A non-dispersive approach for a Raman gas sensor

Although Raman spectroscopy is widely used on solids and liquids, its application on gaseous samples is far less commonplace due to technical issues related to dealing with very weak signals over a strong background. A demonstration of a possible approach for a simple, noninvasive Raman-based gas detector is presented and evaluated. This setup is meant to perform nitrogen and oxygen gas concentration measurements through Raman scattering working with optical filters instead of the traditional spectrograph and a lighting-grade 532 nm diode-pumped solid state laser as the pumping source. An industrial-grade CMOS camera is used as the detector, taking full advantage of the low noise and spatial resolution of this device. The system has been tested for both oxygen and nitrogen in a gas flow cell. Nitrogen measurement in a glass vial is reported in order to demonstrate and show some of the advantages that could be obtained with the use of an imaging detector instead of a single pixel one. The reported measurements show that even without using a dispersion spectrometer, this approach enables an indicative, noninvasive gas detection through glass vials with significant rejection of the elastic scattering contribution

Growth and Photosynthetic Efficiency of Microalgae and Plants with Different Levels of Complexity Exposed to a Simulated M-Dwarf Starlight

Oxygenic photosynthetic organisms (OPOs) are primary producers on Earth and generate surface and atmospheric biosignatures, making them ideal targets to search for life from remote on Earth-like exoplanets orbiting stars different from the Sun, such as M-dwarfs. These stars emit very low light in the visible and most light in the far-red, an issue for OPOs, which mostly utilize visible light to photosynthesize and grow. After successfully testing procaryotic OPOs (cyanobacteria) under a simulated M-dwarf star spectrum (M7, 365-850 nm) generated through a custom-made lamp, we tested several eukaryotic OPOs: microalgae (Dixoniella giordanoi, Microchloropsis gaditana, Chromera velia, Chlorella vulgaris), a non-vascular plant (Physcomitrium patens), and a vascular plant (Arabidopsis thaliana). We assessed their growth and photosynthetic efficiency under three light conditions: M7, solar (SOL) simulated spectra, and far-red light (FR). Microalgae grew similarly in SOL and M7, while the moss P. patens showed slower growth in M7 with respect to SOL. A. thaliana grew similarly in SOL and M7, showing traits typical of shade-avoidance syndrome. Overall, the synergistic effect of visible and far-red light, also known as the Emerson enhancing effect, could explain the growth in M7 for all organisms. These results lead to reconsidering the possibility and capability of the growth of OPOs and are promising for finding biosignatures on exoplanets orbiting the habitable zone of distant stars

Transcriptomic and photosynthetic analyses of Synechocystis sp. PCC6803 and Chlorogloeopsis fritschii sp. PCC6912 exposed to an M-dwarf spectrum under an anoxic atmosphere

IntroductionCyanobacteria appeared in the anoxic Archean Earth, evolving for the first time oxygenic photosynthesis and deeply changing the atmosphere by introducing oxygen. Starting possibly from UV-protected environments, characterized by low visible and far-red enriched light spectra, cyanobacteria spread everywhere on Earth thanks to their adaptation capabilities in light harvesting. In the last decade, few cyanobacteria species which can acclimate to far-red light through Far-Red Light Photoacclimation (FaRLiP) have been isolated. FaRLiP cyanobacteria were thus proposed as model organisms to study the origin of oxygenic photosynthesis as well as its possible functionality around stars with high far-red emission, the M-dwarfs. These stars are astrobiological targets, as their longevity could sustain life evolution and they demonstrated to host rocky terrestrial-like exoplanets within their Habitable Zone.MethodsWe studied the acclimation responses of the FaRLiP strain Chlorogloeopsis fritschii sp. PCC6912 and the non-FaRLiP strain Synechocystis sp. PCC6803 to the combination of three simulated light spectra (M-dwarf, solar and far-red) and two atmospheric compositions (oxic, anoxic). We first checked their growth, O2 production and pigment composition, then we studied their transcriptional responses by RNA sequencing under each combination of light spectrum and atmosphere conditions.Results and discussionPCC6803 did not show relevant differences in gene expression when comparing the responses to M-dwarf and solar-simulated lights, while far-red caused a variation in the transcriptional level of many genes. PCC6912 showed, on the contrary, different transcriptional responses to each light condition and activated the FaRLiP response under the M-dwarf simulated light. Surprisingly, the anoxic atmosphere did not impact the transcriptional profile of the 2 strains significantly. Results show that both cyanobacteria seem inherently prepared for anoxia and to harvest the photons emitted by a simulated M-dwarf star, whether they are only visible (PCC6803) or also far-red photons (PCC6912). They also show that visible photons in the simulated M-dwarf are sufficient to keep a similar metabolism with respect to solar-simulated light.ConclusionResults prove the adaptability of the cyanobacterial metabolism and enhance the plausibility of finding oxygenic biospheres on exoplanets orbiting M-dwarf stars

