eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on-board the Russian/German "Spectrum-Roentgen-Gamma" (SRG) mission. It will perform the first all-sky imaging X-ray survey in the medium X-ray energy band. eROSITA is currently awaiting its launch from Baikonur in early 2019 into an L2 halo orbit. Preparations for eROSITA ground operations have been under way in parallel with the hardware development of the eROSITA telescope, comprising the areas mission planning, telescope operation and data reception, the operation of a data processing pipeline, and the creation of tools for data access and interactive data analysis. eROSITA mission: After a brief calibration and performance verification phase eROSITA will perform a four-year all-sky survey fully covering the sky eight times, which will be followed by several years of dedicated observations of interesting objects. Two ground antennas in Russia (near Moscow and in Siberia) will be available to provide several hours of daily ground contact for commanding and for data reception. eROSITA data rights will be equally divided between the Russian and German partners. Operation and data centers will exist at Max-Planck-Institut für extraterrestrische Physics (MPE) in Garching, Germany and at the Russian Space Research Institute (IKI) in Moscow. Interfaces and procedures for mission planning, telescope operation and data exchange are closely coordinated between both sites. Mission planning and operation: Based on orbit simulations provided by the Russian side, a software environment for optimizing the desired sky coverage and observing efficiency while fulfilling visibility and solar constraints was set up. Agreed upon observing timelines will be converted to eROSITA and SRG command sequences fed to the Russian ground station for up-linking. MPE personnel will be on site either in Moscow or at MPE in Garching during each ground contact to conduct ondemand commanding and to assess instrument health and data quality. Data analysis pipeline and interactive data analysis: The eROSITA data processing pipeline consists of modules for data ingestion, event calibration, exposure calculation, source detection, and the creation of high-level source specific data products. It will be operated at MPE on a daily basis after each ground contact. A subset of the software tasks comprising the data analysis pipeline also functions as interactive data analysis tools. These can be grouped into tasks for X-ray event calibration, selection and binning, exposure, background and sensitivity map creation and for source detection. Data products are provided in a standards compliant FITS format for use with well-known high-level X-ray data analysis tools. A Web based graphical source catalog and data products viewer will allow easy data browsing. Since mid-2014 the interactive eROSITA data analysis package is available to the eROSITA user community, permitting the analysis of simulated eROSITA datasets, created by a sophisticated X-ray modeling and simulation tool.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary scientific payload on board the SRG (Spektrum Röntgen Gamma) mission, scheduled for launch in March 2019. Its destination is the Lagrangian point L2, and its mission is to make a full survey of the X-ray sky. eROSITA is a complex instrument composed of seven identical co-aligned X-ray telescopes with a focal length of 1600mm and an aperture of 7x350mm. Each telescope is equipped with an independent CCD camera. The cold redundant ITC manages all seven cameras as well as the thermal control of the telescope and the interface to the spacecraft. The complexity of this system resides in the fact that the hardware and software interfaces to the spacecraft are minimal. In this respect the ITC has a key role in the management of the instrument, as well as in the science data management. This proved to be an optimal solution in terms of instrument flexibility, but also presented some challenges. The paper presents an overview on the eROSITA system functionality, its interfaces and operational modes together with an outline of the main challenges, which were faced during integration and verification of the complete system. The function of the instrument was verified in the frame of an extensive end-to-end test in vacuum under representative thermal control conditions to verify that the instrument functions under worst case conditions. Currently tests are performed in combination with the spacecraft to verify communication between eROSITA and the spacecraft and the data transfer through the Russian radio complex (TM/TC system). This includes all operational and survival modes. The paper summarizes the main results of the functional tests on instrument level and on spacecraft level.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the main instrument onboard the Russian/German "Spectrum-Roentgen-Gamma" (SRG) mission which will be operated in an L2 orbit. It will perform the first imaging all-sky survey in the medium energy band. The main scientific goals are a) to detect the hot intergalactic medium of ~100 thousand galaxy clusters and groups and hot gas in filaments between clusters to map out the large scale structure in the Universe for the study of cosmic structure evolution, b) to detect systematically all obscured accreting Black Holes in nearby galaxies and many (up to 3 Million) new, distant active galactic nuclei, and c) to study in detail the physics of galactic X-ray source populations, like pre-main sequence stars, supernova remnants and X-ray binaries. The eROSITA flight model was assembled in 2016 and has successfully passed all acceptance tests on instrument level in the facilities of MPE and IABG in Germany. eROSITA was shipped to NPOL (SRG prime contractor) in January 2017. Currently (May 2018) eROSITA has been integrated on the SRG spacecraft and has successfully passed all functional tests. eROSITA is now awaiting its launch from the Baikonur cosmodrome in spring 2019. The launcher will be a PROTON with an upper stage BLOK-DM.
