An energetic electron collimator for the measurement of loss cone fluxes in the Earth's radiation belts is presented. This design addresses the problem of measuring low intensity fluxes in the presence of a large omni-directional background flux. This disc loaded collimator comprises stainless steel baffles and tungsten vanes. Electron rejection is accomplished via baffle spacing with baffles placed more closely deep within the collimator. The collimator was fabricated. Its response was validated at the Goddard Spaceflight Center's Radiation Effects Facility. The baffled design shows an angular cutoff of three orders of magnitude at the geometric cutoff angle for electron energies less than 150 keV.

The forecast of energetic particle fluxes on time scales of hours to weeks, at a given position in space, can be achieved on the basis of experimentally determined particle lifetimes and on real-time measurements of contamination-free spectra. Such elaborated measurements can be provided by the Energetic Particle Telescope (EPT) without any further post-processing. This instrument directly acquires energy spectra of electrons (0.2 - 10 MeV), protons (4 - 300 MeV), α- particles (16 - 1000 MeV) and heavier ions (up to 300 MeV/nucleon). The EPT was developed at the Center for Space Radiations - UCL-Belgium. This paper contains a brief description of the EPT concept and the definition of channels along with a more detailed presentation of the general performances based on the intrinsic detection efficiency functions and the validation test results from an Engineering Model. The EPT capabilities for space-weather related applications are highlighted by an example of forecast of an electron flux.

This paper presents an analysis of the sensitivity changes experienced by three of the eight sensors that comprise the Remote Atmospheric and Ionospheric Detection System (RAIDS) after more than a year operating on board the International Space Station (ISS). These sensors are the Extreme Ultraviolet Spectrograph (EUVS) that covers 550-1100 Å, the Middle Ultraviolet (MUV) spectrometer that covers 1900-3100Å, and the Near Infrared Spectrometer (NIRS) that covers 7220-8740 Å. The scientific goal for RAIDS is comprehensive remote sensing of the temperature, composition, and structure of the lower thermosphere and ionosphere from 85-200 km. RAIDS was installed on the ISS Japanese Expansion Module External Facility (JEM-EF) in September of 2009. After initial checkout the sensors began routine operations that are only interrupted for sensor safety by occasional ISS maneuvers as well as a few days per month when the orbit imparts a risk from exposure to the Sun. This history of measurements has been used to evaluate the rate of degradation of the RAIDS sensors exposed to an environment with significant sources of particulate and molecular contamination. The RAIDS EUVS, including both contamination and detector gain sag, has shown an overall signal loss rate of 0.2% per day since the start of the mission, with an upper boundary of 0.13% per day attributed solely to contamination effects. This upper boundary is driven by uncertainty in the change in the emission field due to changing solar conditions, and there is strong evidence that the true loss due to contamination is significantly smaller. The MUV and NIRS have shown stability to within 1% over the first year of operations.

The Remote Atmospheric and Ionospheric Detection System (RAIDS) is new NASA experiment studying the Earth's thermosphere and ionosphere from a vantage point on the International Space Station (ISS). RAIDS along with a companion hyperspectral imaging experiment were launched in September 2009 to operate as the first US payload on the Japanese Experiment Module-Exposed Facility. The scientific objectives of the RAIDS experiment are to study the temperature of the lower thermosphere (100-200 km), to measure composition and chemistry of the lower thermosphere and ionosphere, and to measure the initial source of O⁺ 83.4 nm emission. The RAIDS sensor complement includes three photometers, three spectrometers, and two spectrographs which span the wavelength range 50-874 nm and scan or image the atmospheric limb 90-300 km. After installation aboard the ISS, RAIDS underwent a 30-day checkout period before entering science operations. RAIDS is serving as a pathfinder for atmospheric remote sensing from the ISS, and the experiment team gained valuable operational insights using this space platform throughout the first year of the mission. This paper describes key aspects of experiment performance relevant to interpreting RAIDS science data and designing future atmospheric remote sensing experiments for the ISS.

