JWST), a mission concept we call New Worlds Probe, which can deliver many of the TPF mission requirements for significantly lower mission cost. We give an overview of the science capabilities, the starshade design and technical maturity, and concepts for starshade-JWST cooperative operation.

The Princeton occulter testbed uses long-distance propagation with a diverging beam and an optimized occulter mask to simulate the performance of external occulters for finding extrasolar planets. We present new results from the testbed in both monochromatic and broadband light. In addition, we examine sensing and control of occulter position using out-of-band spectral leak around the occulter and occulter position tolerancing. These results are validated by numerical simulations of propagation through the system.

A flower-like starshade positioned between a star and a space telescope is an attractive option for blocking the starlight to reveal the faint reflected light of an orbiting Earth-like planet. Planet light passes around the petals and directly enters the telescope where it is seen along with a background of scattered light due to starshade imperfections. We list the major perturbations that are expected to impact the performance of a starshade system and show that independent models at NGAS and JPL yield nearly identical optical sensitivities. We give the major sensitivities in the image plane for a design consisting of a 34-m diameter starshade, and a 2-m diameter telescope separated by 39,000 km, operating between 0.25 and 0.55 um. These sensitivities include individual petal and global shape terms evaluated at the inner working angle. Following a discussion of the combination of individual perturbation terms, we then present an error budget that is consistent with detection of an Earth-like planet 26 magnitudes fainter than its host star.

We present an analysis of the Occulting Ozone Observatory (O3) - a $1 billion class mission dedicated to finding extra-solar planets down to Earth size, performing photometric characterizations of planets and disks, detecting the presence of ozone, and general astrophysics. We present trade studies for the observatory, composed of a 1 to 2 m telescope based on heritage imaging systems and a complementary sized, free-flying occulter spacecraft, to maximize the expected science yield for this mission class. Using a camera with four filters each in the 250- 550 nm and 500-1100 nm bands, this modest-size telescope can detect atmospheric ozone in Earth-like planets, methane in gas giants, determine planetary spin rotation periods, characterize the surface composition of rocky planets and determine or constrain the values of basic orbital elements. We present multiple different mission designs along with the expected number of planetary detections and photometric characterizations.

A starshade with the James Webb Space Telescope (JWST) is the only possible path forward in the next decade to obtain images and spectra of a planet similar to the Earth, to study its habitability, and search for signs of alien life. While JWST was not specifically designed to observe using a starshade, its near-infrared instrumentation is in principle capable of doing so and could achieve major results in the study of terrestrialmass exoplanets. However, because of technical reasons associated with broadband starlight suppression and filter red-leak, NIRSpec would need a slight modification to one of its target acquisition filters to enable feasible observations of Earth-like planets. This upgrade would 1) retire the high risk associated with the effects of the current filter red leak which are difficult to model given the current state of knowledge on instrument stray light and line spread function at large separation angles, 2) enable access to the oxygen band at 0.76 μm in addition to the 1.26 μm band, 3) enable a smaller starshade by relaxing requirements on bandwidth and suppression 4) reduce detector saturation and associated long recovery times. The new filter would not affect neither NIRSpecs scientific performance nor its operations, but it would dramatically reduce the risk of adding a starshade to JWST in the future and enhance the performance of any starshade that is built. In combination with a starshade, JWST could be the most capable and cost effective of all the exoplanet hunting missions proposed for the next decade, including purpose built observatories for medium-size missions.

Starshades have been shown to hold the potential to reveal Earth-like planets around nearby stars and to allow detailed follow-up study including spectroscopy. Ideally this would be performed with a starshade in excess of 50m diameter and a telescope over 4m in diameter. However, such a flagship-class mission is unlikely to be realized in under fifteen years. But much can be accomplished in substantially less expensive missions. I will review the alternatives and provide an assessment of various architectures and what they can accomplish. These alternatives will include using JWST as the telescope, using small dedicated telescopes, and using smaller starshades.

The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astronphysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 μm wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 μm to 2.4 μm, high stability in wavefront sensing and control). We will also discuss the synergy between ATLAST and other anticipated future facilities (e.g., TMT, EELT, ALMA) and the priorities for technology development that will enable the construction for a cost that is comparable to current generation observatory-class space missions.

The ATALST (Advanced Technology for Large Aperture Space Telescopes) effort has presented several design incarnations. Here we will compare the design and performance of the 9.2m segmented, the 8m monolithic on-axis and 8m x 6m off-axis concepts.

