Effects of the fertilizer added with dmpp on soil nitrous oxide emissions and microbial functional diversity

Agricultural sites contribute extensively to atmospheric emissions of climate-altering gases such as nitrous oxide. Several strategies have been considered to mitigate the impact of agriculture on climate, among these the utilization of fertilizers added with nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) may represent a suitable solution. DMPP inhibits the growth and activity of ammonia-oxidizing microorganisms, particularly the ammonia-oxidizing bacteria, which are involved in N2O production. At present, little information is available on the effects of DMPP on the catabolic diversity of soil microbial community. In this study, the N2O emission by soil was performed by using the static chamber technique. The biological determinations of the microbial biomass carbon and the catabolic profile were assessed by measuring the substrate-induced respiration during the entire growing season of a potato crop under two nitrogen treatments: fertilization with and without DMPP. Our results did not show a clear mitigation of N2O emission by DMPP, even if a tendency to lower N2O fluxes in DMPP plots occurred when soil temperatures were lower than 20◦C. Conversely, DMPP deeply affected the microbial biomass and the catabolism of soil microorganisms, exerting a negative effect when it accumulated in excessive doses in the soil, limiting the growth and the capacity of soil microorganism communities to use different substrates

Greenhouse gas emissions from urban area of Naples

Urban areas are among the main causes of greenhouse gases emissions on the planet, despite covering relatively small areas of the land. Recently, a number of projects aim at monitoring the dynamics of city emissions using micro meteorological measurements by applying the technique of eddy correlation for measuring the fluxes of carbon dioxide, water, methane and energy. In this perspective, a super-site for the measurement of atmospheric pollutants from urban sources has been established in Naples (Campania, Southern Italy), where the complex layout of the coast and surrounding mountains favours the development of combined sea breeze upslope winds and the evolution of return flows with several layers of pollutants and subsidence. At the super-site, an eddy covariance tower has been installed on the rooftop of the Meteorological Observatory of Largo San Marcellino, situated in the historical city centre: a fast response ultrasonic anemometer (Gill WindMaster) has been mounted on a 10-m mast, alongside three insulated inlet lines through which the air is sampled for gaseous pollutants and particulate matter. The height of the terrace is on average 35 m above the irregular street level, resulting in an overall measuring height of 45 m. Mixing ratios of CO2, CH4 and H2O are measured by an infrared spectrometer (10 Hz, Los Gatos Research). The results shown that the mean urban levels of CO2 are between 420-520 ppm; the mean levels of CH4 span between 1.85-2.48 ppm. These fluxes are representative of varying footprint source areas, covering the historical centre of Naples, the harbour, and some main traffic arteries of the city. The analysis of these measurements on long-term will allow to establish relationships between the fluxes of greenhouse gases and the other pollutant species measured

Protected silver coating for Ariel telescope mirrors: study of ageing effects

The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel), selected as ESA’s fourth mediumclass mission in the Cosmic Vision program, is set to launch in 2029. The objective of the study is to conduct spectroscopic observations of approximately one thousand exoplanetary atmospheres for better understanding the planetary system formation and evolution and identifying a clear link between the characteristics of an exoplanet and those of its parent star. The realization of the Ariel’s telescope is a challenging task that is still ongoing. It is an off-axis Cassegrain telescope (M1 parabola, M2 hyperbola) followed by a re-collimating off-axis parabola (M3) and a plane fold mirror (M4). It is made of Al 6061 and designed to operate at visible and infrared wavelengths. The mirrors of the telescope will be coated with protected silver, qualified to operate at cryogenic temperatures. The qualification of the coating was performed according to the ECSS Q-ST-70-17C standard, on a set of samples that have been stored in ISO 6 cleanroom conditions and are subjected to periodic inspection and reflectance measurements to detect any potential performance degradation. The samples consist of a set of Aluminum alloy Al 6061-T651 disks coated with protected silver. This paper presents the results of the morphological characterization of the samples based on Atomic Force Microscopy (AFM) and the reflectivity measurement in the infrared by Fourier Transform Infrared (FTIR) spectroscopy

Planning the integration and test of a space telescope with a 1 m aluminum primary mirror: the Ariel mission case

