This paper summarizes the results of an ESA feasibility study of a Wide-Field Optical Infrared Imager (WFI) that would search for Type Ia supernovae at low redshift with the aim to measure the changing rate of expansion of the universe. WFI multi-spectral images of the deep universe could also benefit to many other research area in astrophysics. The WFI payload includes a 2 m class telescope, a 1 square degree field of view imaging camera and a low-resolution integral field spectrometer. A mission concept was identified that consists of a 2000 kg spacecraft launched by a Soyuz-Fregat into a L2 halo orbit. The WFI mission could benefit from the technology developed for the ESA Herschel and Gaia missions and for the NIRSpec ESA instrument. A fully European WFI mission would require improvement of existing European detector and on-board processor technology as well as some effort to support the utilization of the 26 GHz Ka band.
In October 2005, based on a massive response by the Science Community to ESA’s call for themes in space science, a large aperture X-ray Observatory (XRO) was identified as a candidate project for Europe within the frame of the 2015-2025 Cosmic Vision program. Such a mission would represent the natural follow-on to XMM Newton, providing a large aperture X-ray telescope combined with high spectral and time resolution instruments, capable of investigating matter under extreme conditions and the evolution of the early universe.
The paper summarises the results of the most recent ESA internal study activities, leading to an updated mission configuration, with a mirror and a detector spacecraft flying in formation around L2 and a consolidated scientific payload design. The paper also describes the ongoing technology development activities for the payload and for the spacecraft that will play a crucial role in case ESA would decide to develop such a mission.
PLATO stands for PLAnetary Transits and Oscillation of stars and is a Medium sized mission selected as M3 by the
European Space Agency as part of the Cosmic Vision program. The strategy behind is to scrutinize a large fraction of the
sky collecting lightcurves of a large number of stars and detecting transits of exo-planets whose apparent orbit allow for
the transit to be visible from the Earth. Furthermore, as the transit is basically able to provide the ratio of the size of the
transiting planet to the host star, the latter is being characterized by asteroseismology, allowing to provide accurate
masses, radii and hence density of a large sample of extra solar bodies. In order to be able to then follow up from the
ground via spectroscopy radial velocity measurements these candidates the search must be confined to rather bright stars.
To comply with the statistical rate of the occurrence of such transits around these kind of stars one needs a telescope with
a moderate aperture of the order of one meter but with a Field of View that is of the order of 50 degrees in diameter. This
is achieved by splitting the optical aperture into a few dozens identical telescopes with partially overlapping Field of
View to build up a mixed ensemble of differently covered area of the sky to comply with various classes of magnitude
stars. The single telescopes are refractive optical systems with an internally located pupil defined by a CaF2 lens, and
comprising an aspheric front lens and a strong field flattener optical element close to the detectors mosaic. In order to
continuously monitor for a few years with the aim to detect planetary transits similar to an hypothetical twin of the Earth,
with the same revolution period, the spacecraft is going to be operated while orbiting around the L2 Lagrangian point of
the Earth-Sun system so that the Earth disk is no longer a constraints potentially interfering with such a wide field
continuous uninterrupted survey.
Euclid-VIS is a large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled
for launch in 2019. Together with the near infrared imaging within the NISP instrument it forms the basis of the weak
lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5
deg2. By combining 4 exposures with a total of 2240 sec, VIS will reach to V=24.5 (10σ) for sources with extent ~0.3
arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread
function (PSF) over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion galaxies to
high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a
legacy imaging dataset with an unprecedented combination of spatial resolution, depth and area covering most of the
extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the Euclid
The Euclid mission objective is to map the geometry of the dark Universe by investigating the distance-redshift
relationship and the evolution of cosmic structures. The NISP (Near Infrared Spectro-Photometer) is one of the two
Euclid instruments operating in the near-IR spectral region (0.9-2μm). The instrument is composed of:
- a cold (140K) optomechanical subsystem constituted by a SiC structure, an optical assembly, a filter wheel
mechanism, a grism wheel mechanism, a calibration unit and a thermal control
- a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG 2.4μm. The detection subsystem is
mounted on the optomechanical subsystem structure
- a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an
instrument control unit.
This presentation will describe the architecture of the instrument, the expected performance and the technological key
challenges. This paper is presented on behalf of the Euclid Consortium.
