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Está depositada la versión preprint del artículo, We report a detailed study of an unidentified gamma-ray source located in the region of the compact stellar cluster NGC 3603. This is a star-forming region (SFR) powered by a massive cluster of OB stars. A dedicated analysis of about 10 yr of data from 10 GeV to 1 TeV, provided by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, yields the detection of a pointlike source at a significance of 9 sigma. The source photon spectrum can be described by a power-law model with a best-fit spectral index of 2.35 0.03. In addition, the analysis of a deep Chandra image in the 0.5-7 keV band reliably rules out an extragalactic origin for the gamma-rays. We also conclude that the broadband spectral energy distribution of the point source can be explained well with both leptonic and hadronic models. No firm evidence of association with any other classes of known gamma-ray emitters is found; therefore, we speculate that 4FGL J1115.1-6118 is a gamma-ray-emitting SFR., Ministerio de Economía y Competitividad (España), ERDF under the Spanish MINECO, Ramon and Cajal program, Istituto Nazionale Astrofisica (INAF), Agenzia Spaziale Italiana (ASI), United States Department of Energy (DOE), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

This podcast is hosted by Temple Grandin and is provided by the STEM Action Center. This podcast features STEM professionals discussing their work and the benefits of a multifaceted approach to STEM education. During episode five of season two, Temple Gradin speaks with Mark Clampin about NASA’s James Webb Telescope discoveries and its implications for STEM education and technology. The search for habitable planets, the Hubble and James Webb telescopes, and other topics are explored. This podcast runs 34:01 minutes in length. Other podcast episodes are available separately.&nbsp

The X-ray Integral Field Unit (X-IFU) instrument to be on board the future ESA mission Athena X-ray Observatory is a cryogenic micro-calorimeter array of Transition Edge Sensor (TES) detectors aimed at providing spatially resolved high-resolution spectroscopy. As a part of the on-board Event Processor (EP), the reconstruction software will provide the energy, spatial location and arrival time of the incoming X-ray photons hitting the detector and inducing current pulses on it. Being the standard optimal filtering technique the chosen baseline reconstruction algorithm, a particular modification of this technique based on a truncation of the filter in the Time Domain (equivalent to 0-padding the pulse signal) was previously studied on simulated data, proving a better energy resolution results at a lower computational cost. However, the 0-padding technique also showed a larger sensitivity to instrumental conditions, making essential the analysis of its behaviour over real laboratory data. A comparative analysis of X-IFU-like TES laboratory data from NASA and NIST (at different instrumental conditions) with both the 0-padding filter and the standard optimal filters reconstruction shows that, once the corrections for the baseline drift and the jitter (phase introduced by the sampling rate) have been performed, the resolution values obtained using 0-padding are systematically lower than those of the standard filter of the same length and comparable or even lower to the values provided by the full-length filter. The shorter length of the 0-padding filter would be an additional benefit, reducing the computational cost of the reconstruction process.

Chemistry along the star- and planet-formation sequence regulates how prebiotic building blocks-carriers of the elements CHNOPS-are incorporated into nascent planetesimals and planets. Spectral line observations across the electromagnetic spectrum are needed to fully characterize interstellar CHNOPS chemistry, yet to date there are only limited astrochemical constraints at THz frequencies. Here, we highlight advances to the study of CHNOPS astrochemistry that will be possible with the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS). OASIS is a NASA mission concept for a space-based observatory that will utilize an inflatable 14-m reflector along with a heterodyne receiver system to observe at THz frequencies with unprecedented sensitivity and angular resolution. As part of a survey of H2O and HD toward similar to 100 protostellar and protoplanetary disk systems, OASIS will also obtain statistical constraints on the emission of complex organics from protostellar hot corinos and envelopes as well as light hydrides including NH3 and H2S toward protoplanetary disks. Line surveys of high-mass hot cores, protostellar outflow shocks, and prestellar cores will also leverage the unique capabilities of OASIS to probe high-excitation organics and small hydrides, as is needed to fully understand the chemistry of these objects.

