{"id":7183,"date":"2025-12-25T15:32:01","date_gmt":"2025-12-25T15:32:01","guid":{"rendered":"https:\/\/mehnatt.com\/?p=7183"},"modified":"2025-12-25T15:32:01","modified_gmt":"2025-12-25T15:32:01","slug":"short-notes-on-current-affairs-21-12-2025","status":"publish","type":"post","link":"https:\/\/mehnatt.com\/?p=7183","title":{"rendered":"Short notes on Current Affairs 21.12.2025"},"content":{"rendered":"\n<h3 class=\"wp-block-heading has-text-align-center has-ast-global-color-6-background-color has-background\">Tamil Nadu to conduct Hornbill Census<\/h3>\n\n\n\n<ul style=\"font-size:17px\" class=\"wp-block-list\">\n<li><strong>Purpose of the initiative<\/strong>\n<ul class=\"wp-block-list\">\n<li>Tamil Nadu Forest Department plans an extensive field exercise to estimate hornbill populations across forest landscapes.<\/li>\n\n\n\n<li>The survey forms part of the State\u2019s broader hornbill conservation initiative announced earlier in 2025.<\/li>\n\n\n\n<li>The exercise aims to generate reliable population data to inform long-term conservation planning.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Timing and rationale<\/strong>\n<ul class=\"wp-block-list\">\n<li>The survey will be conducted from late December 2025 to March or early April 2026.<\/li>\n\n\n\n<li>It coincides with the hornbills\u2019 breeding season, improving visibility and accuracy of population estimates.<\/li>\n\n\n\n<li>Breeding-season surveys also help identify nesting sites and critical habitats.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Geographical coverage (Phase I)<\/strong>\n<ul class=\"wp-block-list\">\n<li>Tiger Reserves:\n<ul class=\"wp-block-list\">\n<li>Anamalai Tiger Reserve<\/li>\n\n\n\n<li>Srivilliputhur\u2013Megamalai Tiger Reserve<\/li>\n\n\n\n<li>Kalakkad\u2013Mundathurai Tiger Reserve<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Forest ranges:\n<ul class=\"wp-block-list\">\n<li>Karamadai Range<\/li>\n\n\n\n<li>Mettupalayam Range (Coimbatore Forest Division)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Areas were prioritised based on historical records and previous hornbill sightings.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Survey methodology<\/strong>\n<ul class=\"wp-block-list\">\n<li>The line transect method will be employed.<\/li>\n\n\n\n<li>Teams comprising forest personnel, biologists, and researchers will walk several kilometres daily through identified habitats.<\/li>\n\n\n\n<li>Sightings will be recorded to estimate hornbill population density and distribution.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Species expected to be documented<\/strong>\n<ul class=\"wp-block-list\">\n<li>Great Hornbill<\/li>\n\n\n\n<li>Malabar Grey Hornbill<\/li>\n\n\n\n<li>Indian Grey Hornbill<\/li>\n\n\n\n<li>Malabar Pied Hornbill<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Conservation focus beyond population counts<\/strong>\n<ul class=\"wp-block-list\">\n<li>Emphasis on habitat protection, especially large, mature trees with natural hollows essential for hornbill nesting.<\/li>\n\n\n\n<li>Recognition that habitat loss, particularly the removal of old trees, poses a major threat to hornbill survival.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Institutional support and recent developments<\/strong>\n<ul class=\"wp-block-list\">\n<li>In July 2025, Tamil Nadu announced India\u2019s first Centre of Excellence for Hornbill Conservation.<\/li>\n\n\n\n<li>The centre is located at the Anamalai Tiger Reserve in Coimbatore district.<\/li>\n\n\n\n<li>It is expected to support research, monitoring, and conservation interventions.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Expected outcomes and significance<\/strong>\n<ul class=\"wp-block-list\">\n<li>The survey is expected to provide the most accurate hornbill population estimates for the State to date.<\/li>\n\n\n\n<li>Data will guide targeted habitat protection, species management, and policy decisions.<\/li>\n\n\n\n<li>The initiative strengthens Tamil Nadu\u2019s leadership role in hornbill conservation at the national level.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center has-ast-global-color-6-background-color has-background\">Drogue parachutes<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Context and objective<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">ISRO has successfully completed a series of qualification tests for drogue parachutes.<\/li>\n\n\n\n<li style=\"font-size:17px\">These tests are part of the development of the deceleration system for the Gaganyaan crew module.<\/li>\n\n\n\n<li style=\"font-size:17px\">The Gaganyaan mission is India\u2019s first human spaceflight programme.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Nature of the tests<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">The qualification tests focused specifically on drogue parachutes, a critical subsystem of the crew module.<\/li>\n\n\n\n<li style=\"font-size:17px\">Tests were conducted on December 18 and 19.<\/li>\n\n\n\n<li style=\"font-size:17px\">The purpose was to validate performance, reliability, and deployment under simulated re-entry conditions.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Testing facility<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">The tests were carried out at the Rail Track Rocket Sled (RTRS) facility.