Euclid is an ESA Cosmic-Vision wide-field-space mission which is designed to explain the origin of the acceleration of
Universe expansion. The mission will investigate at the same time two primary cosmological probes: Weak gravitational
Lensing (WL) and Galaxy Clustering (in particular Baryon Acoustic Oscillations, BAO). The extreme precision
requested on primary science objectives can only be achieved by observing a large number of galaxies distributed over
the whole sky in order to probe the distribution of dark matter and galaxies at all scales. The extreme accuracy needed
requires observation from space to limit all observational biases in the measurements. The definition of the Euclid
survey, aiming at detecting billions of galaxies over 15 000 square degrees of the extragalactic sky, is a key parameter of
the mission. It drives its scientific potential, its duration and the mass of the spacecraft. The construction of a Reference
Survey derives from the high level science requirements for a Wide and a Deep survey. The definition of a main
sequence of observations and the associated calibrations were indeed a major achievement of the Definition Phase.
Implementation of this sequence demonstrated the feasibility of covering the requested area in less than 6 years while
taking into account the overheads of space segment observing and maneuvering sequence. This reference mission will be
used for sizing the spacecraft consumables needed for primary science. It will also set the framework for optimizing the
time on the sky to fulfill the primary science and maximize the Euclid legacy.
Euclid is a space-borne survey mission developed and operated by ESA. It is designed to understand the origin of the
Universe's accelerating expansion. Euclid will use cosmological probes to investigate the nature of dark energy, dark
matter and gravity by tracking their observational signatures on the geometry of the Universe and on the history of
structure formation. The mission is optimised for the measurement of two independent cosmological probes: weak
gravitational lensing and galaxy clustering. The payload consists of a 1.2 m Korsch telescope designed to provide a large
field of view. The light is directed to two instruments provided by the Euclid Consortium: a visual imager (VIS) and a
near-infrared spectrometer-photometer (NISP). Both instruments cover a large common field of view of 0.54 deg2, to be
able to survey at least 15,000 deg2 for a nominal mission of 6 years. An overview of the mission will be presented: the
scientific objectives, payload, satellite, and science operations. We report on the status of the Euclid mission with a
foreseen launch in 2019.
Euclid is a high precision survey mission under development by the European Space Agency to investigate the properties
of Dark Energy and Dark Matter by means of a weak lensing and baryon acoustic oscillations experiments. The technical
capabilities of Euclid are such that it also addresses other cosmological and astronomical topics, providing an unprecedented
science legacy. The survey mission will carry out an imaging and spectroscopic survey of the entire extragalactic
sky (20,000 deg2). Euclid carries a meter class telescope which feeds two instruments: a visible imager (VIS), a near-infrared
photometer combined with a medium resolution spectrometer (NISP). The two instruments have identical sized
field of views (0.5 deg2) and will operate simultaneously in step-and-stare mode. The nominal mission period is 5 years.
We describe the mission, the satellite, and the payload concepts, which we have adopted at the start of the definition
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.
The IXO mission concept is based on a single aperture telescope with an external diameter of about 3.5 m and a focal
length of 20 m. The focal plane consists of a fixed and a moveable instrument platform (FIP and MIP respectively). The
model payload consists of a suite of five instruments which can each be located at the telescope's focus by the MIP,
1. a wide field imager (WFI) based on a silicon DEPFET array;
2. a Hard-X-ray Imager (HXI), which will be integrated together with the WFI;
3. an X-ray microcalorimeter spectrometer (XMS);
4. an X-ray Polarimeter camera (X-POL) based on a gas cell with integrated anode array;
5. a High-Time Resolution Spectrometer (HTRS) based on a silicon drift detector array.
In addition, the FIP will carry a grating spectrometer (XGS) mounted in a fixed position and which will allow
simultaneous observations with the on-axis instrument.
This paper provides a summary of the preliminary results achieved during the assessment activities presently ongoing at
ESA. Whereas we will provide a brief overview on the overall spacecraft design, we will focus on the payload
description, characteristics, the technology used and the accommodation on the instrument platform.
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.