Chemistry along the star- and planet-formation sequence regulates how prebiotic building blocks-carriers of the elements CHNOPS-are incorporated into nascent planetesimals and planets. Spectral line observations across the electromagnetic spectrum are needed to fully characterize interstellar CHNOPS chemistry, yet to date there are only limited astrochemical constraints at THz frequencies. Here, we highlight advances to the study of CHNOPS astrochemistry that will be possible with the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS). OASIS is a NASA mission concept for a space-based observatory that will utilize an inflatable 14-m reflector along with a heterodyne receiver system to observe at THz frequencies with unprecedented sensitivity and angular resolution. As part of a survey of H2O and HD toward similar to 100 protostellar and protoplanetary disk systems, OASIS will also obtain statistical constraints on the emission of complex organics from protostellar hot corinos and envelopes as well as light hydrides including NH3 and H2S toward protoplanetary disks. Line surveys of high-mass hot cores, protostellar outflow shocks, and prestellar cores will also leverage the unique capabilities of OASIS to probe high-excitation organics and small hydrides, as is needed to fully understand the chemistry of these objects.

EMIR, currently entering into its fabrication and AIV phase, will be one of the first common user instruments for the GTC, the 10 meter telescope under construction by GRANTECAN at the Roque de los Muchachos Observatory (Canary Islands, Spain). EMIR is being built by a Consortium of Spanish and French institutes led by the Institute de Astrofisica de Canarias (IAC). EMIR is designed to realize one of the central goals of 10m class telescopes, allowing observers to obtain spectra for large numbers of faint sources in an time-efficient manner. EMIR is primarily designed to be operated as a MOS in the K band, but offers a wide range of observing modes, including imaging and spectroscopy, both long slit and multiobject, in the wavelength range 0.9 to 2. 5 µm. It is equipped with two innovative subsystems: a robotic reconfigurable multislit mask and disperssive elements formed by the combination of high quality difracction grating and conventional prisms, both at the heart of the instrument. The present status of development, expected performances, schedule and plans for scientific exploitation are described and discussed. The development and fabrication of EMIR is funded by GRANTECAN and the Plan Nacional de Astronomia y Astrofisica (National Plan for Astronomy and Astrophysics, Spain).

High-contrast direct imaging of exoplanets can provide many important observables, including measurements of the orbit, spectra that probe the lower layers of the atmosphere, and phase variations of the planet, but cannot directly measure planet radius or mass. Our future understanding of directly imaged exoplanets will therefore rely on extrapolated models of planetary atmospheres and bulk composition, which need robust calibration. We estimate the population of extrasolar planets that could serve as calibrators for these models. Critically, this population of "standard planets" must be accessible to both direct imaging and the transit method, allowing for radius measurement. We show that the search volume of a direct imaging mission eventually overcomes the transit probability falloff with semimajor axis, so that as long as cold planets are not exceedingly rare, the population of transiting planets and directly imageable planets overlaps. Using current extrapolations of Kepler occurrence rates, we estimate that ∼8 standard planets could be characterized shortward of 800 nm with an ambitious future direct imaging mission like LUVOIR-A and several dozen could be detected at the V band. We show the design space that would expand the sample size and discuss the extent to which ground-and space-based surveys could detect this small but crucial population of planets.

High-contrast direct imaging of exoplanets can provide many important observables, including measurements of the orbit, spectra that probe the lower layers of the atmosphere, and phase variations of the planet, but cannot directly measure planet radius or mass. Our future understanding of directly imaged exoplanets will therefore rely on extrapolated models of planetary atmospheres and bulk composition, which need robust calibration. We estimate the population of extrasolar planets that could serve as calibrators for these models. Critically, this population of "standard planets" must be accessible to both direct imaging and the transit method, allowing for radius measurement. We show that the search volume of a direct imaging mission eventually overcomes the transit probability falloff with semimajor axis, so that as long as cold planets are not exceedingly rare, the population of transiting planets and directly imageable planets overlaps. Using current extrapolations of Kepler occurrence rates, we estimate that ∼8 standard planets could be characterized shortward of 800 nm with an ambitious future direct imaging mission like LUVOIR-A and several dozen could be detected at the V band. We show the design space that would expand the sample size and discuss the extent to which ground-and space-based surveys could detect this small but crucial population of planets.

