GENERATION-X TECHNOLOGY DEVELOPMENT PROGRAM

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GENERATION-X TECHNOLOGY DEVELOPMENT PROGRAM Activity submission in response to the Astro2010 PPP RFI. Roger Brissenden Harvard-Smithsonian Center for Astrophysics (617) 495 7387 [email protected] 1 April, 2009

Generation-X Study Team Members Martin Elvis, Giuseppina Fabbiano, Bill Forman, Ryan Hickox, Paul Gorenstein, Mike Juda, Paul Reid, Dan Schwartz, Harvey Tananbaum, Scott Wolk (Harvard-Smithsonian Center for Astrophysics) Simon Bandler, Ann Hornschemeier, Richard Mushotzky, Robert Petre, William Zhang (NASA GSFC) Stephen O'Dell, Martin Weisskopf (NASA MSFC) Mark Bautz, Claude Canizares, Enectali Figueroa-Feliciano, Mark Schattenburg (MIT) Robert Cameron, Steve Kahn (Stanford University) Niel Brandt, Susan Trolier-McKinstry (Penn State University) Melville Ulmer (Northwestern), Webster Cash (Colorado), Robert Rosner (ANL) Industry Team Members Chuck Lillie (NGST), Steve Jordon (Ball), Linda Abramowicz-Reed (Goodrich), Craig Golisano (ITT), Domenick Tenerelli (Lockheed-Martin) Together with 37 scientific and technical collaborators. http://www.cfa.harvard.edu/hea/genx

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ Summary

The Generation-X (Gen-X) observatory is designed to observe the first black holes and stars at redshift z~10-20, and to trace the evolution through cosmic time of galaxies and their elements using X-ray spectroscopy. Understanding the formation and evolution of the first objects, from very early times into the structure we see in the Universe today is a primary goal of modern astrophysics, and X-ray observations provide a uniquely important probe of the high-redshift Universe. The first objects are expected to be powerful sources of X-rays that penetrate the haze of the high z intergalactic medium and the dust and gas expected around high z galaxies. Pioneering observations of the X-ray universe at high redshift drive mission parameters, e.g., a telescope with collecting area ~50 m2 and angular resolution ~0.1″ at 1 keV, to yield source detections at a flux level of ~2 x 10-20 erg cm-2 s-1 (0.1-10 keV) in ~2 Ms of exposure time. Gen-X will need angular resolution an order of magnitude better than Chandra, and collecting area ~15 times that of the International X-ray Observatory (IXO). To meet these requirements, a focused program of technology development for the optics and science instruments is required. The mission is planned to follow IXO, building on that mission’s science and technology development. We propose a technology development program for the next decade that will evolve the key optics and detector technologies for Gen-X to Technology Readiness Level 6, through a well-planned series of technology demonstration gates. The program is based on our successful 2005 Vision Mission and 2008 Astrophysics Strategic Mission Concept studies. These defined an initial technology development plan for Gen-X and a mission architecture based on NASA’s planned Ares V vehicle that will enable the launch of such a large area X-ray telescope observatory to orbit around L2 in the decade after next. The technology program will evolve the mirror and science instrument technologies through a series of program technology gates. Each gate ties together incremental stages in optics and instrument technology development, allowing for updates of the driving science requirements and system error budget, and for verification of progress before releasing funds for the next gate. To meet the challenge of producing very large area, lightweight, high angular resolution Xray optics we propose pursuing breakthrough technology to adjust the mirror shape on-orbit. The mirror technology program leverages off the achievements of the Constellation-X program and future progress as that development effort proceeds in support of IXO. The program will also build on a number of presently funded NASA optics technology hardware programs. We have identified the three main technology drivers for the optics: the figure adjustment of a mirror element, the development of an aligned mirror module, and development of the on-orbit adjustment process. These “tall poles” are core to the optics program and technology gates. The instrument technology programs are described in three complementary technology white papers for the Gen-X Microcalorimeter (XMS), Wide Field Imager (WFI) and grating array. These papers identify the principal technology drivers as multiplexing a large array, development of the low noise active pixel technology, and development of precision alignment and test facilities respectively. In this paper we describe the Gen-X technology development program with focus on the optics. We provide the schedule and costs for a comprehensive program that covers the optics, instruments and a management component to ensure proper system level trades and to couple tightly the technology developments. It is clear that in order to realize the scientific goals of GenX, a focused technology program of sufficient scale is required. It is also clear that the development of the scalable, high resolution Gen-X optics technology, based on technology and mission experience from the IXO mission, will not only enable the Gen-X science, but also open the future to a full range of high-resolution X-ray telescopes and astrophysics goals. 1

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 1.0 KEY SCIENCE GOALS The design of the Generation-X (Gen-X) mission is driven by the goal of observing the first black holes and stars at redshifts z~10-20, and tracing the evolution of galaxies and their chemical elements through cosmic time. In addition, the dramatic advances in sensitivity and angular resolution provided by Gen-X will open a vast new discovery space for many subfields in astrophysics, analogous to that achieved by Chandra and XMM-Newton. Gen-X will follow the International X-ray Observatory (IXO), building on both the IXO science and technology. We provide here a summary of the primary science goals and discuss selected cases from the broad range of science enabled by Gen-X. A more complete discussion of the science is provided in the six related Astro2010 science white papers[1-6]. Figure 1: Simulated 2 Ms exposure of a 2′x2′ extragalactic field with Gen-X (left) compared with the same region in a ~2 Ms Chandra image (right), characteristic of the deepest current Chandra exposures. The population of high-redshift black holes as small as ~103 M can be detected and studied with Gen-X.

1.1 Primary Science Goals and Objectives 1.1.1 The Formation and Growth of the First Black Holes Theories of star formation in the early Universe suggest that the first populations of black holes, with masses ~100 M , were formed at z ~ 15-20 from the deaths of the first massive stars[7]. These black holes are expected to be the progenitors of the supermassive black holes (SMBHs, with masses as high as 109 M ) that power quasars observed at high redshift (observed to z~6) and that lie nearly dormant at the centers of massive galaxies today. Theory allows for several paths to the formation of SMBHs, which follow very different evolutionary scenarios. While some SMBHs may form through Eddington-limited accretion onto a seed black hole, others are predicted to form by direct collapse of “quasi-stars” embedded within massive gaseous envelopes, which allow super-Eddington accretion and thus shorter formation timescales[8]. Black hole – black hole mergers may also play an important role[9]. Further, the observed local relation between MBH and galaxy bulge properties[10] implies feedback between black hole growth and galaxy evolution[11]; however the details of these processes at high redshift, when the first galaxies are forming, remains unknown. Gen-X will allow direct tests of the evolution of the first black holes and their host galaxies, by detecting significant populations of accreting black holes with masses as low as ~103 M at high redshifts (to z ~15; higher for super-Eddington luminosities or more massive systems). At present, Chandra has detected luminous quasars at z > 6 with SMBH masses ~109 M [12], but these objects represent the rare, extremely massive end of the black hole population. To detect accretion activity from less massive (and more numerous) black holes, to identify their seeds at higher redshifts, and to constrain the mechanisms by which they formed and evolved will require the large advance in sensitivity and angular resolution provided by Gen-X. Assuming Eddington-limited growth, the progenitors of a 5x106 M black hole at z=6 would have M ~ 5x103 M and LX~1041 ergs s-1 at z=10, and would have an X-ray flux of ~10-19 erg cm-2 s-1, readily detect

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ able in 1 Ms with Gen-X. At its limiting sensitivity in a 2 Ms observation (Fig. 1), Gen-X will detect SMBH seeds with MBH ~ few x103 M radiating at the Eddington limit to z~15. By probing the properties of SMBH’s to high redshift, Gen-X will discriminate among the formation models and provide key insights into how the black holes that form the bulk of the black hole mass distribution in the local Universe formed and grew[13]. In addition, by understanding SMBH growth at high redshift, we can determine the effects of this growth on galaxy evolution and on the reionization of the Universe. 1.1.2 The First Galaxies and Stars Gen-X will provide a unique probe of the first generation of stars and galaxies. Light from z=15, where the first star formation occurs, can only be detected at X-ray wavelengths or at > 2 µm, as absorption by the neutral intergalactic medium (IGM) removes all optical and UV photons with wavelengths < 0.12(1+z) µm (i.e., shortward of Ly-α). A direct signature of the first galaxy formation should be X-ray emission at characteristic X-ray temperatures of 0.1-1 keV from the collapsing proto-galaxies before they cool and form the first stars.[14] In addition, young stellar populations produce copious X-rays. Given the scaling between star formation and X-ray luminosity (LX=1041 ergs s-1 per 100 M per year of star formation) similar X-ray luminosities are produced by both proto-galaxy collapse and the first generation of star formation. At z=6, a luminous star-forming galaxy with LX ~ 5x1041 erg s-1 will have an X-ray flux ~10-18 erg cm-2 s-1. Gen-X will enable X-ray spectroscopy at this faint flux, which more than an order of magnitude beyond the spectroscopic capability of IXO or other planned X-ray missions. Gen-X will study emission from both collapsing proto-galaxies and star formation at high redshifts, using high-resolution imaging and spectroscopy. Since a resolution of 0.1″ corresponds to physical scales of 0.8, 0.6 and 0.3 kpc at z=3, 6 and 15 respectively, Gen-X will spatially resolve the extended regions of star formation and hot gas and separate them from nuclear SMBH emission. Gen-X will also use spectroscopy to separate hard X-ray binary (XRB) emission from hot gas[15-21]. Spectral emission lines will be redshifted into the very soft X-ray band, and simulations demonstrate that Gen-X will be able to determine redshifts, temperatures and metallicities for primordial galaxies. For objects with kT~0.5 keV at z~6, a detector resolution 400 counts.