The Teledyne microdosimeter is a novel miniature dosimeter that has become recently available to satellite manufacturers and programs to provide awareness of the total radiation dose received by the satellite and its associated subsystems. A characterization of the response of the dosimeter to protons of energies from 30 - 200 MeV as a function of angle, energy and dose rate is presented in this paper. In addition, the response of the dosimeter to a simulated Solar proton event with several different levels of shielding has been measured. These results show that the dosimeter response is relatively uniform over a wide range of conditions for protons. Monte Carlo modeling of the dosimeter for isotropic particle fluxes (both electrons and protons) has also been accomplished. It is shown that a simplified model is appropriate in determining the response of the dosimeter when using it to design low cost, simple instruments for space weather and situational awareness applications.

ADAHELI ADvanced Astronomy for HELIophysics is a solar satellite designed to investigate the fast dynamics of the solar photosphere and chromosphere performing visible and NIR broad-band and monochromatic observations of selected atomic lines. ADAHELI is an Italian Space Agency (ASI) project, approved for a feasibility study within the ASI Small Missions call. ISODY Interferometer for SOlar DYnamics is a Gregorian telescope and its focal plane suite (FPS). The FPS is composed of a high-resolution fast acquisition system, based upon a tandem of Fabry-Pérot interferometers operating in the visible and NIR regions on selected solar atmospheric lines, a broad band channel, and a correlation tracker used as image stabilization system. In this contribution we describe the Fabry-Pérot étalon prototype, based on the capacitance-stabilised concept, realized in our laboratory to perform preliminary mechanical and optical tests with a view to a future Fabry-Pérot étalon prototype for space application.

The "Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire", ASPIICS, is a solar coronagraph to be flown on the PROBA 3 Technology mission of the European Space Agency. ASPIICS heralds the next generation of coronagraphs for solar research, exploiting formation flying to gain access to the inner corona under eclipse-like conditions in space. The science goal is high spatial resolution imaging and two-dimensional spectrophotometry of the Fe XIV, 530.3 nm, emission line. This work describes a liquid crystal Lyot tunable-filter and polarimeter (LCTP) that can implement this goal. The LCTP is a bandpass filter with a full width at half maximum of 0.15 nm at a wavelength of 530.3 nm. The center wavelength of the bandpass is tunable in 0.01 nm steps from 528.64 nm to 533.38 nm. It is a four stage Lyot filter with all four stages wide-fielded. The free spectral range between neighboring transmission bands of the filter is 2.7 nm. The wavelength tuning is non-mechanical using nematic liquid crystal variable retarders (LCVR's). A separate LCVR of the Senarmont design, in tandem with the filter, is used for the polarimetric measurements. A prototype of the LCTP has been built and its measured performances are presented here.

We will describe the status of current ground-based solar spectroscopic and imaging instruments used in solar observations. We will describe the advantages and disadvantages of using these two classes of instruments with examples drawn from the Improved Solar Optical Observing Network (ISOON) and Synoptic Long Term Investigations of the Sun (SOLIS) Network. Besides instrumental requirements and lessons learned from existing ground-based instruments, this talk will also focus on the future needs and requirements of ground-based solar optical observations.

We present the methods and results for the figure testing and spectral calibration of the narrow- and wide-band etalons for the Improved Solar Observing Optical Network's dual-etalon tunable imaging filters. The ISOON system comprises a distributed network of ground-based patrol telescopes that gather full-disk data for the monitoring of solar activity and for the development of more reliable space weather models. The etalon figure testing consists mainly of testing the cavity flatness and coating uniformity of each etalon. For this testing a series of exposures is taken as the etalon is tuned through a stable spectral line and a full-aperture line profile correlation method is employed to map the variations in the effective cavity thickness. Calibration of the etalons includes absolute calibration of the cavity mean spacing change corresponding to a controller step and calibration of plate parallelism and spacing settings for each spectral region of interest. Developmental acceptance testing and calibration procedures were performed in a laboratory environment using a HeNe laser source. A calibration method that uses illumination in the telluric lines is also described. This latter method could be used to conduct calibration in the field without the use of an artificial light source.

Two mission concepts (plan A: out-of-ecliptic mission and plan B: high resolution spectroscopic mission) have been studied for the next Japanese-led solar mission Solar-C, which will follow the scientific success of the Hinode mission. The both mission concepts are concluded as equally important and attractive for the promotion of space solar physics. In the meantime we also had to make efforts for prioritizing the two options, in order to proceed to next stage of requesting the launch of Solar-C mission at the earliest opportunity. This paper briefly describes the two mission concepts and the current status on our efforts for prioritizing the two options. More details are also described for the plan B option as the first-priority Solar-C mission. The latest report from the Solar-C mission concept studies was documented as "Interim Report on the Solar-C Mission Concept."

