The objective of the so-called fringe sensor DWARF - derived from DARWIN AstRonomical Fringe Sensor is to measure all relevant perturbations and to provide real time control data to achieve co-phasing of the freeflying telescopes of the DARWIN system. An overview of the design of the sensor Breadboard (BB), as it has been designed and built at Kayser-Threde as Prime with main partners ONERA and Alcatel Space under ESA contract 17012/03/NL/EC is presented. An extensive test campaign has been carried out at ONERA. The respective optical test setup is outlined and the achieved performances for retrieval of primary and higher order aberrations are presented. As final outcome of the BB study the essential elements to build a fringe sensor (FS) flight model are shortly characterized and the respective development roadmap is sketched.
Scientific experiments on mineral and biological samples with Raman excitation below 300nm show a wealth of scientific information. The fluorescence, which typically decreases signal quality in the visual or near infrared wavelength regime can be avoided with deep ultraviolet excitation. This wavelength regime is therefore regarded as highly attractive for a compact high performance Raman spectrometer for in-situ planetary research. Main objective of the MIRAS II breadboard activity presented here (MIRAS: Mineral Investigation with Raman Spectroscopy) is to evaluate, design and build a compact fiber coupled deep-UV Raman system breadboard. Additionally, the Raman system is combined with an innovative scanning microscope system to allow effective auto-focusing and autonomous orientation on the sample surface for high precise positioning or high resolution Raman mapping.
Imaging spectrometers featuring a grating disperser allow for a compact system design. However, due to the limited
diffraction efficiency of the grating these instruments suffer from low throughput and high sensitivity to polarization.
Prism spectrometers do not have these disadvantages, but they show a low angular dispersion with noticeable non-linearity,
which is the main driver of the overall spectrometer dimensions. The envelope of a prism spectrometer can be
significantly decreased when prisms with curved surfaces are used. They allow for a reconfiguration of the concentric
Offner relay which is well known for its good imaging quality and its low distortion. In the document at hand a novel
type of compact Offner spectrometers with curved prisms is presented. As an example the optic design of EnMAP, a
German space born hyperspectral imager is given.
The Environmental Mapping and Analysis Program (EnMAP) is a German space based hyperspectral mission planned
for launch in 2012. The hyperspectral instrument covers the wavelength range from 420nm to 2450nm using a dual
spectrometer layout. Both f/3 spectrometers employ a prism disperser for maximum throughput and are linked to the
common foreoptics by a micromechanical field splitter. Together with custom designed silicon and MCT-based detector
arrays this sensor design exhibits a peak system SNR of 1000 at 495nm and of more than 300 at 2200nm. Stable and
precise in orbit performance is ensured by a multi loop thermal control system and a system calibration which relies on
onboard sources as well as a full aperture diffuser.
The Environmental Mapping and Analysis Program (EnMAP<sup>1,2</sup>) is a joint response of German Earth observation research institutions, value-adding (VA) resellers and space industry to the increasing demand on accurate, quantitative information about the evolution of terrestrial ecosystems. With its hyperspectral capabilities covering the visible, near- and short-wave infrared wavelengths, EnMAP will provide high quality, standardized, and consistent data on a timely and frequent basis. Its primary focus will be on the considerable improvement of already standardized products and the development of new quantitative and highly informative data and its derivatives. Only an imaging spectrometer, such as EnMAP, can resolve and detect biophysical, biochemical, and geochemical variables in distinct detail. This will tremendously increase our understanding of coupled biospheric and geospheric processes and thus, enable the management to ensure the sustainability of our vital resources.
After a successfully accomplished phase A, EnMAP has been approved by the German Aerospace Agency in the beginning of 2006. The instrument performance allows for a detailed monitoring, characterisation and parameter extraction of vegetation targets, rock/soils, and inland and coastal waters on a global scale. By the scientific lead of the GeoForschungsZentrum Potsdam (GFZ) and the industrial prime ship of Kayser-Threde, the ongoing planning aims towards an internationalisation of the mission approach.
The EnMAP instrument provides information based on 218 contiguous spectral bands in the wavelength range from 420 nm to 2450 nm. It is characterized by a SNR of > 500:1 in the VNIR and an SNR of >150:1 in the SWIR range at a ground resolution of 30 m x 30 m.
Interferometer performances are linked to the measurement and the correction of telescope aberrations. For cophasing the large number of beams required by the DARWIN mission with the specified requirements (realtime piston/tip/tilt correction and measurement of higher orders up to spherical aberration), focal-plane approach has been selected due to its simple opto-mechanical device. Several focal-plane algorithms, developed at ONERA and gathered in the stand-alone MASTIC tool, were validated by experiment with a dedicated breadboard on the laboratory test bench BRISE. Our study shows the correct behaviour of the algorithms for linearity and repeatability; specific requirements are reached for piston/tip/tilt and higher order aberrations. These results confirm the validity of focal-plane sensors for the cophasing of multiple-aperture telescopes.