This paper presents the shunt damping of a unimorph piezoelectric mirror intended to be used as an active secondary corrector in future space telescopes. We propose to take advantage of the actuation capability of the piezoelectric mirror, to increase its natural damping during the critical launch phase of the spacecraft. The piezoelectric actuators, intended to be used for active optics, are shunted on a passive resistive and inductive RL circuit during the launch operation. The proposed concept is verified numerically and experimentally on a piezoelectric deformable mirror prototype, developed on behalf of the European Space Agency. We show that the shunt damping significantly reduces the response of the most critical mode of the mirror (− 23 dB) as well as the stress in the mirror when subjected to a typical vibro-acoustic launch load. This reduces the risk of damaging the mirror during the delicate launch phase, without increasing the complexity of the design., SCOPUS: ar.j, info:eu-repo/semantics/published

Aims. In this paper we investigate the detectability of the molecular oxygen in icy dust grain mantles towards astronomical objects. Methods. We present a systematic set of experiments with O2-H2O ice mixtures designed to disentangle how the molecular ratio affects the O2 signature in the mid- And near-infrared spectral regions. All the experiments were conducted in a closed-cycle helium cryostat coupled to a Fourier transform infrared spectrometer. The ice mixtures comprise varying thicknesses from 8 × 10-3 to 3 μm. The absorption spectra of the O2-H2O mixtures are also compared to the one of pure water. In addition, the possibility to detect the O2 in icy bodies and in the interstellar medium is discussed. Results. We are able to see the O2 feature at 1551 cm-1 even for the most diluted mixture of H2O:O2 = 9:1, comparable to a ratio of O2/H2O = 10% which has already been detected in situ in the coma of the comet 67P/Churyumov-Gerasimenko. We provide an estimate for the detection of O2 with the future mission of the James Webb Space Telescope (JWST). © ESO 2018.

e-ASTROGAM is a concept for a breakthrough observatory space mission carrying a γ-ray telescope dedicated to the study of the non-thermal Universe in the photon energy range from 0.15 MeV to 3 GeV. The lower energy limit can be pushed down to energies as low as 30 keV for gamma-ray burst detection with the calorimeter. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with remarkable polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous and current generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will be a major player of the multiwavelength, multimessenger time-domain astronomy of the 2030s, and provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LISA, LIGO, Virgo, KAGRA, the Einstein Telescope and the Cosmic Explorer, IceCube-Gen2 and KM3NeT, SKA, ALMA, JWST, E-ELT, LSST, Athena, and the Cherenkov Telescope Array., QC 20181105

The Auto-collimating Flat Mirror Assembly (AFMA) simulated the rotation of the Gaia satellite around its vertical axis. As such, it was one of the most important ground support equipment tools to test the payload performance of the Gaia mission. Although the performance of TNO's design during commissioning was excellent, one of the challenges of the AFMA design and realisation has proven to be the prediction of the dynamic behaviour of AFMA and the accurate prediction of its performance. Therefore, the dynamic behaviour of Gaia AFMA has recently been re-analysed. Dynamical points of attention are shown, and possible design improvements have been derived.

During 2014 and 2015, NASA's Neutron star Interior Composition Explorer (NICER) mission proceeded successfully through Phase C, Design and Development. An X-ray (0.2-12 keV) astrophysics payload destined for the International Space Station, NICER is manifested for launch in early 2017 on the Commercial Resupply Services SpaceX-11 flight. Its scientific objectives are to investigate the internal structure, dynamics, and energetics of neutron stars, the densest objects in the universe. During Phase C, flight components including optics, detectors, the optical bench, pointing actuators, electronics, and others were subjected to environmental testing and integrated to form the flight payload. A custom-built facility was used to co-align and integrate the X-ray "concentrator" optics and silicon-drift detectors. Ground calibration provided robust performance measures of the optical (at NASA's Goddard Space Flight Center) and detector (at the Massachusetts Institute of Technology) subsystems, while comprehensive functional tests prior to payload-level environmental testing met all instrument performance requirements. We describe here the implementation of NICER's major subsystems, summarize their performance and calibration, and outline the component-level testing that was successfully applied.