Future X-ray astrophysics missions, such as the International X-ray Observatory, IXO, require the development of novel
optics in order to deliver the mission's large aperture, high angular resolution and low mass requirements. A series of
activities have been pursued by ESA, leading a consortium of European industries to develop Silicon Pore Optics for use
as an x-ray mirror technology.
A novel process takes as the base mirror material commercially available silicon wafers, which have been shown to
possess excellent x-ray reflecting qualities. These are ribbed, curved and stacked concentrically in layers that have the
desired shape at a given radii of the x-ray aperture. Pairs of stacks are aligned and mounted into doubly reflecting mirror
modules that can be aligned into the x-ray aperture without the very high angular and position alignment requirements
that need to be achieved for mirror plates within the mirror module. The use of this silicon pore optics design
substantially reduces mirror assembly time, equipment and costs in comparison to alternative IXO mirror designs.
This paper will report the current technology development status of the silicon pore optics and the roadmap expected for
developments to meet an IXO schedule. Test results from measurements performed at the PTB lab of the Bessy
synchrotron facility and from full illumination at the Panter x-ray facility will be presented.
X-rays at various energies can be focussed with reflective optics at grazing incidence with a well-known reflectivity
achieving a high effective area by means of various designs. On XMM the high collecting area was achieved by means
of thin mirror shells which were made by nickel replication combining the parabola and hyperbola sections according to
the WOLTER I design in a single element. 58 of these "elements" were combined to build a mirror assembly with an
effective area of 1450 cm2 @1.5 keV per mirror assembly. In order to achieve a higher effective area for IXO the density
needs to be reduced. This could be achieved by pore optics elements integrated into a set of 8 petals made of Cesic® as
an optical bench. This design is fitting into the fairing of Ariane with a diameter of 4.2 m and achieves an effective area
of 3.36 m2. It will withstand the high launch loads of up to 60 g and provide a negligible degradation to the optical
performance due to thermal loads and gravitational relaxation. The design, including the interfaces to the telescope and
to the pore optics, will be presented.
The International X-ray Observatory (IXO) is a candidate mission in the ESA Space Science Programme Cosmic Visions
2015-2025. IXO is being studied as a joint mission with NASA and JAXA. The mission concept and X-ray telescope
accommodation have both been studied in the ESA Concurrent Design Facility. Competitive industrial studies will now
further investigate the issues raised, and will elaborate mission concepts.
In parallel the required technologies are being developed, with the main emphasis under ESA responsibility being
focused on Silicon Pore Optics (SPO). A technology development plan has been made and its implementation is
The paper presents a summary of the ESA system studies of IXO and provides an overview of the related ESA led
technology preparation activities.
In order to better understand the properties of exoplanetary systems, the Cosmic Vision mission "PLAnetary Transits and
Oscilliations of stars" (PLATO) will detect and characterise exoplanets using their transit signature in front of a large
sample of bright stars as well as measuring the seismic oscillations of the parent star of these exoplanets. PLATO is a
potential mission of the European Space Agency's Science programme Cosmic Vision 2015-2025, with a planned launch
by the end of 2017. The mission will be orbiting the Sun-Earth second Lagrangian point, which provides a stable thermal
environment and maximum uninterrupted observing efficiency. The payload will consist of a number of individual
catadioptric telescopes, covering a large field-of-view on the sky. It will allow for continuous observation of predetermined
star fields in order to detect many exoplanetary systems as well as smaller exoplanets with longer orbital
periods. Such performance is achieved by high time-resolution, high precision, and high duty-cycle visible photometry
using catadioptric telescopes with CCD detectors. In order to fulfill the specific science requirements, special attention is
being paid to the opto-mechanical design of the payload, in order to maximize the field-of-view and throughput of the
optical system, while minimizing the image distortion, mass and volume of each telescope to ensure compatibility with
the launcher's maximum payload capability. Ground-based observations will complement the observations made by
PLATO to allow for further exoplanetary characterization. The paper provides a summary of the preliminary results
achieved by the ESA internal pre-assessment study.
The XEUS (X-ray Evolving Universe Spectroscopy) proposal has been recently selected by the science advisory
structure of the European Space Agency as an L-class candidate mission. On this basis, XEUS will undergo an
assessment study, in line with the Cosmic Vision 2015-2025 selection process. The mission would represent a follow-up
to XMM-Newton, providing a next generation X-ray observatory at disposal of the astrophysics community.
