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Land of gas and dust – exploring bursting cavities on comet 67P
No full textGas and dust outbursts are recurring phenomena on comets, offering critical insights into their subsurface activities. On comet 67P/Churyumov–Gerasimenko, two distinct outburst types have been identified: CO2-dominated ‘summer fireworks’ near perihelion and water-driven events often linked to cliff collapses outside the perihelion period. While CO2-dominated outbursts are thought to originate from subsurface gas cavities, the properties of these cavities remain poorly understood. In this study, we modelled the outgassing dynamics and dust velocities of outburst events using Rosetta/ROSINA data to estimate the characteristics of subsurface gas cavities and their impact on ejected particle dynamics. Our results indicate that CO2-dominated events involve subsurface cavities with radii ranging from 15 to 62 m for an equivalent half-sphere geometry, depending on gas distribution assumptions. Conversely, water-driven outbursts would require subsurface temperatures far above equilibrium, supporting the hypothesis of mechanical processes like cliff collapses exposing ices to sublimation. Dust velocities in CO2-dominated events – while aligning with results from other Rosetta instruments – were notably higher across all grain sizes compared to water-driven events, reflecting distinct dynamics in dust ejection. These findings highlight the critical role of subsurface gas reservoirs in driving explosive outbursts and suggest a strong connection between cometary activity, volatile distribution, and structural conditions. This study emphasizes the need for high-resolution data on subsurface volatiles from future missions and more refined modelling and experiments to further elucidate these mechanisms, with potential broader implications for our understanding of cometary activity
Multi-Platform Observations of the Radial Penetration of Substorm Injected Electrons and Subsequent Slot-Filling Event
No full textOn 15 February 2018 a co-rotating interaction region (CIR) from an equatorial coronal hole reached the Earth. The CIR initiated a moderate and slowly intensifying geomagnetic storm, which began with a large and strong substorm injection. The substorm injection was exceptionally well-observed by an array of spacecraft including LANL-GEO satellites, Van Allen Probes (RBSP), Arase (ERG), and MetOp/POES, as well as ground-based instruments. These observations enable the unambiguous identification of several important features that have been impossible to measure directly in other events. The substorm injection extended well inside the geosynchronous orbit. A fortuitous conjunction of RBSP-A (moving inbound) and Arase (simultaneously moving outbound at the same magnetic local time) allows us to establish, very precisely, the location of the inner edge of the injection region at L = 3.8−3.9. In supporting observations, North American riometers saw precipitation extending down to L ≈ 4 but not lower. Arase and RBSP-A also observed whistler-mode hiss waves inside the plasmasphere. Analysis of the resonance conditions shows, conclusively, and for the first time, that they were produced by the drifting injected electrons. RBSP-A observations also show the injection (or transport) of electrons into or through the slot region within hours of the substorm injection onset. Previous studies were not able to clearly connect or separate substorm injections and slot-filling processes. These new observations clearly identify slot-filling as a spatially and temporally separate process that is not a direct result of substorm injection
Inventaire des archives de la commune de Custinne : Dépôt 2025 : 1920-1976 (1982)
No full textCet inventaire offre une vue d’ensemble claire et rigoureuse de deux siècles de vie communale à Custinne, depuis l’organisation locale jusqu’aux évolutions du territoire et de la population. Un outil fiable pour comprendre en profondeur l’histoire d’une communauté rurale et les traces qu’elle a laissées dans ses archives. On y découvre l’évolution d’un territoire composé de hameaux, de terres agricoles, de bois et de patrimoines emblématiques — de l’église Sainte-Hélène à la chapelle Saint-Gilles — ainsi que la vie quotidienne d’une population en déclin progressif au fil des recensements. Les documents éclairent toutes les facettes de l’administration locale : délibérations du Conseil et du Collège, finances, cadastre, élections, travaux publics, enseignement, affaires militaires, bienfaisance et organisation du culte.The records described in this inventory are held at the State Archives in Nalur (inventory code 525 - I 263).This inventory is the fixed published version dated 16-12-2025. For the dynamic inventory under active revision, including recent updates and additions, please consult our online search platform AGATHA. In AGATHA, you can also request the archival items you wish to consult in the reading room
Jaarverslag Rijksarchief 2024
No full text2024 was een kanteljaar voor het Rijksarchief: tussen financiële druk en digitale vernieuwing bewees de instelling haar veerkracht. Met strikte begrotingsdiscipline, strategische keuzes en de lancering van AGATHA, een vernieuwende online zoekomgeving, bouwde het Rijksarchief verder aan een toegankelijk en toekomstgericht collectief geheugen. Ondanks beperkte middelen bleef de missie helder: kennis bewaren, delen en duiden. Dit jaarverslag toont hoe het Rijksarchief zijn rol als hoeder van transparantie en democratie versterkt, en hoe het – te midden van onzekerheid – blijft investeren in een digitale toekomst waar geschiedenis en samenleving elkaar ontmoeten
Inventaire des archives de la commune de Sainte-Cécile : Dépôt 2011 (1812) 1844-1976 (1980)
No full textCet inventaire donne accès à un riche fonds d’archives communales retraçant près de deux siècles de vie locale à Sainte-Cécile, de l’époque napoléonienne à la fusion des communes. Il couvre l’ensemble des missions communales : administration, finances, patrimoine, état civil, population, enseignement, assistance publique, élections, travaux publics et culte. Ces documents offrent un éclairage concret sur l’évolution du village, de ses institutions et de ses habitants. Structuré selon les normes archivistiques en vigueur, l’inventaire constitue un outil de recherche clair et fiable pour l’histoire locale, sociale, démographique et généalogique, à destination des chercheurs comme du grand public.The records described in this inventory are held at the State Archives in Arlon (inventory code 521 - AEA 197).This inventory is the fixed published version dated 31-12-2025. For the dynamic inventory under active revision, including recent updates and additions, please consult our online search platform AGATHA. In AGATHA, you can also request the archival items you wish to consult in the reading room
The Venus Emissivity Mapper (VEM): instrument science performance requirements derived from VERITAS and EnVision
No full textWe present the Venus Emissivity Mapper (VEM) onboard NASAs Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS) and ESAs (EnVision) Venus orbiter missions. The VEM instrument (on EnVision called VenSpec-M), is a multispectral imager for mapping of the Venus surface and its lower atmosphere. This is realized by observation through narrow-band atmospheric windows present in the near-infrared spectral region around 1 μm. For the first time, VEM will provide a global Venus coverage of > 70% with a high signal-to-noise ratio on the order of 100 to detect thermal emissions like volcanic activity, surface rock composition, water abundance and cloud formation. Since VEM for VERITAS and VenSpec-M for EnVision are being developed almost simultaneously, the instrument development approach can be made very efficient. By tailoring the science level, interface and environmental requirements of both missions to a joint requirements baseline, a single instrument design can be established. Focusing on the science requirement breakdown, this paper presents the key scientific requirements derived from VERITAS and EnVision and how they translate into verifiable technical instrument requirements. The VEM/VenSpec-M project is in its preliminary design phase. The instrument preliminary design review (PDR) is planned in 2025 for VERITAS and EnVision. Two flight models (FMs) are currently scheduled for delivery to the VERITAS S/C in 2028 and one FM to the EnVision S/C in 2029. First VEM/VenSpec-M data obtained from Venus orbit is expected after launch of the two missions currently scheduled in 2031
