The X-Ray Imaging and Spectroscopy Mission (XRISM) project at JAXA officially started in 2018. Following the development of onboard components, the proto-flight test was conducted from 2021 to 2023 at JAXA Tsukuba Space Center. The spacecraft was launched from JAXA Tanegashima Space Center on September 7, 2023 (JST), and onboard components, including the science instruments, were activated during the in-orbit commissioning phase. Following the previous report in 2020, we report the spacecraft ground tests, the launch operation, in-orbit operations, and the status and plan of initial and subsequent guest observations.
Supermassive black holes (SMBH) interact with gas in the interstellar and intergalactic media (ISM/IGM) in a process termed “feedback” that is key to the formation and evolution of galaxies and clusters. Characterizing the origins and physical mechanisms governing this feedback requires tracing the propagation of outflowing mass, energy and momentum from the vicinity of the SMBH out to megaparsec scales. Our ability to understand the interplay between feedback and structure evolution across multiple scales, as well as a wide range of other important astrophysical phenomena, depends on diagnostics only available in soft x-ray spectra (10-50 Å). Arcus combines high-resolution, efficient, lightweight x-ray gratings with silicon pore optics to provide R~2500 with an average effective area of ~200 cm2, an order of magnitude larger than the Chandra gratings. Flight-proven CCDs and instrument electronics are strong heritage components, while spacecraft and mission operations also reuse highly successful designs.
The XRISM X-ray observatory will fly two advanced instruments, the Resolve high-resolution spectrometer and the Xtend wide-field imager. These instruments, particularly Resolve, pose calibration challenges due to the unprecedented combination of spectral resolution, spectral coverage, and effective area, combined with a need to characterize the imaging fidelity of the full instrument system to realize the mission’s ambitious science goals. We present the status of the XRISM in-flight calibration plan, building on lessons from Hitomi and other X-ray missions. We present a discussion of targets and observing strategies to address the needed calibration measurements, with a focus on developing methodologies to plan a thorough and flexible calibration campaign and provide insight on calibration systematic error. We also discuss observations that exploit Resolve’s spectral
The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to the 2016 Hitomi mission that ended prematurely. Like Hitomi, the primary science goals are to examine astrophysical problems with precise highresolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. XRISM carries a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly and a co-aligned X-ray CCD camera that covers the same energy band over a large field of view. XRISM utilizes Hitomi heritage, but all designs were reviewed. The attitude and orbit control system were improved in hardware and software. The number of star sensors were increased from two to three to improve coverage and robustness in onboard attitude determination and to obtain a wider field of view sun sensor. The fault detection, isolation, and reconfiguration (FDIR) system was carefully examined and reconfigured. Together with a planned increase of ground support stations, the survivability of the spacecraft is significantly improved.
Arcus provides high-resolution soft X-ray spectroscopy in the 12-50 Å bandpass with unprecedented sensitivity, including spectral resolution < 2500 and effective area < 250 cm2. The three top science goals for Arcus are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback, and (3) to explore how stars form and evolve. Arcus uses the same 12 m focal length grazing-incidence Silicon Pore X-ray Optics (SPOs) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. Combined with the high-heritage NGIS LEOStar-2 spacecraft and launched into 4:1 lunar resonant orbit, Arcus provides high sensitivity and high efficiency observing of a wide range of astrophysical sources.
Arcus, a Medium Explorer (MIDEX) mission, was selected by NASA for a Phase A study in August 2017. The observatory provides high-resolution soft X-ray spectroscopy in the 12-50 Å bandpass with unprecedented sensitivity: effective areas of >350 cm^2 and spectral resolution >2500 at the energies of O VII and O VIII for z=0-0.3. The Arcus key science goals are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, groups, and clusters, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback and (3) to explore how stars, circumstellar disks and exoplanet atmospheres form and evolve. Arcus relies upon the same 12m focal length grazing-incidence silicon pore X-ray optics (SPO) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. Arcus will be launched into an ~ 7 day 4:1 lunar resonance orbit, resulting in high observing efficiency, low particle background and a favorable thermal environment. Mission operations are straightforward, as most observations will be long (~100 ksec), uninterrupted, and pre-planned. The baseline science mission will be completed in <2 years, although the margin on all consumables allows for 5+ years of operation.
The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi,“Resolving astrophysical problems by precise high-resolution X-ray spectroscopy”.1 This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission’s initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020’s and 2030’s. Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: “Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects”. To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 × 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.
The Soft X-ray Spectrometer onboard the Astro-H (Hitomi) orbiting x-ray observatory featured an array of 36 silicon thermistor x-ray calorimeters optimized to perform high spectral resolution x-ray imaging spectroscopy of astrophysical sources in the 0.3- to 12-keV band. Extensive preflight calibration measurements are the basis for our modeling of the pulse height–energy relation and energy resolution for each pixel and event grade, telescope collecting area, detector efficiency, and pulse arrival time. Because of the early termination of mission operations, we needed to extract the maximum information from observations performed only days into the mission when the onboard calibration sources had not yet been commissioned and the dewar was still coming into thermal equilibrium, so our technique for reconstructing the per-pixel time-dependent pulse height–energy relation had to be modified. The gain scale was reconstructed using a combination of an absolute energy scale calibration at a single time using a fiducial from an onboard radioactive source and calibration of a dominant time-dependent gain drift component using a dedicated calibration pixel, as well as a residual time-dependent variation using spectra from the Perseus cluster of galaxies. The energy resolution was also measured using the onboard radioactive sources. It is consistent with instrument-level measurements accounting for the modest increase in noise due to spacecraft systems interference. We use observations of two pulsar wind nebulae to validate our models of the telescope area and detector efficiency and to derive a more accurate value for the thickness of the gate-valve Be window, which had not been opened by the time mission operations ceased. We use observations of the Crab nebula to refine the pixel-to-pixel timing and validate the absolute timing.
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
Arcus, a Medium Explorer (MIDEX) mission, was selected by NASA for a Phase A study in August 2017. The observatory provides high-resolution soft X-ray spectroscopy in the 12-50Å bandpass with unprecedented sensitivity: effective areas of >450 cm2 and spectral resolution >2500. The Arcus key science goals are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, groups, and clusters, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback and (3) to explore how stars, circumstellar disks and exoplanet atmospheres form and evolve. Arcus relies upon the same 12m focal length grazing-incidence silicon pore X-ray optics (SPO) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. Mission operations are straightforward, as most observations will be long (~100 ksec), uninterrupted, and pre-planned, although there will be capabilities to observe sources such as tidal disruption events or supernovae with a ~3 day turnaround. Following the 2nd year of operation, Arcus will transition to a proposal-driven guest observatory facility.
Arcus will be proposed to the NASA Explorer program as a free-flying satellite mission that will enable high-resolution soft X-ray spectroscopy (8-50) with unprecedented sensitivity – effective areas of >500 sq cm and spectral resolution >2500. The Arcus key science goals are (1) to determine how baryons cycle in and out of galaxies by measuring the effects of structure formation imprinted upon the hot gas that is predicted to lie in extended halos around galaxies, groups, and clusters, (2) to determine how black holes influence their surroundings by tracing the propagation of out-flowing mass, energy and momentum from the vicinity of the black hole out to large scales and (3) to understand how accretion forms and evolves stars and circumstellar disks by observing hot infalling and outflowing gas in these systems. Arcus relies upon grazing-incidence silicon pore X-ray optics with the same 12m focal length (achieved using an extendable optical bench) that will be used for the ESA Athena mission. The focused X-rays from these optics will then be diffracted by high-efficiency off-plane reflection gratings that have already been demonstrated on sub-orbital rocket flights, imaging the results with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. The majority of mission operations will not be complex, as most observations will be long (~100 ksec), uninterrupted, and pre-planned, although there will be limited capabilities to observe targets of opportunity, such as tidal disruption events or supernovae with a 3-5 day turnaround. After the end of prime science, we plan to allow guest observations to maximize the science return of Arcus to the community.
The Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) is one of three Small Explorer (SMEX)
missions selected by NASA for Phase A study, with a launch date in 2020. The PRAXyS Observatory exploits grazing
incidence X-ray mirrors and Time Projection Chamber Polarimeters capable of measuring the linear polarization of
cosmic X-ray sources in the 2-10 keV band. PRAXyS combines well-characterized instruments with spacecraft rotation
to ensure low systematic errors. The PRAXyS payload is developed at the Goddard Space Flight Center with the Johns
Hopkins University Applied Physics Laboratory, University of Iowa, and RIKEN (JAXA) collaborating on the
Polarimeter Assembly. The LEOStar-2 spacecraft bus is developed by Orbital ATK, which also supplies the extendable
optical bench that enables the Observatory to be compatible with a Pegasus class launch vehicle.