1.1.3 The Evolution of Galaxies, Black Holes and the Enrichment by Heavy Elements In addition to studying the formation of galaxies at very high redshifts, Gen-X will probe the X-ray evolution of galaxies from the peak of star formation to lower redshifts. The cosmic star formation rate (SFR) was 10-100 times higher at z~1-3 than at present[23]. Since X-ray luminosi-

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ ties in “normal” galaxies are well correlated with the SFR[24], X-ray evolution with z is expected[25], and has been observed with Chandra to z~1 [26]. Chandra “stacking” analysis of the integrated emission of large samples of “Lyman break” galaxies[27-30] (z~3) reveals still higher Xray luminosities at higher z. Gen-X will detect and study hundreds of actively star forming galaxies at z~3 (Fig. 2). This high redshift sample will enable robust statistical studies of their X-ray characteristics, allowing, for example, estimates of the true SFR even in dust-enshrouded protogalaxies and measurements of the production of heavy elements. Gen-X will also enable studies of quasar winds and jets[31,32], which can have dramatic effects for accretion onto a central SMBH, stopping and even reversing the in-flow. Quasar outbursts may trigger galaxy-wide winds in elliptical galaxies[33-36]. These winds should cause shocks in the surrounding ISM, triggering localized star formation, and may also be important for the chemical evolution of the early Universe. High resolution Gen-X spectroscopy (requiring a dispersive spectrometer with E/dE =104) can determine the physics of these winds, measuring mass loss rates, abundances and velocities. In addition, Gen-X will spatially resolve features of relativistic AGN jets in unprecedented detail. Gen-X will thus allow us to study AGN outflows in hundreds of systems over a wide range of z, so determining the AGN duty cycle, gas flow speeds and energetics, and probing the feedback process behind the M-σV relation[37]. For virtually all massive galaxies within 30 Mpc, Gen-X will spatially resolve the SMBH sphere of influence (the Bondi radius), something that can now be accomplished only for very few nearby galaxies. For the best studied systems, e.g., M87, Gen-X will resolve the accretion flow to 10% of the Bondi radius allowing direct observation of the gas flow and the effects of angular momentum transport. This would provide important clues to the factors that govern accretion of hot gas by AGN. Finally, Gen-X will provide key insights into the interaction between radio jets and hot gas in clusters, groups, and massive ellipticals. Gen-X spectroscopy of the cavities and shocks observed by Chandra will allow us to better understand the energy transfer between the relativistic plasma of the jet and the thermal plasma in the surrounding environment. 1.2 Additional Broad Based Science Capabilities In addition to the primary science goals, Gen-X will address a broad range of science. 1.2.1 Accreting Binary Populations and ISM Evolution in Galaxies Gen-X will observe the populations of accreting compact objects and the hot ISM in galaxies, which carry information about the star-formation and chemical enrichment history of galaxies and the behavior of matter in extreme gravitational and/or magnetic fields. Gen-X will enable measurements of the mass spectrum and number density of stellar compact objects (Fig. 3). The resolution and sensitivity will allow observers to follow the evolutionary paths of binary stellar systems and determine if they are related to gravitational-wave sources and γ-ray bursts. Observations will measure the evolution in X-ray output per unit star-formation rate, and whether accreting binaries are related to enhanced star-forming activity, lower metallicity, or environment. Comparison with predictions from X-ray binary population synthesis will provide additional constraints on the cosmological evolution of compact object populations. Observations of high redshift galaxies can provide additional constraints on the enrichment cycles of the elements of life (i.e., how stars enrich the ISM and how galactic outflows regulate star formation). 1.2.2 Supernovae and Their Consequences Gen-X will dramatically improve our understanding of supernovae (SNe) and their byproducts, which play central roles in galaxy evolution, cosmic ray acceleration, and the formation of compact objects. High-resolution imaging and spectroscopy of SNRs will address crucial 4

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ issues in shock physics. Studies of non-thermal filaments, along with post shock temperature and ionization structure on small scales, will constrain the level of particle acceleration by shocks. Expansion studies, coupled with spectral line diagnostics, will provide constraints on electronion equilibration timescales in fast shocks. Sensitive high-resolution X-ray studies of SNe will provide strong constraints on the properties of the progenitors. The high angular resolution of Gen-X will spatially separate supernovae from other galactic emission in external galaxies to ~15 Mpc. High-quality spectroscopy of core-collapse systems will establish the nature of their X-ray emission and measure the density of the surrounding medium and ejecta properties. In addition, the origin of Type Ia SNe will be determined by their X-ray light curves, which can distinguish between single- and double-degenerate progenitor formation scenarios. Imaging of Galactic pulsar wind nebulae (PWNe) at high sensitivity and resolution will reveal how rotational energy of a rapidly-spinning neutron star is converted into an expanding bubble of energetic particles and magnetic flux, accompanied by energetic jets, and how these particles escape to ultimately enhance the energy density of the Galaxy. IXO will contribute significantly to understanding the extended nebular structure for some PWNe. However, observing the detailed structure that reveals the pulsar geometry, the shock sites, and the instability regions requires increases in sensitivity and angular resolution that Gen-X will provide. Figure 3: Simulations of an interacting galaxy pair at 200 Mpc (left) and at z=1 (right), similar to a Balmer break galaxy. Gen-X resolves X-ray binaries to allow X-ray “population synthesis”, measurement of the chemical enrichment of the ISM by SNR, and other key aspects of galaxy evolution.

1.2.3 Diffuse Baryonic Matter Galaxy clusters, whose dominant baryonic component is hot, X-ray emitting gas, are the largest virialized structures in the Universe. Gen-X, with its high sensitivity and unmatched angular resolution, will open new windows for the study of galaxy clusters. Sharp features such as shock fronts, cold fronts, and buoyant bubbles provide unique opportunities to measure the microphysical gas properties including viscosity, electron-ion equilibration and ionization timescales, and the structure of magnetic fields. These properties govern mixing and transport processes and possible heating of the ICM by feedback from the central black hole. For clusters within ~200 Mpc, Gen-X’s resolution is 10% of the particle mean free path. Therefore, Gen-X will provide definitive measurements of the transport coefficients governing the physical processes. In addition, Gen-X will allow us to probe the outer regions of clusters all the way to the infall shock, where the intergalactic matter flows into the cluster along the filaments of the Cosmic Web. Key physical processes at infall shocks include cosmic-ray acceleration and magnetic field generation, as well as compression and heating of the inflowing intergalactic medium, allowing us to study its elemental abundances and energy content. In addition, Gen-X will study absorption features in cluster outskirts; several hundred background sources behind the outer regions of the Coma cluster will be available for detection of Fe and O absorption. Even a z = 0.2 cluster such as A2163 should have ~10 background sources. This will open a unique possibility to combine emission and absorption by the same medium and directly observe, for example, the ioni-

