The Normal-incidence Extreme Ultraviolet Photometer (NExtUP) is a smallsat mission concept designed to measure the EUV radiation conditions of exoplanet host stars, and F-M type stars in general. EUV radiation is absorbed at high altitude in a planetary atmosphere, in the exosphere and upper thermosphere, where the gas can be readily heated to escape temperatures. EUV heating and ionization are the dominant atmospheric loss drivers during most of a planet’s life. There are only a handful of accurately measured EUV stellar fluxes, all dating from Extreme Ultraviolet Explorer (EUVE) observations in the ‘90s. Consequently, current models of stellar EUV emission are uncertain by more than an order of magnitude and dominate uncertainties in planetary atmospheric loss models. NExtUP will use periodic and aperiodic multilayers on off-axis parabolic mirrors and a prime focus microchannel plate detector to image stars in 5 bandpasses between 150 and 900°A down to flux limits two orders of magnitude lower than reached by EUVE. NExtUP may also accomplish a compelling array of secondary science goals, including using line-of-sight absorption measurements to understand the structure of the local interstellar medium, and imaging EUV emission from energetic processes on solar system objects at unprecedented spatial resolution. NExtUP is well within smallsat weight limits, requires no special orbital conditions, and would be flown on a spacecraft supplied by MOOG Industries. It draws on decades of mission heritage expertise at SAO and LASP, including similar instruments successfully launched and operated to observe the Sun.
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.
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.
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.
An x-ray spectrograph consisting of aligned, radially ruled off-plane reflection gratings and silicon pore optics (SPO) was tested at the Max Planck Institute for Extraterrestrial Physics PANTER x-ray test facility. SPO is a test module for the proposed Arcus mission, which will also feature aligned off-plane reflection gratings. This test is the first time two off-plane gratings were actively aligned to each other and with an SPO to produce an overlapped spectrum. We report the performance of the complete spectrograph utilizing the aligned gratings module and plans for future development.
Addressing the astrophysical problems of the 2020’s requires sub-arcsecond x-ray imaging with square meter
effective area. Such requirements can be derived, for example, by considering deep x-ray surveys to find the
young black holes in the early universe (large redshifts) which will grow into the first super-massive black holes.
We have envisioned a mission, the Square Meter Arcsecond Resolution Telescope for X-rays (SMART-X), based
on adjustable x-ray optics technology, incorporating mirrors with the required small ratio of mass to collecting
area. We are pursuing technology which achieves sub-arcsecond resolution by on-orbit adjustment via thin film
piezoelectric “cells” deposited directly on the non-reflecting sides of thin, slumped glass. While SMART-X will
also incorporate state-of-the-art x-ray cameras, the remaining spacecraft systems have no requirements more
stringent than those which are well understood and proven on the current Chandra X-ray Observatory.
Kelly Korreck, Justin Kasper, Anthony Case, Peter Daigneau, Jay Bookbinder, Davin Larson, Jasper Halekas, Michael Stevens, Micheal Ludlam, Will Marchant
KEYWORDS: Space operations, Data archive systems, Solar processes, Electrons, Sun, Data centers, System on a chip, Sensors, Data processing, Calibration
Solar Probe Plus, scheduled to launch in 2018, is a NASA mission that will fly through the Sun's atmosphere for the first time. It will employ a combination of in situ plasma measurements and remote sensing imaging to achieve the mission's primary goal: to understand how the Sun's corona is heated and how the solar wind is accelerated. The Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite consists of a Faraday cup and three electrostatic analyzers. In order to accomplish the science objectives, an encounter-based operations scheme is needed. This paper will outline the SWEAP science operations center design and schemes for data selection and down link.
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).
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?
This paper describes the implementation of a solar simulator, know as the Solar Environment Simulator (SES), that can
simulate solar flux levels up to those encountered at 9.8 solar radii. The paper outlines the design, and the challenges of
realizing the SES. It also describes its initial uses for proving out the design of the Solar Winds Electrons, Alphas, and
Protons (SWEAP) Faraday cup.