A nine month primary mission will provide sensitive observations of multiple black hole and neutron star sources, where
theory predicts polarization is a strong diagnostic, as well as exploratory observations of other high energy sources.
The primary mission data will be released to the community rapidly and a Guest Observer extended mission will be
vigorously proposed.
The Soft X-ray Spectrometer (SXS) onboard the Astro-H (Hitomi) orbiting x-ray observatory featured an array of 36 silicon thermistor x-ray calorimeters optimized to perform high spectral resolution x-ray imaging spectroscopy of astrophysical sources in the 0.3-12 keV band. Extensive pre- flight calibration measurements are the basis for our modeling of the pulse-height-energy relation and energy resolution for each pixel and event grade, telescope collecting area, detector efficiency, and pulse arrival time. Because of the early termination of mission operations, we needed to extract the maximum information from observations performed only days into the mission when the onboard calibration sources had not yet been commissioned and the dewar was still coming into thermal equilibrium, so our technique for reconstructing the per-pixel time-dependent pulse-height-energy relation had to be modified. The gain scale was reconstructed using a combination of an absolute energy scale calibration at a single time using a fiducial from an onboard radioactive source, and calibration of a dominant time-dependent gain drift component using a dedicated calibration pixel, as well as a residual time-dependent variation using spectra from the Perseus cluster of galaxies. The energy resolution was also measured using the onboard radioactive sources. It is consistent with instrument-level measurements accounting for the modest increase in noise due to spacecraft systems interference. We use observations of two pulsars to validate our models of the telescope area and detector efficiency, and to derive a more accurate value for the thickness of the gate valve Be window, which had not been opened by the time mission operations ceased. We use observations of the Crab pulsar to refine the pixel-to-pixel timing and validate the absolute timing.
The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
Arcus is a NASA/MIDEX mission under development in response to the anticipated 2016 call for proposals. It is a freeflying, soft X-ray grating spectrometer with the highest-ever spectral resolution in the 8-51 Å (0.24 – 1.55 keV) energy range. The Arcus bandpass includes the most sensitive tracers of diffuse million-degree gas: spectral lines from O VII and O VIII, H- and He-like lines of C, N, Ne and Mg, and unique density- and temperature-sensitive lines from Si and Fe ions. These capabilities enable an advance in our understanding of the formation and evolution of baryons in the Universe that is unachievable with any other present or planned observatory. The mission will address multiple key questions posed in the Decadal Survey1 and NASA’s 2013 Roadmap2: How do baryons cycle in and out of galaxies? How do black holes and stars influence their surroundings and the cosmic web via feedback? How do stars, circumstellar disks and exoplanet atmospheres form and evolve? Arcus data will answer these questions by leveraging recent developments in off-plane gratings and silicon pore optics to measure X-ray spectra at high resolution from a wide range of sources within and beyond the Milky Way. CCDs with strong Suzaku heritage combined with electronics based on the Swift mission will detect the dispersed X-rays. Arcus will support a broad astrophysical research program, and its superior resolution and sensitivity in soft X-rays will complement the forthcoming Athena calorimeter, which will have comparably high resolution above 2 keV.
We present an overview of the set of celestial sources used for in-flight calibration of x-ray detectors by past and operational missions. We show the rationale behind their choice as a guideline for future missions aiming at optimizing the critical early phases of their science operations.
NASA's Chandra X-ray Observatory continues to provide an unparalleled means for exploring the high-energy universe. With its half-arcsecond angular resolution, Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, neutron stars, black holes, and solar system objects. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address ever more demanding science questions—such as the formation and growth of black hole seeds at very high redshifts; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, we initiated a concept study for such a mission, dubbed X-ray Surveyor. The X-ray Surveyor strawman payload is comprised of a high-resolution mirror assembly and an instrument set, which may include an X-ray microcalorimeter, a high-definition imager, and a dispersive grating spectrometer and its readout. The mirror assembly will consist of highly nested, thin, grazing-incidence mirrors, for which a number of technical approaches are currently under development—including adjustable X-ray optics, differential deposition, and new polishing techniques applied to a variety of substrates. This study benefits from previous studies of large missions carried out over the past two decades and, in most areas, points to mission requirements no more stringent than those of Chandra.
ISS-Lobster is a wide-field X-ray transient detector proposed to be deployed on the International Space Station. Through its unique imaging X-ray optics that allow a 30 deg by 30 deg FoV, a 1 arc min position resolution and a 1.6x10-11 erg/(sec cm2) sensitivity in 2000 sec, ISS-Lobster will observe numerous events per year of X-ray transients related to compact objects, including: tidal disruptions of stars by supermassive black holes, supernova shock breakouts, neutron star bursts and superbursts, high redshift Gamma-Ray Bursts, and perhaps most exciting, X-ray counterparts of gravitational wave detections involving stellar mass and possibly supermassive black holes. The mission includes a 3-axis gimbal system that allows fast Target of Opportunity pointing, and a small gamma-ray burst monitor. In this article we focus on ISS-Lobster measurements of X-ray counterparts of detections by the world-wide ground-based gravitational wave network.
X-ray polarization measurements hold great promise for studying the geometry and emission mechanisms in the strong gravitational and magnetic fields that surround black holes and neutron stars. In spite of this, the observational situation remains very limited; the last instrument dedicated to X-ray polarimetry flew decades ago on OSO-8, and the few recent measurements have been made by instruments optimized for other purposes. However, the technical capabilities to greatly advance the observational situation are in hand. Recent developments in micro-pattern gas detectors allow use of the polarization sensitivity of the photo-electric effect, which is the dominant interaction in the band above 2 keV. We present the scientific and technical requirements for an X-ray polarization observatory consistent with the scope of a NASA Small Explorer (SMEX) mission, along with a representative catalog of what the observational capabilities and expected sensitivities for the first year of operation could be. The mission is based on the technically robust design of the Gravity and Extreme Magnetism SMEX (GEMS) which completed a Phase B study and Preliminary Design Review in 2012. The GEMS mission is enabled by time projection detectors sensitive to the photo-electric effect. Prototype detectors have been designed, and provide engineering and performance data which support the mission design. The detectors are further characterized by low background, modest spectral resolution, and sub-millisecond timing resolution. The mission also incorporates high efficiency grazing incidence X-ray mirrors, design features that reduce systematic errors (identical telescopes at different azimuthal angles with respect to the look axis, and mounted on a rotating spacecraft platform), and a moderate capability to perform Target of Opportunity observations. The mission operates autonomously in a low earth, low inclination orbit with one to ten downlinks per day and one or more uplinks per week. Data and calibration products will be made available through the High Energy Astrophysics Science and Archival Research Center (HEASARC).
We present the design and scientific motivation for Arcus, an X-ray grating spectrometer mission to be deployed on the International Space Station. This mission will observe structure formation at and beyond the edges of clusters and galaxies, feedback from supermassive black holes, the structure of the interstellar medium and the formation and evolution of stars. The mission requirements will be R>2500 and >600 cm2 of effective area at the crucial O VII and O VIII lines, values similar to the goals of the IXO X-ray Grating Spectrometer. The full bandpass will range from 8-52Å (0.25-1.5 keV), with an overall minimum resolution of 1300 and effective area >150 cm2. We will use the silicon pore optics developed at cosine Research and proposed for ESA’s Athena mission, paired with off-plane gratings being developed at the University of Iowa and combined with MIT/Lincoln Labs CCDs. This mission achieves key science goals of the New Worlds, New Horizons Decadal survey while making effective use of the International Space Station (ISS).
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.
Recent advances in X-ray microcalorimeters enable a wide range of possible focal plane designs for the X-ray
Microcalorimeter Spectrometer (XMS) instrument on the future Advanced X-ray Spectroscopic Imaging Observatory
(AXSIO) or X-ray Astrophysics Probe (XAP). Small pixel designs (75 μm) oversample a 5-10″ PSF by a factor of 3-6
for a 10 m focal length, enabling observations at both high count rates and high energy resolution. Pixel designs utilizing
multiple absorbers attached to single transition-edge sensors can extend the focal plane to cover a significantly larger
field of view, albeit at a cost in maximum count rate and energy resolution. Optimizing the science return for a given
cost and/or complexity is therefore a non-trivial calculation that includes consideration of issues such as the mission
science drivers, likely targets, mirror size, and observing efficiency. We present a range of possible designs taking these
factors into account and their impacts on the science return of future large effective-area X-ray spectroscopic missions.