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ zation nonequilibrium and stripping of metal-rich gas from small halos in the cluster infall region. The sensitivity and angular resolution of Gen-X will allow observation of cluster formation and mergers at z>1 along with the effects (e.g., “pre-heating” and chemical enrichment) of AGN feedback and starbursts, near their peak of activity. 1.2.4 Stars and Planets Gen-X will enable a wide range of new science for stars and their interactions with their planets. One of the great successes of Chandra has been the deep surveys of nearby regions of star formation. Gen-X will survey nearly every region of massive star formation in the Galaxy. Doppler mapping will be possible on all varieties of cool stars, and tomography of the thousands of stellar coronae will allow the characterization of the coronae of G type stars in the Galaxy. Gen-X will also directly impact our understanding of exoplanets. Magnetic entanglement of stars and hot Jupiters has been predicted and indirectly observed. This entanglement enables Gen-X to be sensitive to exo-planet eclipses by primary stars for 200 stars to 50 pc with X-ray eclipse depths of 1.5%, and for 1,000 stars to 100 pc with depths of 5%. 1.3 Investigations and Measurements The Gen-X primary science objectives are well matched to a broad range of the present NASA goals. Table 2 maps the 2007 NASA Science Plan Research Objectives to the Gen-X key science objectives and then flows them to the observations (measurements) required to accomplish the science objectives. These observations in turn map to the set of derived mission parameters as discussed in Section 2.1. Table 2: Flow from NASA Strategic & Science Plan Objectives to Gen-X Objectives & Measurements NASA Research Gen-X Key Science Gen-X Required Observations Objectives Objectives Understand how the first The First Black Holes & 2Ms deep surveys to find MBH ~ few x103 M to z~15 stars and galaxies formed, the First Stars emitting at Ledd with flux of 2x10-20 erg cm-2 s-1 (0.1-10 and how they changed keV). over time into the objects The Evolution of BHs & 106 s deep surveys to resolve AGN from binaries and hot recognized in the present Galaxies, and heating of gas and to measure broadband spectra in 1041 ergs s-1 universe. baryonic gas galaxies at z~3. -Physics of the Cosmos Chemical Evolution of 104-105 s observations for Fe, Si and O lines from SNR -Cosmic Origins the Universe to 10 Mpc, normal galaxies to 200 Mpc, clusters to their epoch of formation. Understand the origin and Relativistic Jets Detailed images and spectra to measure knot speed and destiny of the universe, structure from imaging black hole jets. 105 s observation phenomena near BHs, every 2 years. and the nature of gravity. Probing the Inner ReSpatially resolve emission from hot gas inside the Bondi -Physics of the Cosmos gions of Accretion Flows radius for all massive galaxies within 30 Mpc. Understand the fundaStellar Magnetic Fields High-resolution X-ray spectra of stellar coronae to demental physical processes and Reconnection Physics termine roles of magnetic field, rotation, age and mass. of space plasma systems. Diverse Plasma High-resolution X-ray spectra and plasma diagnostics -Physics of the Cosmos Environments for: stellar coronae, planetary magnetospheres, SNR, hot gas in galaxies and clusters of galaxies, and accretion disks in XRBs and AGN. Understand how individEmbedded Star Census of 100,000 young stars in Galactic starburst ual stars form and how Clusters complexes (Sgr B2, NGC 3603, W49, W51, 30 Dor) those processes ultimately Protostars Direct imaging, e.g., of the TW Hya protoplanetary disk affect the formation of in 106 s, and indirect reverberation mapping of dozens of planetary systems. Ophiuchus disks, using the 6.4 keV fluorescent iron line. -Exoplanet Exploration

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 2.0 TECHNICAL OVERVIEW The Generation-X mission concept provides the large effective area and high angular resolution X-ray telescope and the focal-plane instrumentation needed to address the science objectives discussed above. NASA’s planned development of the Ares V vehicle will enable launch of a very large area X-ray telescope observatory into orbit around L2. We use electro-active materials to impart in-plane strains that correct the mirror figure to a 0.1″ half-power-diameter (HPD) focus. Our current concepts evolved from our Vision Mission (VM) study[38,39] and current Astrophysics Strategic Mission Concept (ASMC) study being funded by NASA[40]. Studies by the GSFC Integrated Mission Design Center and JPL Team-X[38,39] of preliminary mission concepts, not including the optics or science instruments, found that the deployment mechanisms and thermal control would be difficult design areas, but not beyond the expected state of the art in the next decade. Our primary technical discussion (§2.3) concentrates on development of the large area, 50 m2, and high quality imaging, 0.1″ HPD, grazing incidence (GI) mirror assembly, discusses our program in terms of a set of technology development gates (§2.4), and identifies the three technology “tall poles” discussed in §3. The program schedule and costs (§5 and 6) cover the complete Gen-X technology development program including science instruments.[49-51] 2.1 Required Capabilities Table 3 summarizes the baseline mission parameters, derived from the science objectives and required observations (Table 2). To collect 5 counts from an Eddington limited 3,000 M black hole at z=15, in 2x106 sec, requires an effective area of 50 m2. Such a modest number of counts is still sufficient for source detection, localization, and identification with counterparts at other wavelengths[41]. With the anticipated baseline detector background, we then require 0.1″ resolution for 5 counts to be statistically significant with an expected background of 0.08 counts per resolution element in a 2x106 sec exposure*. These two parameters – effective area and angular resolution – drive the mission. System trade-offs will be made among energy resolution, bandwidth, background, field of view and exposure time as the technology matures.

Table 3: Gen-X Derived Mission Parameters Parameter Effective Area Angular Resolution Energy Resolution

Baseline 50 m2 0.1″ HPD at 1 keV E/dE=104

Background (0.5 – 2.0 keV) Energy Range Field of View, WFI Field of View, XMS Time Resolution Sky Availability

0.004 cts ks-1 arcsec-2 0.1 – 10 keV 5′ radius 3′ radius 50 µs 50%

2.2 Implementation Concept NASA’s planned Ares V launch capability provides sufficient fairing size and lift capacity for us to consider a relatively straightforward observatory concept. We will unfold the optic onorbit and use rigid-body adjustments to align the constituent modules. Fig. 4 shows the baseline architecture consisting of a single, 50 m2 effective area X-ray telescope with 60 m extendible optical bench and a single science instrument focal plane package. The Gen-X effective area is not limited by the lift-capacity of the Ares V but by the volume of the shroud. The mass estimate for Gen-X based on the JPL Team-X study is 22,300 kg, well within the expected Ares V capability of ~60,000 kg to L2. Increased mass may be considered if it gives improved X-ray performance. The grazing incidence (GI) telescope will be built up from about 7,000 pairs of primary (P) and secondary (S) mirror elements – about the same number as IXO. These pairs are azimuthal *

For a Wolter-Schwarzschild prescription, there are 13x106 resolution elements within 5′, so that one expects 3.6 false sources with a 5σ detection threshold. This implies 5 to 10 counts for a significant detection in 2 Ms, going from the on-axis to 5′ off-axis position.

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ segments of a circular shell. Mirror pairs from many shells are nested within modules that provide mechanical support, alignment, and thermal and electrical services. The telescope concept has an 8.3 m diameter inner section filled with 125 shells, and four 60 fold-out sections (one split) giving a partially filled 16 m diameter mirror. Each section contains several modules. Each mirror element (mirror segment) will include piezo-electric actuators so that the mirror figure can be adjusted on-orbit to achieve 0.1″ HPD angular resolution. Adjustment feedback is provided by a dedicated moveable X-ray detector positioned in the optical path at a series of fixed distances forward of the focal plane, where the converging rays from each shell are imaged as distinct rings. The piezo actuators are adjusted until each shell’s arc-like image has the correct centroid, extent, and uniform profile[42]. Assuming our nominal adjuster size, we estimate a sufficient number of photons can be detected from Sco X-1 every 500 sec. We would need to measure ~50 distinct fields, so at a 50% duty cycle for positioning and ground calculation and commanding, 10 full adjustment iterations could be done in a week to a month. Adjustments will correct deformations due to the thermal environment which will then be controlled to remain stable. The science instrument package will have the capability to position at the aim point either the XMS, giving non-dispersive resolution of 2 eV from 0.2 – 6 keV, or the WFI, a self triggering active pixel image detector giving high throughput over 0.1 – 10 keV and over-sampling the telescope response. The grating spectrometer with 10 m2 effective area (1 keV) will give spectral resolving power of 104 over 0.3 – 1 keV, for point-like sources. Figure 4: Baseline Gen-X architecture in the deployed configuration.

2.3 Adjustable Optics 2.3.1 State of the Art The Chandra X-ray Observatory represents the state of the art of cosmic X-ray imaging, with its sub arc-second point spread function (PSF) and ~0.08 m2 effective area. Chandra employed thick (15 to 25 mm), full-cylinder Zerodur shells as optics, each individually polished to extremely high accuracy. Such thick, and heavy, shells are inconsistent with achieving the 50 m2 effective area within launch mass limits and affordable fabrication costs. XMM Newton, comprised of ~1 mm thick electroformed mirrors, has ~5 times more area than Chandra, but its mirror technology provided 15″ imaging. IXO will have 3 m2 effective area at 1 keV and 5 arcsecond imaging. The slumped glass optics technology developed for IXO and being used for NuSTAR, has sufficiently low areal density, and serves as the starting point for Gen-X mirror development. Thus, Gen-X technology development will leverage off IXO development. The breakthrough technology we will pursue is the development of optics that are adjustable on-orbit. As a straw-man point design, the GI X-ray telescope consists of about 250 nested shells. Groups of segments of shells form modules, containing individual primary/secondary pairs manufactured from approximately 1 m x 1 m thin glass sheets. Electro-active material deposited on the back surface is energized on-orbit to adjust the low spatial frequency components of mirror figure. Each mirror segment will be mounted with tilt and decenter adjustment capability. Individual modules will be adjusted mechanically to a relatively modest tolerance of 10 µm, corresponding to 0.03″ contribution (10% in quadrature) to the 0.1″ HPD image. 8

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 2.3.2

Requirements Flowdown of the top-level requirement of 0.1″ HPD is used to estimate final mirror figure requirements. While a full error budget flow-down will be formulated as part of the technology development, we have determined mirror figure requirements, after figure correction using the adjustable optics, consistent with the imaging requirement[41] (Fig. 5). Figure 5: Chandra and Gen-X required axial figure error Power Spectral Densities (PSD). The Chandra PSD is consistent with 0.5″ HPD at 1 keV. The Gen-X requirement is consistent with 0.1″ HPD at 1 keV.