The upcoming Solar Probe Plus (SPP) mission requires that its in-situ plasma instrument (the Faraday Cup) survive and
operate over an unprecedented range of temperatures. One of the key risk mitigation activities during Phase B has been
to develop and implement a simulator that will enable thermal testing of the Faraday Cup under flight-like conditions.
While still in the initial start-up, the SES has proven to be an instrumental component in the process of predicting the inflight
performance of the SWEAP Faraday Cup. With near continuously variable power control above the threshold of
1.6kW/lamp up to approximately 6.5kW/lamp, the SES has been used to determine the system response to a wide range
of incoming flux, thereby making it possible to correlate detailed thermal models to a high degree of certainty (see Ref.
[1], Figure 1.1).
The SES consists of a set of repurposed, and slightly re-designed standard movie projectors. The projectors have proven
to be an economical and effective means to safely hold and control the xenon short-arc lamps that are the basis of the
SES. This paper outlines the key challenges controlling the extremely high flux levels (~70w/cm^2) necessary to make
the SES a useful test facility.
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.
The upcoming Solar Probe Plus (SPP) mission requires novel approaches for in-situ plasma instrument design. SPP’s
Solar Probe Cup (SPC) instrument will, as part of the Solar Wind Electrons, Alphas, and Protons (SWEAP) instrument
suite, operate over an enormous range of temperatures, yet must still accurately measure currents below 1 pico-amp, and
with modest power requirements.
This paper discusses some of the key technology development aspects of the SPC, a Faraday Cup and one of the few
instruments on SPP that is directly exposed to the solar disk, where at closest approach to the Sun (less than 10 solar
radii (Rs) from the center of the Sun) the intensity is greater than 475 earth-suns. These challenges range from materials
characterization at temperatures in excess of 1400°C to thermal modeling of the behavior of the materials and their
interactions at these temperatures. We discuss the trades that have resulted in the material selection for the current
design of the Faraday Cup. Specific challenges include the material selection and mechanical design of insulators,
particularly for the high-voltage (up to 8 kV) grid and coaxial supply line, and thermo-optical techniques to minimize
temperatures in the SPC, with the specific intent of demonstrating Technology Readiness Level 6 by the end of 2013.
We describe an X-ray Observatory mission with 0.5” angular resolution, comparable to the Chandra X-ray Observatory, but with 30 times more effective collecting area. The concept is based on developing the new technology of adjustable X-ray optics for ultra thin (0.4 mm), highly nested grazing incidence X-ray mirrors. Simulations to date indicate that the corrections for manufacturing and mounting can be determined on the ground and the effects of gravity release can be calculated to sufficient accuracy, so that all adjustments are applied only once on-orbit, without the need of any on-orbit determination of the required corrections. The mission concept is based on the Chandra Observatory, and takes advantage of the technology studies which have taken place over the past fifteen years developing large area, light weight mirrors.
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.
SMART-X is a mission concept for a 2.3 m2 effective area,
0.5" angular resolution X-ray telescope, with 5' FOV, 1" pixel
size microcalorimeter, 22' FOV imager, and high-throughput
gratings.
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 International X-ray Observatory (IXO) project is the result of a merger between the NASA Con-X and ESA/JAXA
XEUS mission concepts. A facility-class mission, IXO will address the leading astrophysical questions in the "hot
universe" through its breakthrough optics with 20 times more collecting area at 1 keV than any previous X-ray
observatory, its 3 m2 collecting area with 5 arcsec angular resolution will be achieved using a 20m focal length
deployable optical bench. To reduce risk, two independent optics technologies are currently under development in the
U.S. and in Europe. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution
spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond
spectroscopic timing, and high count rate capability. IXO covers the 0.1-40 keV energy range, complementing the
capabilities of the next generation observatories, such as ALMA, LSST, JWST, and 30-m ground-based telescopes.
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?
This paper presents an overview of the IXO mission science drivers, its optics and instrumental capabilities, the status of
its technology development programs, and the mission implementation approach.