AXSIO’s two focal plane instruments (the imaging X-ray Microcalorimeter Spectrometer and the X-ray Grating
Spectrometer) will deliver a 100-fold increase in capability over the current generation of instruments for high-resolution
spectroscopy, microsecond spectroscopic timing, and high count rate capability. AXSIO covers the 0.1 - 12keV energy
range, complementing the capabilities of the next generation observatories such as ALMA, LSST, JWST, and 30-m
ground-based telescopes These instruments allow AXSIO to accomplish most of the IXO science goals at a significantly
reduced complexity and cost. These capabilities will enable studies of a broad range of scientific questions such as what
happens close to a black hole, how supermassive black holes grow, how large scale structure forms, and what are the
connections between these processes?
The 2010 Decadal Survey of Astronomy and Astrophysics found the science of the International X-ray Observatory (IXO) compelling, noting that “Large-aperture, time-resolved, high-resolution X-ray spectroscopy is required for future progress on all of these fronts, and this is what IXO can deliver.” In line with Decadal recommendations to reduce cost while maintaining core capabilities, we have developed the Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO). AXSIO reduces IXO's six instruments to two fixed detectors - the imaging X-ray Microcalorimeter Spectrometer and the X-ray Grating Spectrometer. These instruments allow AXSIO to accomplish most of the IXO science goals at a significantly reduced complexity and cost. We present an overview of the AXSIO mission science drivers, its optics and instrumental capabilities, the status of its technology development programs, and the mission implementation approach.
The 2010 Astrophysics Decadal Survey recommended a significant technology development program towards realizing the scientific goals of the International X-ray Observatory (IXO). NASA has undertaken an X-ray mission concepts study to determine alternative approaches to accomplishing IXO’s high ranking scientific objectives over the next decade given the budget realities, which make a flagship mission challenging to implement. The goal of the study is to determine the degree to which missions in various cost ranges from $300M to $2B could fulfill these objectives. The study process involved several steps. NASA released a Request for Information in October 2011, seeking mission concepts and enabling technology ideas from the community. The responses included a total of 14 mission concepts and 13 enabling technologies. NASA also solicited membership for and selected a Community Science Team (CST) to guide the process. A workshop was held in December 2011 in which the mission concepts and technology were presented and discussed. Based on the RFI responses and the workshop, the CST then chose a small group of notional mission concepts, representing a range of cost points, for further study. These notional missions concepts were developed through mission design laboratory activities in early 2012. The results of all these activities were captured in the final Xray mission concepts study report, submitted to NASA in July 2012. In this presentation, we summarize the outcome of the study. We discuss background, methodology, the notional missions, and the conclusions of the study report.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy
universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV.
These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3–12 keV with
high spectral resolution of ΔE ≦ 7 eV, enabled by a micro-calorimeter array located in the focal plane of
thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5–80 keV, located in the focal plane of
multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4–12 keV,
with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera
type soft gamma-ray detector, sensitive in the 40–600 keV band. The simultaneous broad bandpass, coupled
with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
In September 2011 NASA released a Request for Information on “Concepts for the Next NASA X-ray Astronomy
Mission” and formed a Community Science Team to help study the submitted concepts and evaluate their science return
relative to the goals identified by the 2010 Astrophysics Decadal Survey “New Worlds, New Horizons” report. After
reading the responses and participating in a community workshop, the team identified a number of candidate mission
concepts, including one combining advances in large-area precision optics with new X-ray microcalorimeter
technology. However, the exact mission requirements (effective area, field of view, point spread function, etc) were not
fixed. We will present a range of mission designs, describing the results of the NASA/GSFC Mission Design Lab study
of one possible mission along with available deltas that would increase capability or decrease cost.
The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is a sounding rocket experiment
that will
combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to
obtain high- spectral-resolution images of extended X-ray sources. The target for Micro-X’s first
flight (slated for January
2013) is the Puppis A supernova remnant. The Micro-X observation of the bright eastern knot of
Puppis A will obtain a line-dominated spectrum with up to 27,000 counts collected in 300 seconds at
2 eV resolution across the 0.3-2.5 keV band. Micro-X will determine the thermodynamic and
ionization state of the plasma, search for line shifts and broadening associated with dynamical
processes, and seek evidence of ejecta enhancement. We describe the progress made in developing
this payload, including the detector, cryogenics, and electronics
assemblies.
High-energy astrophysics is a relatively young scientific field, made possible by space-borne telescopes. During the
half-century history of x-ray astronomy, the sensitivity of focusing x-ray telescopes-through finer angular resolution
and increased effective area-has improved by a factor of a 100 million. This technological advance has enabled
numerous exciting discoveries and increasingly detailed study of the high-energy universe-including accreting (stellarmass
and super-massive) black holes, accreting and isolated neutron stars, pulsar-wind nebulae, shocked plasma in
supernova remnants, and hot thermal plasma in clusters of galaxies. As the largest structures in the universe, galaxy
clusters constitute a unique laboratory for measuring the gravitational effects of dark matter and of dark energy. Here,
we review the history of high-resolution x-ray telescopes and highlight some of the scientific results enabled by these
telescopes. Next, we describe the planned next-generation x-ray-astronomy facility-the International X-ray
Observatory (IXO). We conclude with an overview of a concept for the next next-generation facility-Generation X.
The scientific objectives of such a mission will require very large areas (about 10000 m2) of highly-nested lightweight
grazing-incidence mirrors with exceptional (about 0.1-arcsecond) angular resolution. Achieving this angular resolution
with lightweight mirrors will likely require on-orbit adjustment of alignment and figure.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
pursued.
The International X-ray Observatory (IXO) is designed to conduct spectroscopic, imaging, and timing studies
of astrophysical phenomena that take place as near as in the solar system and as far as in the early universe. It
is a collaborative effort of ESA, JAXA, and NASA. It requires a large X-ray mirror assembly with an
unprecedented X-ray collection area and a suite of focal plane detectors that measure every property of each
photon. This paper reports on our effort to develop the necessary technology to enable the construction of the
mirror assembly required by IXO.
The International X-ray Observatory mission is a collaborative effort of NASA, ESA, and
JAXA. It will have unprecedented capabilities in spectroscopy, imaging, timing and
polarization measurement. A key enabling element of the mission is a flight mirror
assembly providing unprecedented large effective area (3 m2) and high angular resolution
of (5 arcseconds half-power diameter). In this paper we outline the conceptual design of
the mirror assembly and development of technology to enable its construction.
The International X-Ray Observatory (IXO) is a NASA, ESA, and JAXA joint mission. It requires a
mirror assembly with unprecedented characteristics that cannot be provided by existing optical
technologies. In the past several years, the project office at NASA Goddard Space Flight Center has
supported a vigorous mirror technology development program. This program includes the fabrication of
lightweight mirror segments by slumping commercially available thin glass sheets, the support and
mounting of these thin mirror segments for accurate metrology, the mounting and attachment of these
mirror segments for the purpose of X-ray tests, and development of methods for aligning and integrating
these mirror segments into mirror assemblies. This paper describes our efforts and developments in these
areas.
The Constellation-X Observatory is currently planned as NASA's next major X-ray observatory to be launched towards
the end of the next decade. The driving science goals for the mission are to: 1) Trace the evolution of Black Holes with
cosmic time and determine their contribution to the energy output of the Universe; 2) Observe matter spiraling into
Black Holes to test the predictions of General Relativity; 3) Use galaxy clusters to trace the locations of Dark Matter and
follow the formation of structure as a function of distance; 4) Search for the missing baryonic matter; 5) Directly observe
the dynamics of Cosmic Feedback to test models for galaxy formation; 6) Observe the creation and dispersion of the
elements in supernovae; and 7) Precisely constrain the equation of state of neutron stars. To achieve these science goals
requires high resolution (R > 1250) X-ray spectroscopy with 100 times the throughput of the Chandra and XMMNewton.
The Constellation-X Observatory will achieve this requirement with a combination of four large X-ray
telescopes on a single satellite operating in the 0.25 to 10 keV range. These telescopes will feed X-ray micro-calorimeter
arrays and grating spectrometers. A hard X-ray telescope system will provide coverage up to at least 40 keV. We
describe the mission science drivers and the mission implementation approach.