Future generations of space-based telescopes will require increasingly large primary reflectors, with very tight optical-quality tolerances. However, as their size grow, it becomes more and more difficult to meet the requirements, due to the manufacturing complexity and the associated costs. Chapters 2 and 3 propose two concepts of Adaptive Optics deformable mirrors, intended to be used as secondary corrector to compensate for manufacturing errors, gravity release and thermal distortion of large lightweight primary mirrors of space telescopes: (i) A scalable segmented bimorph mirror, based on independent PZT patches glued on Silicon wafers, providing a large number of degrees of freedom, a low mass while overcoming the problem of a low resonance mode; and (ii) A monolithic bimorph mirror, controlled by an array of independent electrodes, done by laser ablation on a single PZT patch. The modelling, the control strategy and the technological aspects are described. The performances of the manufactured prototypes are demonstrated experimentally. These prototypes have been developed in the framework of the ESA project, Bimorph Adaptive Large Optical Mirror Demonstrator (BIALOM). Chapter 4 introduces alternative designs, allowing to face the thermal distortion inherent to the bimorph architecture. They are compared in terms of stroke, voltage budget and first resonance frequency. These designs are required to be controlled in both directions using only positive voltages. Finally, the last chapter explores the feasibility of the shape control of a small size active thin shell reflector (with double curvature). The prototype is intended to be a technology demonstrator of a future large and very light active primary reflector. The behavior of the shell is studied through numerical simulations, and a preliminary design is proposed. This investigation is carried out in the framework of the ESA project: Multilayer Adaptive Thin Shell Reflectors (MATS)., Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object between the energy-range 25-80 keV in one 6 hour flight. Polarization measurements in soft gamma-rays are expected to provide a powerful probe into high-energy emission mechanisms in/around neutron stars, black holes, supernova remnants, active-galactic nuclei etc. The pathfinder flight was performed in July 2013 for 14 days from Sweden to Russia. The polarization is measured using Compton scattering and photoelectric absorption in an array of 61 well-type phoswich detector cells (PDCs) for the pathfinder instrument. The PDCs are surrounded by 30 BGO crystals which form a side anti-coincidence shield (SAS) and passive polyethylene neutron shield. There is a neutron detector consisting of LiCaAlF6 (LiCAF) scintillator covered with BGOs to measure the background contribution of atmospheric neutrons. The data acquisition system treats 92 PMT signals from 61 PDCs + 30 SASs + 1 neutron detector, and it is developed based on SpaceWire spacecraft communication network. Most of the signal processing is done by digital circuits in Field Programmable Gate Arrays (FPGAs). This enables the reduction of the mass, the space and the power consumption. The performance was calibrated before the launch., QC 20150604

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic lighthouse program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. The main scientific objectives of HERD are indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 104 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of seven X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side SKTs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10-5; effective geometrical factors of >3 m2sr for electron and diffuse gamma-rays, >2 m2sr for cosmic ray nuclei. R and D is under way for reading out the LYSO signals with optical fiber coupled to image intensified CCD and the prototype of one layer of CALO. © 2014 SPIE., QC 20150605

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study., QC 20150611

The Gaia payload ensures maximum passive stability using a single material, SiC, for most of its elements. Dedicated metrology instruments are, however, required to carry out two functions: monitoring the basic angle and refocusing the telescope. Two interferometers fed by the same laser are used to measure the basic angle changes at the level of μas (prad, micropixel), which is the highest level ever achieved in space. Two Shack- Hartmann wavefront sensors, combined with an ad-hoc analysis of the scientific data are used to define and reach the overall best-focus. In this contribution, the systems, data analysis, procedures and performance achieved during commissioning are presented. © 2014 SPIE.

Future space telescopes must maintain lower mass of the mirrors to keep launch cost down while increasing the size and performance of the space telescope. Although much work has been done in both adaptive optics and robust control, this thesis explores the application of several Multi-Input, Multi-Output controller designs for wavefront control of a Segmented Mirror Telescope with 936 actuators and 732 sensors. This thesis builds on previous robust control design by combining classical control with an H (Infinity) robust controller on a Singular Value Decomposition reduced model. It also presents reduction using Zernike polynomials and applies it to the integral control model as an alternate to Singular Value Decomposition model reduction. All methods were able to meet the 10 Hz bandwidth by design. Therefore, the analysis shows that there are several trade-offs that can be made based on control system size and desired performance. The H (Infinity) controller is combined in parallel with the integral controller for this thesis. The analysis shows that the parallel combined controller outperforms all other controllers; however, the cost analysis shows that a simpler Zernike reduced model can achieve slightly reduced performance at a much lower cost., http://archive.org/details/combinedintegral109454494, US Navy (USN) author., Approved for public release; distribution is unlimited.