High spectral resolution, high cadence, imaging x-ray spectroscopy has the potential to revolutionize the study of
the solar corona. To that end we have been developing transition-edge-sensor (TES) based x-ray microcalorimeter
arrays for future solar physics missions where imaging and high energy resolution spectroscopy will enable
previously impossible studies of the dynamics and energetics of the solar corona. The characteristics of these xray
microcalorimeters are significantly different from conventional microcalorimeters developed for astrophysics
because they need to accommodate much higher count rates (300-1000 cps) while maintaining high energy
resolution of less than 4 eV FWHM in the X-ray energy band of 0.2-10 keV. The other main difference is a
smaller pixel size (less than 75 x 75 square microns) than is typical for x-ray microcalorimeters in order to
provide angular resolution less than 1 arcsecond. We have achieved at energy resolution of 2.15 eV at 6 keV in a
pixel with a 12 x 12 square micron TES sensor and 34 x 34 x 9.1 micron gold absorber, and a resolution of 2.30
eV at 6 keV in a pixel with a 35 x 35 micron TES and a 57 x 57 x 9.1 micron gold absorber. This performance
has been achieved in pixels that are fabricated directly onto solid substrates, ie. they are not supported by silicon
nitride membranes. We present the results from these detectors, the expected performance at high count-rates,
and prospects for the use of this technology for future Solar missions.
The background that will be observed by IXO's X-ray detectors naturally separates into two components: (1) a Cosmic X-ray Background (CXB), primarily due to unresolved point sources at high energies (E>2 keV), along with Galactic component(s) at lower energies that are generated in the disk and halo as well as the Local Bubble and charge exchange in the heliosphere, and (2) a Non-X-ray Background (NXB) created by unvetoed particle interactions in the detector itself. These may originate as relativistic particles from the Sun or Galactic Cosmic Rays (GCR), creating background events due to both primary and secondary interactions in the spacecraft itself. Stray light and optical transmission from bright sources may also impact the background, depending upon the design of the baffles and filters.
These two components have distinct effects on observations. The CXB is a sum of power-law, thermal, and charge exchange components that will be focused and vignetted by the IXO mirrors. The NXB, in contrast, is due to particle, not photon, interactions (although there will be some fluorescence features induced by particle interactions), and so will not show the same effects of vignetting or trace the effective area response of the satellite. We present the overall background rates expected from each of these processes and show how they will impact observations. We also list the expected rates for each CXB process using both mirror technologies under consideration and the predicted NXB for each detector.
The New Hard X-ray Mission (NHXM) has been designed to provide a real breakthrough on a number of hot
astrophysical issues that includes: black holes census, the physics of accretion, the particle acceleration mechanisms, the
effects of radiative transfer in highly magnetized plasmas and strong gravitational fields. NHXM combines fine imaging
capability up to 80 keV, today available only at E<10 keV, with sensitive photoelectric imaging polarimetry. It consists
of four identical mirrors, with a 10 m focal length, achieved after launch by means of a deployable structure. Three of the
four telescopes will have at their focus identical spectral-imaging cameras, while a X-ray imaging polarimeter will be
placed at the focus of the fourth. In order to ensure a low and stable background, NHXM will be placed in a low Earth
equatorial orbit. Here we will provide an overall description of this mission and of the developments that are currently
occurring in Italy. In the meanwhile we are forming an international collaboration, with the goal to have a consortium
of leading Institutes and people that are at the forefront of the scientific and technological developments that are
relevant for this mission.
The International X-ray Observatory (IXO) has a top level requirement that the observing efficiency be 85%. This is a
challenging requirement, given that the observing efficiencies for CXO and XMM-Newton are between 60% and 70%.
However, the L2 orbit for IXO means that it will not be subject to the earth block/radiation zone effects that are seen for
CXO and XMM-Newton. Outside of these effects the efficiencies for CXO and XMM-Newton do approach 85%, so
this requirement appears achievable for IXO. In this paper we itemize the effects which impact the observing efficiency,
in order to guide the design of the observatory. Meeting the 85% requirement should be possible but will require careful
attention to detail.
