OHB (Italy)

Comet Interceptor is a science mission by the European Space Agency (ESA), with international collaboration from JAXA, designed to study a dynamically new long-period comet or an interstellar object. The spacecraft's scientific payload includes fluxgate magnetometers requiring magnetic cleanliness program. Maintaining magnetic field stability at the FGMs is critical, with variations constrained to below 5 nT peak-to-peak during operations. To ensure compliance, specific testing and analysis were conducted on the expected key contributors. This paper details the magnetic cleanliness program implemented for COMET-I, describing test methodologies, results, and the mitigation strategies adopted to ensure the performance of the magnetometers.

Release mechanisms are crucial devices for the success of space missions. In LISA, the first gravitational waves observatory in space, the grabbing positioning and release mechanism (GPRM) is responsible for setting all the test masses (TMs) in the free-fall condition necessary for starting science observations. This mechanism is considered a key equipment for the success of the entire space mission. The GPRM was initially tested in LISA Pathfinder (LPF), a space mission flown between 2015 and 2017, and an anomaly was encountered in the TM velocity after the release, which also resulted in some failures. One of the suspected reasons of this behavior is that the trajectory of the release mechanism deviates from the nominally rectilinear one. We find that this anomaly is due to the presence of high and asymmetric friction between moving parts. In this paper, we characterize experimentally the deviation from the linear trajectory, using LPF qualification models of the mechanism available on ground, and we identify the mechanical features that determine the friction-driven spurious lateral motion via a numerical finite element model. The results are one of the basis to improve the design of the GPRM for LISA. Some risk-reduction strategies and design guidelines are also presented and discussed.

This paper describes the ridge-waveguide stub filter configuration that was integrated in the Ku/Ka-band antenna-feed chain developed during the A/B1 phases of the Copernicus Imaging Microwave Radiometer (CIMR) programme. The filter geometry is based on the direct cascade of asymmetric stubs that are alternatively arranged along the opposite sides of the main ridge-waveguide. This arrangement results in maximization of the gaps between the metal surfaces. Hence, the layout presented allows for the rejection of all the relevant modes, while minimizing insertion loss that is a key figure-of-merit in radiometric applications. The filter was designed by the spectral element-method presented in [10].

Scheduled to launch in late 2021 the Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer Mission designed to open up a new window of investigation -- X-ray polarimetry. The IXPE observatory features 3 identical telescope each consisting of a mirror module assembly with a polarization-sensitive imaging x-ray detector at its focus. An extending beam, deployed on orbit provides the necessary 4 m focal length. The payload sits atop a 3-axis stabilized spacecraft which among other things provides power, attitude determination and control, commanding, and telemetry to the ground. During its 2-year baseline mission, IXPE will conduct precise polarimetry for samples of multiple categories of x-ray sources, with follow-on observations of selected targets. IXPE is a partnership between NASA and the Italian Space Agency (ASI).

MWI (Micro Wave Imager) is one of the sensors of MetOp Second Generation Sat-B devoted to observe clouds and precipitations, water vapor and temperature gross profiles.MWI will provide global microwave imaging data useful to retrieve information on precipitating and non-precipitating liquid and frozen hydrometeors and relevant surface characteristics (e.g. windspeed over ocean and sea-ice coverage). The present paper will give an overview of the instrument design and will report on the status of the development and verification.

Aims. Metis is the first solar coronagraph designed for a space mission and is capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona in a square field of view (FoV) of ±2.9° in width, with an inner circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7R⊙to about 9R⊙, owing to the eccentricity of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close (0.28 AU, at the closest perihelion) vantage point, achieving increasing out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, allow longer-term studies of the off-limb coronal features, thus finally disentangling their intrinsic evolution from effects due to solar rotation.Methods. Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H ILyman-αline at 121.6 nm. The visible light channel also includes a broadband polarimeter able to observe the linearly polarised component of the K corona. The coronal images in both the UV H ILyman-αand polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15 000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 s can be achieved when observing coronal fluctuations in visible light.Results. The Metis measurements, obtained from different latitudes, will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes the acceleration process and where the onset and initial propagation of coronal mass ejections (CMEs) take place. The near-Sun multi-wavelength coronal imaging performed with Metis, combined with the unique opportunities offered by the Solar Orbiter mission, can effectively address crucial issues of solar physics such as: the origin and heating/acceleration of the fast and slow solar wind streams; the origin, acceleration, and transport of the solar energetic particles; and the transient ejection of coronal mass and its evolution in the inner heliosphere, thus significantly improving our understanding of the region connecting the Sun to the heliosphere and of the processes generating and driving the solar wind and coronal mass ejections.Conclusions. This paper presents the scientific objectives and requirements, the overall optical design of the Metis instrument, the thermo-mechanical design, and the processing and power unit; reports on the results of the campaigns dedicated to integration, alignment, and tests, and to the characterisation of the instrument performance; describes the operation concept, data handling, and software tools; and, finally, the diagnostic techniques to be applied to the data, as well as a brief description of the expected scientific products. The performance of the instrument measured during calibrations ensures that the scientific objectives of Metis can be pursued with success.

The neutral particles sensor ELENA (Emitted Low Energy Neutral Atoms) for the ESA/JAXA BepiColombo mission to Mercury (in the SERENA instrument suite) is devoted to measure low energetic neutral atoms. The main goal of the experiment is measuring the sputtering emission from planetary surfaces, from E=20eV up to E=5keV, within 1D (2 deg. x 76 deg. ). ELENA original project had also a particle discrimination system based on Time-of-Flight (TOF) of particles through the shutter on the Micro Channel Plates detector (MCP), it has been withdrawn from the flight model due to design and development problems. The ELENA SCOE is the configuration/testing system of ELENA, it allows to command operations and to set up configuration parameters on the instrument and to monitor the incoming data. The TC/TM simulation/encoding/decoding software is developed respecting the CCSDS/ECSS standards implemented by ESA, and it's SCOS2000 compatible. TC generation, HK data monitoring and basic science data analysis are operated by the SERENA EGSE, developed by the Finnish Meteorological Institute (FMI), Helsinki, Finland. The data stream outcoming from the EGSE is then preprocessed from TM to user readable formats: FITS and then ASCII csv tables with metadata collected in a detached XML file, called label. This task is performed using the PacketLib, ProcessorLib, and DISCoS (PPD) framework and is going to be used as the first level prototype of the BepiColombo Science Ground Segment processing pipeline, based in ESAC, Madrid, Spain and implemented using the PDS4 data format.