The paper provides an overview of the recent study activities performed by ESA, including a critical review of the main
requirements and a discussion on the associated impact at system level. The model payload presently considered for
XEUS is also presented, as well as the technology developments needs.
XEUS, the 'X-ray Early Universe Spectroscopy Mission', is a potential candidate for inclusion into the Cosmic Visions 1525 Science Programme of the European Space Agency ESA [1,2]. It is being studied jointly with the Japanese Aerospace Exploration Agency JAXA.
The newly developed Silicon-based High resolution Pore Optics (HPO) combines low mass density with good angular resolution, and enables the development of novel mission design concepts for the implementation of a new generation of space based X-ray telescope [3, 4, 5]. This optics technology allows also for the application of complex reflective coatings , improving the effective area of the telescope and permitting an enhancement in the engineering of the desired response function.
This paper gives an overview of the telescope optical design and optical bench architecture, including the deployment scheme. Further, the performance predictions based on ray tracing are discussed and the overall telescope design of XEUS is presented.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory and is being proposed in response to the Cosmic Vision 2015-2025 long term plan for ESA's Science Programme. Novel light-weight optics with an effective area of 5 m2 at 1 keV and 2 m2 at 7 keV and 2-5" HEW spatial resolution together with advanced detectors will provide much improved imaging, spectroscopic and timing performances and open new vistas in X-ray astronomy in the post 2015 timeframe. XEUS will allow the study of the birth, growth and spin of the super-massive black holes in early AGN, allow the cosmic feedback between galaxies and their environment to be investigated through the study of inflows and outflows and relativistic acceleration and allow the growth of large scale structures and metal synthesis to be probed using the hot X-ray emitting gas in clusters of galaxies and the warm/hot filamentary structures observable with X-ray absorption spectroscopy. High time resolution studies will allow the Equation of State of supra-nuclear material in neutron stars to be constrained. These science goals set very demanding requirements on the mission design which is based on two formation flying spacecraft launched to the second Earth-Sun Lagrangian point by an Ariane V ECA. One spacecraft will contain the novel high performance optics while the other, separated by the 35 m focal length, will contain narrow and wide field imaging spectrometers and other specialized instruments.
Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterise their atmospheres. Darwin is conceived as a space "nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the off-axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern
Observatory (ESO) intend to build a ground-based technology demonstrator called GENIE (Ground based European Nulling Interferometry Experiment). Such a ground-based demonstrator built
around the Very Large Telescope Interferometer (VLTI) in Paranal will
test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The instrument will operate in the L' band around 3.8 μm, where the thermal emission from the telescopes and the atmosphere is reduced. GENIE will be able to operate in two different configurations, i.e. either as a single Bracewell nulling interferometer or as a double-Bracewell nulling interferometer with an internal modulation scheme.
The prime objective of GENIE (Ground-based European Nulling Interferometry Experiment) is to obtain experience with the design, construction and operation of an IR nulling interferometer, as a preparation for the DARWIN / TPF mission. In this context, the detection of a planet orbiting another star would provide an excellent demonstration of nulling interferometry. Doing this through the atmosphere, however, is a formidable task. In this paper we assess the prospects of detecting with nulling interferometry on ESO's VLTI, low-mass companions in orbit around their parent stars. With the GENIE science simulator (GENIEsim) we can model realistic detection scenarios for the GENIE instrument operating in the VLTI environment, and derive detailed requirements on control-loop performance, IR background subtraction and the accuracy of the photometry calibration. We analyse the technical feasibility of several scenarios for the detection of low-mass companions in the L'-band.
Two competitive design studies for the Ground-based European Nulling Interferometer Experiment (GENIE) have been initiated by the European Space Agency and the European Southern Observatory in November 2003. The GENIE instrument will most probably consist of a two-telescope Bracewell interferometer, using the 8-m Unit Telescopes and/or the 1.8-m Auxiliary Telescopes of the VLTI, and working in the infrared L' band (3.5 - 4.1 microns). A critical issue affecting the overall performance of the instrument is its capability to compensate for the phase and intensity fluctuations produced by the atmospheric turbulence. In this paper, we present the basic principles of phase and intensity control by means of real-time servo loops in the context of GENIE. We then propose a preliminary design for these servo loops and estimate their performance using GENIEsim, the science simulation software for the GENIE instrument.