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 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.
One of the key instruments on the Reconnection and Microscale (RAM) Solar-Terrestrial Probe mission is a normal incidence multilayer x-ray telescope designed to provide 10 milli-arc-sec imaging of the solar corona. To achieve this level of imaging it will be necessary to fabricate meter-class reflective optics with diffraction limited performance at 193 Angstroms. Because of the use of multilayer optics, surface micro-roughness must also be maintained at very low levels (a few Angstroms rms) to maintain good reflectance. To ease fabrication constraints and the sometimes competing requirements of micro-roughness and figure, we have explored a number of potential designs and fabrication approaches for RAM. Figure error budgets and optical designs are shown, demonstrating that RAM can be built with existing mirror fabrication technology.
Hot magnetized plasmas - typified by the solar corona - are ubiquitous throughout the universe. The physics governing the dynamics of such plasmas takes place on remarkably small spatial and temporal scales, while both the cause activity and the response occur on large spatial scales. Thus both high resolution and large fields of view are needed. Observations from SMM, Yohkoh, EIT and TRACE show that typical solar active region structures range in temperature from 0.5 to 10 MK, and up to 40MK in flares, implying the need for broad temperature coverage. The RAM S-T Probe consists of a set of imaging and spectroscopic instruments that will enable definitive studies of fundamental physical processes that govern not only the solar atmosphere but much of the plasma universe. Few problems in astrophysics have proved as resistant to solution as the microphysics that results in the production of high-energy particles in hot magnetized plasmas. Theoretical models have focused in recent years on the various ways in which energy may be transported to the corona, and there dissipated, through the reconnection of magnetic fields. Theory implies that the actual dissipation of energy in the corona occurs in spatially highly localized regions, and there is observational support for unresolved structures with filling factors 0.01 - 0.001 in dynamic coronal events.
The Solar-B X-ray telescope (XRT) is a grazing-incidence modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. XRT, designed for full sun imaging over the wavelength 6-60 Angstroms, will be the highest resolution solar X-Ray telescope ever flown. Images will be recorded by a 2048 X 2048 back-illuminated CCD with 13.5 μm pixels (1 arc-sec/pixel ) with full sun field of view. XRT will have a wide temperature sensitivity in order to observe and discriminate both the high (5-10 MK) and low temperature (1-5 MK) phenomena in the coronal plasma.
This paper presents preliminary results of the XRT mirror calibration performed at the X-ray Calibration Facility, NASA-MSFC, Huntsville, Alabama during January and February 2005. We discuss the methods and the most significant results of the XRT mirror performance, namely: characteristics of the point response function (PSF), the encircled energy and the effective area. The mirror FWHM is 0.8" when corrected for 1-g, finite source distance, and CCD pixelization. With the above corrections the encircled energy at 27 μm and 1keV is 52%. The effective area is greater than 2cm2 at 0.5keV and greater than 1.7cm2 at 1.0keV.
We present scientific as well as engineering overview of the X-Ray Telescope (XRT) aboard the Japanese Solar-B mission to be launched in 2006, with emphasis on the focal plane CCD camera that employs a 2k x 2k back-thinned CCD. Characterization activities for the flight CCD camera made at the National Astronomical Observatory of Japan (NAOJ) are discussed in detail with some of the results presented.
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.
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite
SOLAR-B (launch in 2006) aimed at providing full Sun field of view at
~ 1.5" angular resolution, will be equipped with two wheels of focal-plane filters to select spectral features of X-ray emission from the Solar corona, and a front-end filter to significantly reduce the visible light contamination. We present the results of the X-ray calibrations of the XRT flight filters performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumental set-up, the adopted measurement technique, and present the transmission vs. energy and position measurements.
