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In this contribution we present a method to calibrate a radiometer at high irradiance levels (18 kW/m2). The method has been developed in the frame of the ESA Technology Research Programme. The radiometer under test is used as a reference detector in solar simulators. In order to underpin that the irradiance level that is generated in the solar simulator is within the required levels of uncertainty, the performance of the reference radiometer has been validated. The concept of the calibration of the radiometer is that the radiometer cavity is exposed to a known optical flux, provided by a laser. Taking into account the area of the cavity aperture, which is measured independently with a coordinate measurement machine, the average irradiance level is determined. The reading of the radiometer is then compared to the applied irradiance level. For this calibration the challenge is not only to achieve SI traceability at high irradiance levels, but also to meet other requirements like not to exceed a pre-determined level of irradiance at any position of the radiometer cavity, to avoid potential damage. The measurement uncertainty for the calibration of the instrument is

In the frame of the development of a videogrammetric system to be used in thermal vacuum chambers at the European Space Research and Technology Centre (ESTEC) and other sites across Europe, the design of a network using micro-cameras was specified by the European Space agency (ESA)-ESTEC. The selected test set-up is the photogrammetric test of the Herschel Satellite Flight Model in the ESTEC Large Space Simulator. The photogrammetric system will be used to verify the Herschel Telescope alignment and Telescope positioning with respect to the Cryostat Vacuum Vessel (CVV) inside the Large Space Simulator during Thermal-Vacuum/Thermal-Balance test phases. We designed a close-range photogrammetric network by heuristic simulation and a videogrammetric system with an overall accuracy of 1:100,000. A semi-automated image acquisition system, which is able to work at low temperatures (-170°C) in order to acquire images according to the designed network has been constructed by ESA-ESTEC. In this paper we will present the videogrammetric system and sub-systems and the results of real measurements with a representative setup similar to the set-up of Herschel spacecraft which was realized in ESTEC Test Centre.

This paper presents the modeling and the comparison of two acquisition systems developed at the Test Centre Division, European Space and Technology Centre, of the European Space Agency in the frame of two investigations: 1) on microelectromechanical-systems-based sensors for the detection of very low-g accelerations and 2) on the feasibility of a compact and low-power multisensor acquisition platform for environmental tests of spacecrafts or subsystems. A Simulink-based approach is proposed for fast, accurate, and reconfigurable modeling of both systems, taking into consideration the sensors and the acquisition chain. This paper aims to highlight the importance of the models as key tools to predict the distortion and noise sources, to allow fast setup of the experiments, and to manage the signal conditioning process. The validity of the proposed technique, applied to the two acquisition systems, is assessed by comparing the predicted results with tests on the real system. Finally, this paper aims to prove, by comparing the two approaches (dedicated acquisition system and multisensor acquisition platform), the importance of the characterization of the whole acquisition system when high performances need to be achieved.

In the frame of the development of a photogrammetric system to be used in thermal/vacuum chambers at the European Space Research and Technology Centre (ESTEC) of European Space Agency (ESA) and other sites across Europe, the design of a network using micro-cameras was specified by ESA-ESTEC. A thermal/vacuum qualified photogrammetric system, which is able to work and acquire images in vacuum and at cryo-temperatures, was constructed by ESA-ESTEC Test Centre Division. The current system uses four space qualified one-mega pixel cameras and is able to measure large space structures in vacuum and at temperatures down to −170 ∘ C with a global accuracy better than 1 part per 100,000 in object space. Several tests aiming at the qualification of the sensors and system in terms of operation and accuracy have been carried out. Special measures have been developed and special attention has been taken into account specifically for the first application of the photogrammetric system. It is to verify the ESA’s Herschel Telescope Flight Model alignment positioning.

In the frame of the development of a videogrammetric system to be used in thermal/vacuum chambers at the ESA-ESTEC and other sites across Europe, the design of a network using micro-cameras was specified by ESA-ESTEC. The selected test set-up is the photogrammetric test of the Herschel Spacecraft Flight Model in the ESTEC Large Space Simulator. The videogrammetric system will be used to verify the Herschel Telescope alignment and Telescope positioning with respect to the Local Oscillator Unit inside the Large Space Simulator during thermal/vacuum/balance test phases. We designed a close-range photogrammetric network by heuristic simulation with a global accuracy of 1:100,000. A thermal/vacuum qualified videogrammetric system, which is able to work in vacuum and at cryo-temperatures in order to acquire images according to the designed network, was constructed by ESA-ESTEC Test Centre Division. In this paper we will present the videogrammetric system, the photogrammetric considerations, accuracy aspects, the result of photogrammetric network simulations, and real measurements. The results of real videogrammetric measurements of a dummy setup similar to the setup of Herschel spacecraft show a successful performance of the system in terms of functionality and accuracy.

The paper presents a low-g acceleration acquisition system, realized at the Test Centre Division, Europeans Space and Technology Centre of the European Space Agency. The system has been developed in the frame of an investigation on MEMS based sensors for the detection of very low g accelerations. A possible use of this type of technology is in the field of environmental noise measurement or in specific spacecraft testing where the effects of micro-vibrations induced by the activations of actuators need to be monitored. A Simulink-based approach is proposed for fast, accurate and reconfigurable modeling of the measuring system (sensor plus acquisition chain). The paper shows how such models are essentials to exactly predict the distortion and noise sources, to allow for fast set-up of the experiments, and to manage the signal conditioning process. The validity of the proposed technique is assessed by comparing the predicted results with tests on the real implemented system.

The cost reduction is a key factor in the preparation of new scientific missions for space exploration and therefore in the design of Space Craft (S/C). In order to achieve this goal, investigations are carried out in order to verify the usability of components off the shelf (COTS) and technologies widely used in the industry. In this frame, a test campaign has been performed at the European Space and Technology Centre (ESTEC) of the European Space Agency (ESA). The campaign aims at characterizing the CAN bus in terms of EMC, specifically radiated emission, in a typical configuration for a small satellite, evaluating the effect of different configurations in its performances. The CAN bus has been selected because it is considered a good alternative to the reliable MIL-STD-1553B bus, often used as control bus of a Space Craft.

In the frame of the development of new Electrical Ground Support Equipment (EGSE) for the testing phase of a spacecraft and its subsystems, the Engineering Services Section, within the Testing Division, Mechanical Systems Department, at the European Space and Technology Centre (ESTEC), has started an investigation aiming to verify the performances of a contact-less measurement system based on a high-speed camera and image processing techniques. This shall be used as an additional tool during the future test campaigns to be held at ESTEC, every time a non-intrusive GSE is required. The system is based on a Photron TM High Speed System, composed of a High Speed camera connected to its frame-grabber via a Panel Link TM bus, and a SW interface for the camera control. Derivative Filters and techniques for edge detection, such as the Sobel, Prewitt and Laplace algorithms, have been used for the image enhancement and processing during several tests campaigns, which have been held to evaluate the measurement system. The improvement of the detection of the movement of the specimen has been achieved by sticking, where possible, one or more optical targets over the surface of the test article. The targets are of two types: for ambient and vacuum qualified. The performances of the measuring system have been evaluated and are summarized in this paper. The limitations of the proposed tool have been assessed, together with the identifications of the possible scenarios where this system would be useful and could be applied to increase the effectiveness of the verification phase of a spacecraft-subsystem.