We present an experiment to measure the thermal background level and its fluctuations with the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). The Mid Infrared
Instrument (MIDI) operating between 8 and 12 micron was used in both dispersed and non-dispersed modes. By using an interferometric instrument, in non-interferometric mode, we probe the same optical path as can be expected for other infrared interferometric instruments, e.g. GENIE and MIDI itself. Most of the infrared thermal background detected with MIDI originates from the VLTI infrastructure. This can be attributed to the absence of a pupil re-imaging mirror. Only for a small region around the optical axis of the system the signal from the VLTI infrastructure can be considered small and the atmospheric background fluctuations can be characterized.
The fluctuations of the thermal emission are described in terms of their power spectral densities (PSD). We have identified two regions in the PSD. For the low frequency range (0-10 Hz) the
fluctuations are dominated by the Earth atmosphere. The slope of the log-log PSD is close to -1. For the high frequency (larger than 10 Hz) range the fluctuations are due to photon noise and the PSD flattens off. Many narrow peaks are present in the PSD. Peaks at 1 and 50 Hz occur in almost all data sets and are identified as the effects of the MIDI closed cycle cooler and the power lines respectively. Other peaks at 10 and 30 Hz, as well as peaks above 50 Hz, are assumed to be VLTI or MIDI-specific frequencies.
Future nulling space interferometers, such as Darwin and TPF, under study by the European Space Agency and NASA respectively, will rely on fast internal modulation techniques in order to extract the planet signal from the much larger background noise. In this modulation scheme, the outputs of a number of sub-arrays are combined with a variable, achromatic phase shift. In this paper, we discuss the use of well-known OPD modulation techniques in nulling interferometry. The main attractiveness of this approach is that a small OPD modulation at frequency f will modulate the stellar leakage at frequency 2f, since leakage does not depend from the sign of the OPD. In turn, a planet transiting a quasi-linear portion of the transmission map will induce a signal at frequency f at the nulled output, which can be extracted by coherent detection techniques. The properties of this modulation scheme are analyzed, using the Bracewell configuration as a test case. The significance of this technique for ESA's Darwin mission, and its ground-based technology precursor GENIE, are discussed.
We describe in-orbit measurements of the mirror vignetting in
the XMM-Newton Observatory, using observations of SNR G21.5-09 with the EPIC imaging cameras. The instrument features that complicate these measurements are briefly described. We show the spatial and energy dependences of measured vignetting, outlining assumptions made in deriving the eventual agreement between theory and measurement. Alternate methods to confirm these are described. We briefly describe an analysis of the stray-light rejection of the telescope.
The IR Space Interferometer Darwin is an integral part of ESA's Cosmic Vision 2020 plan, intended for a launch towards the middle of next decade. It has been the subject of a feasibility study and is now undergiogn technological development. The scientific scope is aimed towards developing a system that could carry out the search for, and characterization of Earth-like planets orbiting other stars. A secondary objective is to carry out imaging of astrophysical objects with unprecedented spatial resolution. The implementation of Darwin is based on the new technique of 'nulling interferometery', in the mid-IR and becomes the culmination of a decade of technology- and science precursor missions. Darwin is also foreseen to be carrie dout in an international context.
Darwin is one of the most challenging space projects ever
considered by the European Space Agency (ESA). Its principal
objectives are to detect Earth-like planets around nearby stars and to characterize their atmospheres. Darwin is conceived as a space
"nulling interferometer" which makes use of on-axis destructive
interferences to extinguish the stellar light while keeping the
off-axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern Observatory (ESO) intend to build a ground-based technology
demonstrator called GENIE (Ground based European Nulling
Interferometry Experiment). Such a ground-based demonstrator built
around the Very Large Telescope Interferometer (VLTI) in Paranal will
test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The present paper will describe the objectives and the status of the project.
The combined effective area of the three EPIC cameras of the XMM-Newton Observatory, offers the greatest collecting power ever deployed in an X-ray imaging system. The resulting potential for high sensitivity, broad-band spectroscopic investigations demands an accurate calibration. This work summarizes the initial in-orbit calibration activities that address these requirements. We highlight the first steps towards effective area determination, which includes the maintenance of gain CTI calibration to allow accurate energy determination. We discuss observations concerning the timing and count-rate capabilities of the detectors. Finally we note some performance implications of the optical blocking filters.
