Sentinel-5/UVNS instrument is an Earth atmospheric monitoring spectrometer developed within the Copernicus program. The mission objective is to monitor the chemical composition of the Earth’s atmosphere on a daily basis. Airbus Defense and Space GmbH acts as the prime contractor for the instrument under a European Space Agency contract. The current paper will focus on four themes. First it will provide a brief historical and technical overview of the Sentinel-5/UVNS instrument. Second, the key design drivers will be described. Third, the key optical technologies carried on board the instrument will be elaborated. Finally, the paper concludes with a short look at the current state of the instrument’s development cycle.

Euclid is the ESA mission to map the geometry of the dark Universe using two cosmological probes, namely Weak Lensing and Baryonic Acoustic oscillations. The visual imager, a CCD based optical imaging channel will be used to measure the shapes of galaxies in one single wide visual band spanning the wavelength range of 550-920 nm. The focal plane array supports 36 CCDs (4k×4k pixels each) with 0.101 arcsec pixel platescale, giving a geometric field of 0.55 deg2. With the weak lensing technique, the mass distribution of the lensing structures can be traced back. The originally baselined CCDs were e2v CCD203-82. Following the results from a dedicated radiation damage test activity on their CCD204 variant, a new version, called 273 has been designed and made available in a front-illuminated version in April 2012. For Euclid, the accuracy with which the shape of the galaxies has to be measured is considerable: 1% and has never been demonstrated. The radiation damage effects will adversely affect this measurement and thus need to be characterized. Therefore, several test campaigns on the characterization of the CCD radiation damages for Euclid are carried out by ESA and by the Euclid Imaging Consortium. For this purpose, a test bench has been implemented at ESTEC to characterize CCD devices, with radiometric measurements, point source illumination and lab simulation of typical Euclid sky images. The preliminary results obtained at ESA on a non-irradiated front-illuminated Euclid prototype CCD 273-84-2-F16 will be shown in this article.

The visual imaging instrument VIS on board Euclid baselines 36 newly designed CCD273-84 devices from e2v. While these new devices have a 4kx4k format with four readout nodes, the Euclid Imaging Consortium (EIC) has performed extensive test campaigns on both irradiated and un-irradiated devices of the 4kx1k Euclid precursor variant CCD204-22. In support of the CCD development and characterization, and to enable an independent assessment of the Euclid CCDs (the procurement of which is ESA’s responsibility), ESA/ESTEC has built a test bench. This test bench allows for a flexible operation and readout of the CCDs, originally for CCD204 and shortly also for CCD273-84. It provides the basic tools for noise and gain calibration, and CTI, QE, MTF and PRNU measurements. In addition, the bench provides scanning spot illumination with a spot size well below the pixel size, for measurement of the intra-pixel response of the CCDs before and after radiation damage. Such measurements are of great importance for the characterization and modeling of the VIS instrument’s PSF, in particular to enable the prediction of the evolution of the PSF shape under the influence of the L2 radiation environment during the mission. This set-up will also allow for simulation of typical Euclid sky images in the lab. The capabilities and validation of this bench at ESA are described in this paper.

The Advanced Telescope for High ENergy Astrophysics (ATHENA) is one of the three candidates that competed for the first large-class mission (L1) in ESA's Cosmic Vision 2015-2025 programme, with a launch planned by 2022 and is the result of the IXO reformulation activities. ATHENA is an ESA-led project and is conceived as the next generation X-ray observatory. It is meant to address fundamental questions about accretion around black-holes, reveal the physics underpinning cosmic feedback, trace the large scale structure of baryons in galaxy clusters and the cosmic as well as a large number of astrophysics and fundamental physics phenomena. The observatory consists of two identical mirrors each illuminating a fixed focal plane instrument, providing collectively 1 m(2) effective area at 1 keV. The reference payload consists of a medium resolution wide field imager (WFI) and a high resolution X-ray micro-calorimeter spectrometer (XMS). The WFI is based on a monolithic Si DepFET array providing imaging over a 24 x 24 arcmin(2) field of view and a good PSF oversampling. The sensor will measure X-rays in the range 0.1-15 keV and provides near Fano limited energy resolution (150eV at 6keV). The XMS is based on a micro-calorimeter array operating at its transition temperature of similar to 100mK and provides <3eV resolution. The detector array consists of 32 x 32 pixels covering a 2.3 x 2.3 arcmin(2) field of view, co-aligned with the WFI. This paper summarizes the results of the reformulation exercise and provides details on the payload complement and its accommodation on the spacecraft. Following the ESA Science Programme Committee decision on the L1 mission in May 2012, ATHENA was not selected to enter Definition Phase.