The Italian National Project of Astrobiology-Life in Space-Origin, Presence, Persistence of Life in Space, from Molecules to Extremophiles

The \u2018\u2018Life in Space\u2019\u2019 project was funded in the wake of the Italian Space Agency\u2019s proposal for the development of a network of institutions and laboratories conceived to implement Italian participation in space astrobiology experiments

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

Tunable diode laser absorption spectroscopy for oxygen detection

The evolution of diode laser sources for optical communications during the last years led to commercial availability of devices which are suitable for gas absorption spectroscopy in the near and mid infrared. In this work it is shown how the traditional limits of Tunable Diode Laser Absorption Spectroscopy are addressed with digital signal processing techniques and careful optical design towards the realization of gas sensing instruments with the stability, robustness and reliability that are required in an industrial environment. Being one of the most challenging gases to be sensed with this technique, oxygen was considered under many measurement aspects such as: • Non invasive monitoring; • Gas in scattering media sensing; • Sensing with back-scattering targets; • Pressure measurement techniques for weak absorption signals; • Time resolved, dynamic sensing; • Temperature measurement through absorption spectroscopy. Many of these aspects were considered together, leading to the developement of instruments tailored for real life industrial applications such as: • Oxygen sensing in partially transparent containers such as wine or soft drink bottles; • Monitoring of double glazing insulating glass gas filling machines; • Oxygen sensing in containers with backscattering targets such as food packagings. Other applications for the technique and experiments involving Gas in Scattering Media Absorption Spectroscopy were explored during a 6 months period at the Lunds Universitet - Lunds Tekniska Högskola - Atomfysik (Sweden) under the supervision of Prof. S. Svanberg: • Gas probing into porous fruit samples; • Gas sensing inside the human body as a medical diagnosis technique; • Oxygen measurement in fully scattering food containers; • Multi-line absorption spectroscopy as a temperature measurement.L’evoluzione delle sorgenti laser a diodo per le comunicazioni ottiche negli ultimi anni ha portato ad una disponibilità commerciale di dispositivi che si prestano alla spettroscopia di assorbimento di gas nel vicino e medio infrarosso. In questo lavoro si mostra come i limiti tradizionali della spettroscopia di assorbimento a diodi laser sintonizzabili vengano affrontati con tecniche di elaborazione numerica di segnali ed una attenta progettazione ottica rivolta alla realizzazione di strumenti per il rilevamento di gas caratterizzati dalla stabilità, robustezza ed affidabilità necessari per un ambiente industriale. Trattandosi di uno dei gas più critici per il rilevamento con questa tecnica, l’ossigeno è stato affrontato sotto molteplici aspetti di misura come: • Monitoraggio non invasivo; • Rilevazione di gas in mezzi diffondenti; • Rilevazione tramite bersagli retrodiffondenti; • Tecniche di misura di pressione per deboli segnali di assorbimento; • Rilevazione dinamica con risoluzione temporale; • Misure di temperatura attraverso spettroscopia di assorbimento. Molti di questi aspetti sono stati considerati simultaneamente portando allo sviluppo di strumenti appropriati ad un uso nel mondo reale in applicazioni industriali quali: • Rilevazione di ossigeno in contenitori parzialmente trasparenti come bottiglie di vino e bibite; • Controllo di macchine per il riempimento di pannelli isolanti in vetrocamera; • Rilevazione di ossigeno in contenitori con bersagli retrodiffondenti, quali confezioni alimentari. Altre applicazioni della tecnica ed esperimenti sulla spettroscopia di assorbimento di gas in mezzi porosi sono stati esplorati durante un periodo di 6 mesi presso Lunds Universitet - Lunds Tekniska Högskola - Atomfysik (Svezia) sotto la supervisione del Prof. S. Svanberg: • Analisi di gas in campioni porosi di frutta; • Rilevazione di gas all’interno del corpo umano come tecnica per la diagnostica medica; • Misura di ossigeno in contenitori completamente diffondenti per alimenti; • Spettroscopia di assorbimento multi-riga come misura di temperatura