Ariel (Atmospheric Remote-Sensing Infrared Exoplanet Large Survey) is ESA’s M4 mission of the “Cosmic Vision” program, with launch scheduled for 2029. Its purpose is to conduct a survey of the atmospheres of known exoplanets through transit spectroscopy. Ariel is based on a 1 m class telescope optimized for spectroscopy in the waveband between 1.95 and 7.8 µm, operating at cryogenic temperatures in the range 40–50 K. The Ariel Telescope is an off-axis, unobscured Cassegrain design, with a parabolic recollimating tertiary mirror and a flat folding mirror directing the output beam parallel to the optical bench. The secondary mirror is mounted on a roto-translating stage for adjustments during the mission. The mirrors and supporting structures are all realized in an aerospace-grade aluminum alloy T6061 for ease of manufacturing and thermalization. The low stiffness of the material, however, poses unique challenges to integration and alignment. Care must be therefore employed when designing and planning the assembly and alignment procedures, necessarily performed at room temperature and with gravity, and the optical performance tests at cryogenic temperatures. This paper provides a high-level description of the Assembly, Integration and Test (AIT) plan for the Ariel telescope and gives an overview of the analyses and reasoning that led to the specific choices and solutions adopted

The instrument control unit of the AIRS instrument on-board the ARIEL mission: design status after PDR

ARIEL (Atmospheric Remote-sensing InfraRed Large-survey) is the fourth medium-class mission (M4) of the European Space Agency, part of the Cosmic Vision program, whose launch is planned by late 2029. ARIEL aims to study the composition of exoplanet atmospheres, their formation and evolution. The ARIEL’s target will be a sample of about 1000 planets observed with one or more of the following methods: transit, eclipse and phase-curve spectroscopy, in both visible and infrared light. The scientific payload is composed by a reflective telescope having a 1m-class elliptical primary mirror, built in solid Aluminum, and two focal-plane instruments: FGS and AIRS. FGS (Fine Guidance System)3 has the double purpose of performing photometry (0.50-0.55 µm) and low resolution spectrometry over three bands (from 0.8 to 1.95 µm) and, simultaneously, to provide data to the spacecraft AOCS (Attitude and Orbit Control System). AIRS (ARIEL InfraRed Spectrometer) instrument will perform IR spectrometry in two wavelength ranges: between 1.95 and 3.9 µm (with a spectral resolution R > 100) and between 3.9 and 7.8 µm with a spectral resolution R > 30. This paper provides the status of the ICU (Instrument Control Unit), an electronic box whose purpose is to command and supply power to the AIRS warm front-end (as well as acquire science data from its two channels) and to command and control the TCU (Telescope Control Unit)

Development, manufacturing, and testing of Ariel’s structural model prototype flexure hinges

The Atmospheric Remote-Sensing Infrared Exoplanet Large Survey (Ariel) is the M4 mission adopted by ESA's "Cosmic Vision" program. Its launch is scheduled for 2029. The mission aims to study exoplanetary atmospheres on a target of ∼ 1000 exoplanets. Ariel's scientific payload consists of an off-axis, unobscured Cassegrain telescope. The light is directed towards a set of photometers and spectrometers with wavebands between 0.5 and 7.8 μm and operating at cryogenic temperatures. The Ariel Space Telescope consists of a primary parabolic mirror with an elliptical aperture of 1.1· 0.7 m, all bare aluminum. To date, aluminum mirrors the size of Ariel's primary have never been made. In fact, a disadvantage of making mirrors in this material is its low density, which facilitates deformation under thermal and mechanical stress of the optical surface, reducing the performance of the telescope. For this reason, studying each connection component between the primary mirror and the payload is essential. This paper describes, in particular, the development, manufacturing, and testing of the Flexure Hinges to connect Ariel's primary Structural Model mirror and its optical bench. The Flexure Hinges are components already widely used for space telescopes, but redesigning from scratch was a must in the case of Ariel, where the entire mirror and structures are made of aluminum. In fact, these flexures, as well as reducing the stress due to the connecting elements and the launch vibrations and maintaining the alignment of all the parts preventing plastic deformations, amplified for aluminum, must also have resonance frequencies different from those usually used, and must guarantee maximum contact (tolerance in the order of a micron) for the thermal conduction of heat. The entire work required approximately a year of work by the Ariel mechanical team in collaboration with the industry

The instrument control unit of the ARIEL payload: design evolution following the unit and payload subsystems SRR (system requirements review)