The NeXT (New exploration X-ray Telescope), the new Japanese X-ray Astronomy Satellite following Suzaku,
is an international X-ray mission which is currently planed for launch in 2013. NeXT is a combination of wide
band X-ray spectroscopy (3-80 keV) provided by multi-layer coating, focusing hard X-ray mirrors and hard
X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-10 keV) provided by thin-foil
X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane
detector for a soft X-ray telescope and a non-focusing soft gamma-ray detector. With these instruments, NeXT
covers very wide energy range from 0.3 keV to 600 keV. The micro-calorimeter system will be developed by
international collaboration lead by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with
high spectral resolution of ΔE ~7 eV by the micro-calorimeter will enable a wide variety of important science
themes to be pursued.
The New Exploration X-ray Telescope (NeXT) is an X-ray astronomical observatory slated to be launched from
Japan in 2013. Its objectives range from high resolution imaging and spectroscopy below ~12 keV to studying
the hard X-ray sky up to ~70 keV. To accomplish these goals, it will carry, among other instruments, 4 grazing
incidence, imaging telescopes, two covering the soft X-ray band and the remaining the higher energies. The
soft X-ray telescopes will be similar to ones flown onboard Suzaku, with a larger outer diameter (45 cm) and
longer focal length (6 m). The NASA's GSFC foil mirror group is collaborating with the Nagoya University
and ISAS/JAXA in the implementation of the the soft X-ray mirrors. Our science driven goal is a <1.3' Half
Power Diameter (HPD) Point Spread Function, improved from Suzaku ~1.7' HPD. We address important area
in the fabrication process where we plan to make changes; (1) substrate shaping, (2) replication process, (3)
reflector assembly, (4) alignment bar accuracy, and (5) focal length miss match among segments. Having done
some of them, we measured 1.26' HPD for 60-pair quadrant reflectors. But it still includes bad sectors (>1.8'
HPD) towards the quadrant boundary, while most of middle sectors are at 1' HPD level. The bad sectors can
be corrected with new assembly approach where we actively tune and then fix reflectors at their right position
or whole conical shell reflectors instead of segmented ones. In this proceeding, we present a proposed NeXT soft
X-ray telescope performance, report the current status of the development and introduce the new whole shell
mirror.
The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. Our first target is the Puppis A supernova remnant, which will be observed in January 2011. The Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with up to 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plasma diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. We describe the progress made in developing this payload, including the detector, cryogenics, and electronics assemblies. A detailed modeling effort has been undertaken to design a rocket-bourne adiabatic demagnetization refrigerator with sufficient magnetic shielding to allow stable operation of transition edge sensors, and the associated rocket electronics have been prototyped and tested.
The Constellation-X Spectroscopy X-ray Telescope (SXT) is a segmented, tightly nested Wolter-I telescope with a
requirement of approximately 12.5 arcseconds HPD for the mirror system. The individual mirror segments are 0.4 mm
thick, formed glass, making the task of mounting, alignment and bonding extremely challenging. Over the past year we
have developed a series of tools to meet these challenges, the latest of which is an upgrade to the 600-meter x-ray beam
line at GSFC. The new facilities allow us to perform full aperture and sub-aperture imaging tests of mirror segment
pairs to locate the source of deformations and correlate them with our optical metrology. We present the optical
metrology of the axial figure and Hartmann focus, x-ray imaging performance predictions based on analysis of the
optical metrology, and both full aperture and sub-aperture x-ray imaging performance of test mirror segment pairs at
8.05 keV.
KEYWORDS: X-rays, Sensors, Mirrors, Signal to noise ratio, Spectral resolution, Plasmas, Galaxy groups and clusters, Temperature metrology, Ionization, Iron
Spatially resolved X-ray spectroscopy with high spectral resolution allows the study of astrophysical processes in
extended sources with unprecedented sensitivity. This includes the measurement of abundances, temperatures, densities,
ionisation stages as well as turbulence and velocity structures in these sources. An X-ray calorimeter is planned for the
Russian mission Spektr Röntgen-Gamma (SRG), to be launched in 2011. During the first half year (pointed phase) it will
study the dynamics and composition of of the hot gas in massive clusters of galaxies and in supernova remnants (SNR).
During the survey phase it will produce the first all sky maps of line-rich spectra of the interstellar medium (ISM).
Spectral analysis will be feasible for typically every 5° x 5° region on the sky. Considering the very short time-scale for
the development of this instrument it consists of a combination of well developed systems. For the optics an extra
eROSITA mirror, also part of the Spektr-RG payload, will be used. The detector will be based on spare parts of the
detector flown on Suzaku combined with a rebuild of the electronics and the cooler will be based on the design for the
Japanese mission NeXT. In this paper we will present the science and give an overview of the instrument.
As NASA's next major space X-ray observatory, the Constellation-X mission (Bookbinder et al. 2008)
requires mirror assemblies with unprecedented characteristics that cannot be provided by existing optical
technologies. In the past several years, the project has supported a vigorous mirror technology
development program. This program includes the fabrication of lightweight mirror segments by slumping
commercially available thin glass sheets, the support and mounting of these thin mirror segments for
accurate metrology, the mounting and attachment of these mirror segments for the purpose of X-ray tests,
and development of methods for aligning and integrating these mirror segments into mirror assemblies.
This paper describes our efforts and developments in these areas.
As NASA's next major x-ray astronomical mission following the James Webb Space Telescope,
Constellation-X requires technology advances in several areas, including x-ray optics, x-ray detectors,
and x-ray gratings. In the area of x-ray optics, the technology challenge is in meeting a combination of
angular resolution, effective area, mass, and production cost requirements. A vigorous x-ray optics
development program has been underway to meet this challenge. Significant progress has been made in
mirror fabrication, mirror mount and metrology, and mirror alignment and integration. In this paper we
give a brief overview of our development strategy, technical approaches, current status, and expectations
for the near future and refer interested readers to papers with an in-depth coverage of similar areas.
One of the most important aspects of the Constellation-X x-ray optics development is the fabrication of
lightweight mirror segments. Given its multi-faceted requirements, i.e., good angular resolution, light
weight, and low production cost, we have adopted a glass slumping or forming technique that takes
advantage of the naturally excellent microroughness of thin float glass sheets. In this paper we present
measured quantities of formed mirror segments and compare them with requirements to show that the
formed mirror segments have met all except the sag requirement. The larger than acceptable sag error
may be an artifact of the measurement process. It may also be caused by coating stress or residual thermal
stress resulting from the slumping process. Our immediate future task is to identify the source(s) of the
sag error and address them accordingly.
The Constellation-X mission will address questions central to the NASA Beyond Einstein Program, using high
throughput X-ray spectroscopy to measure the effects of strong gravity close to the event horizon of black holes, study
the formation and evolution of clusters of galaxies to precisely determine cosmological parameter values, measure the
properties of the Warm-Hot Intergalactic Medium, and determine the equation of state of neutron stars. Achieving these
science goals requires a factor of ~100 increase in sensitivity for high resolution spectroscopy over current X-ray
observatories. This paper briefly describes the Constellation-X mission, summarizes its basic performance parameters
such as effective area and spectral resolution, and gives a general update on the mission. The details of the updated
mission configuration, compatible with a single Atlas-V 551 launch vehicle, are presented.
Micro-X is a proposed sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. We describe the payload and the science targeted by this mission including the discussion of three possible Micro- X targets: the Puppis A supernova remnant, the Virgo Cluster, and Circinus X-1. For example, a Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plama diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. For clusters of galaxies, Micro-X can uniquely study turbulence and the temperature distribution function. For binaries, Micro-X's high resolution spectra will separate the different processes contributing to the Fe K lines at 6 keV and give a clear view of the geometry of the gas flows and circumstellar gas.
Future X-ray telescopes invariably require much higher angular resolutions and/or much larger effective
areas than those already flown, and they will typically be designed and built with mirror segments, in
contrast with the typical past X-ray telescope of complete shells. While the segmented approach has many
advantages, it has one significant disadvantage: its complexity and difficulty associated with mirror
segment alignment and integration. In this paper, we outline an approach, named "Fabricate and
Assemble," that directly addresses this disadvantage. We will describe the necessary components, their
fabrication, and their integration into a mirror assembly. The salient features of this approach include: (1)
it fully realizes the optical performance potential of each mirror segment, (2) it leaves each mirror in a
stress-free or minimally stressed state, resulting in a stress-free and therefore stable mirror assembly, (3) it
assembles the mirror segment while it is supported so as to minimize or even eliminate the effect of
gravity, and (4) it is highly amenable to being implemented as part of a sequential production line.