The Segmented Mirror Telescope (SMT) housed at the Naval Postgraduate School is a unique, state-of-the-art optical instrument built to explore new technologies needed for future spacebased telescopes. A discrete Fourier transform wavefront reconstruction technique developed at Lawrence Livermore National Laboratory is discussed in this thesis as applied to a hexagonal aperture. A Fourier domain implementation of a spatial-frequency modal controller for a simple spring-mass model of a deformable mirror surface is provided by this thesis. This technique avoids more difficult time-domain solutions, is computationally efficient and scalable to much larger multi-input, multi-output systems than the SMT., http://archive.org/details/segmentedmirrort109455614, Approved for public release; distribution is unlimited.

The primary mirror diameter of affordable space telescopes is limited by mass and manufacturing cost. Currently planned optical/near-IR space telescopes use a segmented primary mirror with relatively few segments, and make limited use of real-time position control. However, control can be used as an enabler for a fundamentally different, very highly-segmented architecture, leading to a significant reduction in areal density, and hence a significant increase in the realistically achievable diameter of a space telescope. Small segments can be thinner, and overall mirror stiffness provided by control rather than a back-support structure. However, the resulting control problem involves thousands of actuators and sensors, and many lightly damped modes within the bandwidth. A local control approach similar to that previously developed for large deformable mirrors can provide robust performance for this problem. This is illustrated here for a 30m diameter primary mirror composed of 12 000 0.3m diameter segments. The areal density might be as low as 3-4 kg/m2, nearly an order of magnitude lower than current designs., QC 20140911

Heritage space telescope mirror technology-i.e. large, monolithic glass primary mirrors-has reached an upper limit on allowable aperture diameter given launch vehicle volume and mass constraints. The next generation of space telescopes will feature lightweight, actively controlled, segmented primary mirrors in order to achieve the advances in angular resolution and sensitivity that larger aperture diameters permit. Active control via embedded surface-parallel electrostrictive actuators provides the capability to change a mirror segment's optical prescription on orbit, to correct either quasi-static disturbances or manufacturing errors. Commanding low-order prescription changes (e.g. radius of curvature) using discretely-placed actuators, however induces high spatial frequency residual error in the mirror surface figure, resulting in wavefront error (WFE) that degrades optical performance. A key challenge is reducing this actuator-induced high frequency WFE to below acceptable levels while simultaneously commanding a particular change in global shape. This thesis considers a new set of geometric design variables that affect high-spatial frequency residual error in an effort to mitigate actuator-induced WFE. Specifically less conventional variations in rib height, actuator geometry, and rib-to-facesheet intersection geometry are exploited to achieve improved performance in silicon carbide (SiC) mirrors. A parametric finite element model is used to explore the trade space among these new parameters and to predict performance improvements. Simulation results show that these additional geometric considerations reduce actuator-induced WFE while keeping mirror mass and complexity constant.

A brief survey of normal and grazing incidence space telescope types is given. The optimization of telescope efficiency either by dedicated single, bi-layer or multilayer coatings is described. An outlook of solar and stellar coronagraphs is included., Published in the book "Space Telescopes," p165-191, 2010.

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. © 2010 SPIE.

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. © 2010 SPIE.

Future space telescopes will contain lightweight, flexible, segmented mirrors. Traditional control approaches for mirror alignment and shape control may be inadequate due to flexibilities and low natural frequencies. Using adaptive optics for space telescopes presents a possible solution. This research proposes innovative H(infinity) robust control techniques for these types of systems. An H(infinity) controller is synthesized for a complex analytical model with 997 inputs, 936 outputs, and 332 states. To accomplish this, a new technique for model reduction using Zernike polynomials was developed. The H(infinity) controller was able to achieve a minimum 15 Hz control bandwidth. The previous integral controller was unable to meet the 10 Hz bandwidth requirement. The H(infinity) design process used was validated on a simpler adaptive optics testbed. The experimental verification also showed that the robust control techniques outperformed the classical control techniques in the presence of disturbances. The significant contributions are a Zernike polynomial method for model reduction, robust controller synthesis for a complex adaptive optics analytical model, and experimental verification on an AO testbed. Although the robust control design is more complex, it provides improved performance in the presence of uncertainty in the disturbances and modeling., The original document contains color images.