2.3.3

Technology Description We will develop adjustable mirrors – thin optics with thin film electro-active∗ actuators deposited directly on the back surface – whose surface figure can be locally corrected via surfaceparallel strains without the need for a reaction structure. Such optics would be adjusted only once (or very infrequently) during an on-orbit calibration to remove figure errors that could not be measured and controlled accurately enough on the ground. Prior work on Gen-X[43] has suggested that with good mirror roughness and adjustment of figure errors with spatial periods longer than 30 – 40 mm, the 0.1″ goal can be achieved. Our approach to developing adjustable GI mirrors is to start with either 0.1-0.15 mm thick electroplated nickel/cobalt replicated mirror segments, or 0.2-0.4 mm thick glass sheets (such as used in the LCD TV industry) which are slumped to conic section shapes on precision mandrels. A thin (few µm thick) layer of piezo-electric material is directly deposited on the back surface of the mirror segment, and next, a “pixelated” array of electrodes is deposited on the piezo material to form an array of discrete piezo cells (Fig. 6). As a voltage is applied to any given outer electrode, strain is introduced in the piezo in the plane of the mirror surface, introducing local bending in the mirror and deforming it. By controlling the shape of the deformation to compensate local figure errors in the mirror, we expect to correct figure to a precision not achievable by direct fabrication and metrology of such thin mirrors. 2.3.4 Mirror Design Considerations Mirror shells are segmented because full shells are impractical for such large sizes. We envision using segments as large as 1 m x 1 m, which implies an angular span of ~7.8 for a 16 m diameter telescope (thin LCD type glass sheets are now commercially available as large as 2 x 2.5 m[44]). The mirror segments will be supported at their edges or corners. The boundary conditions of how the mirrors are supported and the impact of the supports on the figure will be an important part of the technology development, and will be explored as part of finite element modeling (FEM) and experiments. Mirror segments will be divided into a grid of electro-active cells, with the azimuthal extent of the cells larger than the axial extent since X-ray performance is much less sensitive to azimuthal errors. For technology investigation we will start with axial piezo cell sizes of the order of 20 mm, with azimuthal extent of 25 – 50 mm.

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We will speak to piezo-electric activators here as a baseline approach, while our technology plan also considers electrostrictive materials as an alternate possibility.

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________

Figure 6: Diagram (not to scale) of the pixelation of the actuator structures. The electrodes are divided into discrete pixels via the dielectric structures (shown in green to left). The FEM output (right) shows a grid pattern dividing the mirror into pixels.

It is possible to model and measure the local deformations as a function of strain and piezo location, determining a set of influence functions. With these, calculating the required sets of piezo voltages to correct mirror figure error becomes a 2-dimension deconvolution, or optimization, problem. Effects such as crosstalk, cell size and shape, can dramatically affect the level of optimization, and so these will be a focus of our investigations. In addition, piezo cell size affects the spatial frequency bandwidth of correctable figure errors, and will also be investigated. These technologies will be explored as part of the work towards meeting the first of the Technology Gates (TG) as described in §2.4. Our technology development includes scaling up and extending IXO technology. In particular we baseline taking the slumped glass mirrors produced, extending them from the 0.4 m x 0.2 m IXO size to the 1 m x 1 m size for Gen-X, and making modest improvement in the intrinsic upper-mid-frequency figure. This requires making larger mandrels, and also developing metrology instruments appropriate to those sizes. Slumping ovens must also be correspondingly larger. Note that Gen-X will have a smaller number of mandrels than IXO, because each can be used for 2 or 3 different shells since the errors induced are small compared to the capability for on-orbit adjustment (see TG-2 and TG-3, §2.4). The ground alignment process will require significant facility accommodations to achieve sufficient stability against vibrations, thermal variations, air flow, etc. Development of facilities to conduct the tests outlined in the demonstration gates will be part of the development process. The key technology is the ability to control the figure of 1 m x 1 m plates to 0.1″. This demonstration will not require a focal length of 60 m (TG-3 and TG-4, §2.4), easing facility requirements needed to demonstrate success. On-orbit alignment and figure adjustment will make use of two feedback methods. First, an on-orbit scanning Hartmann test instrument, similar to that used to align Chandra to ~ ¼ arcsecond, will be used for “medium” alignment and figure correction. By using a smaller sized beam than for Chandra, it should be possible to correct not only alignment and low order azimuthal figure, but also low order axial figure (these will also be the largest amplitude errors). Once this level of correction has been achieved, intra-focal ring (or actually, arc) images will be obtained using bright celestial X-ray sources and the dedicated X-ray detector placed well forward of focus. Analysis of profiles across the arc image will enable fine adjustment of figure. The three steps of controlling mirror figure, making an aligned module, and adjusting the complete telescope on-orbit are the three technology “tall poles”.

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 2.3.5

Alternative Approaches Other efforts in adjustable GI optics have focused on gluing piezo-electric actuators to the back surface of mirrors. In some cases, similar to more conventional active optics, the strain direction is normal to the mirror surface. In other cases, several hundred µm thick piezos with their strain direction parallel to the mirror surface are glued to the back surface. This last approach has been applied to synchrotron mirrors that have achieved ~1 – 2″ resolution[45-47]. In addition, a group of investigators in the United Kingdom have formed a “Smart Optics” consortium that is attempting to develop grazing incidence X-ray bimorph mirrors using thick (200 µm), curved piezos glued to the back surface of the mirror[48]. We believe the direct deposition of thin piezo-electric material is superior to the bonding approach because the deposited piezo should result in significantly less stress, will introduce less stress and distortion variations, and will not add appreciably to mirror mass. Fabrication issues with bonding 106 separate piezos, including wiring, are far more difficult than deposition onto back surfaces, where one can ultimately “print” the piezo leads to a connector block. 2.4 Technology Development Plan We have structured our development plan around a series of five program level technology gates that integrate the development programs for the optics and science instruments together with a management task. Each separate development program has its own series of TGs that demonstrate progress toward achieving Technology Readiness Level (TRL) 6. We discuss the program and instrument milestones in §5 and discuss here the optics gates. The optics gates will successively demonstrate the build-up of a telescope starting from controlling the shape of a single mirror, co-aligning primary and secondary mirror pairs, co-aligning pair to pair within a module, and finally aligning different modules. Gate 1a: Demonstrate predictable piezo deformations. On a flat, thin mirror, demonstrate control of displacements to 4 nm rms over a range of +/- 400 nm for spatial frequencies up to the Nyquist limit, and verify an acceptably low level of power is transferred to higher spatial frequency. Gate 1b: Make a conical mirror element to sufficient figure and smoothness. On a single optical piece, less than full Gen-X size, verify that material of sufficiently low upper mid-frequency ripple and micro-roughness can be obtained and maintained through the slumping process. Verify that the mandrel can be measured and manufactured, and used multiple times for slumping. Completion of gates 1a and 1b demonstrates TRL-3, experimental proof of concept. Gate 2: A conical mirror pair (P and S) is measured in X-rays, adjusted predictably and verified by re-measurement. On conical optics made for IXO, deposit piezos, align the secondary to primary, and demonstrate the same predictable behavior in X-rays. Gate 3: A Gen-X size P/S pair is adjusted and measured in X-rays. Procure Gen-X size optics, manufactured to the required specs, align the secondary to the primary, and demonstrate predictable adjustment in X-rays to the required imaging precision. Completion of gates 2 and 3 demonstrates TRL-4, component validation in laboratory. Gate 4: A single module, populated by a few shells, is adjusted and measured in X-rays. Install several individual mirror pair shells in a flight like mount and align them to each other to required precision. Then measure an X-ray image in a test facility. Completion of this gate demonstrates TRL-5, breadboard validation in a relevant environment. Gate 5: A single module fully populated with shells, including X-ray mirrors and mirror simulators, is subjected to relevant environmental testing. Then it is aligned to a second sparsely populated module and measured. Completion of this gate demonstrates TRL-6, prototype validation in a relevant environment. 11