A fast and unambiguous identification of microorganisms is necessary not only for medical purposes but also in technical processes such as the production of pharmaceuticals. Conventional microbiological identification methods are based on the morphology and the ability of microbes to grow under different conditions on various cultivation media depending on their biochemical properties. These methods require pure cultures which need cultivation of at least 6 h but normally much longer. Recently also additional methods to identify bacteria are established e.g. mass spectroscopy, polymerase chain reaction (PCR), flow cytometry or fluorescence spectroscopy. Alternative approaches for the identification of microorganisms are vibrational spectroscopic techniques. With Raman spectroscopy a spectroscopic fingerprint of the microorganisms can be achieved. Using UV-resonance Raman spectroscopy (UVRR) macromolecules like DNA/RNA and proteins are resonantly enhanced. With an excitation wavelength of e.g. 244 nm it is possible to determine the ratio of guanine/cytosine to all DNA bases which allows a genotypic identification of microorganisms. The application of UVRR requires a large amount of microorganisms (> 10<sup>6</sup> cells) e.g. at least a micro colony. For the analysis of single cells micro-Raman spectroscopy with an excitation wavelength of 532 nm can be used. Here, the obtained information is from all type of molecules inside the cells which lead to a chemotaxonomic identification. In this contribution we show how wavelength dependent Raman spectroscopy yields significant molecular information applicable for the identification of microorganisms on a single cell level.
While investigating the feasibility of the accommodation of X-ray instrumentations on the International Space Station (ISS) a major question remained still open, i.e. the unknown extent of degradation of X-ray mirror surfaces and X-ray detector material caused by contamination in the ISS environment. Therefore, a sample expose experiment has been started in 2001 to investigate these effects in detail using the Russian expose facility provided by the Russian space industry company RKK Energia. While Kayser-Threde GmbH was responsible to organize and coordinate the experiment, gold-coated Zerodur and silicon samples have been provided by the Max-Planck-Institute (MPE). In total 5 samples were flown with the expose facility and have been exposed to the ISS environment for a total duration of 756 days. The analyses of 4 of them are presented in this paper. X-ray reflection measurements before and after the experiment at MPE's PANTER X-ray test facility and microscopy inspections revealed a thin structured surface layer which reduced the X-ray reflection of the exposed mirror samples dramatically. In addition, the samples have been analyzed with a scanning electron microscope, an energy dispersive X-ray spectrometer, and electron spectroscopy for chemical analysis. The results of all these measurements revealing the degradation of the X-ray mirrors and polished silicon detector surfaces are presented.
EnMAP (Environmental Mapping and Analysis Program) is one of the selected proposals for the national German Space Program. The EnMap project includes the technological design of the Hyperspectral Spaceborne Instrument and the algorithms development of the classification. EnMap will be developed to meet the requirements of the observation and investigation of ecosystem parameters for forestry, soil/geological environments and coastal zones/inland waters. It provides high-quality calibrated data and data products to be used as inputs for improved modelling and understanding of biospheric/geospheric processes, high-spectral resolution observations of biophysical, biochemical, and geochemical variables. This contribution describes some technological and theoretical aspects of the technical solution of the Hyperspectral Pushbroom Sensor working in the VNIR and SWIR spectral range. The Hyperspectral Pushbroom Imaging Spectrometer requires at least two different 2−dimensional detector array types, with one dimension for the spatial and the second dimension for the image information. The VNIR quantum detector will be sensitive from 420 nm up to 1030 nm and the SWIR detector from 950 nm up to 2450 nm. The VNIR modelling shows the difficulties of the SNR of the blue channels. Some measures will be discussed to improve this situation. The discussion will be lead to the requirements of the CCD, focal plane and to the data acquisition scenarios. The SWIR stability modelling gives an overview of the requirements to the detector and of some problems of the detector related system design.
The mission ROSITA (ROentgen Survey with an Imaging Telescope Array) will perform the first imaging all-sky survey in the medium energy X-ray range up to 10 keV with an unprecedented spectral and angular resolution. Thus, ROSITA leads to an improved understanding of obscured black holes in Active Galactic Nuclei. In addition, ROSITA represents an important pathfinder for beyond 2015 space telescopes like XEUS and Constellation X. Targeting for a flight in 2008/2009 on one side ROSITA is considered as technology test bed for later X-ray cornerstone missions, on the other side the measurement data will form a good basis for later detailed surveys with the corresponding high resolution pointing systems.
The high throughput x-ray spectroscopy mission XMM is the second cornerstone project in the European Space Agency (ESA) long-term program for space science. This observatory has at its heart three large x-ray telescopes, which will provide a large collecting area with a spatial resolution better than 15 arcsec. In 1998, the three Flight Models and the two spare models of the x-ray telescope have been delivered to ESA, after verification and calibration at the Centre Spatial de Liege and at the Max Planck Institute near Munich. They show mechanical and optical performances much better than the specification. Their performance will undoubtedly bring an important benefit for the astronomers. The most challenging part of the development of these telescopes was the design, the manufacturing and the testing of the x-ray mirrors, during four intensive years. In this paper, we will first summarize the development and the excellent results of the mirrors. Then, we will discuss the lessons learned during this development, mainly in terms of management and technical aspects, including design, manufacturing and testing. These lessons will be drawn in perspective of the future x-ray missions such as Constellation X, Xeus and ASTRO-F.