ARIEL (Atmospheric Remote-sensing InfraRed Large-survey) is a medium-class mission of the European Space Agency, part of the Cosmic Vision program, whose launch is foreseen by early 2029. ARIEL aims to study the composition of exoplanet atmospheres, their formation and evolution. The ARIEL’s target will be a sample of about 1000 planets observed with one or more of the following methods: transit, eclipse and phase-curve spectroscopy, at both visible and infrared wavelengths simultaneously. The scientific payload is composed by a reflective telescope having a 1m-class elliptical primary mirror, built in solid Aluminium, and two focal-plane instruments: FGS and AIRS. FGS (Fine Guidance System)1 has the double purpose, as suggested by its name, of performing photometry (0.50-0.55 µm) and low resolution spectrometry over three bands (from 0.8 to 1.95 µm) and, simultaneously, to provide data to the spacecraft AOCS (Attitude and Orbit Control System) with a cadence of 10 Hz and contributing to reach a 0.02 arcsec pointing accuracy for bright targets. AIRS (ARIEL InfraRed Spectrometer) instrument will perform IR spectrometry in two wavelength ranges: between 1.95 and 3.9 µm (with a spectral resolution R > 100) and between 3.9 and 7.8 µm with a spectral resolution R > 30. This paper provides the status of the ICU (Instrument Control Unit), an electronic box whose purpose is to command and supply power to AIRS (as well as acquire science data from its two channels) and to command and control the TCU (Telescope Control Unit)

Preliminary surface charging analysis of Ariel payload dielectrics in early transfer orbit and L2-relevant space environment

Ariel [1] is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars. The operational orbit of the spacecraft is baselined as a large amplitude halo orbit around the Sun-Earth L2 Lagrangian point, as it offers the possibility of long uninterrupted observations in a fairly stable radiative and thermo-mechanical environment. A direct escape injection with a single passage through the Earth radiation belts and no eclipses is foreseen. The space environment around Earth and L2 presents significant design challenges to all spacecraft, including the effects of interactions with Sun radiation and charged particles owning to the surrounding plasma environment, potentially leading to dielectrics charging and unwanted electrostatic discharge (ESD) phenomena endangering the Payload operations and its data integrity. Here, we present some preliminary simulations and analyses about the Ariel Payload dielectrics and semiconductors charging along the transfer orbit from launch to L2 include

FEA testing the pre-flight Ariel primary mirror

Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is an ESA M class mission aimed at the study of exoplanets. The satellite will orbit in the lagrangian point L2 and will survey a sample of 1000 exoplanets simultaneously in visible and infrared wavelengths. The challenging scientific goal of Ariel implies unprecedented engineering efforts to satisfy the severe requirements coming from the science in terms of accuracy. The most important specification – an all-Aluminum telescope – requires very accurate design of the primary mirror (M1), a novel, off-set paraboloid honeycomb mirror with ribs, edge, and reflective surface. To validate such a mirror, some tests were carried out on a prototype – namely Pathfinder Telescope Mirror (PTM) – built specifically for this purpose. These tests, carried out at the Centre Spatial de Liège in Belgium – revealed an unexpected deformation of the reflecting surface exceeding a peek-to-valley of 1µm. Consequently, the test had to be re-run, to identify systematic errors and correct the setting for future tests on the final prototype M1. To avoid the very expensive procedure of developing a new prototype and testing it both at room and cryogenic temperatures, it was decided to carry out some numerical simulations. These analyses allowed first to recognize and understand the reasoning behind the faults occurred during the testing phase, and later to apply the obtained knowledge to a new M1 design to set a defined guideline for future testing campaigns

The telescope assembly of the Ariel space mission: an updated overview

Ariel (Atmospheric Remote-Sensing Infrared Exoplanet Large Survey) is the adopted M4 mission in the framework of the ESA “Cosmic Vision” program. Its purpose is to survey the atmospheres of known exoplanets through transit spectroscopy. The launch is scheduled for 2029. The scientific payload consists of an off-axis, unobscured Cassegrain telescope feeding a set of photometers and spectrometers in the waveband 0.5-7.8 µm and operating at cryogenic temperatures (55 K). The Telescope Assembly is based on an innovative fully aluminium design to tolerate thermal variations to avoid impacts on the optical performance; it consists of a primary parabolic mirror with an elliptical aperture of 1.1 m (the major axis), followed by a hyperbolic secondary that is mounted on a refocusing system, a parabolic re-collimating tertiary and a flat folding mirror directing the output beam parallel to the optical bench. An innovative mounting system based on 3 flexure hinges supports the primary mirror on one of the optical bench sides. The instrument bay on the other side of the optical bench houses the Ariel IR Spectrometer (AIRS) and the Fine Guidance System / NIR Spectrometer (FGS/NIRSpec). The Telescope Assembly is in phase B2 towards the Critical Design Review; the fabrication of the structural and engineering models has started; some components, i.e., the primary mirror and its mounting system are undergoing further qualification activities. This paper aims to update the scientific community on the progress concerning the development, manufacturing and qualification activity of the ARIEL Telescope Assembly