The Near Infrared Spectro-Photometer (NISP) on board the Euclid ESA mission will be developed and tested at various
levels of integration by using various test equipment. The Electrical Ground Support Equipment (EGSE) shall be
required to support the assembly, integration, verification and testing (AIV/AIT) and calibration activities at instrument
level before delivery to ESA, and at satellite level, when the NISP instrument is mounted on the spacecraft. In the case of
the Euclid mission this EGSE will be provided by ESA to NISP team, in the HW/SW framework called "CCS Lite", with
a possible first usage already during the Warm Electronics (WE) AIV/AIT activities. In this paper we discuss how we
will customize that "CCS Lite" as required to support both the WE and Instrument test activities. This customization will
primarily involve building the NISP Mission Information Base (the CCS MIB tables) by gathering the relevant data from
the instrument sub-units and validating these inputs through specific tools. Secondarily, it will imply developing a
suitable set of test sequences, by using uTOPE (an extension to the TCL scripting language, included in the CCS
framework), in order to implement the foreseen test procedures. In addition and in parallel, custom interfaces shall be set
up between the CCS and the NI-IWS (the NISP Instrument Workstation, which will be in use at any level starting from
the WE activities), and also between the CCS and the TCC (the Telescope Control and command Computer, to be only
and specifically used during the instrument level tests).
The NISP instrument on board the Euclid ESA mission will be developed and tested at different levels of integration
using various test equipment which shall be designed and procured through a collaborative and coordinated effort. The
NISP Instrument Workstation (NI-IWS) will be part of the EGSE configuration that will support the NISP AIV/AIT
activities from the NISP Warm Electronics level up to the launch of Euclid. One workstation is required for the NISP
EQM/AVM, and a second one for the NISP FM. Each workstation will follow the respective NISP model after delivery
to ESA for Payload and Satellite AIV/AIT and launch. At these levels the NI-IWS shall be configured as part of the
Payload EGSE, the System EGSE, and the Launch EGSE, respectively. After launch, the NI-IWS will be also re-used in
the Euclid Ground Segment in order to support the Commissioning and Performance Verification (CPV) phase, and for
troubleshooting purposes during the operational phase.
The NI-IWS is mainly aimed at the local storage in a suitable format of the NISP instrument data and metadata, at local
retrieval, processing and display of the stored data for on-line instrument assessment, and at the remote retrieval of the
stored data for off-line analysis on other computers.
We describe the design of the IWS software that will create a suitable interface to the external systems in each of the
various configurations envisaged at the different levels, and provide the capabilities required to monitor and verify the
instrument functionalities and performance throughout all phases of the NISP lifetime.
In this paper we describe the detailed design of the application software (ASW) of the instrument control unit (ICU) of
NISP, the Near-Infrared Spectro-Photometer of the Euclid mission. This software is based on a real-time operating
system (RTEMS) and will interface with all the subunits of NISP, as well as the command and data management unit
(CDMU) of the spacecraft for telecommand and housekeeping management. We briefly review the main requirements
driving the design and the architecture of the software that is approaching the Critical Design Review level. The
interaction with the data processing unit (DPU), which is the intelligent subunit controlling the detector system, is
described in detail, as well as the concept for the implementation of the failure detection, isolation and recovery (FDIR)
algorithms. The first version of the software is under development on a Breadboard model produced by
AIRBUS/CRISA. We describe the results of the tests and the main performances and budgets.
Athena is one of L-class missions selected in the ESA Cosmic Vision 2015-2025 program for the science theme of the Hot and Energetic Universe. The Athena model payload includes the X-ray Integral Field Unit (X-IFU), an advanced actively shielded X-ray microcalorimeter spectrometer for high spectral resolution imaging, utilizing cooled Transition Edge Sensors. This paper describes the preliminary architecture of Instrument Control Unit (ICU), which is aimed at operating all XIFU’s subsystems, as well as at implementing the main functional interfaces of the instrument with the S/C control unit. The ICU functions include the TC/TM management with S/C, science data formatting and transmission to S/C Mass Memory, housekeeping data handling, time distribution for synchronous operations and the management of the X-IFU components (i.e. CryoCoolers, Filter Wheel, Detector Readout Electronics Event Processor, Power Distribution Unit). ICU functions baseline implementation for the phase-A study foresees the usage of standard and Space-qualified components from the heritage of past and current space missions (e.g. Gaia, Euclid), which currently encompasses Leon2/Leon3 based CPU board and standard Space-qualified interfaces for the exchange commands and data between ICU and X-IFU subsystems. Alternative architecture, arranged around a powerful PowerPC-based CPU, is also briefly presented, with the aim of endowing the system with enhanced hardware resources and processing power capability, for the handling of control and science data processing tasks not defined yet at this stage of the mission study.