A single Constellation-X Spectroscopy X-ray Telescope (SXT) mirror segment pair is being aligned in the Optical
Alignment Pathfinder 2 (OAP2) platform using a combination of mechanical and optical techniques. Coarse positioning
was provided through a contact probe, the alignment was refined in a collimated while-light facility used for the Suzaku
(ASTRO-E2) satellite, and then finalized with a combination of a Centroid Detector Assembly (CDA) and an
interferometer coupled to a novel conical null lens providing surface map imaging over 60% of the mirror surface at one
time. Due to a variety of reasons, the positioning and figure of the mirror segment under examination can shift, and we
test how reliably high quality alignment can be reproduced on any given day. Also, the mirror segment's deformation
response to deliberate misalignments has been tested, providing a response matrix for these thin glass mirror segments.
We describe recent progress in the technology development program for the mirror system for the Constellation-X Spectroscopy X-ray Telescope (SXT). Development of this mirror represents a significant technology challenge, as it must provide a combination of large effective area (3 sq. m) and modest angular resolution (15 arc second half power diameter requirement; 5 arc second goal) with a limited mass allocation. The baseline design incorporates over 200 nested Wolter 1 mirrors. Each of these in turn is segmented in order to simplify handling of the mirrors and facilitate mass production. The X-ray reflecting surfaces are fabricated from thin, thermally formed glass sheets. Production improvements have yielded mirror segments that approach the performance requirement without the need for epoxy replication. A mounting and alignment approach incorporating piezoelectric actuators has been shown to manipulate mirror segments with the required precision without introducing significant distortion. Substantial improvements in metrology methodology have provided insights into the mirror segment forming and alignment processes. We describe the technical advances made over the past year and summarize near-term plans.
Constellation-X is NASA's next major X-ray observatory. It requires X-ray mirrors with high throughput (3 m2 effective area at 1 keV), moderate angular resolution (15" half power diameter), and light weight (about an order of magnitude lighter than XMM/Newton's). Over the past few years we have been developing a glass forming technology for making mirrors. This technology by construction meets from the outset two (throughput and weight) of the three requirements. Our development effort has been concentrated on improving the angular resolution. Our progress so far has shown that this technology not only can meet the angular resolution requirement of 15" HPD, but also has the potential to reach Constellation-X's goal of 5" HPD. This paper is a snapshot of our X-ray mirror development effort as of May 2006. It briefly describes the mirror fabrication process, results achieved, and important issues that are being worked on.
The Constellation-X mission's Spectroscopic X-Ray Telescopes (SXT) require an angular resolution of 15" half-power diameter (HPD) with extremely lightweight grazing incidence mirrors. The areal density of the mirror must be about 1 kg/m2 or less. In comparison with the state of the art X-ray mirrors represented by the XMM/Newton telescopes, this is approximately an order of magnitude less in mass areal density while maintaining the same angular resolution. We use a precision glass forming technique to fabricate mirrors that are 0.4mm thick and optical metrology to demonstrate that these mirrors can meet the stringent figure and micro-roughness requirements of the Constellation-X mission. We expect in the next few years to significantly improve the production yield and mirror quality to meet the goal of the mission, which is 5" HPD for two reflections at the same mass.
The Constellation-X Spectroscopy X-ray Telescope (SXT) is a large diameter, high throughput, grazing incidence imaging mirror system, designed to perform high sensitivity spectroscopy of cosmic X-ray sources in the 0.2-10.0 keV band. The baseline effective area requirement is ~3 m2 at 1 keV. The system-level angular-resolution requirement is a 15-arcseconds half-power diameter, with a 5-arcsecond goal. The effective area is attained through a modular design, involving the nesting of many confocal, thin-walled Wolter I mirror segments. Considerable progress has been made in developing thin, thermally formed, glass mirror substrates that meet or better the angular-resolution requirement. Several approaches to mounting and aligning reflector segments into a mirror system are under investigation. We report here on the progress of the SXT technology development program toward reaching the performance goals.
The Constellation X-ray Mission is a high-throughput X-ray facility emphasizing observations at high spectral resolution (R ~ 300-3000) while covering a broad energy band (0.25-60 keV). The mission is intended to achieve a factor of 25-100 increase in sensitivity over current high resolution X-ray spectroscopy missions. Constellation-X is the X-ray astronomy equivalent of the Keck and the VLT, complementing the high spatial resolution capabilities of Changra. Constellation-X achieves its high-throughput and reduces mission risk by dividing the collecting area across four separate spacecraft launched two at a time into an L2 orbit. We describe the overall mission concept and also present a brief overview of alternate concepts which are under consideration. We discuss recent progress on the key technologies, including: lightweight, high-throughput X-ray optics, micro-caloriment spectrometer arrays, low-power and low-weight CCD arrays, lightweight gratings, multilayer coatings to enhance the hard X-ray performance of X-ray optics, and hard X-ray detectors.
KEYWORDS: X-rays, Spectroscopy, Galaxy groups and clusters, Space telescopes, General relativity, Iron, Stars, X-ray telescopes, Astronomy, Astrophysics
The Constellation-X mission will address the questions: "What happens to matter close to a black hole?" and "What is Dark Energy?" These questions are central to the NASA Beyond Einstein Program, where Constellation-X plays a central role. The mission will address these questions by using high throughput X-ray spectroscopy to observe the effects of strong gravity close to the event horizon of black holes, and to observe the formation and evolution of clusters of galaxies in order to precisely determine Cosmological parameters. To achieve these primary science goals requires a factor of 25-100 increase in sensitivity for high resolution spectroscopy. The mission will also perform routine high-resolution X-ray spectroscopy of faint and extended X-ray source populations. This will provide diagnostic information such as density, elemental abundances, velocity, and ionization state for a wide range of astrophysical problems. This has enormous potential for the discovery of new unexpected phenomena. The Constellation-X mission is a high priority in the National Academy of Sciences McKee-Taylor Astronomy and Astrophysics Survey of new Astrophysics Facilities for the first decade of the 21st century.
Large collecting area x-ray telescopes are designed to study the early Universe, trace the evolution of black holes, stars and galaxies, study the chemical evolution of the Universe, and study matter in extreme environments. The Constellation-X mission (Con-X), planned for launch in 2016, will provide ~ 104 cm2 collecting area with 15 arc-sec resolution, with a goal of 5 arc-sec. Future missions require larger collecting area and finer resolution. Generation-X (Gen-X), a NASA Visions Mission, will achieve 100 m2 effective area at 1 keV and angular resolution of 0.1 arc-sec, half power diameter. We briefly describe the Con-X flowdown of imaging requirements to reflector figure error. To meet requirements beyond Con-X, Gen-X optics will be thinner and more accurately shaped than has ever been accomplished. To meet these challenging goals, we incorporate for the first time active figure control with grazing incidence optics. Piezoelectric material will be deposited in discrete cells directly on the back surface of the optical segments, with the strain directions oriented parallel to the surface. Differential strain between the two layers of the mirror causes localized bending in two directions, enabling local figure control. Adjusting figure on-orbit eases fabrication and metrology. The ability to make changes to mirror figure adds margin by mitigating risk due to launch-induced deformations and/or on-orbit degradation. We flowdown the Gen-X requirements to mirror figure and four telescope designs, and discuss various trades between the designs.
KEYWORDS: Cameras, Mirrors, Charge-coupled devices, Telescopes, X-rays, Sensors, CCD cameras, Galaxy groups and clusters, Electronics, Digital signal processing
What is the nature of the Dark Energy that is driving the universe apart? Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales which is dominated by the Dark Energy. DUO will measure 10.000 clusters of galaxies, the power spectrum of density fluctuations of clusters and their number density as a function of cosmic time. Although designed long before the existence of Dark Energy was claimed, the ABRIXAS type X-ray telescope turns out to be ideally suited for this task: DUO is, in essence, a re-flight of the ABRIXAS X-ray telescope which some modifications of the focal plane instrumentation. First of all, we will use new CCDs which are improved versions of the pn-CCDs successfully flown on XMM-Newton. A modular concept having seven individual cameras in the foci of the seven mirror systems allows us to design the orientation of the seven telescopes with respect to each other matching the scientific needs of the DUO mission. Details of the concept including mechanical, electrical and thermal aspects are given.
The status of technology development for the Constellation-X Spectroscopy X-ray Telescope (SXT) mirror is presented. The SXT mirror combines a large (1.6 m) aperture with modest (12 arc sec half power diameter) angular resolution and low mass (750 kg). The overall collecting area, larger than 9,600 square cm at 0.25 keV, requires high throughput, and thus nesting of a substantial number of thin reflectors. A phased development program is underway to develop reflectors, mounting and alignment approaches, and metrology techniques for components and the mirror has a whole. The latest results in all these areas are summarized, along with an overview of results of optical testing of reflector performance.