ESA’s next large X-ray mission ATHENA is designed to address the Cosmic Vision science theme 'The Hot and Energetic Universe'. It will provide answers to the two key astrophysical questions how does ordinary matter assemble into the large-scale structures we see today and how do black holes grow and shape the Universe. The ATHENA spacecraft will be equipped with two focal plane cameras, a Wide Field Imager (WFI) and an X-ray Integral Field Unit (X-IFU). The WFI instrument is optimized for state-of-the-art resolution spectroscopy over a large field of view of 40 amin x 40 amin and high count rates up to and beyond 1 Crab source intensity. The cryogenic X-IFU camera is designed for high-spectral resolution imaging. Both cameras share alternately a mirror system based on silicon pore optics with a focal length of 12 m and large effective area of about 2 m2 at an energy of 1 keV. Although the mission is still in phase A, i.e. studying the feasibility and developing the necessary technology, the definition and development of the instrumentation made already significant progress. The herein described WFI focal plane camera covers the energy band from 0.2 keV to 15 keV with 450 μm thick fully depleted back-illuminated silicon active pixel sensors of DEPFET type. The spatial resolution will be provided by one million pixels, each with a size of 130 μm x 130 μm. The time resolution requirement for the WFI large detector array is 5 ms and for the WFI fast detector 80 μs. The large effective area of the mirror system will be completed by a high quantum efficiency above 90% for medium and higher energies. The status of the various WFI subsystems to achieve this performance will be described and recent changes will be explained here.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian/German Spektrum-Roentgen-Gamma (SRG) mission which is now officially scheduled for launch on September 2017, eROSITA will perform a deep survey of the entire X-ray sky. Within the first 4 years of the mission the sky will be scanned 8 times. In the soft band (0.5-2 keV), it will be about 30 times more sensitive than ROSAT, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. eROSITA is currently (June 2016) in its final integration and test phase. All seven FM Mirror Assemblies and Camera Assemblies (+ 1 spare) have been tested and calibrated. All subsystems and components are well within their expected performances.
The WFI (Wide-Field Imager) instrument is one of two instruments of the ATHENA (Advanced Telescope for High- ENergy Astrophysics) mission. ATHENA is the second L-class mission in ESA’s Cosmic Vision plan with launch in 2028 and will address the science theme “The Hot and Energetic Universe” by measuring hot gas in clusters and groups of galaxies as well as matter flow in black holes.
A moveable mirror assembly focusses the X-ray light to the focal plane of the WFI. The instrument consists of two separate detectors, one with a large DEPFET array of 512x512 pixels and one small and fast detector with 64x64 DEPFET pixels and a readout time of only 80 μs. The mirror system will achieve an angular resolution of 5” HEW. The rather large field of view of 40’x40’ in combination with rather high power consumption is challenging not only for the thermal control system.
DEPFET sensors as well as front-end electronics and electronics boxes have to be cooled, where a completely passive cooling system with radiators and heat pipes is highly favored. In order to reduce the necessary radiator area, three separate cooling chains with three different temperature levels have been foreseen. So only the DEPFET sensors are cooled down to the lowest temperature of about 190K, while the front-end electronics is supposed to be operated between 250K and 290K. The electronics boxes can be operated at room temperature, nevertheless the excess heat has to be removed.
After first estimations of heat loads and radiator areas, a more detailed model of the camera head has been used to identify gradients between the cooling interfaces and the components to be cooled. This information is used within phase A1 of the project to further optimize the design of the instrument, e.g. material selection.
The Athena mission was selected for the second large-class mission, due for launch in 2028, in ESA’s Cosmic Vision program. The current solution for the optics is based on the Silicon Pore Optics (SPO) technology with the goal of 2m2 effective area at 1keV (aperture about 3m diameter) with a focal length of 12m. The SPO advantages are the compactness along the axial direction and the high conductivity of the Silicon. Recent development in the fabrication of mirror shells based on the Slumped Glass Optics (SGO) makes this technology an attractive solution for the mirror modules for Athena or similar telescopes. The SGO advantages are a potential high collecting area with a limited vignetting due to the lower shadowing and the aptitude to curve the glass plates up to small radius of curvature. This study shows an alternative mirror design based on SGO technology, tailored for Athena needs. The main challenges are the optimization of the manufacturing technology with respect to the required accuracy and the thermal control of the large surface in conjunction with the low conductivity of the glass. A concept has been elaborated which considers the specific benefits of the SGO technology and provides an efficient thermal control. The output of the study is a preliminary design substantiated by analyses and technological studies. The study proposes interfaces and predicts performances and budgets. It describes also how such a mirror system could be implemented as a modular assembly for X-ray telescope with a large collecting area.