We report instrument outline as well as science of the photon-counting soft X-ray telescope that we have been studying as a possible scientific payload for the Japanese Solar-C mission whose projected launch around 2019. Soft X-rays (~1- 10 keV) from the solar corona include rich information on (1) possible mechanism(s) for heating the bright core of active regions seen in soft X-rays (namely, the hottest portion in the non-flaring corona), (2) dynamics and magnetohydrodynamic structures associated with magnetic reconnection processes ongoing in flares, and even (3) generation of supra-thermal distributions of coronal plasmas associated with flares. Nevertheless, imaging-spectroscopic investigation of the soft X-ray corona has so far remained unexplored due to difficulty in the instrumentation for achieving this aim. With the advent of recent remarkable progress in CMOS-APS detector technology, the photon-counting X-ray telescope will be capable of, in addition to conventional photon-integration type exposures, performing imaging-spectroscopic investigation on active regions and flares, thus providing, for example, detailed temperature information (beyond the sofar- utilized filter-ratio temperature) at each spatial point of the observing target. The photon-counting X-ray telescope will emply a Wolter type I optics with a piece of a segmented mirror whose focal length 4 meters, combined with a focal-plane CMOS-APS detector (0.4-0.5"/pixel) whose frame read-out rate required to be as high as 1000 fps.

We present an optical and thermal design of one of major instrumental payload planned for SOLAR-C mission/Plan-B (high resolution spectroscopic option): the telescope assembly of Solar Ultra-violet Visible and near IR observing Telescope (SUVIT). To accommodate a launcher's nosecone size, a wide observing wavelength coverage from UV (down to 280 nm) through near IR (up to 1100 nm), and an 0.1 arcsec resolution in the field of 200 arcsec diameter, a short telescope design was made for a 1.5 m aperture solar Gregorian telescope with the compact design of three-mirror collimator unit.

It is presented the conceptual design of a focal plane instrument for the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar mission SOLAR-C. A primary purpose of the telescope is to achieve precise as well as high resolution spectroscopic and polarimetric measurements of the solar chromosphere with a big aperture of 1.5 m, which is expected to make a significant progress in understanding basic MHD processes in the solar atmosphere. The focal plane instrument consists of two packages: A filtergraph package is to get not only monochromatic images but also Dopplergrams and magnetograms using a tunable narrow-band filter and interference filters. A spectrograph package is to perform accurate spectro-polarimetric observations for measuring chromospheric magnetic fields, and is employing a Littrow-type spectrograph. The most challenging aspect in the instrument design is wide wavelength coverage from 280 nm to 1.1 μm to observe multiple chromospheric lines, which is to be realized with a lens unit including fluoride glasses. A high-speed camera for correlation tracking of granular motion is also implemented in one of the packages for an image stabilization system, which is essential to achieve high spatial resolution and high polarimetric accuracy.

This paper will describe the scientific goals of our sounding rocket program, the Solar Ultraviolet Magnetograph Investigation (SUMI). This paper will present a brief description of the optics that were developed to meet SUMI's scientific goals, discuss the spectral, spatial and polarization characteristics of SUMI's optics, describe SUMI's flight which was launched 7/30/2010, and discuss what we have learned from that flight.

The SOHO/CELIAS Solar EUV Monitor (SEM) has measured absolute extreme ultraviolet (EUV) solar irradiance nearly continuously over a 15 year period that includes two solar cycle minima, 22/23 (1996) and 23/24 (2008). Calibration of the SEM flight instrument and verification of the data have been maintained through measurements from a series of sounding rocket calibration underflights that have included a NIST calibrated SEM clone instrument as well as a Rare Gas Ionization Cell (RGIC) absolute detector. From the beginning of SEM data collection in 1996, the SOLERS 22 fixed reference solar spectrum has been used to calculate absolute EUV flux values from SEM raw data. Specifically, the reference spectrum provides a set of weighting factors for determining a weighted average for the wavelength dependent SEM response. The spectrum is used for calculation of the second order contamination in the first order channel signals, and for the comparison between SEM flux measurements with broader-band absolute RGIC measurements. SOHO/SEM EUV flux measurements for different levels of solar activity will be presented to show how the choice of reference spectra now available affects these SEM data. Both fixed (i.e. SOLERS 22) and non-fixed (Solar Irradiance Platform/Solar 2000 and SDO/EVE/MEGS) reference spectra have been included in this analysis.

