The ECAPS Experiment for Solar Cell Characterization in the Stratosphere

The ECAPS project (Experimental Characterization of Advanced Photovoltaics in the Stratosphere) aims at the characterization of performance of a number of different solar cells in the stratospheric environment. ECAPS has been selected to fly as a zero-pressure balloon payload in the frame of the HEMERA H2020 project. Flight is scheduled for August 2022 from CNES’ base in Timmins, Canada. Testing solar cells in the stratosphere is of great interest for the development of High-Altitude Pseudo Satellite (HAPS) platforms, which will be equipped with high efficiency, flexible solar cells capable to operate at 20-30 km altitude for weeks or months, as well as to perform high-quality calibration of spacecraft solar cells in a near-air mass zero environment. The experiment includes a panel with up to 4 solar cells of different kinds (multi-junction GaAs, CIGS, perovskite, etc.), a dedicated I/V curve recording circuit, temperature and irradiance sensors, and an inertial measurement unit to monitor the instantaneous attitude of the gondola. During the ascent part of the flight, the I/V characteristic curves of the cells will be continuously recorded so to allow for comparison of performance of the different photovoltaic technologies in identical, real stratospheric flight conditions, as well as to detect performance changes with external temperature, irradiance and altitude. Upon recovery of the experiment, post-flight inspection will also yield useful information on the solar cell compatibility with the high altitude environment

The ESA "Plasma Laboratory in Space" study

The European Space Agency has initiated, in the context of its General Studies Programme, a study of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by “space plasma physics”. A team of experts has been set-up to review a broad range of area including industrial plasma physics and pure plasma physics, astrophysical and solar-terrestrial areas. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on spatial scale (102 to104 m) intermediate between what is achievable on ground experiment and usual solar system plasma observations

Role of oxidative stress in chronic otitis media with effusion in children

Chronic otitis media with effusion (OME) is a common pathologic condition characterized by nonpurulent fluid in the middle ear (ME) that leads to moderate conductive hearing loss and flat tympanogram. During OME inflammatory cells generate large amounts of superoxide radicals to improve bactericidal activity. Overproduction of oxygen-derived free radicals induces oxidative damage in humans. Glutathione (GSH) is one of the major components of the antioxidant system that protects cells from oxidative stress. The aim of the study was to evaluate oxidative stress in chronic OME by investigation of ME fluids collected during myringotomy.  During myringotomy, fluid was collected from the ME to evaluate lipid peroxide levels in the effusion. Immunohistochemical study was also performed to assess the anatomical features of tympanic membrane. Fifty-nine children with ME effusion without any resolution after repeated medical treatments were enrolled in the study.  No morphological significant changes were observed. Lipid peroxide levels in all samples were high (mean 11.5 nmole/million cells), similar to the values found in other chronic diseases. GSH might be employed during surgery while applying ventilation tubes and after surgery to prevent oxidative stress. The high oxidant levels in chronic OME observed in our research and the improvement seen in children after antioxidant treatment suggest that oxygen-derived free radicals play an important role in chronic OME.

Plasma kinetics issues in an ESA study for a plasma laboratory in space

A study supported by the European Space Agency (ESA), in the context of its General Studies Programme, performed an investigation of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by ‘space plasma physics’. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on a spatial scale (101–104 m) intermediate between what is achievable on the ground and the usual solar system plasma observations. Detailed feasibility studies have been performed for three experiments: active magnetic experiments, largescale discharges and long tether–plasma interactions. The perspectives opened by these experiments are discussed for magnetic reconnection, instabilities, MHD turbulence, atomic excited states kinetics, weakly ionized plasmas,plasma diagnostics, artificial auroras and atmospheric studies. The discussion is also supported by results of numerical simulations and estimates

Upgraded Pulsating Heat Pipe Only For Space (U-Phos): Results of the 22nd Rexus Sounding Rocket Campaign

A large tube may still behave, to a certain extent, as a capillary in a micro-gravity environment. This very basic concept is here applied to a two-phase passive heat transfer devices in order to obtain a new family of hybrid wickless heat pipes. Indeed, a Loop Thermosyphon, which usually consists of a large tube, closed end to end in a loop, evacuated and partially filled with a working fluid and intrinsically gravity assisted, may become a capillary tube in space condition and turn its thermo-fluidic behavior into a so called Pulsating Heat Pipe (PHP), or better, a Space Pulsating Heat Pipe (SPHP). Since the objective of the present work is to experimentally demonstrate the feasibility of such a hybrid device, a SPHP has been designed, built, instrumented and tested both on ground and microgravity conditions on the 22nd ESA REXUS Sounding Rocket Campaign. Ground tests demonstrate that the device effectively work as a gravity assisted loop thermosyphon, whether the sounding rocket data clearly reveal a change in the thermal hydraulic behavior very similar to the PHP. Since a microgravity period of approximately 120s is not sufficient to reach a pseudo steady state regime, further investigation on a longer term weightless condition is mandatory

U-PHOS Project: Development of a Large Diameter Pulsating Heat Pipe Experiment on board REXUS 22

U-PHOS Project aims to analyse and characterise the behaviour of a large diameter Pulsating Heat Pipe (PHP) on board REXUS 22 sounding rocket. A PHP is a passive thermal control device consisting of a serpentine capillary tube, evacuated, partially filled with a working fluid and finally sealed. In this configuration, the liquid and vapour phases are randomly distributed in the form of liquid slugs and vapour plugs. The heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. On ground conditions, a small diameter is required in order to obtain a confined slug flow regime. In milli-gravity conditions, buoyancy forces become less intense and the PHP diameter may be increased still maintaining the slug/plug flow configuration typical of the PHP operation. Consequently, the PHP heat power capability may be increased too. U-PHOS aims at proving that a Large Diameter PHP effectively works in milli-g conditions by characterizing its thermal response during a sounding rocket flight. The actual PHP tube is made of aluminum (3 mm inner diameter, filled with FC-72), heated at the evaporator by a compact electrical resistance, cooled at the condenser by a Phase Change Material (PCM) embedded in a metallic foam. The tube wall temperatures are recorded by means of Fibre Bragg Grating (FBG) sensors; the local fluid pressure is acquired by means of a pressure transducer. The present work intends to report the actual status of the project, focusing in particular on the experiment improvements with respect to the previous campaign

FEEP and MicroFEEP Development

Two interesting fields of applications are envisaged for a miniaturized, modular FEEP thruster: first, micronewton-level missions. For drag-free control and fine pointing of scientific spacecraft, a miniaturized device would offer additional, albeit limited, dry mass savings, and increased ease of distributing the thrusters over the spacecraft surface, as required. The second field is that of missions in the 1 - 10 mN thrust range, including attitude control and orbit maintenance of small to medium satellites. In this case, a modular FEEP thruster can lead to significant mass savings, due to both the reduced dry mass of the propulsion hardware and to the low propellant consumption resulting from the high specific impulse (about 8000 s). As for the associated high power-to-thrust ratio, this is becoming more and more manageable with the increased power availability of modern spacecraft buses. In this early phase of the miniaturized FEEP development, several engineering problems have been addressed, including silicon compatibility with the propellant (cesium, indium or other liquid metals) and propellant reservoir sealing. Electrode geometry optimization has been also investigated. Prototype microslits have been manufactured with the desired geometrical parameters, and emission tests are underway. Various accelerator electrode configurations, featuring arrays of wires and perforated thin plates, have been studied