The new frontier in astrophysics is the study of the very first stars, galaxies and black holes in the early Universe. These objects are beyond the grasp of the current generation of X-ray telescopes such as Chandra, and so the Generation-X Vision Mission has been proposed as an X-ray observatory which will be capable of detecting these earliest objects. Xray imaging and spectroscopy of such distant objects will require an X-ray telescope with large collecting area and high angular resolution. The Generation-X concept has 100 m2 collecting area at 1 keV (1000 times larger than Chandra) and 0.1 arcsecond angular resolution (several times better than Chandra and 50 times better than the resolution goal for Constellation-X). The baseline mission involves four 8 m diameter telescopes operating at Sun-Earth L2. Such large telescopes will require either robotic or human-assisted in-flight assembly. To achieve the required effective area with launchable mass, very lightweight grazing incidence X-ray optics must be developed, having an areal density 100 times lower than in Chandra, with perhaps 0.1 mm thick mirrors requiring on-orbit figure control. The suite of available detectors for Generation-X should include a large-area high resolution imager, a cryogenic imaging spectrometer and a grating spectrometer.
Dark Energy dominates the mass-energy content of the universe (about 73%) but we do not understand it. Most of the remainder of the Universe consists of Dark Matter (23%), made of an unknown particle. The problem of the origin of Dark Energy has become the biggest problem in astrophysics and one of the biggest problems in all of science. The major extant X-ray observatories, the Chandra X-ray Observatory and XMM-Newton, do not have the ability to perform large-area surveys of the sky. But Dark Energy is smoothly distributed throughout the universe and the whole universe is needed to study it. There are two basic methods to explore the properties of Dark Energy, viz. geometrical tests (supernovae) and studies of the way in which Dark Energy has influenced the large scale structure of the universe and its evolution. DUO will use the latter method, employing the copious X-ray emission from clusters of galaxies. Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales is dominated by the Dark Energy. In order to take the next step in understanding Dark Energy, viz. the measurement of the 'equation of state' parameter 'w', an X-ray telescope following the design of ABRIXAS will be accommodated into a Small Explorer mission in lowearth orbit. The telescope will perform a scan of 6,000 sq. degs. in the area of sky covered by the Sloan Digital Sky Survey (North), together with a deeper, smaller survey in the Southern hemisphere. DUO will detect 10.000 clusters of galaxies, measure the number density of clusters as a function of cosmic time, and the power spectrum of density fluctuations out to a redshift exceeding one. When combined with the spectrum of density fluctuations in the Cosmic Microwave Background from a redshift of 1100, this will provide a powerful lever arm for the crucial measurement of cosmological parameters.
Constellation-X is NASA's next major X-ray astronomical observatory. Its salient features are its very large effective X-ray collecting area (about 30,000 cm2 at 1 keV) and high resolution gratings and cryogenic detector systems. The large mirror effective area presents unique and unprecedented challenges in optical fabrication and metrology. In this paper we report on the development of very lightweight X-ray mirrors that address these challenges. We use a two-step mirror fabrication process: (1) slumping thin (0.4mm) flat glass sheets to generate high quality substrates that may have mid-frequency figure errors, and (2) reducing or eliminating the mid-frequency errors using an epoxy replication process. We discuss problems and the potential associated with each of these two steps. Based on our work to date, we expect that this technology to be able to meet the baseline Constellation-X requirements, i.e, 15" HPD (half-power diameter) at the observatory level. In the next few years, we will further advance this technology and expect it to reach the Constellation-X goal: 5" HPD at the observatory level.
The Constellation-X mission is a follow-on to the current Chandra and XMM missions. It will place in orbit an array of four X-ray telescopes that will work in unison, having a substantial increase in effective area, energy resolution, and energy bandpass over current missions. To accomplish these ambitious increases new optics technologies must be exploited. The primary instrument for the mission is the Spectroscopy X-Ray Telescope (SXT), which covers the 0.21 to 10 keV band with a combination of two x-ray detectors: a reflection grating spectrometer with CCD readout and a micro-calorimeter. Mission requirements are an effective area of 15,000 cm2 near 1 keV and a 15 arc-sec (HPD) image resolution with a goal of 5 arc-sec. The Constellation-X SXT uses a segmented design with lightweight replicated optics. A technology development program is being pursued with the intent of demonstrating technical readiness prior to the program new start. Key elements of the program include the replication of the optical elements, assembly and alignment of the optics into a complete mirror assembly and demonstration of production techniques needed for fabrication of multiple units. These elements will be demonstrated in a series of engineering development and prototype optical assemblies which are increasingly flight-like. In this paper we present an image angular resolution error budgets for the SXT and for the Optical Assembly Pathfinder #2 (OAP2), the first of engineering development units intended to be tested in x-rays. We describe OAP2 image error sources and performance analyses made to assess error sensitivities. Finally we present an overall prediction of as-tested imaging performance in the x-ray test facility.
As NASA’s next facility-class x-ray mission, Constellation X will provide high-throughput, high-resolution spectroscopy for addressing fundamental astrophysical and cosmological questions. Key to the Constellation-X mission is the development of lightweight grazing-incidence optics for its Spectroscopy X-ray Telescopes (SXT) and for its Hard X-ray Telescopes (HXT). In preparation for x-ray testing Constellation-X SXT and HXT development and demonstration optics, Marshall Space Flight Center (MSFC) is upgrading its 100-m x-ray test facility, including development of a five degree-of-freedom (5-DoF) mount for translating and tilting test articles within the facility’s large vacuum chamber. To support development of alignment and assembly procedures for lightweight x-ray optics, Goddard Space Flight Center (GSFC) has prepared the Optical Alignment Pathfinder Two (OAP2), which will serve as a surrogate optic for developing and rehearsing x-ray test procedures. In order to minimize thermal distortion of the mirrors during x-ray testing, the Harvard-Smithsonian Center for Astrophysics (CfA) has designed and implemented a thermal control and monitoring system for the OAP2. CfA has also built an aperture wheel for masking and sub-aperture sampling of the OAP2 to aid in characterizing x-ray performance of test optics.
The Constellation-X observatory is planned to have four identical satellites, each of which carries, among other instruments, a Spectroscopic X-ray Telescope (SXT). The SXT has a 10m focal length and 1.6 m diameter aperture. It has a total effective X-ray collection area of ~7,500 cm2 at 1 keV. Mission science requirements call for an angular resolution of 15" half-power diameter (HPD) at the observatory level. Combining the large collection area requirement, the angular resolution requirement, and a mass requirement, we are faced with an unprecedented task of fabricating X-ray mirror segments with an areal density of only 1 kg/m2 which is typically called gossamer optics. We have adopted at two-step process for fabricating the mirror segments: (1) first slump a flat sheet of glass onto a forming mandrel to create a substrate, and then (2) epoxy-replicate the substrate off a precision replication mandrel to eliminate any defects or errors on its surface. As of the writing of this paper in late August 2003, we have demonstrated a process for reliably making excellent substrates. Best mirror segments fabricated so far, if aligned and mounted without error, have an angular resolution in the vicinity of 20" HPD, close to, but not quite, meeting requirements. We expect that in the next year, when forming mandrels that meet requirements are procured, we will be able to fabricate mirror segments that actually meet and even possibly exceed the SXT requirements. In this paper, we report on the baseline mirror fabrication method and the status of its development as of August 2003.
The Constellation-X SXT mirrors and housings continue to evolve toward a flight-like design. Our second-generation alignment housing, the Optical Alignment Pathfinder 2 (OAP2), is a monolithic titanium structure that is nested inside the OAP1 alignment jig, described in a previous paper (J. Hair, et. al., SPIE 2002). In order to perform x-ray tests in a configuration where the optical axis is horizontal, and continue to develop more flight-like structures, we needed to design a strong, but lightweight housing that would impart minimal deformations on the thin segmented mirrors when it is rotated from the vertical orientation used for optical alignment to the horizontal orientation that is used for x-ray testing. This paper will focus on the design of the OAP2 housing, and the assembly and alignment of the optics within the OAP1 plus OAP2 combination using the Centroid Detector Assembly (CDA). The CDA is an optical alignment tool that was successfully used for the HRMA alignment on the Chandra X-ray Observatory. In addition, since the glass we are using is so thin and flexible, we will present the response of the optical alignment quality of a Wolter-I segment to known deformations introduced in by the OAP1 alignment housing.