The solar chromosphere is an important boundary, through which all of the plasma, magnetic fields and energy in the corona and solar wind are supplied. Since the Zeeman splitting is typically smaller than the Doppler line broadening in the chromosphere and transition region, it is not effective to explore weak magnetic fields. However, this is not the case for the Hanle effect, when we have an instrument with high polarization sensitivity (~ 0.1%). "Chromospheric Lyman- Alpha SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect linear polarization produced by the Hanle effect in Lyman-alpha line (121.567 nm) and to make the first direct measurement of magnetic fields in the upper chromosphere and lower transition region. To achieve the high sensitivity of ~ 0.1% within a rocket flight (5 minutes) in Lyman-alpha line, which is easily absorbed by materials, we design the optical system mainly with reflections. The CLASP consists of a classical Cassegrain telescope, a polarimeter and a spectrometer. The polarimeter consists of a rotating 1/2-wave plate and two reflecting polarization analyzers. One of the analyzer also works as a polarization beam splitter to give us two orthogonal linear polarizations simultaneously. The CLASP is planned to be launched in 2014 summer.

LEMUR is a VUV imaging spectrograph with 0.28" resolution. Incident solar radiation is imaged onto the spectrograph slit by a single mirror telescope consisting of a 30-cm steerable f/12 off-axis paraboloid mirror. The spectrograph slit is imaged and dispersed by a highly corrected grating that focuses the solar spectrum over the detectors. The mirror is coated with a suitable multilayer with B4C top-coating providing a reflectance peak around 18.5 nm besides the usual B4C range above 500Å. The grating is formed by two halves, one optimized for performances around 185Å and the other above 500Å. Three intensified CCD cameras will record spectra above 50 nm while a large format CCD array with an aluminum filter will be used around 185Å.

The primary science objective of the Coronal Suprathermal Particle Explorer (C-SPEX) is to investigate the spatial and temporal variations of coronal suprathermal particle populations that are seeds for acceleration to solar energetic particles (SEPs). It is understood that such seed particle populations vary with coronal structures and can change responding to solar flare and coronal mass ejection (CME) events. Models have shown that higher densities of suprathermal protons can result in higher rates of acceleration to high energies. Understanding the variations in the suprathermal seed particle population is thus crucial for understanding the variations in SEPs. However, direct measurements are still lacking. C-SPEX will measure the variation in the suprathermal protons across various coronal magnetic structures, before/after the passage of CME shocks, in the post-CME current sheets, and before/after major solar flares. Understanding the causes for variation in the suprathermal seed particle population and its effect on the variation in SEPs will also help build the predictive capability of SEPs that reach Earth. The CSPEX measurements will be obtained from instrumentation on the International Space Station (ISS) employing well-established UV coronal spectroscopy techniques.

On the Solar Orbiter mission, the Extreme Ultraviolet Imager (EUI) set of filtergraph-telescopes consists of two highresolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide images of the solar atmosphere in the extreme ultraviolet and in the Lyman-α line of hydrogen at 121.6 nm. The Lyman-α HRI, in particular, will provide imaging of the upper chromospheres/lower transition region of the Sun at unprecedented high cadence and at an angular resolution of 1"; (corresponding to a spatial resolution of 200 km at perihelion). For vacuum-ultraviolet imaging of the Sun the main requirements for the instrumentation are high resolution, high cadence, and large dynamic range. We present here the novel solutions of the instrument design and show in detail the predicted performance of this telescope. We describe in detail how the high throughput and spectral purity at 121.6 nm is achieved. The technical solutions include multilayer coatings of the telescope mirrors for high reflectance at 121.6 nm, combined with interference filters and a multichannel-plate intensified CMOS active pixel camera. We make use of the design flexibilities of this camera to optimize the dynamic range in the focal plane.

