ESA Science & Technology - Publication Archive

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.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

One of the instruments on the International X-ray Observatory (IXO), under study with NASA, ESA and JAXA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor thermometers. The pixels have metallic X-ray absorbers and are read-out by multiplexed SQUID electronics. The requirements for this instrument are demanding. In the central array (40 x 40 pixels) an energy resolution of < 2.5 eV is required, whereas the energy resolution of the outer array is more relaxed (~ 10 eV) but the detection elements have to be a factor 16 larger in order to keep the number of read-out channels acceptable for a cryogenic instrument. Due to the large collection area of the IXO optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. In this paper we will summarize the instrument status and performance. We will describe the results of design studies for the focal plane assembly and the cooling systems. Also the system and its required spacecraft resources will be given.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

Different optical designs are under consideration for the International X-ray Observatory (IXO). In this paper we show results of simulations of the segmented shell Wolter-I design, of the Silicon Pore Optics (SPO) conical Wolter-I approximation and of the Silicon based Kirkpatrick-Baez design. We focus particularly on the issue of stray light. When a source is off axis, such that it is not imaged on the detector, some of its light may still be directed by the optics onto the detector plane. Sources close to the pointing direction can thereby introduce an extra background radiation level in the detectors. This phenomenon is investigated by numerical ray tracing of the three designs, yielding detector images of the stray light, and an indication of which part of the mirror that light originates. Results show the similarities and differences of the designs with respect to stray light, and give a quantitative indication of the level of background radiation in different cases. Furthermore, for the Silicon Pore Optics design, two different ways of partially blocking the stray light have been modelled, indicating that a reduction of the stray light can be achieved. In general, the results that have been found indicate that for the simulated set-ups the stray light levels are compliant with the design specifications of the International X-ray Observatory.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

We present a study of the background for the array of microcalorimeters onboard of the International X-ray Observatory space mission. We investigated through simulations the rates at the focal plane of soft and hard particles in L2 orbit. Assuming the presence of an anticoincidence instrument, we derived an estimate of the residual background. The preliminary results reported in this paper are based on a number of simplifications of the actual picture. Efforts to improve the model are on-going.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

The High Time Resolution Spectrometer (HTRS) is one of the five focal plane instruments of the International X-ray Observatory (IXO). The HTRS is the only instrument matching the top level mission requirement of handling a one Crab X-ray source with an efficiency greater than 10%. It will provide IXO with the capability of observing the brightest X-ray sources of the sky, with sub-millisecond time resolution, low deadtime, low pile-up (less than 2% at 1 Crab), and CCD type energy resolution (goal of 150 eV FWHM at 6 keV). The HTRS is a non-imaging instrument, based on a monolithic array of Silicon Drift Detectors (SDDs) with 31 cells in a circular envelope and a X-ray sensitive volume of 4.5 cm² x 450 microns. As part of the assessment study carried out by ESA on IXO, the HTRS is currently undergoing a phase A study, led by CNES and CESR. In this paper, we present the current mechanical, thermal and electrical design of the HTRS, and describe the expected performance assessed through Monte Carlo simulations.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

The technique which combines high resolution spectroscopy with imaging capability is a powerful tool to extract fundamental information in X-ray Astrophysics and Cosmology. TES (Transition Edge Sensors)-based microcalorimeters match at best the requirements for doing fine spectroscopy and imaging of both bright (high count rate) and faint (poor signal-to-noise ratio) sources. For this reason they are considered among the most promising detectors for the next high energy space missions and are being developed for use on the focal plane of the IXO (International X-ray Observatory) mission. In order to achieve the required signal-to-noise ratio for faint or diffuse sources it is necessary to reduce the particle-induced background by almost two orders of magnitude. This reduction can only be achieved by adopting an active anticoincidence technique. In this paper, we will present a novel anticoincidence detector based on a TES sensor developed for the IXO mission. The pulse duration and the large area of the IXO TESarray (XMS X-ray Microcalorimeter Spectrometer) require a proper design of the anticoincidence detector. It has to cover the full XMS area, yet delivering a fast response. We have therefore chosen to develop it in a four-pixel design. Experimental results from the large-area pixel prototypes will be discussed, also including design considerations.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