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 3.0 TECHNOLOGY DRIVERS The three major technology drivers (“tall poles”) discussed here are all related to the development of a 0.1″ HPD telescope. Major drivers for the instruments that would constitute an eventual mission are discussed in the companion technology white papers[49-51]. 3.1 Figure Adjustment of a Mirror Element We will demonstrate progress towards our goal of predictably adjusting the figure of GI Xray mirrors to achieve 0.1″ HPD imaging by proceeding through TG-1A, 1B, 2, and 3. We leverage our Gen-X development by starting with the state of the art achieved for the IXO mission. As the prime candidate mirror element we consider 0.2-0.4 mm thick borosilicate glass, slumped to achieve a figure as close as possible to that desired. As part of our program we will procure larger mandrels, consider other glass suppliers and formulations, and investigate thermal forming release layers for the mandrels. One specific area to pursue is use of Pt or Pt/Au release layers. As an alternate material to glass, we will consider electro-plated Ni/Co mirror segments[52,53]. A major investigation concern is the deposition of piezo-electric (alternately, electrostrictive) material on the back side of the mirrors. This activity has started at SAO with deposition of thin film piezo-electric material onto flat glass at Pennsylvania State University (PSU). We need to investigate the deposition process to determine optimum layer thickness for minimum additional stresses, for appropriate dynamic range of strains, and for uniformity. Continuing programs at SAO are discussed in §4.0. We need to study the optimal shape and patterns for the piezo actuators. One key issue is to avoid transferring power from low frequency figure errors to error frequencies above the Nyquist limit of the actuators. FEM done by Xinetics of electrostrictive actuators[54] shows that this can be done to ~0.1 nm rms for long period errors. Our current programs will measure the influence functions of individual actuators, both experimentally and via FEM simulation. Subsequent to optimizing these influence functions, we will determine what power is aliased to higher frequencies during the correction process, which then defines a specification of how much better, if any, our starting figure must be compared to the IXO mirror 3″ HPD budget. A significant part of this equation is the boundary conditions: i.e., how each piece is held for alignment and mounted in a module, as discussed in §3.2. Holding a small angular span segment (with a relatively large radius of curvature) by two edges localizes deformations due to strain in a single piezo cell. This is seen in Fig. 7, where the result of FEM for a Gen-X sized mirror (1 m x 1 m) segment is shown. In Fig. 7, an ~6 ppm strain was applied to a single piezo cell near the center of the mirror, producing the localized deformation seen in darker blue. The initial parts of this development will employ visible light measurements (e.g., Zygo interferometry) of the mirror/actuator elements. We will develop algorithms for using those data to determine what adjustments must be made via the piezo actuators. We expect to reduce the figure errors by 70% to 90% in one measurement/adjustment cycle. We will extend the algorithms to apply to on-orbit adjustment Figure 7: FEM simulation of segment via X-ray measurements, discussed in §3.3. response to strain in an individual piezo. cell. 12

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 3.2 Development of an Aligned Module For an aligned module, primary and secondary mirrors corresponding to a shell segment must be mounted and co-aligned to one another. TG-2 demonstrates this with IXO size mirrors, and TG-3 requires a demonstration with a full size Gen-X mirror pair. In addition, measurement precision and control of the optics are demonstrated to specifications consistent with 0.1″ HPD. In order to meet TG-4, the mirror pair must be co-aligned to mirror pairs corresponding to other shells within the same module. In the mounted configuration we must be able to perform figure adjustment to allow verification via X-ray performance. For TG-2 we would take a primary and secondary mirror from the IXO slumping ovens, and deposit piezos on the back surface. Relative positions and tilts are adjusted and measured with the mirror pair held in a metrology mount, with particular attention paid to implementing the correct boundary conditions for holding the pieces within a module. Predicting and measuring the boundary conditions will require a combination of FEM and optical measurement. We note that by TRL-6 the mount must meet the requirements imposed by the launch loads and vibro-acoustic environment of the Ares V vehicle. These are currently unknown but expected to be comparable with present heavy lift vehicles, and we have a large mass margin allowing us to address the issue via vibro-acoustic isolation mounting of the telescope. We note that mounted IXO mirror segments of thickness within the Gen-X study range have passed Atlas V acoustic loads and vibration testing. For TG-3 the mounts must be scaled up to accommodate the size of the Gen-X mirrors. This will require an upgrade of facility stability and of the metrology instrumentation. Gen-X will likely adopt a WolterSchwarzschild design*, so that the algorithm for the final figure will be modified from that used for the IXO P/S design. In aligning a mirror pair, there is a degeneracy between tilt and de-center, symmetry to rotation about the optical axis, and partial degeneracy between tilt and focus, so there are 4 degrees of freedom requiring precision control. For TG-4 we need to align a subset of distinct shells within a module (Fig. 8). There are 5 precision degrees of freedom, allowing rotation about the optical axis. This requires design of flight like modules applicable to any of the differently sized modules needed to create the complete telescope. The module design needs to accommodate all the leads and multiplexing control for the actuators. We need to develop positioning and metrology equipment, and mounting procedures for a full set of shells within a module. Some of these processes are already being developed for IXO. Figure 8: A module provides for alignment of the S to P segments for each shell, and for the shells to each other, to a precision of 0.03″. The insert shows the separate mirror segments that can be adjusted in 5-degrees of freedom by alignment actuators (not shown). *

A Wolter-Schwarzschild design has fewer off-axis aberrations than the more common Wolter-I design (used for Chandra, XMM-Newton, and IXO). This gives a better point-spread function off-axis, while still resulting in a perfect on-axis image. In technical optics terms, the Wolter-Schwarzschild design satisfies the Abbe sine condition, whereas a Wolter-I design does not. With respect to optical figure, the practical differences between the two designs are small and would not impact the desired level or complexity of the figure correction.

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3.3 Development of the On-orbit Adjustment Process After deployment on-orbit, there must be a module-to-module adjustment to a precision of ~10 µm, or 0.033″. We must develop measurement systems, and algorithms to use the data from those systems, to assess the necessary fine-tuning of the alignment and figure. The results of the algorithms are commands to the on-orbit adjustment actuators. Progress toward this goal will be demonstrated via our TG-2, 3, and 4. Gates 1 through 5 will all contribute to demonstrating this technology, with TG-5 proving the readiness for flight implementation. Module to module adjustment can be accomplished with an opto-mechanical system that positions the modules to a precision in the 10 µm range (determined by error budgets). We will investigate if this can be done closed loop or require open loop control via ground commanding. The precision adjustments of the reflecting mirror locations and figures would be accomplished via a Hartmann type optical system to adjust the rigid-body alignment and positioning of each mirror pair, followed by observation of a bright celestial X-ray source to perform the figure measurement. We have presented a concept and specifications for a system to perform the X-ray correction[55] and this will be developed. The Hartmann system will require optical flat(s), laser sources, and quad-cell type light detectors as part of the on-orbit equipment. While using the standard double-pass principle, we may choose to sub-aperture in order to measure distinct portions of the mirror along the axial direction. This system will be functionally equivalent to the metrology used to align the Chandra Observatory optical elements to ~ ¼ arc-sec. The principle of X-ray adjustment is to position a dedicated high throughput imaging detector at various positions 2 to 8 m forward of the focal plane, which produces arc-like images of azimuthally resolved portions of the rays converging from individual shells, when looking at a bright, on-axis celestial X-ray point source. The profile across the arc can be resolved into ~100 elements, and the exact shape of this profile gives information on the low order figure distortions and therefore on what actuator adjustments are needed (Fig. 9). Initial evaluations[53] show that the necessary X-ray statistical precision can be achieved, and that the tolerances on the size, throughput, and positional accuracy and knowledge of the detector are feasible. Algorithms to process the data and compute the required adjustments must be developed. This includes breaking the degeneracy of correction to the primary vs. secondary mirror. We start by investigating obvious choices such as simulated annealing, Legendre-Fourier decomposition of the shape errors, and forward folding of assumed shape errors to attempt to fit the data. The entire initial adjustment process could be allowed to take a month or longer, given that adjustment updates are expected to be extremely infrequent (of order years). AlgoBins rithm development will proceed in conjunction Figure 9: A simulated profile of the innermost with figure and alignment development disring, divided into 100 bins, clearly shows a patcussed above, and will be needed to support tern of perturbations to the axial figure due to a sum of polynomials of amplitude 0.1 µm. The those developments. The Hartmann and X-ray adjustments 100 bins over-sample the 50-actuator pairs in the axial direction. Perfect adjustment would show a most likely will be open loop, via transmission flat distribution. of data to the ground for processing and development of commanding. It might turn out that only one of those two systems will suffice to perform the final on-orbit adjustments. 14