The High Throughput X-ray Spectroscopy Mission XMM-Newton of the European Space Agency (ESA) was launched on December 10, 1999 by an Ariane V rocket. The satellite observatory uses three grazing incidence telescopes coupled to reflection grating spectrometers and x-ray CCD cameras. Each x-ray telescope consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. The XMM-Newton Science Operation Center has completed a coherent program for the in- orbit calibration and performance verification of the x-ray observatory. This paper presents first measurement results of the x-ray telescopes image quality and effective area obtained during this campaign.
The in-orbit imaging performance of the three X-ray telescopes on board of the X-ray astronomy observatory XMM- Newton is presented and compared with the performance measured on ground at the MPE PANTER test facility. The comparison shows an excellent agreement the on ground and in-orbit performance.
In the frame of XMM testing, all the mirror modules have been illuminated by a vertical EUV collimated beam a the Centre Spatial de Liege. A mirror module consists in 58 co- focal and co-axial Wolter I mirrors. Up to now the images obtained at CSL have been used to assess the Mirror Module optical performances in a flight representative configuration, and also to verify the impact of the thermal environmental and vibration test on the optical performance. Due to the highly complex design of the Mirror Modules, simulating XMM images in details is very difficult. The Point Spread Function of some of the mirror modules presents slight asymmetry. In the facility design study, it has been demonstrated that the diffraction impact at 58.4 nm is negligible with respect to the half energy width mirror module specification. Presently all the mirror modules are better than 165 arcsec. This paper presents first the diffraction contribution on the image. In a second step a point spread function is built by using the metrological mirror shell data. EUV images are then analyzed to evaluate the impact of the mirror interface structure integration process on the PSF. An analytical model of the measured EUV pSF is developed. The modelization technique is applied to simulate in-orbit image. Finally the different modelizations are evaluated and compared.
The high throughput x-ray Spectroscopy Mission XMM is a 'Cornerstone' project of the ESA Horizon 2000 Science Program. The optical heart of this satellite consists in 3 Mirror Assemblies (MA). Each MA includes a Mirror Module (MM) containing 58 x-ray optical quality Mirror Shells (MS) and an x-ray (XRB) which reduces straylight. Two of the three MAs are equipped with a Reflection Grating Assembly (RGA) for spectral analysis. Tests are performed in the CSL FOCALX facility. The goal of the presented tests is to evaluate the x-ray effective area of a MM. These test are accomplished in a vertical configuration. An x-ray pencil beam is used for x-ray reflectivity measurements at Al, Au, Cu and Mo lines between 1.5 and 13 keV. A partial illumination collimated x-ray beam with a C continuous spectrum allows to measure the effective area of the MM over a 1.5-9 keV range. This paper gives a short description of the tested specimens, and presents the test configuration in CSL Focal X facility. The paper focuses on a compete and original way to work out experimentally effective areas of an x-ray telescope. Analysis of the achieved results is carried out.
The X-ray Multi-Mirror Mission is one of the four 'Cornerstone' projects in the ESA Long-Term Program for Space Science. Presently, five XMM Mirror Modules (MM) have been tested in the FOCALX facility of CSL. The MMs are illuminated by a vertical EUV collimated beam allowing to get the optical performance in an effective flight configuration. To fully analyze the MM characteristics, reflectivity measurements are performed in X-ray thanks to a pencil beam. The reflectivity measurements of single shell are performed at Al, Au, Cu, Mo lines between 1.5 and 13 keV. This information is used to evaluate the effective area in X-rays. Wing scattering measurements are performed and show a good correlation with the Power Spectral Density measured with a PROMAP microscope interferometer during mirror shell manufacturing. This paper deals first with the presentation and comparison of the result achieved on the five MMs. In a second step the results of complementary tested, performed to cross check the data and to get a better understanding of the MM behavior, are discussed.
The high throughput x-ray spectroscopy mission (XMM) is a 'Cornerstone' Project in the ESA long-term Program for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and x-ray CCD cameras. Each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and confocal configuration. The calibration of the mirror system includes the development of a representative numerical model and its validation against extensive calibration test performed on ground at the CSL and PANTER test facilities. The present paper describes the calibration of the x-ray image quality of the first XMM flight mirror module.
