FORESAIL-1 cubesat mission to measure radiation belt losses and demonstrate de-orbiting

Abstract Today, the near-Earth space is facing a paradigm change as the number of new spacecraft is literally sky-rocketing. Increasing numbers of small satellites threaten the sustainable use of space, as without removal, space debris will eventually make certain critical orbits unusable. A central factor affecting small spacecraft health and leading to debris is the radiation environment, which is unpredictable due to an incomplete understanding of the near-Earth radiation environment itself and its variability driven by the solar wind and outer magnetosphere. This paper presents the FORESAIL-1 nanosatellite mission, having two scientific and one technological objectives. The first scientific objective is to measure the energy and flux of energetic particle loss to the atmosphere with a representative energy and pitch angle resolution over a wide range of magnetic local times. To pave the way to novel model - in situ data comparisons, we also show preliminary results on precipitating electron fluxes obtained with the new global hybrid-Vlasov simulation Vlasiator. The second scientific objective of the FORESAIL-1 mission is to measure energetic neutral atoms (ENAs) of solar origin. The solar ENA flux has the potential to contribute importantly to the knowledge of solar eruption energy budget estimations. The technological objective is to demonstrate a satellite de-orbiting technology, and for the first time, make an orbit manoeuvre with a propellantless nanosatellite. FORESAIL-1 will demonstrate the potential for nanosatellites to make important scientific contributions as well as promote the sustainable utilisation of space by using a cost-efficient de-orbiting technology.Peer reviewe

Reactions of SIV species with organic compounds: formation mechanisms of organo-sulfur derivatives in atmospheric aerosols

@ CARE+MPI:JSH:YDU:SPR:CGOInternational audienceSecondary organic aerosol (SOA) have an important impact on climate, air quality and human health. However the chemical reactions involved in their formation and growth are not fully understood or well-constrained in climate models. It is well known that inorganic sulfur (mainly in oxidation states (+IV) and (+VI)) plays a key role in aerosol formation, for instance sulfuric acid is known to be a good nucleating gas. In addition, acid-catalyzed heterogeneous reactions of organic compounds has shown to produce new particles, with a clear enhancement in the presence of ozone (Iinuma 2013). Organosulfates have been detected in tropospheric particles and aqueous phases, which suggests they are products of secondary organic aerosol formation process (Tolocka 2012). Originally, the production of organosulfates was explained by the esterification reaction of alcohols, but this reaction in atmosphere is kinetically negligible. Other formation pathways have been suggested such as hydrolysis of peroxides and reaction of organic matter with sulfite and sulfate radical anions (SO3-•, SO4-•) (Nozière 2010), but it remains unclear if these can completely explain atmospheric organo-sulfur aerosol loading.To better understand the formation of organo-sulfur compounds, we started to investigate the reactivity of SIV species (SO2 and SO32-) with respect to specific functional groups (organic acids and double bonds) on atmospherically relevant carboxylic acids and alkenes. The experiments were carried out in the homogeneous aqueous phase and at the solid-gas interface. A custom built coated-wall flow tube reactor was developed to control relativity humidity, SO2 concentration, temperature and gas flow rate. Homogeneous and heterogeneous reaction kinetics were measured and resulting products were identified using liquid chromatography coupled with an orbitrap mass spectrometer (LC-HR-MS). The experiments were performed with and without the presence of ozone in order to evaluate any impact on the SIV oxidation and product formation. Preliminary results reveal that oxidation of SIV species can occur under a variety of atmospherically relevant conditions. Furthermore, LC-HR-MS analysis confirms the formation of organo-sulfur compounds that could derive from sulfate and/or the sulfite radical anion. These results elucidate the role of organo-sulfates aqueous and interfacial chemistry, important for our scientific understanding of atmospheric SOA formation

A Potentially New Aerosol Particle Source Due to Photochemistry at the Ocean Surface Microlayer