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 4.0 ORGANIZATION, PARTNERSHIPS AND CURRENT STATUS Gen-X Study Team and Program Organization The current team conducted the initial VM study of Gen-X and further developed the technology development plan under the present ASMC study. The team is broad-based, including academia, non-profit, NASA, and a range of industry partners, and represents an experience base that covers every major U.S. and most international X-ray astronomy missions flown to date. For our two Gen-X studies, we organized into science, mission and technology teams, with the PI providing the management and coordination functions with support from the managing NASA center (GSFC). This structure proved highly effective, allowing the science requirements, mission implementation and technology plans to be tightly coupled. We propose to proceed to the funded technology development program with the same team: SAO as the PI institution supported by GSFC as lead NASA center. The optics and instrument programs will be conducted by SAO/PSU/GSFC/MSFC (optics), GSFC/MIT (XMS), MIT/SAO (WFI) and MIT/U. Iowa (gratings). SAO would lead the management, science and mission systems engineering tasks, including interfacing with our industry partners led by NGST, and coordinate with the science community through a Gen-X Science Working Group. The team is ready to proceed to implement the Gen-X technology development plan. This program organization will also allow the required knowledge transfers to NASA during the program to support the start of flight program. Current Status: Optics Hardware Programs An internally funded program at SAO (PI, Paul Reid) began the development work of depositing thin film piezo electric material onto flat glass substrates at PSU. To date, crystallized piezo material has been successfully deposited on the back of thermally formed glass flats. Good electrical properties have been measured (Fig. 10) with acceptable deposition stresses: ~100 MPa, similar to reflective coating stresses[56]. Our ASMC study is funding an investigation at NGST/Xinetics into electrostrictive control of optics. SAO is conducting two follow-on programs in adjustable optics. The first is a 3-year APRA grant (PI, Paul Reid) to develop adjustable optics on thin, flat, electroplated metal mirrors from MSFC, aiming to demonstrate sub-arc-second capability. Among the areas of investigation are FEM of the effects of thin film piezos in correcting optical figure, development of piezo materials and deposition processes suitable for use with a variety of mirror materials, including thermally formed mirrors, and examining the impacts of piezo cell size and shape on impulse functions. A key investigation is to optimize the influence function shapes to minimize unwanted higher frequency Figure 10: Repeatability over 40 cycles of spatial error content into the surface figure and its ermeasured polarization hysteresis for 1 µm ror PSD. piezo film showing no degradation. The second program is a 2-year grant from the Moore Foundation (PI, S. Murray). This grant includes development for both adjustable grazing incidence optics and detector development. P. Reid (a Co-I) is responsible for the adjustable optics part of the program. This program complements efforts being undertaken under the APRA program by assessing glass optics and adjustment of curved glass mirrors from GSFC. These programs provide an important basis for proceeding into the full optics program.

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 5.0 GEN-X TECHNOLOGY DEVELOPMENT SCHEDULE The Gen-X technology development program is comprised of four coordinated technology development activities for the optics, XMS, WFI and Gratings under a management, science and mission system engineering task (Fig. 11). Each activity is structured with a set of technology gates that correspond to increasing TRL and act as decision points for any down-selects of alternative technologies. The overall program is structured around six Program Technology Gates (PTG-1–6) that integrate the optics and instrument technology development activities. PTG reviews verify that groups of gate reviews have been met, provide system-level decision points for down selects, and allow for updates of the requirement flow from science to technology implementation. The program begins in FY11 with parallel development of the optics and science instrument technology. Progressive gates lead to TRL-6 by FY23. We provide below a summary of the schedule for each program component. Optics: The optics tasks Table 4: Optics Tech. Development Tasks mapped to TG and Tall Pole shown in Table 4 and Fig. 11 TG TG TG TG TG TG Tall tie to five technology gates Development Task 1A 1B 2 3 4 5 Pole that progress the technology Piezo deposition 1     from a single mirror to a full Finite Element Model 1,2,3       module (TRL-6). The tall Measure influence func. 1   poles 1–3 refer to §3.1–3.3 Piezo cell size/shape 1   respectively, with the colors Correcting mirror figure 1,3      indicating a general mapping Extending to large size 2   to the tasks. TG-1A will be Improving mid freq. 2   met by presently funded proGround alignment 2   grams and provides for a 3  smooth transition into the full On-orbit align/adjust program. XMS: The XMS technology program discussed by Bandler[49] defines eight task areas as shown (three tasks are combined on the fourth line) designed to meet the TG performance requirements. Development paths for two sensor technologies are provided, one for a Transition Edge Sensor and the other for a Magnetic Microcalorimeter. Both paths provide for position sensitive detectors and address the driving requirements for multiplexing, key for a 106-pixel device. WFI: The WFI sensor program discussed by Bautz[50] defines 16 cycles of sensor development phased over four technology gates together with the performance requirements needed to reach TRL-6. TG-1 focuses on advancing pixel-level performance and is reached when the sensor technology achieves TRL-3. TG-2 is aimed at chip-level performance and coincides with TRL-4. TG-3 represents flight qualification of a single chip of the multi-chip focal plane, and TG-4 marks flight qualification of the focal plane design. The requirements for TG-1 govern pixel size, read noise and rate, quantum efficiency and spectral resolution. Those for TG-2 relate to the size and pixel format of individual detector tiles in the focal plane, as well as chip-level architecture and frame rate. TG-3 represents flight qualification of a single focal plane tile, while TG-4 drives integration of all required processing and data management functions in a tileable sensor format. Gratings: The Gratings technology program discussed by McEntaffer[51]. describes two grating spectrometer approaches. One, based on blazed reflection gratings in an extreme offplane mount,[57] and the other on critical-angle transmission gratings.[58] Both technologies are pursued in parallel. The program benefits from significant leverage from the planned IXO development that requires TRL-6 for its X-ray Grating Spectrometer by FY14 (TG-1). This leads to four Gen-X technology gates progressing from TRL-3 to TRL-6 by PTG-5. 16

Figure 11: The Gen-X technology development schedule integrates the optics and instrument (XMS, WFI, Gratings) technology development through six Program Technology Gates (PTG) with increasing TRL.


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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 6.0 COST ESTIMATES The cost estimate for the Gen-X technology program is shown in Table 5 and was developed under the present ASMC study. As requested by NASA, the estimates were made by the study team and finalized as part of the work leading up to the submission of this paper. The costs were developed using a grass roots methodology based on the tasks required to reach each technology gate. Where applicable, comparisons with analogous technology development programs have also been made, taking into account the differences in the technology under development, and the differences in complexity. Such comparisons have only been made when our team has held direct responsibility for those programs. Table 5: Gen-X technology program costs ($M) in fixed FY09 dollars showing TRL with time. FY: 11 12 13 14 15 16 17 18 19 20 21 22 Optics 3.9 4.6 5.9 12.4 11.0 9.8 10.9 9.4 10.7 10.9 7.5 7.9 XMS 1.9 1.9 2.3 2.3 2.3 2.7 3.9 2.6 2.3 2.1 WFI 2.0 2.0 2.0 3.0 3.0 3.0 2.8 2.5 1.5 1.5 0.8 Gratings 0.5 0.5 0.5 0.5 1.0 2.0 2.0 2.0 2.0 1.0 Mgmt., Sci., SE 0.5 0.5 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 Total 8.8 9.5 11.4 18.9 18.0 18.2 20.3 17.2 17.2 16.2 9.0 8.6 2 3 4 5 6 ↵ ↵ ↵ ↵ ↵ TRL Legend

23 7.8

0.7 8.5

Total 112.7 24.3 24.0 12.0 8.7 181.7

Table 5 shows the phasing of costs for FY11-FY23 with increasing TRL indicated by the color, for example, the optics reaching TRL-3 by the end of FY12. The total program cost profile ramps up over the first 3 years then is relatively flat through FY20 during parallel optics and in↓ ↓ ↓ ↓ strument efforts then ramps down for the remaining optics work. The ramp up is driven in part by the IXO schedule with its optics and instrument technologies reaching TRL-6 by FY14. The ↓ IXO schedule has been taken into account to allow for relevant technology transfer for the optics, XMS and gratings, and for synergy during development. We also assume a significant involve↓ ment by industry, particularly in the optics and mission systems engineering tasks, to the level of matching funds. The costs for the optics, XMS, WFI and gratings have also been reduced by a ↓ total of $2.6M in FY11 and FY12 to take into account contributions by existing hardware programs such as those described for the optics in §4. The program is phased to progress the optics to TRL-5 and the instruments to TRL-6 within the coming decade (FY20) thus providing a sound basis for proceeding to the start of mission Phase A early in the next decade. The remaining work for the optics to reach TRL-6 accounts for ~20% ($23M) of the overall optics plan and could be included naturally in the costs for Phase A. We consider the cost of the total program to be comparable with the technology development efforts of similar class missions. We have not estimated the cost of the Gen-X mission in this paper; however, preliminary estimates made under the VM study show that the mission will be at the “Observatory Class” level. Given this, we find that our technology program cost estimate is comparable with similar technology development efforts for missions such as Chandra, IXO and JWST, taking into account complexity and when technologies reached TRL-6 (during the early portions of Phase-A for these missions.)* We provide below a summary of the costs basis for each of the five program components. Full details of the instrument costs are provided in their associated technology white papers.[47-49]

*

We assume here that for Gen-X, all technology development is completed during pre-phase A.