SiC/Mg multilayers have been used as coatings of the Sounding-rocket CORonagraphic Experiment (SCORE) telescope mirrors launched during the NASA HERSCHEL program. This materials couple has been largely studied by researchers since it provides higher performances than a standard Mo/Si multilayer; the SCORE mirrors show in fact a peak reflectance of around 40% at HeII 30.4 nm. Nevertheless, long term stability of this coating is an open problem. A study on the aging and stability of this multilayer has been carried on. SiC/Mg multilayer samples characterized by different structural parameters have been deposited. They have been measured just after deposition and four years later to verify degradation based on natural aging. Experimental results and analysis are presented.

Membranes a few hundred nanometers thick are used in EUV optics to make, for example, beams splitters or passband filters. Despite their necessity in numerous applications these components are, because of their thinness, extremely fragile and their implementation in space instruments is always difficult. The authors are developing thin film filters for the Full Sun Imager, one of the EUV telescopes on board the Solar Orbiter mission with objectives of high optical efficiency and mechanical strength. These filters are specifically designed to isolate one or the other of the two passbands (17.4 and 30.4 nm) reflected by the telescope's dual band mirror coating. In this paper we present the optical properties of the prototype components.

Dissipation in the solar corona is expected to occur in extremely thin current sheets of order 1-100 km. Emission from these current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required < 0.1 arcsec resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few 0.001 arcsec resolution, with much more relaxed tolerances than conventional imaging technology. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region.

This article will give an overview of all effects that determine the spectral features amplitude (SFA). The origin of spectral features is explained and methods are indicated that can be used to minimize the SFA. Spectral features are observed in the ratio between two spectra of sun calibration measurements. Mechanisms helping to reduce spectral features are spectral averaging, angular averaging, and temporal averaging. It will be shown what optical design choices can be made in order to benefit from these SFA reducing mechanisms. In the final chapter some insight in the modeling is given where four types of diffusers are compared.

High-precision full-Stokes polarimetry at near diffraction limited spatial resolution is important to understand numerous physical processes on the Sun. In view of the next generation of ground based solar telescopes, we have explored, through numerical simulation, how polarimetric accuracy is affected by atmospheric seeing, especially in the case of large aperture telescopes with increasing ratio between mirror diameter and Fried parameter. In this work we focus on higher-order wavefront aberrations. The numerical generation of time-dependent turbulence phase screens is based on the well-known power spectral method and on the assumption that the temporal evolution is mainly caused by wind driven propagation of frozen-in turbulence across the telescope. To analyze the seeing induced cross-talk between the Stokes parameters we consider polarization modulation scheme based on a continuously rotating waveplate with rotation frequencies between 1 Hz and several 100 Hz. Further, we have started the development of a new fast solar imaging polarimeter, based on pnCCD detector technology from PNSensor. The first detector will have a size of 264 x 264 pixels and will work at frame rates of up to 1kHz, combined with a very low readout noise of 2-3 e- ENC. The camera readout electronics will allow for buffering and accumulation of images corresponding to the different phases of the fast polarization modulation. A high write-out rate (about 30 to 50 frames/s) will allow for post-facto image reconstruction. We will present the concept and the expected performance of the new polarimeter, based on the above-mentioned simulations of atmospheric seeing.

A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of 2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567 nm), aiming to detect the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The polarimeter of CLASP consists of a rotating half-waveplate, a beam splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is used for these optical components, because MgF2 exhibits birefringent property and high transparency at ultraviolet wavelength. The development and comprehensive testing program of the optical components of the polarimeter is underway using the synchrotron beamline at the Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first objective is deriving the optical constants of MgF2 by the measurement of the reflectance and transmittance against oblique incident angles for the s-polarized and the p-polarized light. The ordinary refractive index and extinction coefficient along the ordinary and extraordinary axes are derived with a least-square fitting in such a way that the reflectance and transmittance satisfy the Kramers-Krönig relation. The reflection at the Brewster's Angle of MgF2 plate is confirmed to become a good polarization analyzer at Ly-alpha. The second objective is the retardation measurement of a zeroth-order waveplate made of MgF2. The retardation of a waveplate is determined by observing the modulation amplitude that comes out of a waveplate and a polarization analyzer. We tested a waveplate with the thickness difference of 14.57 um. The 14.57 um waveplate worked as a half-waveplate at 121.74 nm. We derived that a waveplate with the thickness difference of 15.71 um will work as a half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP polarimeter using the MgF2 half-waveplate and polarization analyzers, and succeeded in obtaining the modulation patterns that are consistent with the theoretical prediction. We confirm that the performance of the prototype is optimized for measuring linear polarization signal with the least effect of the crosstalk from the circular polarization.