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite SOLAR-B (launch in 2006) is equipped with a modified Wolter I grazing incidence X-ray telescope (focal length 2700 mm) to image the full Sun at ~ 1.5" angular resolution onto a 2048 x 2048 back illuminated CCD focal plane detector. The X-ray telescope consisting of one single reflecting shell is coated with ion beam sputtered Iridium over a binding layer of Chromium to provide nearly 5 square centimetres effective area at 60 Å. We present preliminary results of X-ray calibrations of the XRT flat mirror samples performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We describe the instrumental set-up, the adopted measurement technique, and present the measured reflectivity vs. angle of incidence at few energies.
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.
The Reflection Grating Spectrometer of the Constellation-X mission has
two strong candidate configurations. The first configuration, the
in-plane grating (IPG), is a set of reflection gratings similar to
those flown on XMM-Newton and has grooves perpendicular to the
direction of incident light. In the second configuration, the
off-plane grating (OPG), the grooves are closer to being parallel to
the incident light, and diffract along a cone. It has advantages of
higher packing density, and higher reflectivity. Confinement of these
gratings to sub-apertures of the optic allow high spectral
resolution. We have developed a raytrace model and analysis technique
for the off-plane grating configuration. Initial estimates indicate
that first order resolving powers in excess of 1000 (defined with
half-energy width) are achievable for sufficiently long wavelengths
(λ ≥ 12Å), provided separate accommodation is made
for gratings in the subaperture region farther from the zeroth order
location.
Cosmic soft X-ray spectroscopy exploits principal transitions of astrophysically abundant elements to infer physical properties of objects in the sky. Most of these transitions, however, fall well below 2 keV, or 6 Angstroms. Consquently, grating spectrometers offer the current, best means by which to analyze soft X-rays from such sources, where throughput and resolving power must be maximized together. We describe grating spectrometer design candidates for the future mission Constellation-X, and how the grating array on board (~1000 gratings in a 1600mm diameter, each for 4 instruments) may be implemented. Grating fabrication and grating alignment approaches require special consideration (over the XMM-Newton RGS experience), because of grating replication fidelity and instrument mass constraints.
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.
A hot, magnetized plasma such as the solar corona has the property that much of the physics governing its activity takes place on remarkably small spatial and temporal scales, while the response to this activity occurs on large scales. Observations from SMM, TRACE, SOHO and Yohkoh have shown that typical solar active regions have loops ranging in temperature from 0.5 to 10 MK, and flares up to 40MK. The spatial and temporal domains involved have been heretofore inaccessible to direct observations from Earth, so that theory has relied heavily on extrapolations from more accessible regimes, and on speculation. The RAM Solar-Terrestrial Probe consists of a set of carefully selected imaging and spectroscopic instruments that enable definitive studies of the dynamics and energetics of the solar corona.
The Constellation-X mission has seen significant evolution in its concept over the previous two years. These evolutions yield a mission concept that achieves all of the originally proposed science goals, while meeting launch vehicle constraints. The most obvious change to the mission concept has been to reduce the number of satellites in the mission from six to four, while increasing the size of the optics to maintain the effective area. In a parallel evolution, the telescope focal lengths have increased from 8.4 to 10m to maintain approximately the same energy response from the optics. This paper will summarize the current designs and some of the issues associated with the optics for its two telescope systems.
The X-ray observations from the Yohkoh SXT provided the greatest step forward in our understanding of the solar corona in nearly two decades. We believe that the scientific objectives of the Solar-B mission can best be achieved with an X-ray telescope (XRT) similar to the SXT, but with significant improvements in spatial resolution and in temperature response that take into account the knowledge gained from Yohkoh. We present the scientific justification for this view, discuss the instrumental requirements that flow from the scientific objectives, and describe the instrumentation that will meet these requirements. XRT is a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. The 2048 X 2048 back-illuminated CCD has 13.5 (mu) pixels, corresponding to 1.0 arcsec and giving full Sun field of view. This will be the highest resolution GI X-ray telescope ever flown for Solar coronal studies, and it has been designed specifically to observe both the high and low temperature coronal plasma.