We present new images and photometry of the massive star forming complex Cygnus X obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope. A combination of IRAC, MIPS, UKIRT Deep Infrared Sky Survey (UKIDSS), and Two Micron All Sky Survey (2MASS) data are used to identify and classify young stellar objects. Of the 8,231 sources detected exhibiting infrared excess in Cygnus X North, 670 are classified as Class I and 7,249 are classified as Class II. Using spectra from the FAST spectrograph at the Fred L. Whipple Observatory and Hectospec on the MMT, we spectrally typed 536 sources in the Cygnus X complex to identify the massive stars. We find that YSOs tend to be grouped in the neighborhoods of massive B stars (spectral types B0 to B9). We present a minimal spanning tree analysis of clusters in two regions in Cygnus X North. The fraction of infrared excess sources that belong to clusters with greater or equal to 10 members is found to be 50-70%. Most Class II objects lie in dense clusters within blown out H II regions, while Class I sources tend to reside in more filamentary structures along the bright-rimmed clouds, indicating possible triggered star formation., Accepted for publication in The Astrophysical Journal, v720 n1, Sep 2010. Sponsored in part by the National Science Foundation Research Experiences for Undergraduates (REU) and Department of Defense Awards to Stimulate and Support Undergraduate Research Experiences (ASSURE) programs under Grant no. 0754568 and by the Smithsonian Institution.

Future long dwell high resolution imagery satellites and space telescopes will require very large flexible primary mirrors. These large mirrors face many challenges including optical surface imperfections, structural vibrations, and jitter. A flexible mirror can overcome some of these challenges by applying adaptive optics techniques to correct mirror deformations and aberrations to produce image quality data. This paper examines and develops control techniques to control a deformable mirror subjected to a disturbance. The experimental portion of the work uses discrete time proportional integral control with second order filters to control disturbances in a deformable mirror and correct aberrations in an adaptive optics system using laser light. Using an adaptive optics testbed containing two deformable mirrors, two fast steering mirrors, two wave front sensors, a position sensor, and a combination of lenses the system corrects a simulated dynamic disturbance induced in the deformable mirror. Experiments using the described testbed successfully demonstrate wavefront control methods, including a combined iterative feedback and gradient control technique. This control technique results in a three fold improvement in RMS wavefront error over the individual controllers correcting from a biased mirror position. Second order discrete time notch filters are also used to remove induced low frequency actuator and sensor noise at 0.8 Hz, 2 Hz and 5 Hz. Additionally a 2 Hz structural disturbance is simulated on a Micromachined Membrane Deformable Mirror and removed using discrete time notch filters combined with a modal iterative closed loop feedback controller, showing a 36 fold improvement in RMS wavefront error over the iterative closed loop feedback alone., The original document contains color images.

Dome C, being one of the summits of the Antarctic plateau, is an exceptional site for astronomy. Its advantages over a temperate-latitude site for a wide range of observations are considerable, as well as becoming increasingly appreciated by the scientific community. We discuss what these advantages are, and some of the science possibilities they offer. They fall under four principal regimes: (i) diffraction-limited observations (i.e. ? > 3 ?m), (ii) wide-field thermal infrared observations (i.e. ? > 2.2 ?m), (iii) when observations are seeing-limited (i.e. from 0.4-3 ?m) and (iv) new windows (i.e. in the mid-IR and submm). Each regime offers particular advantages over corresponding observations made from a temperate site. When more than one of these advantages applies the gains can be potent. The science possibilities are many, ranging from solar system science, such as monitoring the global climate of Mars and Venus, to the study of the distant universe, such as ultra-deep fields to probe the assembly process of galaxies and the search for the `first light` through thermal-IR emission from gamma ray bursters. In this paper we discuss a range of science opportunities offered by each of these regimes, making use of a 2 m-class telescope. Such a facility would serve as an essential next step in the development of Antarctic astronomy, and the far-reaching possibilities offered by larger telescopes and interferometers on the Antarctic plateau. © EAS, EDP Sciences 2007.