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GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 6.1 Optics Budget Estimate The budget for the development of adjustable grazing incidence optics technology was estimated using a grass roots methodology, drawing on experience with other relevant programs including IXO, Chandra, the presently funded APRA and Moore programs (§4), experience at PSU, and from industry. Our present programs, while modest, contain the core elements of the Gen-X program and allow us to scale costs for those items, with appropriate correction factors, to the proposed development. In total we estimate a $112.7M program comprised of 66% labor, 22% equipment and 12% facilitization. Cost estimates for labor, materials, facilities modification and usage, test equipment and other associated items were developed for each of the nine tasks included in Table 4, phased as per Fig. 11. We discuss the costs for the nine tasks under the assumption that they are conducted using facilities at SAO, PSU, GSFC and MSFC, and with some matching funds from our industrial partners for their tasks. Piezo deposition: Costs are scaled from current work at PSU and include estimates for equipment and facility modification to accommodate the larger optic sizes. These include a Rapid Thermal Annealer for film deposition and larger coating-deposition chambers. We estimate $2.8M for equipment and facility modification a labor profile that ramps to 4.0 FTE by FY14 through task completion in FY17. Finite element modeling: This activity will run for the full duration of the program. Costs have been scaled from APRA and Moore work, and were increased to account for modeling both adjustable mirror operation, and handling and processing equipment such as metrology mounts, mirror module support, and alignment operations. We estimate 2 FTE throughout the program. Measure influence functions: Costs were scaled from the identical Moore and APRA tasks. Additional cost and effort are included to modify/purchase metrology equipment (interferometer, null corrector) and expand the metrology field from ~150 mm to 1 m. We estimate the need for approximately 3 FTE/yr until the task is completed by the end of FY12. Optimize piezo cell size/shape: Costs are scaled from the Moore and APRA efforts by a factor of 3 as we plan a much more extensive investigation of this issue. This will also include additional deposition work by PSU. Influence functions measured under this task, and FEM, are included as above. The activity runs from FY11 – FY14, averaging 6 FTE/year, including PSU. Correcting mirror figure: This activity runs for the duration of the program. Efforts ramp up to 10 FTE/year by FY20, with remaining costs associated with fixturing, electronics design and hardware, and other specialized control and test hardware. Extending mirror size: This activity takes place over FY15 and FY16, although we plan on long-lead purchases for mandrels and a larger thermal forming oven in FY14. Cost estimates are based upon IXO experience. Facilitization and equipment are estimated at $4.7M including installation and setup of various new facilities, and labor at 10 FTE/year. Improving mid-spatial frequency: These costs are based upon both IXO plans and past SAO IR&D activities, and include purchase of test mandrels and coating deposition work. This effort runs for FY15 and FY16, and we estimate 7 FTEs in labor and $1.9M for hardware and thermal forming mandrels. Ground alignment: We estimate the costs based upon IXO experience, as 10-12 FTE/year for FY17-FY20, required for design and test of module sized hardware, metrology, and mirror segment mounting. A cost of $6.2M is estimated for fabrication of fixturing and hardware. On-orbit correction: These costs include modeling and software development, alignment metrology hardware development (the Hartmann test instrument and the moveable ring image detector), and X-ray testing facilitization. We estimate the cost of test hardware (Chandra ground testing as the basis) at $8.6M and labor ramping from 4 FTE in FY18 to 12 FTE in FY21-FY23. 19

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ 6.2 XMS Budget Estimate The XMS budget assumes leverage from the IXO program during FY11-16. Over this period, ~65% of the Gen-X funding is allocated to detector development and ~35% to develop the necessary microwave multiplexing. The detector funding will support development of two detector technologies (see §5). Following down select, the budget increases in FY17 to develop a larger prototype demonstration system in a relevant environment. Cost estimates are based on our experience with prior flight hardware programs such as Astro-E and Suzaku, and present development programs for Astro-H and IXO. This experience suggests ~80% of costs are required for labor, with the remainder needed for providing cryogens, development of cryogenic apparatus, purchase of commercial electronics, fabrication upgrades, and other supplies. Based on these prior programs, we estimate a labor profile that ramps to an average 8.0 FTE/year for FY13-20. 6.3 Wide Field Imager Budget Estimate A technology development plan for the WFI will proceed in a series of development cycles each made up of a design, fabrication and evaluation phase. We assume that four teams will develop the two sensor architectures in parallel through WFI technology gate TG-3 in FY18, by which time a preferred architecture will be selected. Subsequent development through WFI TG-4 will focus on a single sensor architecture. In all, 16 development cycles are required, at a total estimated cost of $24M over 10.5 years. We derive this cost from our experience with currently funded active pixel sensor development work at MIT, SAO and PSU with FFRDC and commercial partners, that one development cycle costs approximately $1.5M. 6.4 Gratings Budget Estimate Based on our experience with the Chandra and XMM-Newton gratings flight hardware development programs, ~80% of program costs are needed for labor. The remainder covers laboratory costs such as the materials and supplies needed for micro-fabrication processes, and building of prototypes of grating assembly, alignment and test hardware. Prior to FY14, a funding level to 2.0 FTE (one full-time staff and a student) is required in order to perform feasibility studies of key areas where Gen-X performance exceeds IXO requirements (primarily driven by the higher spectral resolution requirement). During this phase we leverage the development of the IXO Xray Grating Spectrometer. After FY14, a level of 3-5 FTE in each of the two competing technologies (see §5) will be required, again based on our Chandra/XMM-Newton experience. 6.5 Program Management, Science and Mission Systems Engineering The cost estimate includes a steady state of 3.5 FTE per: 0.5 FTE management, 1.0 FTE of science, 1.0 FTE of systems engineering, 1.0 FTE of engineering spread over several disciplines (thermal, mechanical and electrical). The estimate was made based on present experience with the development towards IXO and prior experience during the Chandra development phase. We conclude by noting that we expect this important program will leverage significant resources from the science community for the SWG and related analysis and requirement work, and from industry for technology development, mission design work and additional systems engineering. In the case of industry, we have received significant contributions during our two studies, up to matching funding levels, and have confidence in similar continued involvement throughout the full program. Such contributions have been factored in to the estimates above. Abbreviations and References: http://www.cfa.harvard.edu/hea/genx/astro2010/refs

20

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ Please note that the list of abbreviations and references on the following pages are provided for convenience and should not be considered part of the formal submission of this paper. The URL on the last page of the paper (p. 20) provides a link to the same material in pdf format. List of Abbreviations AGN Active Galactic Nuclei ANL Argonne National Laboratory APRA Astronomy and Physics Research and Analysis ASMC Astrophysics Strategic Mission Concept BH Black Hole Co-I Co-Investigator Con-X Constellation X-Ray observatory FEM Finite Element Modeling FFRDC Federally Funded Research and Development Center FTE Full Time Equivalent FY Fiscal Year Gen-X Generation-X GI Grazing Incidence GSFC Goddard Space Flight Center HPD Half Power Diameter ICM Intracluster Medium IGM Intergalactic Medium ISM Interstellar Medium ITT ITT Corp. IXO International X-Ray Observatory JPL Jet Propulsion Laboratory JWST James Webb Space Telescope keV Kiloelectron Volt L2 Second Sun-Earth Libration Point LCD Liquid Crystal Display lp Lines Per MBH Black Hole Mass MIT Massachusetts Institute of Technology

Mpc Million Parsecs MSFC Marshall Space Flight Center NGST Northrop Grumman Space Technology P Primary pc Parsec PI Principal Investigator PSD Power Spectral Density PSF Point Spread Function PSU Pennsylvania State University PTG Program Technology Gate PWNe Pulsar Wind Nebulae ROSES Research Opportunities in Space and Earth Sciences S Secondary SAO Smithsonian Astrophysical Observatory SFR Star Formation Rate SMBH Super Massive Black Hole SNe Supernovae SNR Supernova Remnant SWG Science Working Group TG Technology Gate TRL Technology Readiness Level U. Iowa University of Iowa UV Ultraviolet VM Vision Mission WBS Work Breakdown Structure WFI Wide Field Imager XMM X-ray Multi-Mirror Mission XMS X-Ray Microcalorimeter Spectrometer XRB X-Ray Binary

21

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ References [1]

Lehmer, B., et al., 2009, “The Formation and Growth of the First Black Holes”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-BH.pdf

[2]

Elvis, M., et al., 2009, “Active Galaxies and Quasars in 2010-2020”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-AGN.pdf

[3]

Slane, P., et al., 2009, “Supernovae and Their Consequences: Studies with the Generation-X Mission”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-SNR.pdf

[4]

Zezas, A., et al., 2009, “Accreting binary populations and ISM evolution in galaxies”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-GAN.pdf

[5]

Wolk, S., et al., 2009, “Ultrahigh sensitivity and resolution X-ray studies of planets and stars”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-PSG.pdf

[6]

Markevitch, M., et al., 2009, “Diffuse Baryonic Matter with Generation-X”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-DBM.pdf

[7]

Heger, A., & Woosley, S. E., 2002, “The Nucleosynthetic Signature of Population III”, Astrophysical Journal, 567, 532.

[8]

Begelman, M. C., Volonteri, M., and Rees, M. J., 2006, “Formation of supermassive black holes by direct collapse in pre-galactic haloes”, Royal Astronomical Society Monthly Notices, 370, 289.

[9]

Volonteri, M., Haardt, F., and Madau, P., 2003, “The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy Formation”, Astrophysical Journal, 582, 559.

[10]

Gebhardt, K., et al., 2000, “A Relationship between Nuclear Black Hole Mass and Galaxy Velocity Dispersion”, Astrophysical Journal Letters, 539, L13.

[11]

Croton, et al., 2006, “The many lives of active galactic nuclei: cooling flows, black holes and the luminosities and colours of galaxies”, Royal Astronomical Society Monthly Notices, 365, 11.