The Doppler-Intensity-Magnetograms with a Magneto-optical filter Instrument at two heights (DIMMI-2h) is a double channel imager using Magneto Optical Filters (MOF) in the potassium 770 nm and sodium 589 nm lines. The instrument will provide simultaneous dopplergrams (velocity fields), continuum intensity and longitudinal magnetic flux images at two heights in the solar atmosphere corresponding to low and high photosphere. Dimmi- 2h is the possible piggy-back payload on ADAHELI satellite. The spatial resolution (approximately 4 arcsec) and the high temporal cadence (15 s) will permit to investigate low and medium oscillating modes (from 0 to below 1000) up to approximately 32 mHz in the frequency spectrum. The acquisition of long-term simultaneous velocity, intensity and magnetic information up to these high frequencies will permit also the study of the propagation and excitation of the waves with a frequency resolution never obtained before.

We used a laser system for determining the bandpasses of the two vapour cells, the Magneto-Optical Filter (MOF) and the Wing Selector (WS), which are the core of solar narrow-band filters based on the MOF technology. A new result, which we called the Intensity Effect, was found: the MOF and WS bandpasses depend not only on the temperature at which the cell is heated and the external magnetic field in which the cell is embedded, but also on the radiation intensity entering the cell. A theoretical interpretation of the Intensity Effect is proposed in terms of the kinetic equilibrium of the potassium atomic populations inside the vapour cell. We need to take the Intensity Effect into account for setting-up MOF based instruments for solar and stellar observations as well as for modelling the MOF and WS spectral transmissions.

The Turin Astronomical Observatory, Italy, has implemented in ALTEC, Turin, a new Optical Payload Systems (OPSys) facility for testing of contamination sensitive optical space flight instrumentation. The facility is specially tailored for tests on solar instruments like coronagraphs. OPSys comprises an ISO 7 clean room for instrument assembly and a relatively large (4.4 m³) optical test and calibration vacuum chamber: the Space Optics Calibration Chamber (SPOCC). SPOCC consists of a test section with a vacuum-compatible motorized optical bench, and of a pipeline section with a sun simulator at the opposite end of the optical bench hosting the instrumentation under tests. The solar simulator is an off-axis parabolic mirror collimating the light from the source with the solar angular divergence. After vacuum conditioning, the chamber will operate at an ultimate pressure of 10^-6 mbar. This work describes the SPOCC's vacuum system and optical design, and the post-flight stray-light tests to be carried out on the Sounding-rocket Experiment (SCORE). This sub-orbital solar coronagraph is the prototype of the METIS coronagraph for the ESA Solar Orbital mission whose closest perihelion is one-third of the Sun-Earth distance. The plans are outlined for testing METIS in the SPOCC simulating the observing conditions from the Solar Orbiter perihelion.

Close observations of the solar atmosphere and surface are required in order to understand the solar activity and its influence on Earth. This task will be performed from Solar Orbiter mission which will reach a very close distance from the Sun: the minimum perihelion distance will be only 0.28 AU. At these distances, the spacecraft and instruments are immersed in a very harsh environment characterized by high temperature, solar wind particles and ions. The stability of the optical coatings at these working conditions are a crucial point in an instrument design and a thorough investigation of the environment effects must be carried out for a secure validation. In this work we present the first experiment carried on in laboratory to establish the effect of solar wind low energy particles bombardment in some optical coatings.

Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer time, a 4-year operation is considered around the next solar maximum in 2025.

Liquid-crystal variable retarders (LCVRs) are an emergent technology for space-based polarimeters, following its success as polarization modulators in ground-based polarimeters and ellipsometers. Wide-field double nematic LCVRs address the high angular sensitivity of nematic LCVRs at some voltage regimes. We present a work in which wide-field LCVRs were designed and built, which are suitable for wide-field-of-view instruments such as polarimetric coronagraphs. A detailed model of their angular acceptance was made, and we validated this technology for space environmental conditions, including a campaign studying the effects of gamma, proton irradiation, vibration and shock, thermo-vacuum and ultraviolet radiation.