The Constellation-X mission is a large collecting area x-ray facility, emphasizing observations at high spectral resolution while covering a broad energy band. By increasing the telescope aperture and utilizing efficient spectrometers the mission will achieve a factor of 100 increased sensitivity over current high resolution x-ray spectroscopy missions. The use of focusing optics across the 10-40 keV band will provide a similar factor of 100 increased sensitivity in this band. Key technologies under development for the mission include lightweight high throughput x-ray optics, multilayer coatings to enhance the hard x-ray performance of x-ray optics, micro-calorimeter spectrometer arrays with 2 eV resolution, low power and low weight CCD arrays, lightweight gratings and hard x-ray detectors. When observations commence towards the end of the next decade, Constellation-X will address many pressing questions concerning the extremes of gravity and the evolution of the Universe.
Orbiting x-ray and XUV observatories are pushing the achievable image resolution and with it, the requirements on mounted mirror performance. The transitional region and coronal explorer (TRACE) observatory uses a center mounted primary mirror that must maintain its orientation in roll as well as pitch and way. A conformable bedding was used to support the mirror against the expected launch loads in a re-assembled mount, without inducing unacceptable mirror distortion. The novel mirror mount design is discussed, and its resulting performance described. This paper outlines the TRACE primary mirror assembly design. The evolution of the design from the Space Weather and Terrestrial Hazards assembly to the TRACE baseline design is presented.
The process of observing the Sun in the x-ray and extreme UV (XUV), as we are now doing with the TRACE telescope, requires blocking the tremendous amount of visible and RI light that dominates the flux from the sun. If it is not blocked, the energy will swamp the desired spectrum and cause thermal problems inside the telescope. The most effective approach removing the energy is by filtering the incoming light. One of the best materials for eliminating the undesirable wavelengths is aluminum, which is semi- transparent to x-ray and XUV, but blocks most light with wavelength redward of 850 angstrom. Unfortunately the aluminum must be extremely must be extremely thin, < 1600 angstrom thick, to provide the necessary XUV transparency. To overcome the structural problem of supporting large areas of extremely thin aluminum, the aluminum film is bonded on a nickel mesh.
This paper describes the conceptual design of a soft x-ray telescope, super-x, which we will propose for the Japan/US/UK Solar-B mission. Super-X will break new ground in both angular resolution and solar coronal temperature discrimination. The telescope design is based upon the successful transition region and coronal explorer instrument. It features four XUV spectral channels spanning the 0.3 to 20 MK temperature range with an angular resolution of approximately 0.27 seconds of arc. We will describe considerations affecting spectral line selection and some details of the characteristics of the instrument.
HIREX is a suite of three complementary solar-pointed instruments that is being proposed to NASA under the NASA MIDEX announcement of opportunity. The main instrument is a 0.6m clear aperture, 240m effective focal length normal incidence XUV telescope operated at 171 angstrom, with a spatial resolution of 0.01 inch. This main telescope is complemented by two other instruments: 1) a 0.3 m context telescope that images in a wavelength range that covers the UV and XUV spectral regime, based on the TRACE design. This context telescope places the high magnification, limited field of view images created by the high resolution telescope in both spatial and temperature context. 2) A spectrometer covering the spectral range from 170-220 angstrom, based on the SERTS design.
The High Throughput X-ray Spectroscopy (HTXS) mission is dedicated to observations at high spectral resolution. The HXTS mission represented a major advanced, providing as much as a factor of 100 increase in sensitivity over currently planned high resolution X-ray spectroscopy missions. This X- ray equivalent of the Keck Telescope will mark the start of a new era when high quality X-ray spectral will be obtained for all classes of X-ray sources, over a wide range of luminosity and distance. With its increased capabilities, HTXS will address many fundamental astrophysics questions such as the origin and distribution of the elements from carbon to zinc, the formation and evolution of clusters of galaxies, the validity of general relativity in the strong gravity limit, the evolution of supermassive black holes in active galactic nuclei, the details of supernova explosions and their aftermath, and the mechanisms involved in the heating of stellar coronae and driving of stellar winds.
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