The WFI (Wide Field Imager) instrument is planned to be one of two complementary focal plane cameras on ESA’s next X-ray observatory Athena. It combines unprecedented survey power through its large field of view of 40 arcmin x 40 arcmin together with excellent count-rate capability (≥ 1 Crab). The energy resolution of the silicon sensor is state-of-the-art in the energy band of interest from 0.2 keV to 15 keV, e.g. the full width at half maximum of a line at 6 keV will be ≤ 150 eV until the end of the nominal mission phase. This performance is accomplished by using DEPFET active pixel sensors with a pixel size of 130 μm x 130 μm well suited to the on-axis angular resolution of 5 arcsec of the mirror system. Each DEPFET pixel is a combined detector-amplifier structure with a MOSFET integrated onto a fully depleted 450 μm thick silicon bulk. Two different types of DEPFET sensors are planned for the WFI instrument: A set of four large-area sensors to cover the physical size of 14 cm x 14 cm in the focal plane and a single smaller gateable DEPFET sensor matrix optimized for high count-rate observations. Here we present the conceptual design of the instrument with focus on the critical subsystems and describe the instrument performance expectations. An outline of the model philosophy and the project organization completes the presentation.
In 2016 the X-ray Survey Telescope eROSITA, designed and built at MPE, will be launched on the Russian Spektr- Roentgen-Gamma Mission. A compact bundle of 7 co-aligned mirror modules with a focal length of 1600 mm and 54 nested mirror shells each form the X-ray telescope. The sensitivity of the telescope in terms of effective area, field-ofview (61'), and angular resolution (~16" HEW on-axis) will yield a high grasp of about 1000 cm2 deg2 around 1 keV with an average angular resolution of ~26" HEW over the field-of-view (30" including optical and spacecraft error contributions). All flight mirror modules including a flight spare have been completed and passed their acceptance tests in December 2013. The mirror modules now have all been mated with their corresponding X-ray baffles to form mirror assemblies and the passed rigorous environmental vibration and thermal cycling tests. Here we report on the results of these measurements and on the calibration measurements planned for the completed flight mirror assemblies.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian/German Spektrum-Roentgen-Gamma (SRG) mission which is now officially scheduled for launch on March 26, 2016. eROSITA will perform a deep survey of the entire X-ray sky. In the soft band (0.5-2 keV), it will be about 30 times more sensitive than ROSAT, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. The design driving science is the detection of large samples of galaxy clusters to redshifts z < 1 in order to study the large scale structure in the universe and test cosmological models including Dark Energy. In addition, eROSITA is expected to yield a sample of a few million AGN, including obscured objects, revolutionizing our view of the evolution of supermassive black holes. The survey will also provide new insights into a wide range of astrophysical phenomena, including X-ray binaries, active stars and diffuse emission within the Galaxy. eROSITA is currently (June 2014) in its flight model and calibration phase. All seven flight mirror modules (+ 1 spare) have been delivered and measured in X-rays. The first camera including the complete electronics has been extensively tested (vacuum + X-rays). A pre-test of the final end-toend test has been performed already. So far, all subsystems and components are well within their expected performances.
eROSITA is the core instrument on the Spektrum-Röntgen-Gamma (SRG) mission, scheduled for launch in 2016. The main tasks of the thermal control system are heating of the mirror modules, cooling of the camera electronics, cooling of the CCD detectors and temperature control of the telescope structure in general. Special attention is paid to the camera cooling, since it is the most critical one. The complex assembly with the sevenfold symmetry of the eROSITA telescope requires an innovative design. Large distances and a very low operating temperature (–90°C to –100°C) place high demands on the cooling chain. In total, three different types of low-temperature ethane heat pipes are used to transport the heat from the cameras to two radiators outside the telescope structure. Extreme environmental temperature gradients with the Sun on the one side and the cold space on the other present a real challenge not only to the camera cooling systems, but to the overall thermal control. A thermal model of the complete telescope was used to predict the thermal behavior of the telescope and its subsystems. Through various tests, this model could be improved step by step. The most complex test was the space simulation test of the eROSITA qualification model in January 2013 at the IABG facilities in Ottobrunn, Germany. About 50 heaters, a liquid-nitrogen-cooled chamber and a Sun simulator provided realistic mission conditions. Approximately 200 temperature sensors monitored the relevant temperatures during the test. The results were predominantly within the predicted intervals and therefore not only verified the complete concept but also enabled a further refining of the thermal model. This, in turn, allows for reliable predictions of the thermal behavior during the mission. Some deviations required minor changes in the final design which were implemented and re-qualified in a separate test of the thermal control system flight model in March 2014 in the PANTER test facility of MPE. The results of both tests will be presented in this contribution.