The Constellation X-ray Observatory consists of four identical spacecraft, each carrying a complement of high sensitivity X-ray instrumentation. At the heart of each is the grazing incidence mirror of the Spectroscopy X-ray Telescope (SXT). This mirror has a diameter of 1.6 m, a focal length of 10 m, mass not exceeding ~650 kg. The required angular resolution is 15 arc seconds and the effective area at 1 keV must exceed 7,500 cm2. Achieving these performance requirements in a cost effective way within the allocated mass is accomplished via a modular design, incorporating lightweight, multiply-nested, segmented Wolter Type I X-ray mirrors. The reflecting elements are composed of thin, thermally formed glass sheets, with epoxy-replicated X-ray reflecting surfaces. Co-alignment of groups of reflectors to the required sub-micron accuracy is assisted by precision silicon microstructures. Optical alignment incorporates the Centroid Detector Assembly (CDA) originally developed for aligning the Chandra mirror. In this talk we present an overview of recent progress in the SXT technology development program. Recent efforts have concentrated on producing an engineering unit that demonstrates all the key fabrication and alignment processes, and meets the angular resolution performance goal. Additionally, we describe the initial steps toward flight mirror production, anticipating a Constellation-X launch early in the next decade.
We report on the fabrication and performance of prototype optics for the Constellation-X hard X-ray telescope (HXT). The prototypes utilize segmented-glass optics. Multiple glass segments are combined to produce telescope shells. The shells are separated by and epoxied to graphite rods, and each layer of rods is precisely machined to match the required optical geometry of the corresponding glass shell. This error-compensating, monolithic assembly and alignment (EMAAL) procedure is novel. Two prototypes are described. The first used 10cm long thermally-slumped glass pieces produced by slumping into a concave mandrel with no subsequent replication. This prototype obtained 45" (2-bounce HPD). The second prototype was the first attempt to mount epoxy-replicated, thermally-slumped glass optics using EMAAL. The latter prototype demonstrated our ability to produce and mount glass shells whose figure and performance are faithful representations of the original replication mandrel. The average performance was 45", with the best replicated segment providing 33" (2-bounce HPD) performance, consistent with the ~30" measured with laser reflectometry and interferometry prior to mounting. Both these prototypes substantially exceeded the HXT requirement of 60".
As NASA's next major x-ray observatory, Constellation-X will have a photon collection area of 30,000 cm2 at 1 keV, which, after folding other instrumental respojnses, translates into an effective aera of 15,000 cm2. The observatory consists of four identical satellites each of which carries a spectroscopic x-ray telescope mirror assembly (SXT) that is 1.6 m in diameter and has a focal length of 10 m and a collection area of 7,500 cm2 at 1 keV and an angular resolution of 15" HPD at the system level. Each mirror assembly consists of a large number of mirror segments precisely assembled together. Our development of the mirror segments is divided into two steps. The first one is to develop the basic approach and fabricate segments within the constraints of existing infra-structure to meet the angular resolution requirement, but not mirror segments precisely assembled together. Our development of the mirror segments is divided into two steps. The first one is to develop the basic approach and fabricate segments within the constraints of existing infra-structure to meet the angular resolution requirement, but not mirror segment size requirement. We have all but successfully competed this part of the development. We are now on the verge of going into the second step, that is to fabricate mirror segments of larger sizes to reduce the number of segments that have to be aligned and integrated. In this paper, we report on the requirements and the development status of the mirror segments. These assembly and other requirements of the SXT are reported elsewhere.
The Constellation-X mission will perform X-Ray science with improvements in energy resolution and effective area over its predecessor missions. The primary instrument on each of the four Constellation-X spacecraft is the Spectroscopy X-Ray Telescope (SXT). The SXT is a 1.6m diameter grazing incidence mirror assembly comprised of approximately 4000 optic elements. In order for the optic elements to work together to achieve the required 15 arcsec image resolution for the telescope, each optic must be aligned very precisely. To enable the alignment of the optic elements to the required tolerances, new technology must be developed through a series of technology demonstrators. The first step in this process is the production of the Optical Assembly Pathfinder (OAP). The OAP represents a small section, or module, of the complete SXT and has been designed to facilitate the evaluation and development of the optic element support, alignment, and adjustment concepts, processes, and procedures. To do this, one pair of optic elements, primary and secondary, will be aligned using optical alignment methods including the Centroid Detector Assembly (CDA) and Interferometry. Ten Optic Adjustment Arms will support the optic elements such that their position and figures can be adjusted. Currently, one section, the primary section, of the OAP has been assembled and is awaiting the installation of an optic element for testing.
We provide an overview of the Constellation-X SXT development program. We describe the performance requirements and goals, and the status of the technology development program. The SXT has a 1.6-meter diameter, a 10-meter focal length, and is to have an angular resolution exceeding 15 arc seconds. It has a modular design, incorporting lightweight, multiply nested, segmented Wolter Type I x-ray mirrors. All aspects of the design lend themselves to mass-production. The reflecting surfaces are produced by epoxy replication off precision mandrels onto glass substrates that have been accurately formed by thermal slumping. Coalignment of groups of relfectors to the required sub-micron accuracy is assisted by precison silicon micorstructures. Optical alignment is performed using the Centroid Detector Assembly originally developed for aligning the Chandra mirror. Recent efforts have concentrated on the producotin of an Engineering Unit, incorporating the components for the first time into a flight-like configuration. We summarize the status of the development of the processes for the key components and the initial metrology results of the Engineering Unit.
The Constellation-X mission is a follow-on to the current Chandra and XMM missions. It will place in orbit an array of four identical X-ray telescopes that will work in unison, having a substantial increase in effective area, energy resolution, and energy bandpass over current missions. To accomplish these ambitious increases new optics technologies must be exploited. The primary instrument for the mission is the Spectroscopy X-Ray Telescope (SXT), which covers the 0.2 to 10 keV band with a combination of two x-ray detectors: a reflection grating spectrometer (RGS) with CCD readout, and
a micro-calorimeter. Mission requirements are an effective area of 15,000 cm2 near 1.25 keV, 6,000 cm2 near 6 keV, and a 15 arcsec (HPD) resolution requirement with a goal of 5 arcsec. The Constellation-X SXT uses a segmented design with lightweight replicated optics. A technology development program is being pursued with the intent of demonstrating technical readiness prior to the program new start. Key elements of the program include the replication of the optical elements, assembly and alignment of the optics into a complete mirror assembly and demonstration of production techniques needed for fabrication of multiple units. In this paper we present the development of SXT assembly and alignment techniques and describe recent work and current status on the first of these assemblies, the Optical Assembly Pathfinder, in which precision mechanical techniques and optical metrology are used to assemble and align the flexible optical elements.
We report recent work on segmented glass optics for the Constellation-H hard x-ray telescope. This effort seeks to both improve the figure of the free-standing glass substrates, and to refine a newly-developed mounting technology for the substrates. We discuss metrology on recently characterized glass shells both unmounted and mounted. We also present plans for several prototype optics to be constructed in the upcoming year.
The prospect of making a lobster-eye telescope is drawing closer with recent developments in the manufacture of microchannel-plate optics. This would lead to an x-ray all-sky monitor with vastly improved sensitivity and resolution over existing and other planned instruments. We consider a new approach, using deep etch x-ray lithography, to making a lobster-eye lens that offers certain advantages even over microchannel-plate technology.
We present an overview of our recent progress toward the development of segmented X-ray mirrors for the Constellation-X mission. Our reference design incorporates thin glass reflector substrates, with axially curved X-ray reflecting surfaces applied via epoxy replication. Alignment is accomplished via a precision structure incorporating ultraprecise etched Si alignment microstructures (as described in associated papers). Recent efforts have been devoted to demonstrating that the figure of prototype small segments and the alignment process will allow us to meet the 15" half-power diameter angular resolution requirement. We discuss the status of this, of our efforts to fabricate meter-class segments, and of the developments of supporting metrological techniques. We summarize our plans for a laboratory demonstration of a prototype mirror meeting the Constellation-X angular resolution and weight requirements.
We present preliminary results from observations of supernova remnants by the Chandra X-ray Observatory. The data include imaging spectroscopy from objects observed with both GTO and GO data. The high spatial resolution of Chandra is revealing a wealth of small-scale structure in these remnants. Specifically, we have resolved the remnant of SN1987A, and have discovered fine-scale structure in N103B and G292.0+1.8.
We describe our design for a mini-Schmidt all-sky monitor. By using standard micro-machining techniques we are able to build a module that is smaller, lighter and has a greater open area than previous prototypes. In addition, we retain the benefit of high quality metal-coated flat glass reflecting surfaces.