<\/li>\n\n\n\n<li style=\"font-size:17px\">The facility is operated by the Terminal Ballistics Research Laboratory (TBRL) in Chandigarh.<\/li>\n\n\n\n<li style=\"font-size:17px\">RTRS enables high-speed testing required for evaluating deceleration and stability systems.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Role of drogue parachutes<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Drogue parachutes are deployed during the atmospheric re-entry phase.<\/li>\n\n\n\n<li style=\"font-size:17px\">They play a crucial role in stabilising the crew module.<\/li>\n\n\n\n<li style=\"font-size:17px\">They reduce the module\u2019s velocity to a safe level before further stages of parachute deployment.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Technical significance<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Successful drogue parachute deployment is essential for crew safety during re-entry.<\/li>\n\n\n\n<li style=\"font-size:17px\">It ensures controlled deceleration and proper orientation of the crew module.<\/li>\n\n\n\n<li style=\"font-size:17px\">The system acts as a precursor to the deployment of larger main parachutes.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Programmatic importance<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">The successful tests mark a key milestone in the Gaganyaan programme.<\/li>\n\n\n\n<li style=\"font-size:17px\">They demonstrate progress toward ensuring safe human spaceflight capability.<\/li>\n\n\n\n<li style=\"font-size:17px\">The results contribute to overall mission readiness and confidence in re-entry systems.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Broader implications<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">The tests highlight collaboration between ISRO and defence research facilities like TBRL.<\/li>\n\n\n\n<li style=\"font-size:17px\">They underscore India\u2019s growing expertise in human-rated spaceflight technologies.<\/li>\n\n\n\n<li style=\"font-size:17px\">Each successful qualification test brings the Gaganyaan mission closer to operational execution.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Drogue Parachutes \u2013 Explained<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\"><strong>What they are<\/strong>\n<ul class=\"wp-block-list\">\n<li>Drogue parachutes are <strong>small, strong parachutes<\/strong> deployed at <strong>high speeds<\/strong>.<\/li>\n\n\n\n<li>They are not meant for final landing but for <strong>initial stabilisation and deceleration<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>Primary purpose<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Stabilise<\/strong> a fast-moving vehicle (spacecraft, aircraft, or payload).<\/li>\n\n\n\n<li><strong>Reduce velocity<\/strong> to a level safe enough for deploying larger main parachutes.<\/li>\n\n\n\n<li>Ensure correct <strong>orientation and control<\/strong> during descent.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>Role in space missions (e.g., ISRO\u2019s Gaganyaan)<\/strong>\n<ul class=\"wp-block-list\">\n<li>Deployed during <strong>atmospheric re-entry<\/strong> of the crew module.<\/li>\n\n\n\n<li>Help counter tumbling or instability caused by high-speed airflow.<\/li>\n\n\n\n<li>Act as the <strong>first stage<\/strong> in a multi-parachute recovery system.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>Why they are critical<\/strong>\n<ul class=\"wp-block-list\">\n<li>Main parachutes cannot be deployed safely at very high speeds.<\/li>\n\n\n\n<li>Drogue parachutes reduce dynamic pressure and loads on the system.<\/li>\n\n\n\n<li>They significantly enhance <strong>crew safety<\/strong> in human spaceflight missions.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>Key characteristics<\/strong>\n<ul class=\"wp-block-list\">\n<li>Smaller size compared to main parachutes.<\/li>\n\n\n\n<li>Designed to withstand <strong>extreme forces and temperatures<\/strong>.<\/li>\n\n\n\n<li>Deploy reliably at <strong>supersonic or near-supersonic speeds<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>Other applications<\/strong>\n<ul class=\"wp-block-list\">\n<li>Military aircraft (to shorten landing distance).<\/li>\n\n\n\n<li>High-speed test vehicles and rockets.<\/li>\n\n\n\n<li>Emergency recovery systems for payloads.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\"><strong>In summary<\/strong>\n<ul class=\"wp-block-list\">\n<li>Drogue parachutes are a <strong>critical intermediate deceleration mechanism<\/strong>.<\/li>\n\n\n\n<li>They bridge the gap between <strong>high-speed flight<\/strong> and <strong>safe final descent<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center has-ast-global-color-6-background-color has-background\">Nuclear Clocks<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Background: Atomic vs Nuclear Clocks<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Conventional <strong>atomic clocks<\/strong> measure time by tracking electron transitions between atomic energy levels.<\/li>\n\n\n\n<li style=\"font-size:17px\">Physicists aim to develop <strong>nuclear clocks<\/strong>, which would count transitions within the atomic nucleus.<\/li>\n\n\n\n<li style=\"font-size:17px\">Nuclear energy levels are <strong>better shielded<\/strong> from environmental disturbances than electrons, promising <strong>greater stability and precision<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Why Thorium-229 Is Special<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\"><strong>Thorium-229 (\u00b2\u00b2\u2079Th)<\/strong> has a unique nuclear excited state only <strong>8.4 electron-volts (eV)<\/strong> above its ground state.