Non-intrusive headspace gas measurements by laser spectroscopy – Performance validation by a reference sensor

Abstract in Undetermined The oxygen concentration in the headspace of a large number of liquid food containers is assessed with non-intrusive diode laser absorption spectroscopy. The results are compared to those given by a traditional intrusive measurement method. The upper portions of the containers are made of translucent but non-transparent plastic materials, through which the laser light is diffusively transmitted. Measurements are performed both on packages with modified atmosphere and with normal air conditions. It is concluded that the novel non-intrusive technique provides oxygen concentrations that generally differ by less than one percentage point from the reference sensor values

Determination of CO2 Content in the Headspace of Spoiled Yogurt Packages

The CO2 formation during food storage can often be correlated with the increase in yeast population. Yogurt and other dairy products are susceptible to yeast contamination. Accumulation of CO2 in the headspace of yogurt packages can lead to the eventual blowing off of the package. Therefore, determination of CO2 in the yogurt packages can indicate eventual unsafety of the product. The aim of this paper was to determine CO2 concentration in the headspace of different yogurt containers contaminated with yeast at the levels of 1 and 5 CFU/ml. Yeast Candida kefyr, previously isolated from spoiled yogurt, was used for contamination. Contaminated and control samples of yogurt were incubated at 30°C. A device based on tunable diode laser absorption spectroscopy was used for the measurement of CO2 concentration. The CO2 content in all analysed samples changed in a similar manner with slow increase to the value of 6% during the first 30 h and, after that, rapid accumulation to 17–20%. The initial level of yeast contamination did not have significant influence to the CO2 content trend. The increase in the number of yeast was observed after 10 h of incubation, and the final value of 6-7 log·CFU/cm3 was reached after 40 h of incubation. The significant increase in the yeast number can be correlated with the CO2 content in a way that CO2 concentration of 6% can be considered as critical for microbial spoilage. Since the TDLAS technique is simple and nondestructive, it can be a promising possibility for detection of the microbial spoilage in food

Passive unmanned sky spectroscopy for remote bird classification

We present a method based on passive spectroscopy with aim to remotely study flying birds. A compact spectrometer is continuously recording spectra of a small section of the sky, waiting for birds to obscure part of the field-of-view when they pass the field in flight. In such situations the total light intensity received through the telescope, looking straight up, will change very rapidly as compared to the otherwise slowly varying sky light. On passage of a bird, both the total intensity and the spectral shape of the captured light changes notably. A camera aimed in the same direction as the telescope, although with a wider field-of-view, is triggered by the sudden intensity changes in the spectrometer to record additional information, which may be used for studies of migration and orientation. Example results from a trial are presented and discussed. The study is meant to explore the information that could be gathered and extracted with the help of a spectrometer connected to a telescope. Information regarding the color, size and height of flying birds is discussed. Specifically, an application for passive distance determination utilizing the atmospheric oxygen A-band absorption at around 760 nm is discussed