The eROSITA space telescope is presently developed for the determination of cosmological parameters and the
equation of state of dark energy via evolution of galaxy clusters. It will perform in addition a census of the obscured
black hole growth in the Universe. The instrument development was also strongly motivated by the intention of a first
imaging X-ray all-sky survey above an energy of 2 keV. eROSITA is scientific payload on the Russian research satellite
SRG and the mission duration is scheduled for 7.5 years. The instrument comprises an array of seven identical and
parallel-aligned telescopes. The mirror system is of Wolter-I type and the focal plane is equipped with a PNCCD camera
for each of the telescopes. This instrumentation permits spectroscopy and imaging of X-rays in the energy band from
0.3 keV to 10 keV with a field of view of 1.0 degree. The camera development is done at the Max-Planck-Institute for
Extraterrestrial Physics and in particular the key component, the PNCCD sensor, has been designed and fabricated at the
semiconductor laboratory of the Max-Planck Society. All produced devices have been tested and the best selected for
the eROSITA project. Based on calculations, simulations, and experimental testing of prototype systems, the flight
cameras have been configured. We describe the detector and its performance, the camera design and electronics, the
thermal system, and report on the latest estimates of the expected radiation damage taking into account the generation of
secondary neutrons. The most recent test results will be presented as well as the status of the instrument development.
The eROSITA X-ray observatory that will be launched on board the Russian Spectrum-RG mission comprises seven X-ray telescopes, each with its own mirror assembly (mirror module + X-ray baffle), electron deflector, filter wheel, and CCD camera with its control electronics. The completed flight mirror modules are undergoing many thorough X-ray tests at the PANTHER X-ray test facility after delivery, after being mated with the X-ray baffle, and again after both the vibration and thermal-vacuum tests. A description of the work done with mirror modules/assemblies and the test results obtained will be reported here. We report also on the environmental tests that have been performed on the eROSITA telescope qualification model.
The μROSI (Micro Roentgen Satellite Instrument) miniature X-ray telescope is the first X-ray telescope specifically designed for an amateur micro satellite. Its mission is to perform an all-sky survey in the soft X-ray band on board the Italian satellite Max-Valier. Due to the limitations imposed by the small size of the spacecraft, the instrument features a silicon drift detector (SDD) with very low power consumption and a focusing optics that consists of 12 nested mirror shells. With a field of view of 1°, μROSI will perform an all-sky survey flying in sun-synchronous orbit (SSO). As a secondary mission objective, the telescope will observe the Earth's upper atmosphere during the all-sky survey, potentially detecting the O2 absorption line.
This paper describes the overall telescope design and gives an overview of the key components of the telescope: the mirror subsystem and the detector subsystem. All subsystems have been tested with flight-like engineering models. The results of these tests are presented in this paper.
The silicon drift detector (SDD) of the μROSI telescope has been tested with a breadboard electronics and the engineering model of the electronics is currently being manufactured. The breadboard test proved that the SDD together with the specifically developed electronics is capable of measuring high resolution spectra in the soft X-ray bandwidth.
One demonstrator mirror shell has been produced and tested in the PANTER X-ray test facility to verify
the X-ray properties. The measurements suggest that the final μROSI mirror system fulfills all requirements for conducting its mission successfully.
The X-ray telescope eROSITA is the main instrument besides the Russian ART-XC on the Spektrum-Rontgen-Gamma mission. Starting from 2014, an all-sky survey will be performed in the range between 0.3-10keV, followed by pointed observations. The main objective of thismission is the detection of 100 0000 galaxy clusters in order to constrain cosmological parameters, amongst others the density distribution and evolution of dark energy.