ATHENA (Advanced Telescope for High Energy Astrophysics) was an L class mission candidate within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch by 2022. ATHENA was conceived as an ESA-led project, open to the possibility of focused contributions from JAXA and NASA. By allowing astrophysical observations between 100 eV and 10 keV, it would represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage. The main scientific objectives of ATHENA include the study of large scale structures, the evolution of black holes, strong gravity effects, neutron star structure as well as investigations into dark matter.The ATHENA mission concept would be based on focal length of 12m achieved via a rigid metering tube and a two-aperture, x-ray telescope. Two identical x-ray mirrors would illuminate fixed focal plane instruments: a cryogenic imaging spectrometer (XMS) and a wide field imager (WFI). The S/C is designed to be fully compatible with Ariane 5 ECA. The observatory would operate at SE-L2, with a nominal lifetime of 5 yr.This paper provides a summary of the reformulation activities, completed in December 2011. An overview of the spacecraft design and of the payload is provided, including both telescope and instruments. Following the ESA Science Programme Committee decision on the L1 mission in May 2012, ATHENA was not selected to enter Definition Phase.

The Exoplanet Characterisation Observatory (EChO) is a medium class mission candidate within the science program Cosmic Vision 2015-2025 of the European Space Agency. It was selected in February 2011 as one of 4 M3 mission candidates to enter an assessment phase. The assessment activities start with the definition of science and mission requirements as well as of a preliminary model payload, followed by an internal Concurrent Design Facility (CDF) study. Parallel industrial studies will follow in 2012, after which the 4 missions will be reviewed to identify candidates entering definition phase studies in 2013. EChO aims at characterising the atmosphere of known transiting exoplanets, potentially from giant Hot Jupiters down to Super-Earths orbiting in the habitable zone of M-dwarf stars. It will use a 1 m class telescope, feeding a spectrometer covering the wave lengths from 0.4 to 11 microns with a potential extension to 16 microns. While spatial differentiation of the exoplanet and its host star is not necessary, spectral differentiation will be achieved by making differential measurements of in- and out- of transit frames to cancel the star signal. This paper describes critical requirements, and gives an overview of the model payload design. It also reports on the results of the CDF.

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, these are: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 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 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 a superconductor with magnetic impurities, Kondo scattering results in the formation of localized states inside the superconducting gap. We show that inelastic electronic transitions involving quasiparticle scattering into and out of the localized states may result in significant changes in the non-equilibrium properties of the superconductor. Using the model of Muller-Hartmann and Zittartz for the extreme dilute limit, and including both deformation potential and spin-lattice coupling, we have calculated the rates of such inelastic transitions between continuum and discrete states, and shown that they may greatly modify quasiparticle interactions. The individual processes are: quasiparticle trapping into discrete states, enhanced recombination with localized quasiparticles, and pair breaking and de-trapping of localized quasiparticles by sub-gap phonons. We find that all these processes give rise to clearly distinguishable temperature dependences of the kinetic parameters.

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 progressing well.The paper presents a summary of the ESA system studies of IXO and provides an overview of the related ESA led technology preparation activities.

We present the results of investigating the coma of comet 9P/Tempel 1 in C2 and continuum, before and after the Deep Impact event of 4 July 2005. A jet-like coma feature was produced by the impact, and its temporal evolution in morphology and brightness has been compared for the dust and gas coma. It shows that the feature remains visible in the dust coma for several days, whereas in the C2 coma it is visible only on the image taken 15.8 hours after the impact and has vanished when the coma was observed again in the following night. The observational evidence strongly supports that the C2 in the feature observed on 4 July 2005 was produced from fresh dust particles released by the outburst and forming an extended source for the production of the C2 radical. This indicates that the disintegration of C2-bearing dust species can directly be observed during the non-steady state conditions present immediately after outbursts and/or nucleus splitting.

In a superconductor with magnetic impurities, scattering of conduction electrons results in the formation of localized states inside the superconducting gap. We show that inelastic electronic transitions involving quasiparticle scattering into and out of the localized states result in significant changes in the non equilibrium properties of the superconductor. The individual processes are: quasiparticle trapping into discrete states, enhanced recombination with localized quasiparticles, and pair breaking and de-trapping of localized quasiparticles by sub-gap phonons. We find that all these processes give rise to clearly distinguishable temperature dependences of the kinetic parameters indicating a possible role of magnetic scattering on the response of a photon detector.

In the framework of the Cosmic Vision 2015-2025 plan, ESA is currently performing assessment studies on a number of candidate space missions. Cryogenic sensors play an important role in several of the astronomy missions. Specifically, the SAFARI instrument on SPICA and the X-ray Microcalorimeter Spectrometer (XMS) on IXO baselines depend on state-of-the-art Transition Edge Sensor Arrays and associated cryogenic readouts. We will present ESA's Cosmic Vision plan, detail the current status of the SPICA/SAFARI and IXO studies and review the performance drivers for the sensor arrays.