The High Throughput X-ray Spectroscopy Mission (XMM) is a "Cornerstone" Project in the ESA long-term Programme for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and X-ray CCD cameras. Each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. The calibration of the mirror system includes the development of a representative numerical model and its validation against extensive calibration tests performed on ground at the CSL and PANTER test facilities. The present paper describes the calibration of the x-ray effective area of the first XMM flight mirror module.
Keywords: XMM, X-ray astronomy, Wolter I telescope, grazing incidence optics
In the frame of the XMM project, several test campaigns are accomplished to qualify the optical elements of the mission. The test described in this paper are performed on a XMM flight model mirror module added with a reflection grating assembly (RGA). The mirror module contains 58 x-ray optical quality shells, an x-ray baffle (XRB) to reduce the straylight. This complete XMM flight model mirror assembly (MA) is tested in a vertical configuration at CSL, in a full aperture or partial EUV collimated beam illumination, and with an x-ray pencil beam. One of the advantages of the EUV collimated beam is to verify the correct position of the RGA when integrated in flight configuration on the mirror module structure. This is not possible in x-ray with a finite source distance. The partial EUV illumination is performed to verify the correct integration of the RGA grating stacks. The pencil beam allows to make an accurate metrology of the XRB position, and to verify the positions of the 0, 1 and 2 diffraction order foci. In this paper, the tested module is first exposed, and the approach to qualify the instrument is described. The analysis of the results achieved over the different test configurations is presented. The impact of the environmental test on the reflection grating box is also diagnosed.
The development of an optical camera based on superconducting tunnel junctions has now reached a stage where practical applications in optical or UV astronomy can be considered. A prototype cryogenic camera (named S-Cam) has been developed, based on a high quantum efficiency 6 X 6 detector array of tantalum Josephson junctions, and operating at a temperature of about 0.4 K. This paper describes the general characteristics of the camera, sensitive in the waveband from 350 to 700 nm and designed to be installed in 1998 at the Nasmyth focus of the William Herschel Telescope in La Palma, Spain. In addition to the performance of the overall system, the preliminary detector unit test results will also be presented. The present S-Cam system performance is discussed in view of future versions of the camera. Provided the field coverage of these cameras can be extended through the development of larger format detector arrays and adequate read-out electronics, they have the potential to provide a significant additional tool for optical and UV astronomy in the next century.
The x-ray multi-mirror mission is one of the four 'cornerstone' projects in the ESA Long-Term Programme for Space Science. The image quality of two complete flight telescopes has been evaluated in a facility whose vertical optical axis minimizes deformation induced by gravity. The specimens illuminated by an EUV (58.4 nm) collimated beam allows the measurement of the point spread function, and the effective area across the field of view. Additionally, an x- ray pencil beam (1.5 and 8 keV) was used to measure the reflectivity on selected shells. The optical performance of the two first XMM flight telescopes was assessed during an environmental test campaign. The impact of the the thermal and vibration tests is presented and the performance of the two telescopes are compared.
The high throughput x-ray spectroscopy mission (XMM) is a 'cornerstone' project in the ESA Long-Term Programme for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and x-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. Each mirror shell is characterized by detailed metrology before further integration into the mirror modules. The present paper describes the mirror metrology and the way metrology data will be used to simulate the mirror performance. Simulation results are compared with x-ray images.
The high throughput x-ray spectroscopy mission (XMM) is a 'cornerstone' project in the ESA Long-Term Programme for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and x-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration, in 1995-96, a qualification model of an XMM mirror module which includes a representative number of mirror shells was manufactured. This model was sent to the CSL and PANTER facilities for UV and x-ray testing. The present paper describes the results of the pre-environmental tests performed at these facilities.