The primary goal of DARWIN is to detect earth-like extrasolar planets and to search for biomarkers. This is achieved by means of nulling interferometry, using three free-flying telescopes and a Beam-Combiner (BC) hub. DARWIN will be able to perform astrophysical imaging with high spectral and spatial resolution. Should one of Darwin's telescope flyers fail, then Darwin's capability of detecting earth-sized exo-planets is dramatically reduced. However, with only two telescopes the imaging mode can continue operating with minimal performance degradation, thus ensuring mission success. This work describes a trade-off study between four conceptual three-beam BC's, that are capable of performing both as a nuller and as an imager. A proposed breadboard design will demonstrate end-to-end Fringe-Tracking (FT) and Optical Path-Length (OPL) control. The BC concept is based on a pupil-plane (Michelson) beam combination scheme. Pupil-plane imaging EC's offer a large overlap in terms of optical layout with the nulling BC concept, making it possible to develop a combined nulling- and imaging BC. This means that a reduced number of optical components can be used compared to a scheme with separate BC's. The BC concept inherently compensates for unequal OPL's, which in ground-based interferometers is compensated for by long stroke Optical Delay Lines (ODL's).

A Darwin precursor breadboard, comprising both fine lateral and longitudinal metrology sensors was designed, built and partially tested. The lateral metrology sensor was designed and built by TNO TPD and more than meets the imposed requirements. The longitudinal metrology sensor consists of a dual wavelength interferometer with an integrated delay line for optical path stabilisation. Here TNO TPD supplied the delay line and implemented the optical path difference stabilisation control. Experiments under ambient conditions show that noise reduction up to five orders of magnitude is achievable.

The FIRST/HIFI mission allows for the local oscillator frequency multiplier chains to be cooled to 120-150 K in order to increase available output power. This paper will discuss the implication of cooling on GaAs based planar Schottky diode varactors for flight applications. A robust testbed that has been built to measure output power over a wide range of frequencies will be described. Preliminary measurements at cryogenic temperatures done on individual multipliers at 200 GHz along with multiplier chains to 400 GHz will be presented. In a 182-212 GHz designed balanced doubler the peak efficiency at 201 GHz improves from 17% to 30% upon cooling from 300K to 50 K. When this stage is used to pump a 362-424 GHz designed balanced doubler the efficiency of the two-stage chain increases from less than 0.8% to 3%. This represents an increase in efficiency of 6 dB., Prepared in cooperation with GMM, VDE/VDE-Gesellschaft Mikroelektronik, Mikro- und Feinwerktechnik; ITS, Informationstechnische Gesellschaft im VDE. This article is from the THz Conference 2000 pp81-84. This article is from ADA398789 International Conference on Terahertz Electronics (8th), Held in Darmstadt, Germany on 28-29 September 2000

Due to mechanical aspects of fabrication, launch, and operational environment, space telescope optics can suffer from unforeseen aberrations, detracting from their intended diffraction-limited performance goals. This dissertation gives the results of simulation and theoretical studies designed to explore how wavefront aberration information for such nearly diffraction-limited telescopes can be estimated via the Gonsalves (least-squares) phase diversity technique. In traditional phase diversity, aberrations are estimated from two images--one conventional, focused image and one image that has been defocused by a known amount. These studies are original and significant in that this effort represents the first time the effects of photon noise have been addressed for this relatively new aberration sensing technique. The effects of image-domain noise such as photon noise are of interest since the aberration estimates are derived from image-domain data. The analysis of this dissertation consists of simulation, theoretical investigation, and experimental application. Simulation studies incorporated models of the proposed Next Generation Space Telescope, as well a more generic, Zernike-aberrated model. Theoretical investigation involved deriving and numerically analyzing the Cramer-Rao lower bound for the phase diversity problem. The practical application dealt with diagnosing aberrations for an adaptive optical, ground-based telescope system.