Due to the minimum lifetime of seven years the thermal control system has to be completely passive without any consumables. With the ideal operational temperature of the CCD cameras being between 173K and 183K, this requires a very effective heat rejection system, consisting of a complex heat pipe system and a good thermal insulation. Simultaneously, a very sensitive temperature control via variable conductance heat pipes is implemented. For special outgassing requirements at the betinning of the mission these heat pipes are not working after launch but can be switched on any time.
On the other hand the mirror moduules have to be tempered at room temperature and more than 200W of the electronics have to be dissipated without affecting the surrounding components or the satellite structure.
The thermal control system has to be able to keep up the required temperature range and has to guarantee the optimum working conditions for all parts of the instrument. Calculations and verification tests validated the thermal concept.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian
Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in 2013. eROSITA will perform an all-sky
survey lasting four years, followed by a phase of three years for pointed observations. eROSITA consists of seven
identical Mirror Modules, each equipped with 54 Wolter-I shells with an outer diameter of 360 mm. This would provide
an effective area of ~1500 cm2 at 1.5 keV and an on axis PSF HEW of 15 arcsec resulting in an effective angular
resolution of 28 arcsec averaged over the field of view. In the focus of each mirror module, a fast frame-store pn-CCD
provides a field of view of 1°in diameter. In this paper we report on the instrument development and its status only.
The X-ray telescope eROSITA is the core instrument besides the Russian ART-XC on the Russian Spektrum-Roentgen-
Gamma satellite which will be launched in 2012 to an orbit around the L2 point of the Earth-Sun-system.
During both survey and pointing phase the solar panels and the antenna constrain the possible mission scenario. The scan
axis is supposed to point constantly towards the earth in the survey phase. In combination with the orbit, the points of
largest exposure - the scan poles - then would be areas of a few hundred deg² instead of small singularities.
The background as a permanent interference factor is limiting the performance as well as transient disruptions like solar
flares. Constraints on the instrument's side are amongst others vignetting, effectivity and aligning of the different
The mission objectives and related performance imply very stringent requirements. Extremely challenging mechanical
requirements in terms of mirror accuracy, alignment and dimensional stability have to be ensured by design and realized
during manufacturing and integration. Although the Wolter telescope design is quite similar to those of XMM, the
manufacturing of the mirrors is even more challenging due to the more unfavorable geometry of the mirrors.
Mirrors, CCD-cameras and camera electronics all have their own, partly narrow working temperature ranges. Therefore
accurate thermal control has to be implemented to ensure that the telescopes are performing within specification.
Objectives of this work are to find the optimum mission scenario as well as certain operating parameters, taking into
account all environmental boundary conditions.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society. The instrument development is in phase C/D since fall 2009. The design driving science is the detection 100.000 Clusters of Galaxies up to redshift z ~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed observations. eROSITA consists of seven Wolter-I telescope modules, each equipped with 54 Wolter-I shells having an outer diameter of 360 mm. This would provide an effective area of ~1500 cm2 at 1.5 keV and an on axis PSF HEW of 15 arcsec resulting in an effective angular resolution of 28 - 30 arcsec, averaged over the field of view. In the focus of each mirror module, a fast frame-store pn-CCD provides a field of view of 1° in diameter.
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument of the Russian SRG
satellite which will be launched in 2011 into an orbit of 600 km height and 30° inclination. It is being developed by the
Max-Planck-Institute fur extraterrestrische Physik (MPE) in Garching, Germany.
It comprises seven nested Wolter-I grazing incidence telescopes, each equipped with its own CCD camera. The seven
eROSITA CCD cameras require a stable operating temperature of about (-80±0,5)°C. Therefore the thermal control
system is vitally important.
The cooling system consists of passive thermal control components only: two radiators, variable conductance heat pipes
(VCHP) and two special thermal storage units.
By reason of the low-earth-orbit and the special scan geometry it is impossible for one radiator to look into the cold
space at all times. The cameras and the radiators are connected by variable conductance heat pipes which can be cut off
when a radiator gets too warm. A novel "latent cold storage unit" guarantees an absolute constant temperature without
any further control mechanism.
X-ray mirrors made of slumped glass could be a light-weight solution for large segmented
X-ray telescopes. Our goal is the development of a slumping process for high accuracy
glass segments with an angular resolution of a few arcseconds. In our studies we try to
understand the influence of the process by experimental means. We have recently built a
new experimental set-up which allows us to study the sequence of the slumping methods.
We report on our laboratory experiments and on the development of metrology methods to
measure the figure of the glass segments.