We present results of a study of a deployable version of the Advanced Technology Large-Aperture Space Telescope (ATLAST), designed to operate in a Sun-Earth L2 orbit. The primary mirror of the segmented 9.2-meter aperture has 36 hexagonal 1.315 m (flat-to-flat) glass mirrors. The architecture and folding of the telescope is similar to JWST, allowing it to fit into the 6.5 m fairing of a modest upgrade to the Delta-IV Heavy version of the Evolved Expendable Launch Vehicle (EELV). We discuss the overall observatory design, optical design, instruments, stray light, wavefront sensing and control, pointing and thermal control, and in-space servicing options.

ATLAST-8m is an 8-meter monolithic UV/optical/NIR space observatory which could be placed in orbit at Sun-Earth L2 by a heavily lift launch vehicle. Two development study cycles have resulted in a detailed concept including a dual foci optical design; several primary mirror launch support and secondary mirror support structural designs; spacecraft propulsion, power and pointing control design; and thermal design. ATLAST-8m is designed to yield never before achieved performance to obtain fundamental astronomical breakthroughs.

The imaging of faint exoplanets near bright stars requires the development of very high contrast detection techniques, including both precise wavefront control and deep starlight rejection. A system-level proof-of-principle experiment carried out at at the Palomar Observatory has recently demonstrated that exoplanets can be detected very near stars even with a fairly small (1.5 m diameter) telescope aperture, such as someday might be used by a first space-based exoplanet imaging mission. Using fine-scale wavefront correction across this small aperture, together with fine pointing and focus control, pre- and post-detection speckle reduction, and a vector vortex coronagraph, it has been possible to achieve extremely good starlight rejection within a small number of diffractions beams of the stellar position. This performance has recently allowed the imaging of the three HR8799 planets and the HD32297 disk, thus providing a first system-level validation of the steps needed to achieve high-contrast observations at very small angles. These results thus serve to highlight the potential of small space telescopes aiming at high-contrast exoplanet observations. Specifically, a small-angle coronagraph enables the use of smaller telescopes, thus potentially reducing mission cost significantly.

Bright source catalogues based on the new mid- and far-infrared all-sky survey by the infrared astronomical satellite AKARI were released into the public domain in March 2010. The mid-infrared catalogue contains more than 870 thousand sources observed at 9 and 18 μm, and the far-infrared catalogue provides information of about 427 thousand sources at 65, 90, 140, and 160 μm. The AKARI catalogues will take over the IRAS catalogues and will become one of the most important catalogues in astronomy. We present the characteristics of the AKARI infrared source catalogues as well as current activity for the future versions.

The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8- meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 point and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The objective is to maintain the primary mirror at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop®1. A detailed model of the primary mirror was required in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew and a 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the solar environment that influences the thermal performance. All assumptions that were used in the analysis are also documented. Estimates of mirror heater power requirements are reported. The thermal model is used to predict gradients across and through the primary mirror using an idealized boundary temperature on the back and sides of the mirror of 280 K.

The Advanced Technology for Large Aperture Space Telescope (ATLAST) concept was assessed as one of the NASA Astrophysics Strategic Mission Concepts (ASMC) studies. Herein we discuss the 9.2-meter diameter segmented aperture version and its wavefront sensing and control (WFSC) with regards to coronagraphic detection and spectroscopic characterization of exoplanets. The WFSC would consist of at least two levels of sensing and control: (i) an outer coarser level of sensing and control to phase and control the segments and secondary mirror in a manner similar to the James Webb Space Telescope but operating at higher temporal bandwidth, and (ii) an inner, coronagraphic instrument based, fine level of sensing and control for both amplitude and wavefront errors operating at higher temporal bandwidths. The outer loop would control rigid-body actuators on the primary and secondary mirrors while the inner loop would control one or more segmented deformable mirror to suppress the starlight within the coronagraphic field-of-view. Herein we discuss the visible nulling coronagraph (VNC) and the requirements it levies on wavefront sensing and control and show the results of closed-loop simulations to assess performance and evaluate the trade space of system level stability versus control bandwidth.

The ENIS wide-field spectrograph is part of the instrument package on board of the European space mission Euclid devoted to map the dark universe and proposed for launch in 2017. ENIS will operate in the near-IR spectral region (0.8-2 μm) and will provide in 4-5 years an accurate and extremely large survey of cosmological redshifts. The instrument focal-plane is based on a combination of state of the art detectors light fed by a slitless spectrograph allowing coverage and analysis of a high number of targets per cycle. During the feasibility study a spectrograph option based on Digital Micromirror Device (DMD) programmable slits, allowing a significant increase in instrumental sensitivity and accuracy, has also been examined. ENIS has been recently (Feb this year) pre-selected for a phase-A study within a group of three medium class missions; final selection is foreseen for the end of next year after a new phase of instrument revision. A description of the work done during the feasibility-study phase for the ENIS focal-plane is here presented.