A NASTRAN structural analysis of a lightweight mirror structure has been completed and is compared with previous experimental measurements. A preliminary design for a 4-meter aperture, 6-meter focal length primary mirror is presented. (Author)

The Hubble Space Telescope (HST) is an orbiting astronomical observatory operating in the spectrum from the near-infrared into the ultraviolet. Launched in 1990 and scheduled to operate through 2010, HST carries and has carried a wide variety of instruments producing imaging, spectrographic, astrometric, and photometric data through both pointed and parallel observing programs. Over 100,000 observations of more than 20,000 targets have been produced for retrieval. A macroscopic, cumulative representation of these observations is shown in the figure below to provide a sense of the enormous volume of astronomical data collected by the HST about our universe, our beginnings, and, consequently, about our future. The telescope is already well known as a marvel of science. This case study hopes to represent the facet of the HST that is a marvel of systems engineering, which, in fact, generated the scientific research and observation capabilities now appreciated worldwide.

Thesis (Ph. D.)--University of Rochester. The Institute of Optics, 2017. "Chapter 3 was co-authored with Alden Jurling, who wrote the introduction as well as Sections 3.2 and 3.3, except for subsections 3.2.5 and 3.3.3"--Page xiii., We present a series of advancements to the state of the art in computational optics, in particular by enabling new areas of application for image-based wavefront sensing via phase retrieval. This includes demonstration of a parameterized model for chromatic aberrations which can improve diagnostics in dispersive optical systems. Potential sign ambiguities are identified and strategies to avoid or remove them are prescribed. The algorithm is also tested in a real-world laboratory environment, with results in good agreement with expected values. As a prerequisite to this advance, we also evaluate a collection of less frequently utilized discrete Fourier transform (DFT) algorithms that have an advantage over the fast Fourier transform in that they allow for an arbitrary scaling factor between the input and output domains. The trade-off in terms of computation speed is demonstrated using timing benchmarks for a variety of physical optics modeling scenarios, and multiple cases are found where the arbitrarily-scaled DFTs are preferable. In addition, we address issues with image-based wavefront sensing that arise from the unusually-large detector plane of a wide-field space telescope, where large chief ray angles at the edges of the field violate the small angle assumption of the usual Fresnel propagationintegral. By starting from an exact expression and adapting an approximation approach previously derived for digital holography with non-parallel planes, we find an algorithm that is both computationally efficient and sufficiently accurate. Finally, we present a computational optical system with an extended depth of field that was achieved by inducing field-independent coma intrinsic to the geometrical optics design via optimized decentration of the lens elements. This is a departure from the more common approach that requires a phase mask to control the wavefront.

Future space telescopes will contain lightweight, flexible, segmented mirrors. Traditional control approaches for mirror alignment and shape control may be inadequate due to flexibilities and low natural frequencies. Using adaptive optics for space telescopes presents a possible solution. This research proposes innovative H[infinity] robust control techniques for these types of systems. An H[infinity] controller is synthesized for a complex analytical model with 997 inputs, 936 outputs, and 332 states. To accomplish this, a new technique for model reduction using Zernike polynomials was developed. The H[infinity] controller was able to achieve a minimum 15 Hz control bandwidth. The previous integral controller was unable to meet the 10 Hz bandwidth requirement. The H[infinity] design process used was validated on a simpler adaptive optics testbed. The experimental verification also showed that the robust control techniques outperformed the classical control techniques in the presence of disturbances. The significant contributions are a Zernike polynomial method for model reduction, robust controller synthesis for a complex adaptive optics analytical model, and experimental verification on an AO testbed. Although the robust control design is more complex, it provides improved performance in the presence of uncertainty in the disturbances and modeling., http://archive.org/details/finesurfacecontr1094510454, Approved for public release; distribution is unlimited.

The Hubble Space Telescope (HST) is an orbiting astronomical observatory operating in the spectrum from the near-infrared into the ultraviolet. Launched in 1990 and scheduled to operate through 2010, HST carries and has carried a wide variety of instruments producing imaging, spectrographic, astrometric, and photometric data through both pointed and parallel observing programs. Over 100,000 observations of more than 20,000 targets have been produced for retrieval. A macroscopic, cumulative representation of these observations is shown in the figure below to provide a sense of the enormous volume of astronomical data collected by the HST about our universe, our beginnings, and, consequently, about our future. The telescope is already well known as a marvel of science. This case study hopes to represent the facet of the HST that is a marvel of systems engineering, which, in fact, generated the scientific research and observation capabilities now appreciated worldwide.