The Astrometric Instrument Model system comprises several monitoring and diagnostic tasks for the astrometric
instrument aboard Gaia. It is a hierarchy of dedicated software modules aimed at decreasing the parameter degeneration
of the relation linking the observations to the instrumental behavior, and optimize the estimation process at the CCD and
field-of-view crossing level. Critical for the system is the definition and maintenance of a physical instrument model
fitting the science data, and able to accommodate non nominal configurations. Precise modeling of the astrometric
response is required for optimal definition of the data reduction and calibration algorithms, and to ensure high sensitivity
to both instrumental and astrophysical source parameters.
The implementation of the simultaneous combination of several telescopes (from four to eight) available at
Very Large Telescope Interferometer (VLTI) will allow the new generation interferometric instrumentation
to achieve interferometric image synthesis with unprecedented resolution and efficiency. The VLTI Spectro
Imager (VSI) is the proposed second-generation near-infrared
multi-beam instrument for the Very Large
Telescope Interferometer, featuring three band operations (J, H and K), high angular resolutions (down to
1.1 milliarcsecond) and high spectral resolutions. VSI will be equipped with its own internal Fringe Tracker
(FT), which will measure and compensate the atmospheric perturbations to the relative beam phase, and in
turn will provide stable and prolonged observing conditions down to the magnitude K=13 for the scientific
combiner. In its baseline configuration, VSI FT is designed to implement, from the very start, the minimum
redundancy combination in a nearest neighbor scheme of six telescopes over six baselines, thus offering better options for rejection of large intensity or phase fluctuations over each beam, due to the symmetric set-up.
The planar geometry solution of the FT beam combiner is devised to be easily scalable either to four or eight
telescopes, in accordance to the three phase development considered for VSI. The proposed design, based
on minimum redundancy combination and bulk optics solution, is described in terms of opto-mechanical
concept, performance and key operational aspects.
In ground based interferometric observations, fringe stabilization over long integration times is a mandatory task in order
to achieve useful performances even on faint sources. This is done by dedicated instruments which search the maximum
of the fringe envelope and consequently correct the optical path of the interfering beams. Localization of the fringe
maximum position is corrupted by noise coming both from turbulent atmosphere and instruments. Atmospheric
fluctuations are corrected at telescope level, but high frequency disturbance, as well as inter-telescope one, still remain.
These residuals must be recognized and separated from the source signal, in order to properly model the instrument
behaviour. Moreover, algorithms for fringe tracking must be strong enough to tolerate residual noise and instrument
We provide some examples of noise performance of both calibration and fringe maximum localization based on
FINITO is the first generation VLTI fringe sensor, optimised for three beam observations, recently installed at Paranal and currently used for VLTI optimisation. The PRIMA FSU is the second generation, optimised for astrometry in dual-feed mode, currently in construction. We discuss the constraints of fringe tracking at VLTI, the basic functions required for stabilised interferometric observations, and their different implementation in the two instruments, with remarks on the most critical technical aspects. We provide an estimate of the expected performance and describe some of their possible observing and calibration modes, with reference to the current scientific combiners.
The VLTI system foresees two generations of fringe sensor: FINITO and PRIMA FSUs. The former is dedicated to H band; it controls the internal OPD with a temporal modulation with an external reference OPD. The latter, working with the ABCD model and in K band, is based on the introduction of known phase offsets for the interferometric signal (spatial phase modulation) and on the measurement of the corresponding combined power. Simulation models for both FSUs are developed with Matlab. Instrumental parameters, i.e. phase, transmission, visibility, are tabulated for ease of maintenance and to speed execution time. For the use of siderostats, due to fast turbulence, the need for intensity calibration arises. Assuming slow intensity variations with respect to phase variations, different algorithms can apply, yielding to numerical control of perturbations as a function of model parameters.