The requirements for the IXO (International X-ray Observatory) telescope are very challenging in respect of angular resolution and effective area. Within a clear aperture with 1.7 m > R > 0.25 m that is dictated by the spacecraft envelope, the optics technology must be developed to satisfy simultaneously requirements for effective area of 2.5 m² at 1.25 keV, 0.65 m² at 6 keV and 150 cm² at 30 keV. The reflectivity of the bare mirror substrate materials does not allow these requirements to be met. As such the IXO baseline design contains a coating layout that varies as a function of mirror radius and in accordance with the variation in grazing incidence angle. The higher energy photon response is enhanced through the use of depth-graded multilayer coatings on the inner radii mirror modules. In this paper we report on the first reflectivity measurements of wedged ribbed silicon pore optics mirror plates coated with a depth graded W/Si multilayer. The measurements demonstrate that the deposition and performance of the multilayer coatings is compatible with the SPO production process.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

We describe the experimental apparatus in use to test an off-plane reflection grating for the soft x-ray (0.3-1.0 keV) bandpass. The grating is a prototype for the X-ray Grating Spectrometer on the International X-ray Observatory (IXO). It has holographically-ruled radial grooves to match the converging beam of a 6.5 m focal length telescope. Laboratory tests are ongoing, with ray tracing indicating that a resolution (DeltaE/E) >3,000 is achievable across the 0.3-1.0 keV bandpass- the requirement to achieve IXO science goals.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

The IXO/XMS instrument baseline is an array of TES sensors. Alternatively, we are now developing a micro-calorimeter array based on Silicon doped sensors. Our strength stands in a very low power consumption at 50 mK, allowing more than 4000 readout channels in the limited power budget of the IXO/XMS cryostat, for a Field of View as large as 6'x6' square while keeping the same spectral resolution. In parallel, we develop the cold (2-4K) frontend electronics based on High Electron Mobility Transistors (GaAlAs/GaAs) and SiGe ASIC electronics to readout, amplify and multiplex the signals. We present the status of our development and our current design study.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

The International X-ray Observatory (IXO) is a candidate mission in the ESA Space Science Programme Cosmic Visions 1525.

IXO is being studied as a joint mission with NASA and JAXA. The mission is building on novel optics technologies to achieve the required performance for this demanding astrophysics observatory. The European X-ray optics technology baseline is the Silicon Pore optics (SPO), which is being developed by an industrial consortium. In a phased approach the performance, environmental compatibility and industrial production aspects are being addressed. As a back-up technology ESA is also investigating slumped glass optics, which forms the baseline for the NASA approach.

The paper, which was presented at the SPIE Astronomical Telescopes and Instrumentation 2010, presents a summary of the ESA-led optics technology preparation activities and the associated roadmap.

The International X-ray Observatory (IXO) is an L class mission candidate within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch by 2020. IXO is an international cooperative project, pursued by ESA, JAXA and NASA. By allowing astrophysical observations between 100 eV and 40 keV, IXO would represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage. The IXO mission concept is based on a single aperture telescope with an external diameter of about 3.5 m, a focal length of 20 m and a number of focal plane instruments, positioned at the focal point via a movable platform. A grating spectrometer, enabling parallel measurements, is also included in the model payload. Two parallel competitive industrial assessment studies are being carried out by ESA on the overall IXO mission, while the instruments are being studied by dedicated instrument consortia. The main results achieved during this study are summarised in this paper which was presented at the SPIE Astronomical Telescopes and Instrumentation 2010 conference.

The International X-ray Observatory (IXO) is an L class mission candidate within the science Programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch by 2020. IXO is an international cooperative project, pursued by ESA, JAXA and NASA. By allowing astrophysical observations between 100 eV and 40 keV using a very large effective collecting area mirror and state-of-the art instruments, IXO would represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage.

This paper was presented at the SPIE conference on Astronomical Instrumentation 2010 conference.

Document id: cR-SPO-SummaryReport

An ESA TRP activity was carried out by cosine Research (NL), Micronit (NL), Kayser-Threde (DE), SRON (NL), DTU (DK) and MPE (DE) with the goal of improving the angular resolution of Silicon Pore X-ray Optics. Silicon Pore Optics is the European baseline mirror technology for the International X-ray Observatory (IXO), one of the three L-class mission candidates under the Cosmic Vision 2015-2025 program.