In a previous paper, we described the experimental set-up and requirements used to study an XMM mandrel by x-ray angle-resolved scattering (ARS). We presented first results and compared them to micro-profilometry data. Here we complete the description of the experimental method and the data analysis of the x-ray ARS studies. We point out several pitfalls and propose solutions to avoid them. We emphasize the need to span a wide intensity dynamical range and the importance to separate the intensities form the specular and the scattered beams. This separation is of particular interest for estimating the rms-roughness from the power spectral density, modeled by a power-law of the spatial frequency. We then compare the results for the roughness with those obtained from profiler measurements. In a second part, the figure measurements of the XMM mandrel are described and analyzed in detail. They have been carried out with both an x-ray pencil beam and an optical long trace profiler. In particular, much attention has been given to the determination of the angle between the two sections of the Wolter I optical configuration and to the effect of the mandrel mounting supports. The PSD was completed with the low-frequency results. Finally, the surface data from the earlier experiment on the Ni-coated normally-polished paraboloid and the superpolished hyperboloid were used to predict the image quality of a Wolter I type optics having the same surface characteristics. The influence of different surface finishes on the image point spread function of a grazing incidence mirror is discussed.
The High Throughput X-Ray Spectroscopy Mission (XMM) is a `Cornerstone' project in the ESA long-term Programme for Space Science. The satellite observatory uses three grazing incidence telescopes coupled to reflection grating spectrometers and x-ray CCD cameras. Each XMM telescope consists of 58 Wolter I mirrors that are replicated from superpolished nickel coated mandrels. The mirror figure and finish specifications are tight and therefore it is essential to assess the surface quality of the mandrels. This is done in the workshop by a metrology system involving different profilometers. However, the performance of a mandrel can also be directly determined with x-ray tests that allow the user to verify the measurements of the workshop instruments. The ESRF synchrotron storage ring produces x-ray beams of very high quality and has a beamline dedicated to high resolution tests of x-ray optical components. One XMM mandrel was characterized on this beamline by a three axis x-ray scattering technique. Power spectral density functions and profile slopes were derived from the x-ray measurements and compared to those determined by the metrology instruments. The present paper describes the x-ray experiment and discusses its results in the context of the XMM mandrel manufacturing program.
The High Throughput X-Ray Spectroscopy Mission (XMM) is a `Cornerstone' Project in the ESA long-term Program for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and X-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. This high packing density requires the production and integration of very thin mirror shells with diameters ranging from 300 to 700 nm. In this paper, we first present the optomechanical design of an XMM mirror module with an emphasis on thermal control and straylight analysis. We then describe the X-ray test results of a mirror development model with an electro-optical breadboard of a CCD focal plane camera.
The High Throughput X-Ray Spectroscopy Mission (XMM) is a `Cornerstone' Project in the ESA long-term Programme for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and X-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module shall consist of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. This high packing density requires the production and integration of very thin mirror shells with diameters included between 300 and 700 mm. In 1991-93, a development program was run which aims to demonstrate the feasibility of such mirrors. Demonstration models which integrate mirrors having different sizes were manufactured using CFRP replication and Nickel electroforming technologies. These were X-ray tested. The proposed paper summarizes the activities and the test results obtained during this program.
XMM is a Cornerstone Mission of the European Space Agency for X-ray Astronomy. It consists of three X-ray telescopes with identical mirror systems. Each mirror system is composed of 58 nested coaxial and cofocal mirror shell (MS). The telescopes operate in the energy range 0.2-10 KeV with a total collecting area greater than 4800 sq cm at 2 KeV. The angular resolution is specified to HEW less than 30 arcsec at 8 KeV. The high packing density requires the production of very thin MS to minimize the loss of collecting area due to the thickness of the shells. The replica technique by electroforming nickel MS from mandrels allow the production of MS with a thickness of a few tenths of a mm. This technique has been successfully applied for the SAX and JET-X X-ray telescopes. In order to demonstrate the capabilities of this technology for the XMM project, a mirror support structure has been manufactured which allows the integration of one MS with different diameters and thickness between 0.4 to 1.0 mm. Mirror shells of different thickness and diameters have been manufactured and X-ray tested. The preliminary results of these measurements are presented.
A simulation set-up radiometrically representative of a high resolution Earth observation condition from a geosynchronous spinning spacecraft has been built. This simulation set-up is used to verify the performance of a commercially matrix CCD (THOMSON-CSF type TH7864) when operating in time delay and integration (ThI) mode. MTF measurements results of this TDI operating CCD are presented in this paper and are compared with M''TF values of the same CCD operating in a conventional staring mode. 1.