We describe recent progress toward producing a segmented mirror that meets the mass and angular resolution requirements for the Constellation-X Spectroscopy X-ray Telescope (SXT). While the segmented approach has its heritage in conical thin foil X-ray mirrors pioneered at GSFC, the Constellation-X implementation introduces innovations in nearly all components. The baseline configuration uses thermally formed glass for reflector substrates; thermally formed Be is being investigated as an option. Alignment is performed using etched Si microstructures that locate reflectors to submicron accuracy. The only aspect preserved from previous mirrors is epoxy replication of the X-ray reflecting surface. Thus far, all developments have been at the component level. Nonetheless, we have made substantial progress toward meeting the Constellation-X SXT angular resolution goal.
In addition to high resolving power in the traditional x-ray band, the Constellation X-ray scientific goals require broad bandpass, with response extending to E >= 40 keV. To achieve this objective, Constellation-X will incorporate a hard x-ray telescope (HXT) based on depth graded multilayer- coated grazing incidence optics and position-sensitive solid state detectors. This paper describes the HXT performance requires, provides an overview of the HXT optics and detector technology development efforts, and present example designs.
We have superpolished a diamond-turned aluminum mandrel to an axial roughness of 0.34 nm rms. The mandrel is made to the Astro-E secondary mirror design for the 81st shell. Precision metrology at 100 mm to submicron scales has established the power spectral density of the mandrel and ultralightweight gold coated replicated segments. Predicted image quality of a set of optimally aligned replicated segments of this and a matching primary is substantially improved as compared to the flight mirrors for Astro-E. This approach using metal mandrels, superpolishing, and replicated ultralightweight foil mirrors, may represent a cost-effective approach to meeting the 15 arcsec half-energy width and weight requirements for the Constellation-X mission. Descriptions of the polishing apparatus, the precision metrology instruments, and the surface data analysis are presented. The general methods describe dare applicable to precision optics for both normal incidence and grazing incidence optics.
Segmented mirrors are one of the two approaches being investigated for both the Spectroscopy X-ray Telescope (SXT) and the Hard X-ray Telescope (HXT) on Constellation-X. Mirrors based on the grazing incidence foil optics pioneered by GSFC will meet the stringent Constellation-X SXT weight requirement, but the currently achieved resolution falls short of the 15 inch half-power diameter (HPD) required for Constellation-X. Significant contributions to the blur arise from the figure of individual reflectors and from inaccurate mounting. Only a small contribution to the HPD of the existing mirrors arises from the conical approximation. In this paper, we describe our program for improving the spatial resolution of segmented mirrors to meet the COnstellation-X requirement. Our effort incorporates accurately figured replication mandrels, mechanically more robust reflector substrates, high accuracy alignment, and ultimately a transition from conical to curved reflecting surfaces.
We present a current status of the development of hard x-ray telescope using Pt/C multilayer supermirror. The telescope system is to be made by combining thin foil replication technology for high throughput mirror and multilayer supermirror coating technology for hard x-ray reflection. After the successful multilayer coating on the replica foil mirror, we made the performance demonstration model of this type of telescope, having 20 replica foil supermirrors, 10 primary and 10 secondary reflectors, with focal length of 4.75 m and radius of 100 mm. Pt/C multilayer supermirror structure was designed and optimized to have high and flat reflectivity for x-ray energy from 25 through 40 keV. After some efforts to avoid heat damage of replica foil mirror during the deposition process of multilayer by DC sputtering system, we could establish the fabrication method of supermirror structure on replica foil mirror. Based on the x-ray measurement, we found that this demonstration model showed the half power diameter of 1.9 arcmin for had x-rays and nearly the same reflectivity and energy band width as expected. In this paper, we present the design of graded multilayer as the supermirror, the fabrication and the performance of this demonstration model.
Lobster-eye optics have been proposed as an exciting development in the field of x-ray all-sky monitors. However, to date their potential has mainly been analyzed in the context of an all-sky monitor for a small satellite mission. We examine the wide range of parameters available for lobster-eye optics with different configurations. The sensitivity of the various schemes is calculated. We have also examined the current state of the art in actual lobster-eye optics. We present our experimental results and discuss realistic targets for manufacture. The impact of these targets on the calculated sensitivities is also described.
The concept of the lobster eye optics was proposed in the nineteen seventies. It has gained widespread interest in x- ray astronomy for its potential for constructing compact and focusing x-ray all sky monitors with unprecedented sensitivities. The majority of the efforts of developing a practical implementation of this optics has been devoted toward slumping square-pore micro-channel plates. While the advantages of the slumped micro-channel plates are obvious in that they can achieve potentially arc-second angular resolutions, the smoothness requirements for reflecting x- rays are hard to meet by micro-channel plates. It is not clear how the interior of the micro-channel plate pores can be polished to the desired smoothness. In this paper we propose the feasibility of a more straightforward approach of implementing the lobster eye optics with flat glass mirrors assembled in a standard Kirkpatrick-Baez configuration. We demonstrate with both simulations and laboratory test results that this implementation is both practical and meets al the requirements of an x-ray all sky monitor.
We present a conceptual design for a new x-ray all sky monitor (ASM). Compared with previous ASMs, its salient features are: (1) it has a focusing capability that increases the signal to background ratio by a factor of 3; (2) it has a broad-band width: 200 eV to 15 keV; (3) it has a large x-ray collection area: approximately 102 cm2; (4) it has a duty cycle of nearly 100%, and (5) it can measure the position of a new source with an accuracy of a few minutes of arc. These features combined open up an opportunity for discovering new phenomena as well as monitoring existing phenomena with unprecedented coverage and sensitivity.
We present new results in the development of high throughput hard x-ray telescopes with multilayer supermirror coatings. Basic techniques to make the supermirror are at first developed in deposition of constant d spacing multilayers. The reflector of multilayer on the float glass achieves high reflectivity, limited by the surface roughness of substrate, while, we need more improvement in getting comparable reflectivity of multilayers on the replica foil. We put the mask just in front of sample, it reduced the nonuniformity of the thickness less than 2%. In order to maximize the effective area and field of view, we have optimized the supermirror parameters; d spacing, number of layer pairs, and thickness ratio of heavy and light element. Multiblock method is introduced to design the supermirror, and it gives high reflectivity of approximately 30% in the 25 - 40 keV band. A test supermirror sputtered on a glass sample exhibits reasonable reflectivities of about 20 - 30%. We designed a telescope system with 45 cm diameter, 20 cm mirror length in two stage, and focal length of 8 m. The effective area of four such telescopes is 320 cm2 for the x rays between 25 and 40 keV. We plan the application of this type of telescope to the balloon experiment named InFOC(mu) S to reveal hard x-ray images of clusters of galaxies or supernova remnants.
We are studying a Next Generation X-ray Observatory, NGXO, that will provide a high resolution spectral capability with large collecting area, at a relatively low cost. The mission consists of two co-aligned telescope systems that provide coverage from 0.3 - 60 keV. One is optimized to cover the 0.3 - 12 keV band with 2 eV spectral resolution using an array of quantum calorimeters with a peak effective area of 2,000 cm2. The spectral resolution will be five times better than the calorimeter planned for Astro-E, with more than a ten-fold increase in effective area over previous high resolution x-ray spectroscopy missions. The second telescope will be the first focusing optics to operate in the 10 - 60 keV energy range, and will have arc minute angular resolution with 500 cm2 collecting area at 30 keV. The sensitivities of the two telescopes are matched to make possible many thousands of high quality x-ray spectral observations, from an available population of more than one million galactic and extragalactic x-ray sources. The NGXO mission is capable of addressing new astrophysical problems which include: determining the mass of a black hole, neutron star, or white dwarf in binary systems from x-ray line radial velocity measurements; determining the 0.3 - 60 keV x-ray spectrum from AGN and determining their contribution to the x-ray background in this energy band; measuring Compton reflection spectra from cold material in accretion driven systems; determining the Hubble constant using resonant line absorption of QSO spectra by rich clusters; searching for a hot 10 million degree intergalactic medium; mapping the dynamics of the intracluster medium; mapping the ionization state, abundance and emission from supernova remnants on a 15 arc second angular scale; and measuring mass motion in stellar flares and the dynamics of accretion flows.
The Broad-Band X-Ray Telescope (BBXRT) was designed to carry out moderate resolution spectrophotometry of cosmic X-ray sources in the 0.3-12 keV band from the Space Shuttle. It consists of a pair of coaligned conical foil telescopes, with cryogenically cooled Si(Li) spectrometers as focal instruments. It was flown as part of the Astro-1 mission in December, 1990. The in-flight performance of the instrument was essentially as predicted on the basis of ground calibration and modelling. We discuss the performance of the system, with emphasis on the conical mirror systems, and present some preliminary scientific results which illustrate the power of broad band, high sensitivity X-ray spectrophotometry.
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