<\/li>\n\n\n\n<li style=\"font-size:17px\">This energy is unusually low for a nucleus and can be accessed using <strong>vacuum-ultraviolet (VUV) laser light<\/strong>.<\/li>\n\n\n\n<li style=\"font-size:17px\">This makes \u00b2\u00b2\u2079Th the leading candidate for building a nuclear clock.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Key Experimental Challenge<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Detecting nuclear excitation in <strong>solid materials<\/strong> has been difficult.<\/li>\n\n\n\n<li style=\"font-size:17px\">Ideally, excitation is detected by observing the <strong>VUV photon<\/strong> emitted when the nucleus relaxes.<\/li>\n\n\n\n<li style=\"font-size:17px\">However, in many solids, relaxation occurs mainly through <strong>internal conversion<\/strong>, where:\n<ul class=\"wp-block-list\">\n<li>Nuclear energy is transferred to an electron<\/li>\n\n\n\n<li>The electron is ejected instead of a photon being emitted<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Innovative Workaround by Researchers<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">An international team (Germany, UK, USA) treated <strong>internal conversion itself as the detection signal<\/strong>.<\/li>\n\n\n\n<li style=\"font-size:17px\">They embedded \u00b2\u00b2\u2079Th in <strong>thorium dioxide (ThO\u2082)<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Material band gap \u2248 <strong>6 eV<\/strong><\/li>\n\n\n\n<li>Lower than the nuclear excitation energy (8.4 eV), enabling electron ejection<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\">Used <strong>VUV laser pulses<\/strong> to excite the thorium nuclei.<\/li>\n\n\n\n<li style=\"font-size:17px\">Measured <strong>electrons emitted<\/strong> when excited nuclei decayed via internal conversion.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Experimental Techniques Used<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">VUV laser pulses initially create a large burst of <strong>photoelectrons<\/strong>, which can overwhelm detectors.<\/li>\n\n\n\n<li style=\"font-size:17px\">Researchers applied <strong>timed electric fields<\/strong> to:\n<ul class=\"wp-block-list\">\n<li>Suppress immediate photoelectron bursts<\/li>\n\n\n\n<li>Extract delayed electrons linked specifically to nuclear decay<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li style=\"font-size:17px\">Additional electric fields guided emitted electrons efficiently to the detector.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Key Results<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Observed a clear resonance at <strong>2,020,407.5 GHz<\/strong>, consistent with earlier measurements.<\/li>\n\n\n\n<li style=\"font-size:17px\">Measured an <strong>internal conversion lifetime of 12.3 seconds<\/strong> in the sample.<\/li>\n\n\n\n<li style=\"font-size:17px\">This corresponds to a clock accuracy of:\n<ul class=\"wp-block-list\">\n<li><strong>1 second error in 15.8 billion years<\/strong>, far exceeding current atomic clock precision<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Scientific and Technological Significance<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Confirms a viable method to <strong>detect nuclear transitions in solids<\/strong>.<\/li>\n\n\n\n<li style=\"font-size:17px\">Expands the range of materials suitable for <strong>nuclear clock development<\/strong>.<\/li>\n\n\n\n<li style=\"font-size:17px\">Enables high-precision probes of the <strong>nuclear environment within materials<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Broader Implications<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Nuclear clocks based on this design can be <strong>significantly miniaturised<\/strong>.<\/li>\n\n\n\n<li style=\"font-size:17px\">Timekeeping could rely on measuring <strong>electron current<\/strong>, avoiding complex optical detection systems.<\/li>\n\n\n\n<li style=\"font-size:17px\">Opens new possibilities for:\n<ul class=\"wp-block-list\">\n<li>Ultra-precise time standards<\/li>\n\n\n\n<li>Fundamental physics tests<\/li>\n\n\n\n<li>Advanced sensing technologies<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Expert Commentary<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Independent researchers from Texas A&amp;M University noted that the work:\n<ul class=\"wp-block-list\">\n<li style=\"font-size:17px\">Broadens the experimental \u201ctoolbox\u201d for nuclear clocks<\/li>\n\n\n\n<li style=\"font-size:17px\">Supports the development of <strong>stable, high-precision nuclear timekeeping devices<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n","protected":false},"excerpt":{"rendered":"<p>Tamil Nadu to conduct Hornbill Census Drogue parachutes Context and objective Nature of the tests Testing facility Role of drogue parachutes Technical significance Programmatic importance Broader implications Drogue Parachutes \u2013 Explained Nuclear Clocks Background: Atomic vs Nuclear Clocks Why Thorium-229 Is Special Key Experimental Challenge Innovative Workaround by Researchers Experimental Techniques Used Key Results Scientific [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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