A simulator of data frames produced by 'multi-accumulation' readout detectors has been developed during the feasibility study for the NIS spectrograph, part of the European Euclid mission. The software can emulate various readout strategies, allowing to compare the efficiency of different sampling techniques. Special care is given to two crucial aspects: the minimization of the noise and the effects produced by cosmic hits. The resulting readout noise is analyzed as a function of the background sources, detector native characteristics and readout strategy, while the image deterioration by cosmic rays covers the simulation of hits and their correction efficiency varying the readout modalities. Simulated "multi-accumulation" frames, typical of multiplexer based detectors, are an ideal tool for testing the efficiency of cosmic ray rejection techniques. In the present case cosmic rays are added to each raw frame conforming to the rates and energy expected in the operational L2 region and in the chosen exposure time. Procedures efficiency for cosmic ray identification and correction can also be easily tested in terms of memory occupancy and telemetry rates.

The Euclid dark energy mission is currently competing in ESA's Cosmic Vision program. Its imaging instrument, which has one visible and one infrared channel, will survey the entire extragalactic sky during the 5 year mission. The near-infrared imaging photometer (NIP) channel, operating in the ~0.92 - 2.0 μm spectral range, will be used in conjunction with the visible imaging channel (VIS) to constrain the nature of dark energy and dark matter. To meet the stringent overall photometric requirement, the NIP channel requires a dedicated on-board flat-field source to calibrate the large, 18 detector focal plane. In the baseline concept a 170 mm Spectralon diffuser plate, mounted to a pre-existing shutter mechanism outside the channel, is used as a flat-field calibration target, negating the need for an additional single-point-failure mechanism. The 117 × 230 mm focal plane will therefore be illuminated through all of the channel's optical elements and will allow flat-field measurements to be taken in all wavelength bands. A ring of low power tungsten lamps, with custom reflecting elements optimized for optical performance, will be used to illuminate the diffuser plate. This paper details the end-to-end optical simulations of this concept, a potential mechanical implementation and the initial tests of the proposed key components.

The Euclid Imaging Channels Instrument of the Euclid mission is designed to study the weak gravitational lensing cosmological probe. The combined Visible and Near Infrared imaging channels will be controlled by a common data handling unit (PDHU), implementing onboard the instrument digital interfaces to the satellite. The PDHU main functionalities include the scientific data acquisition and compression, the instrument commanding and control and the instrument health monitoring. Given the high data rate and the compression needs, an innovative architecture, based on the use of several computing and interface modules, considered as building blocks of a modular design will be presented.

Euclid is a high-precision survey mission to map the geometry of the Dark Universe. The Euclid Mission concept presented in the Assessment Phase Study Report¹ was selected by ESA on February 2010 to undergo a competitive Definition Phase. Euclid is a candidate for launch in the first slice of the Cosmic Vision Plan (M1/M2), with a possible launch date of 2018. In this paper we refer to the instrument baseline configuration identified in the Assessment Phase. It consisted of a Korsch telescope with a primary mirror of 1.2 m diameter and a focal plane hosting 3 scientific instruments, each with a field of view of 0.5 deg²: (1) E-VIS: a CCD based optical imaging channel, (2) E-NIP: a NIR imaging photometry channel, and (3) E-NIS: a NIR slitless spectral channel. We present the conceptual design developed in the Assessment Phase study for the Ground Support Equipment required to support the assembly, integration and verification operations at instrument level for the E-NIS baseline configuration, with particular regards to the scientific and calibration activities.

EUCLID, the ESA Dark Energy Mission, contains a NIR and a visible imagers (NIP & VIS), and an NIR spectrograph (NIS). Different designs of the NIS have been studied especially a slitless design, a Digital Micromirror Device (DMD) design using grisms and another using prisms, and more recently a combination of the NIP and NIS into one instrument. We present the design of the prism DMD NIS. This design has the advantage over the slitless design of having a DMD mask which reduces the background by a factor of more than 100 and all the advantages over the grism DMD NIS that a prism gives over a grism as a higher and more uniform transmission, the absence of parasite orders, and a choice of the slope of the spectral resolution with wavelength. The field per spectrograph was made sufficiently large to reduce the number of spectrographs to two. The design was made so that the mapping of the sky of the NIS is easily compatible with the mapping strategy of the NIP and VIS. Two designs were made. In one, the field is larger but the surface shapes of the optics are complex which makes manufacturing more challenging. In the other, the design was made to be fully compatible with the manufacturing criteria of SESO after extensive discussions to carefully understand the manufacturing limitations especially the formula for highly aspheric surface shapes as biconics. This was done by directly integrating the criteria into the optimization process of ZEMAX. A calibration system that uses the DMD with the micromirrors in their OFF positions was also developed.