SSCI-VIDE+CARE+PAT:SRS:MPI:LTI:SPR:CGOInternational audienceThe sea surface microlayer extensively covers the Earthâs oceans and is host to numerous organic and biogenic compounds which also concentrate there. Many bulk and surface-bound organic materials, such as humic acids, are photosensitizers and, thus have the potential to trigger unique chemistry when irradiated by sunlight. It is well recognized that the exchange of gases and particles with the atmosphere are impacted by the presence of the sea surface microlayer, however, the exact mechanisms which accomplish this are not fully understood. Here, we present a laboratory study on VOC production and emission due to photochemical reactions occurring at the sea surface microlayer followed by secondary organic aerosol (SOA) generation. These data are valuable to the assessment of VOC and SOA atmospheric budgets and increase our fundamental understanding of their production.Laboratory experiments were conducted in a custom-built Teflon reaction chamber with a pure or sea water reservoir containing nonanoic acid, a model surfactant proxy for a surface microlayer, with and without the presence of humic acids. Experiments were performed under irradiation of UV and visible light in a humidified low NOx and low ozone environment. Concentrations of VOCs were measured over time using a proton-transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Characterization of organic and inorganic compounds in water and aerosol was performed using ion chromatography and liquid chromatography-high resolution-mass spectrometry (LC-HR-MS) utilizing a quadrupole-orbitrap detector. Aerosol size distribution and numbers were continually monitored. Physical and chemical characterization of SOA was investigated with scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure (STXM/NEXAFS) spectroscopy using the PolLux X-ray beamline at the Swiss Light Source.Production of VOCs was observed while the chamber air and water were irradiated with UV light for the system, nonanoic acid and pure water (background levels of ozone and NOx). Gas phase products include alkenes, aldehydes and dienes, such as isoprene as observed by PTR-ToF-MS in two different ionization modes (H3O+ and NO+) and confirmed from independent experiments in a controlled Quartz reaction cell. Introduction of ozone into the chamber triggered new particle formation followed by condensational growth, likely due to the ozonolysis of present gas phase products having carbon double bonds to form lower volatility compounds. When a salt water system was used containing humic acid and the surfactant, we find that the VOC and SOA yield is further enhanced under irradiation. A spectroscopic signature of SOA produced in our chamber was acquired with STXM/NEXAFS characterized by oxygenated organic material dominated by the presence of the carboxyl and carbonyl functional groups. Secondary absorption peaks indicated a minor presence of hydroxyl functionality and carbon double bonding. This method allows for spectral comparison between the generated SOA and known SOA spectra from field and laboratory studies.We suggest that light absorbing compounds, or photosensitizers, present at the interface trigger the production of a radical chemistry proceeding through an initiative step of hydrogen-abstraction on the surfactant, nonanoic acid. through hydrogen abstraction. Due to the high concentration of organic in the microlayer, unique chemistry follows involving self-reactions, which are unfavorable in the gas and aqueous phase. Ozonolysis of these products then stimulates SOA formation. These results underscore the significance of photon-induced chemistry at the ocean-atmosphere interface with the potential to significantly impact on VOCs and SOA over the oceans

Organosulfate Formation through the Heterogeneous Reaction of Sulfur Dioxide with Unsaturated Fatty Acids and Long-Chain Alkenes

SSCI-VIDE+CARE+MPI:KLI:JSH:YDU:SPR:CGOInternational audienceThe heterogeneous reaction between SO2 and unsaturated compounds results in the efficient production of organosulfates for several fatty acids and long-chain alkenes. The presence of an acid group, the physical state of the reactants (solid or liquid), the nature of the double bond (cis, trans, terminal), and the use of light irradiation all have an impact on the reaction rate. The reaction was investigated using different set-ups (coated flow tube, aerosol flow tube, and diffuse reflectance infrared Fourier transform cell). The reaction products were identified by high-resolution mass spectrometry and the impact of this reaction on organosulfate formation in the atmosphere is discussed

Organosulfate formation through the heterogeneous reaction of sulfur dioxide with unsaturated compounds

SSCI-VIDE+CARE+CGO:SPRInternational audienceThe atmospheric formation of organosulfur derivatives through reaction with SO2 is generally mediated by oxidants such as O3, OH; recently we have proposed a direct reaction between SO2 and unsaturated compounds as another possible pathway for organosulfate formation in the troposphere. For the first time it was shown recently that a heterogeneous reaction between SO2 and oleic acid (OA; an unsaturated fatty acid) takes place and leads efficiently to the formation of organosulfur products. Here, we demonstrate that this reaction proceeds on various unsaturated compounds, and may therefore have a general environmental impact. We used different experimental strategies i.e., a coated flow tube (CFT), an aerosol flow tube (AFT) and a DRIFT (diffuse reflectance infrared Fourier transform) cell. The reaction products were analyzed by means of liquid chromatography coupled to a high resolution mass spectrometer (LC-HR-MS).We report indeed that SO2 reacts with large variety of C=C unsaturations and that even in the presence of ozone, SO2 reacts with OA leading to organosulfur products. A strong enhancement in product formation is observed under actinic illumination, increases the atmospheric significance of this chemical pathway. This is probably due to the chromophoric nature of the SO2 adduct with C=C bonds, and means that the contribution of this direct addition of SO2 could be in excess of 5%. The detection in atmospheric aerosols of organosulfur compounds with the same chemical formulae as the products identified here seems to confirm the importance of this reaction in the atmosphere

Thermochemical Studies of Epoxides and Related Compounds

Gas-phase heats of formation for the four butene oxide isomers are reported. They were obtained by measuring the condensed-phase heat of reduction to the corresponding alcohol using reaction calorimetry. Heats of vaporization were determined and allow gas-phase heats of formation to be obtained. The experimental measurements are compared to calculations obtained using a variety of computational methods. Overall, the G3 and CBS-APNO methods agree quite well with the experimental data. The influence of alkyl substituents on epoxide stability is discussed. Comparisons to alkenes, cyclopropanes, aziridines, thiiranes, and phosphiranes are also made. Isodesmic-type reactions were used to determine strain energies of the epoxides and related compounds with various substituents