Analysis of CN emission as a marker of organic compounds in meteoroids using laboratory simulated meteors

Fragments of small solar system bodies entering Earth's atmosphere have possibly been important contributors of organic compounds to the early Earth. The cyano radical (CN) emission from meteors is considered as potentially one of the most suitable markers of organic compounds in meteoroids, however, its detection in meteor spectra has been thus far unsuccessful. With the aim to improve our abilities to identify CN emission in meteor observations and use its spectral features to characterize the composition of incoming asteroidal meteoroids, we present a detailed analysis of CN emission from high-resolution spectra of 22 laboratory simulated meteors including ordinary, carbonaceous, and enstatite chondrites, as well as a large diversity of achondrites (i.e., ureilite, aubrite, lunar, martian, howardite, eucrite, and diogenite), mesosiderite, and iron meteorites. We describe the variations of CN emission from different classes of asteroidal meteor analogues, its correlation and time evolution relative to other major meteoroid components. We demonstrate that CN can be used as a diagnostic spectral feature of carbonaceous and carbon-rich meteoroids, while most ordinary chondrites show no signs of CN. Our results point out strong correlation between CN and H emission and suggest both volatile features are suitable to trace contents of organic matter and water molecules present within meteoroids. For the application in lower resolution meteor observations, we demonstrate that CN can be best recognized in the early stages of ablation and for carbon-rich materials by measuring relative intensity ratio of CN band peak to the nearby Fe I-4 lines

Die Kompetenzkatastrophe - oder "Die Wiederkehr der Bildungsphilister durch die Hintertür"

Seit Ende der sechziger Jahre konstruiert man immer wieder Äquivalenzbegriffe für Bildung, in der Regel entlehnt aus anderen Disziplinen. Kompetenz ist der derzeitige Favorit. [Der Autor stellt folgende Fragen in den Mittelpunkt seiner kritischen Betrachtungen :] Gibt es Gründe, die diesen Abschied von dem Bildungsbegriff plausibel erscheinen lassen? Oder hat man „nur“ vergessen, und zwar gründlich? Gründlich den „klassischen“ Bildungsbegriff eines Humboldt oder Schleiermacher, noch gründlicher die Kritik Burckhardts und Nietzsches im Namen einer „wahren Bildung“? Oder sind sie wieder da, die Ziel der schärfsten Polemik von Schiller, Schleiermacher u.a. waren, die „Bildungsphilister“? Hat man sich heute unter dem Banner der Wissensgesellschaft auf die Seite derer geschlagen, die Schleiermacher […] als die „alles verständigen und praktischen Menschen“ bezeichnete, die dabei glaubten, mit ihrem „eitlen Tun und Treiben“ auf dem „Gipfel der Menschheit und des Selbstverständnisses“ zu stehen: Beruf und Geschäft, das sei der Ernst des Lebens, Kultur und Bildung aber der Spaß? (DIPF/Orig.

Spallation on Carbon Ablators

A comprehensive analysis of publicly available research statements on spallation processes of ablative heat shield materials is presented. Based on the published data and numerical simulations thereof, a definition of spallation with respect to its fundamental parameters is given. Results from ablation and spallation experiments as well as analytical and numerical models are compared and discussed with respect to the conditions and mechanisms that lead to spallation. The driving mechanisms are oxidation, pyrolysis gas outflow, shear forces, and thermal stress. Based on the summary of the current state-of-knowledge of spallation, propositions are made for future experimental and numerical investigations

An open carbon–phenolic ablator for scientific exploration

Abstract Space exploration missions rely on ablative heat shields for the thermal protection of spacecraft during atmospheric entry flights. While dedicated research is needed for future missions, the scientific community has limited access to ablative materials typically used in aerospace. In this paper, we report the development of the HEFDiG Ablation-Research Laboratory Experiment Material (HARLEM), a carbon–phenolic ablator designed to supply the need for ablative materials in laboratory experiments. HARLEM is manufactured using polyacrylonitrile-based carbon fiber preforms and a simplified processing route for phenolic impregnation. We characterized the thermal protection performance of HARLEM in arcjet experiments conducted in the plasma wind tunnel PWK1 of the Institute of Space Systems at the University of Stuttgart. We assessed the performance of the new material by measuring surface recession rate and temperature using photogrammetry and thermography setups during the experiments, respectively. Our results show that HARLEM’s thermal protection performance is comparable to legacy carbon–phenolic ablators that have been validated in different arcjet facilities or in-flight, as demonstrated by calculations of the effective heat of ablation and scanning electron microscopy of as-produced samples. In-house manufacturing of carbon–phenolic ablators enables the addition of embedded diagnostics to ablators, allowing for the acquisition of data on internal pressure and more sophisticated pyrolysis analysis techniques