We have identified an important, new source of line broadening in single photon detectors that work on the principle of absorption in a thin metal film. Phonon down-conversion noise arises through the loss of high energy phonons into the substrate during the initial photon energy down-conversion stage. Because of the relatively small number of phonons initially involved in this process, the loss rate is subject to large fluctuations due to the statistical nature of the energy exchange processes. We have modelled the phonon down-conversion noise that arises in the final stage of the down-conversion cascade, during which the deposited energy is converted into predominantly electronic excitations. At this stage of down-conversion in thin films the cascade phonon energy is sufficiently small that the escape interfaces are accessible for all phonons. Solving the system of coupled integral equations for the interacting electron and phonon systems, we have derived explicit expressions for the variance of the deposited energy. We have compared the results with other known noise contributions for the two foremost types of single optical photon detectors, based on superconducting tunnel junctions and transition edge sensors.

In a superconductor with magnetic impurities, Kondo scattering results in the formation of localized states inside the superconducting gap. We show that inelastic electronic transitions involving quasiparticle scattering into and out of the localized states may result in significant changes in the non equilibrium properties of the superconductor. Using the model of Muller-Hartmann and Zittartz for the extreme dilute limit, and including both deformation potential and spin-lattice coupling we have calculated the rates of such inelastic transitions between continuum and discrete states, and shown that they may greatly modify quasiparticle interactions. The individual processes are: quasiparticle trapping into discrete states, enhanced recombination with localized quasiparticles, and pair breaking and detrapping of localized quasiparticles by sub-gap phonons. We find that all these processes give rise to clearly distinguishable temperature dependences of the kinetic parameters.

We show that inelastic scattering of quasiparticles by trace concentrations of magnetic impurities may result in significant changes in the nonequilibrium properties of superconductors. We used the approach of Muller-Hartmann and Zittartz to model Kondo scattering of conduction electrons by the magnetic impurities, and hence, to calculate the rates of (i) quasiparticle trapping into the localized impurity states, (ii) trap-enhanced recombination, (iii) pair breaking, and (iv) detrapping of localized quasiparticles by phonons, including both deformation-potential and spin-lattice couplings. Our results indicate that these processes will give rise to anomalies in the temperature dependence of kinetic parameters, which should be easily observable.

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.

Aims. In 2006 comet 73P/Schwassmann-Wachmann 3, which split in 1995 into five pieces, approached the Sun again with a swarm of new fragments. The same year in May, the conglomerate of sub-fragments from the original fragment B was observed with the S-Cam3 instrument mounted on the 1-m ESA Optical Ground Station (OGS) telescope in Tenerife, Spain. With a total FOV of similar to 876 km x 730 km and a spatial resolution of similar to 73 km/pixel, the S-Cam3 observations provided the possibility to examine dust fragmentation processes, as well as dust and gas outflow, within the first few hundred kilometres of the sub-fragment surfaces.Methods. The superconducting camera, S-Cam3, is an ultra-fast photon counting camera developed by ESA. Cooled to similar to 0.3 K, its sensitive superconducting tunnel junction sensors detect single photons, measuring their arrival time to accuracies of microseconds and determining its crude wavelength. The camera is also essentially noise-free except for sky background photons. Thus S-Cam3 essentially provides high-speed, low-resolution spectra between 395 nm and 1052 nm with a resolution of similar to 35 rim at 500 nm wavelength.Results. The images acquired show three intensity maxima that were identified as most likely from the B fragment itself and two clusters of sub-fragments 253 km and 896 km away from fragment B. Furthermore we could see spatial intensity variations on short time scales (2-4 min), indicating the varying dust and gas emission of "subnuclei". The gas and dust profiles do not show an inverse radial distribution (1/r) in all flow directions, but rather a clear deviation from a free radial outflow. This most likely is due to the gas outflow of one cluster of sub-fragments hitting the outflow of the other cluster. In other words, the material is expanding from one cluster into the other. In addition, the dust particles continue to fragment.

The latest generation of high quality, narrow gap, superconducting tunnel junctions (STJs) exhibits a steady-state and time-dependent behavior which cannot be described satisfactorily by previous treatments of nonequilibrium quasiparticle (qp) dynamics. These effects are particularly evident in experiments using STJs as detectors of photons, over the range from near infrared to x ray. In this paper, we present a detailed theoretical analysis of the spectral and temporal evolution of the nonequilibrium qp and phonon distributions in such STJs excited by single photons, over a wide range of excitation energy, bias voltage, and temperature. By solving the coupled set of kinetic equations describing the interacting excitations, we show that the nonequilibrium qp distribution created by the initial photoabsorption does not decay directly back to the initial undisturbed state in thermal equilibrium. Instead, it undergoes a rapid adiabatic relaxation to a long-lived, excited state, the spectral distribution of which is nonthermal, maintained by a balance between qp creation, recombination, and trapping. The model is able to describe successfully photoabsorption data taken on several different aluminum STJs, using a single set of parameters. Of particular note is the conclusion that the local traps responsible for qp loss are situated specifically in the region of Nb contacts.