This ESA TRP funded activity, 'High Performance X-Ray Optics', started late 2007. The entire production chain of these light-weight and modular X-ray optics has been reviewed, improved, demonstrated and tested, from silicon plate manufacture, over ribbing, dicing, wedging, coating, stacking, assembly and integration up to petal level.

Overview of the key performance requirements for the IXO mission science objectives.

This is SRE-PA/2009.019 issue 6 revision1

The Payload Definition Document (PDD) has been compiled by ESA with major inputs from the various instrument teams, forming part of the IXO Instrument Working Group (IWG). This document is agreed by the IWG chairmen as well as the IWG Instrument contact persons and contributors and describes a reference payload that satisfies the measurement requirements given in the Mission Requirements Document [AD-1].

This reference payload is used to establish the overall system design and the corresponding cost envelope.

This document is the XEUS proposal submitted to ESA in response to the Cosmic Vision call for proposals. It includes descriptions of the scientific objectives, mission profile, instrument payload, spacecraft, operations, and data archiving of XEUS.

Presentation of the IXO mission concept at the IXO Coordination Group meeting on 20 November 2008.

Contents:

1. Introduction
2. IXO mission requirements
3. IXO mission analysis
4. IXO configuration
5. IXO instrument module
6. IXO service module
7. IXO mirror assembly
8. Options
9. Conclusion

The XEUS payload module accommodation study is the basis for the forthcoming XEUS mission system study. The main objectives of the accommodation study are

• to define the preliminary Detector SpaceCraft PayLoad Module (DSC PL design)
• to identify the resources drivers
• to define the interfaces
• to assess the feasibility with core and extended instruments configuration
• to identify the potential solutions for cryogenic chain
• to identify the technology development and the critical issues

The Xeus mission goals are not achievable by means of a monolithic X-ray telescope but requires two satellites in a formation flying configuration at L2:

• The Mirror SpaceCraft (MSC) hosting the Telescope Module, a circular X-ray composite optics with a diameter of 4.25 metres
• The Detector SpaceCraft (DSC) hosting the Payload Module with core instruments of Wide Field Imager (WFI) and Narrow Filed Imager (NFI)

In the L2 Halo orbit, the MSC and DSC in formation flying, will operate like a large X-ray observatory with a focal length of 35 metres.

XEUS (X-ray Evolving Universe Spectroscopy) is one of the missions under consideration by ESA for its Cosmic Vision programme of advanced space exploration concepts set for launch in the 2015-2025 timeframe. Following-on from ESA successes in space observatories like XMM-Newton, XEUS relies on a number of innovative technologies to explore the universe at X-Ray wavelengths (e.g., micropore optics, formation flying control and detector and cooling technologies). Although the launch of XEUS is still some years away, the technology developments needed to meet the exacting science requirements mean that an early start is required to ensure that these technologies can be fully tested and qualified beforehand. At the same time this will enable XEUS to take full advantage of additional performance that these technologies can offer and deliver exciting new science. The XEUS Instrument Accommodation study was specifically focussed on assessing the spacecraft resource and technology development implications of carrying a suite of instruments on XEUS is thus the first step towards the successful implementation of XEUS.

The science requirements for an X-ray Observatory to be deployed in the post-XMM-Newton and Chandra era have been widely debated. Future spectroscopic investigations will require an enormous increase in collecting area to enable the use of the next generation of advanced spectrometers that will provide the necessary plasma diagnostics capability. The key breakthrough needed is to combine a lightweight material which exhibits excellent X-ray reflecting properties, whilst achieving a self-supporting construction that avoids the distortions inherent in fixation of the optics elements. The progress towards such a breakthrough is reported in this Technical Note, describing a successful proof of concept demonstration of many disparate technology advances across a broad development front. More detailed aspects of some of the development activities are provided in the comprehensive suite of papers presented at the 2006 SPIE Annual Symposium. Links to those papers are provided at:

http://www.rssd.esa.int/index.php?project=XEUS&page=SPIE_Documents

This note provides a brief overview of critical issues and some recent updates since the publication of the above papers.