Aperçu du projet MetSpec - météores artificiels en test au sol

International audienceWe provide an overview of the MetSpec project, which aims to connect meteorite ablation laboratory experiments with meteor spectral observations in the atmosphere aiming at the development of a methodology to identify incoming planetary material distribution into the Earth’s atmosphere. We have selected 28 meteorites of different types to represent known planetary material compositions coming from asteroids, Vesta, Mars and the Moon. Some samples have been tested twice which resulted in overall 31 experiments. Three distinct test campaigns were realized in 2020, 2021 and 2022 with the High Enthalpy Flow Diagnostics Group in the Plasma Wind Tunnel PWK1 where they have developed a unique testing scenario. During the last and most elaborated campaign, 16 cameras observed the artificial meteors in the laboratory. Besides videos and online live streaming, instruments included several spectrometers, and optical and imaging instruments covering UV, visible and IR spectral range. This special collection in Icarus collects the resulting output from the different instruments and results. This overview article provides an introduction and summarizes the main findings of the experimental campaigns.Nous présentons une vue d'ensemble du projet MetSpec, qui vise à relier les expériences d'ablation de météorites en laboratoire aux observations spectrales de météorites dans l'atmosphère, dans le but de développer une méthodologie permettant d'identifier la distribution des matériaux planétaires entrants dans l'atmosphère terrestre. Nous avons sélectionné 28 météorites de différents types pour représenter les compositions connues de matériaux planétaires provenant d'astéroïdes, de Vesta, de Mars et de la Lune. Certains échantillons ont été testés deux fois, ce qui a donné lieu à 31 expériences au total. Trois campagnes d'essais distinctes ont été réalisées en 2020, 2021 et 2022 avec le High Enthalpy Flow Diagnostics Group dans la soufflerie à plasma PWK1, où ils ont développé un scénario d'essai unique. Au cours de la dernière campagne, la plus élaborée, 16 caméras ont observé les météores artificiels dans le laboratoire. Outre les vidéos et la diffusion en direct, les instruments comprenaient plusieurs spectromètres et des instruments optiques et d'imagerie couvrant les gammes spectrales de l'UV, du visible et de l'IR. Cette collection spéciale d'Icarus rassemble les résultats obtenus par les différents instruments. Cet article présente une introduction et résume les principaux résultats des campagnes expérimentales

Selective Regulation of Cardiac Organic Cation Transporter Novel Type 2 (OCTN2) in Dilated Cardiomyopathy

Organic cation transporters (OCT1-3 and OCTN1/2) facilitate cardiac uptake of endogenous compounds and numerous drugs. Genetic variants of OCTN2, for example, reduce uptake of carnitine, leading to heart failure. Whether expression and function of OCTs and OCTNs are altered by disease has not been explored in detail. We therefore studied cardiac expression, heart failure–dependent regulation, and affinity to cardiovascular drugs of these transporters. Cardiac transporter mRNA levels were OCTN2>OCT3>OCTN1>OCT1 (OCT2 was not detected). Proteins were localized in vascular structures (OCT3/OCTN2/OCTN1) and cardiomyocytes (OCT1/OCTN1). Functional studies revealed a specific drug-interaction profile with pronounced inhibition of OCT1 function, for example, carvedilol [half maximal inhibitory concentration (IC50), 1.4 μmol/L], diltiazem (IC50, 1.7 μmol/L), or propafenone (IC50, 1.0 μmol/L). With use of the cardiomyopathy model of coxsackievirus-infected mice, Octn2mRNA expression was significantly reduced (56% of controls, 8 days after infection). Accordingly, in endomyocardial biopsy specimens OCTN2 expression was significantly reduced in patients with dilated cardiomyopathy, whereas the expression of OCT1-3 and OCTN1 was not affected. For OCTN2 we observed a significant correlation between expression and left ventricular ejection fraction (r = 0.53, P < 0.0001) and the presence of cardiac CD3+ T cells (r = −0.45, P < 0.05), respectively. OCT1, OCT3, OCTN1, and OCTN2 are expressed in the human heart and interact with cardiovascular drugs. OCTN2 expression is selectively reduced in dilated cardiomyopathy patients and predicts the impairment of cardiac function