[12]

Shemmer, O., et al., 2006, “Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey,” Astrophysical Journal, 644, 86.

[13]

Rhook, K. J., and Haehnelt, M., 2008, “Detecting quasars at very high redshift with next generation X-ray telescopes”, Royal Astronomical Society Monthly Notices, 389, 270.

[14]

Hernquist, L., and Springel, V., 2003, “An analytical model for the history of cosmic star formation”, Royal Astronomical Society Monthly Notices, 341, 1253.

[15]

Ott, J., Walter, F., Brinks, E., 2005, “A Chandra X-ray survey of nearby dwarf starburst galaxies - II. Starburst properties and outflows”, Monthly Notices of the Royal Astronomical Society, 358, 1453.

[16]

Fabbiano, G., 1989, “X rays from normal galaxies”, Annual Review of Astronomy & Astrophysics, Annual Review of Astronomy & Astrophysics, 27, 87.

[17]

Brassington, N. J., Ponman, T. J., Read, A. M., 2007, “The Chandra view of galaxy mergers”, Monthly Notices of the Royal Astronomical Society, 377, 1439.

[18]

David, L. P., Jones, C., and Forman, W., 1992, “X-ray properties of bright far-infrared galaxies”, Astrophysical Journal, 388, 82.

[19]

Shapley, A., Fabbiano, G., and Eskridge, P. B., 2001, “A multivariate statistical analysis of spiral galaxy luminosities. I. Data and results”, Astrophysical Journal Supplement, 137, 139.

[20]

Fabbiano, G., and Shapley, A., 2002, “A multivariate statistical analysis of spiral galaxy luminosities. II. morphology-dependent multiwavelength emission properties”, Astrophysical Journal, 565, 908.

22

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ [21]

Strickland, D. K., Heckman, T. M., Colbert, E. J. M., Hoopes, C. G., Weaver, K. A., 2004, “A High Spatial Resolution X-Ray and Hα Study of Hot Gas in the Halos of Star-forming Disk Galaxies. I. Spatial and Spectral Properties of the Diffuse X-Ray Emission”, Astrophysical Journal Supplement, 151, 193.

[22]

Brandt, W. N., et al., 2001, “The Chandra Deep Field North Survey. V. 1 Ms Source Catalogs”, Astronomical Journal, 122, 2810.

[23]

Hopkins, A. M., Beacom, J. F., 2006, “On the Normalization of the Cosmic Star Formation History”, Astrophysical Journal, 651, 142.

[24]

Persic, M., Rephaeli, Y, 2007, “Galactic star formation rates gauged by stellar end-products”, Astronomy and Astrophysics, 463, 481.

[25]

White, N. E. and Ghosh, P., 1998, “Low-mass x-ray binaries, millisecond radio pulsars, and the cosmic star formation rate”, Astrophysical Journal Letters , 504, 31.

[26]

Georgakakis, A., et al., 2007, “X-ray selected starbursts in the Great Observatories Origin Deep Survey-North”, Monthly Notices of the Royal Astronomical Society, 377, 203.

[27]

Lehmer, B. D., et al., 2005, “X-Ray Properties of Lyman Break Galaxies in the Great Observatories Origins Deep Survey”, Astronomical Journal, 129, 1.

[28]

Nandra, K., et al., 2002, “X-Ray properties of Lyman Break Galaxies in the Hubble Deep Field-North region”, Astrophysical Journal, 576, 625.

[29]

Ptak, A., Mobasher, B., Hornschemeier, A., Bauer, F., Norman, C., 2007, “X-Ray Luminosity Functions of Normal Galaxies in the Great Observatories Origins Deep Survey”, Astrophysical Journal, 667, 826.

[30]

Norman, C., et al., 2004, “The X-Ray-derived Cosmological Star Formation History and the Galaxy X-Ray Luminosity Functions in the Chandra Deep Fields North and South”, Astrophysical Journal, 607, 721.

[31]

Elvis, M., 2000, “A Structure for Quasars”, Astrophysical Journal, 545, 63.

[32]

Elvis, M., 2002, in Mass Outflow in Active Galactic Nuclei: New Perspectives, edited by Crenshaw, D. M., Kraemer, S. B. & George I. M., ASP Conference Proceedings, 255, 303.

[33]

Ciotti, L., Ostriker, J. P., 2007, “Radiative Feedback from Massive Black Holes in Elliptical Galaxies: AGN Flaring and Central Starburst Fueled by Recycled Gas”, Astrophysical Journal, 665, 1056.

[34]

David, L. P., Jones, C., Forman, W., Vargas, I. M., Nulsen, P., 2006, “The Hot Gas Content of LowLuminosity Early-Type Galaxies and the Implications Regarding Supernova Heating and Active Galactic Nucleus Feedback”, Astrophysical Journal, 653, 207.

[35]

Springel, V., Di Matteo, T., Hernquist, L., 2005, “Black Holes in Galaxy Mergers: The Formation of Red Elliptical Galaxies”, Astrophysical Journal Letters, 620, L79.

[36]

Ciotti, L. & Ostriker, J. P., 2001, “Cooling Flows and Quasars. II. Detailed Models of Feedbackmodulated Accretion Flows.” Astrophysical Journal, 551, 131.

[37]

Ferrarese, L., Merritt, D., 2000, “A Fundamental Relation between Supermassive Black Holes and Their Host Galaxies,” Astrophysical Journal, 539, L9.

[38]

Brissenden, R., 2005, “The Generation-X Vision Mission Study Report”, submitted to NASA.

[39]

Brissenden, R., et al., 2008, “The Generation-X Vision Mission Study”, in NASA Space Science Vision Missions, American Institute of Aeronautics and Astronautics, Progress in Astronautics and Aeronautics, 224, ed. Marc S. Allen.

23

GENERATION-X TECHNOLOGY DEVELOPMENT __________________________________________________________________ [40]

http://www.cfa.harvard.edu/hea/genx

[41]

Brandt, N., et al., 2002, “Exploratory Chandra Observations of the Three Highest Redshift Quasars Known”, Astrophysical Journal, 569, L5.

[42]

Schwartz, D. A., et al., 2008, “On-orbit adjustment calculation for the Generation-X X-ray mirror figure“, SPIE, 7011, 25.

[43]

Reid, P. B., et al., 2004, “Constellation-X to Generation-X: evolution of large collecting area moderate resolution grazing incidence x-ray telescopes to larger area high-resolution adjustable optics”, SPIE, 5488, 325.

[44]

http://www.corning.com/displaytechnologies/en/products/eaglexg/large_gen.aspx

[45]

Signorato, R., Carre, J.-F., and Ishikawa, T. 2001, “Performance of the Spring-8 modular piezoelectric bimorph mirror prototype”, SPIE, 4501, 76.

[46]

Signorato, R., 2004, “Synchrotron Radiation Instrumentation”, Eighth International Conference on Synchrotron Radiation Instrumentation, AIP Conference Proceedings, 705, 812.

[47]

Signorato, R., Hausermann, D., Somayazulu, M., Carre, J.-F., 2004, “Performance of an adaptive micro-focusing Kirkpatrick-Baez system for high-pressure studies at the Advanced Photon Source”, SPIE, 5193, 112.

[48]

Doel, P., Atkins, C., Thompson, S., Brooks, D., Yao, J., Feldman, C., Willingale, R., Button, T., Zhang, D., and James, A., “Large thin adaptive X-ray mirrors”, 2007, SPIE, 6705, 19.

[49]

Bandler, S., et al., 2009, “Development of Low-Temperature Detectors For Generation-X and Other Missions Requiring High-Resolution, Large-Format, X-ray Detector Arrays”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-Bandler-XMS.pdf

[50]

Bautz, M., et al., 2009, “Active Pixel X‐ray Sensor Technology Development for the Generation‐X Wide‐Field Image”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/Astro2010-Bautz-WFI.pdf

[51]

McEntaffer, R. L., et al., 2009, “Generation-X Grating Array Technology Development”, http://www.cfa.harvard.edu/hea/genx/media/papers/astro2010/McEntaffer-Gratings.pdf

[52]

Ramsey, B. D. et al., “The development of hard x-ray optics at MSFC”, 2004SPIE.5168..129R

[53]

Ramsey, B. D. and Weisskopf, M. C., 2004 arXiv:astroph/0403449v1

[54]

“Integrated Wavefront Corrector” Phase II Final Report to NASA, Contract NNC07CA30C, Northrop Grumman Xinetics, December 2008.

[55]

Schwartz, D. A. et al., “On-orbit adjustment calculation for the Generation-X x-ray mirror figure”, 2008, SPIE, 7011, 7001-32.

[56]

Reid, P. R. et al, 2009, SPIE, 7437, to be published.

[57]

[58]

McEntaffer, Randall L., Cash, Webster C., and Shipley, A., 2003, “Off-plane gratings for Constelation-X”, SPIE, 4851, 549. Flanagan, K., et al., 2007, “Spectrometer concept and design for x-ray astronomy using a blazed transmission grating”, SPIE, 6688, 1.

24

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