The Euclid mission proposed in the context of the ESA Cosmic Vision program is aimed to study the challenging problem of the Dark Energy, responsible of the acceleration of the Universe. One of the three probes of Euclid is dedicated to study the Baryonic Acoustic Oscillations by means of spectroscopic observations of millions of galaxies in the Near Infrared. One option for the Euclid Near Infrared Spectrograph (ENIS) is a multi-slit approach based on Digital Micromirror Device (DMD) used as reconfigurable slit mask. The Texas Instrument 2048*1080 DMD with 13.68 micrometers pitch has been chosen. ENIS optical design is composed of four arms each using one DMD to cover a total FOV of 0.48 square degree. The fore-optic design has to cope with the difficult task of having simultaneously a fast beam (F/2.7) and a quasi-diffraction limited image on a 24 deg tilted plane. The compact three mirrors spectrograph is using a grism in convergent beam for simplicity and compactness purposes. From the optical design, the mechanical structure is based on a common carbon honeycomb bench to reach the challenging requirements of volume and mass.

Next-generation infrared astronomical instrumentation for ground-based and space telescopes could be based on MOEMS programmable slit masks for multi-object spectroscopy (MOS). This astronomical technique is used extensively to investigate the formation and evolution of galaxies. We are engaged in an ESA study for a technical assessment of using a DMD from Texas Instruments for space applications (for example in ESA EUCLID mission). The DMD features 2048×1080 mirrors on a 13.68μm pitch, where each mirror can be independently switched between an ON (+12°) position and an OFF (-12°) position. For MOS applications in space, the device should work in vacuum, at low temperature, and each MOS exposure would last for typically 1500s with micromirrors held in a static state (either ON or OFF). A specific thermal/vacuum test chamber has been developed for test conditions down to -40°C at 10^-5 mbar vacuum. Imaging capability for resolving each micromirror has also been developed for determining degradation in any single mirror. Our first tests reveal that the DMD remains fully operational at -40°C and in vacuum. A 1038 hours life test in space conditions, Total Ionizing Dose radiation, thermal cycling and vibrations/shocks have also been successfully completed. These results do not reveal any concerns regarding the ability of the DMD to meet environmental space requirements. We have also developed a bench for MOS demonstration using MOEMS devices. DMD chip has been successfully tested revealing good contrast values as well as good functionality for applying any mask pattern, demonstrating its full ability for space instrumentation, especially in multi-object spectroscopy applications.

The Astrometric Instrument Model system comprises several monitoring and diagnostic tasks for the astrometric instrument aboard Gaia. It is a hierarchy of dedicated software modules aimed at decreasing the parameter degeneration of the relation linking the observations to the instrumental behavior, and optimize the estimation process at the CCD and field-of-view crossing level. Critical for the system is the definition and maintenance of a physical instrument model fitting the science data, and able to accommodate non nominal configurations. Precise modeling of the astrometric response is required for optimal definition of the data reduction and calibration algorithms, and to ensure high sensitivity to both instrumental and astrophysical source parameters.

ESA's cornerstone mission Gaia aims at autonomously building a billion-star catalogue by detecting them on board. The scientific and technical requirements make this an engineering challenge. We have devised a prototype to assess achievable performances and assist in sizing the on-board electronics. It is based on a sequence of four tasks: calibrating the CCD data, estimating the sky background, identifying the objects and, finally, characterising them. Although inspired by previous similar studies (APM, Sextractor), this approach has been thoroughly revisited and finely adapted to Gaia. A mixed implementation is proposed which deals with the important data flow and the hard real-time constraints in hardware (FPGA) and entrusts more complex or variable processing to software. This segmentation also corresponds to subdividing the previous operations in pixel-based and object-based domains. Our hardware and software demonstrators show that the scientific specifications can be met, as regards completeness, precision and robustness while, technically speaking, our pipeline, optimised for area and power consumption, allows for selecting target components. Gaia's prime contractor, inspired by these developments, has also elected a mixed architecture, so that our R&D has proven relevant for the forthcoming generation of satellites.

Micro-arcsecond precision must rely on the detailed knowledge of instrument parameters and observing conditions for optimal definition of data reduction and calibration procedures. The variation of instrumental response over the field of view with wavelength and in time is potentially critical and often unavoidable. This work addresses selected topics in modeling of the astrometric instrument of the Gaia mission, evidencing their role in the data reduction strategy. Discussion is extended to how the modeling will impact on the data quality and to how the science data can be used to trace directly the instrument response. Finally mention is provided of the actual implementation of our recipe into the Astrometric Instrument Model, a software tool which will be used during the processing of Gaia data.