{"id":9463,"date":"2022-07-21T17:01:19","date_gmt":"2022-07-21T15:01:19","guid":{"rendered":"https:\/\/scienceetonnante.com\/?p=9463"},"modified":"2022-07-21T17:02:15","modified_gmt":"2022-07-21T15:02:15","slug":"james-webb","status":"publish","type":"post","link":"https:\/\/scienceetonnante.com\/blog\/2022\/07\/21\/james-webb\/","title":{"rendered":"Le t\u00e9lescope spatial James Webb : fonctionnement et performances"},"content":{"rendered":"<p>Une vid\u00e9o en r\u00e9action \u00e0 la sortie de l&rsquo;article qui \u00e9value les performances du t\u00e9lescope spatial James Webb \u00e0 l&rsquo;issue de la p\u00e9riode de mise en service<\/p>\n<p><iframe title=\"LE T\u00c9LESCOPE SPATIAL JAMES WEBB : Pourquoi ? Comment ?\" width=\"770\" height=\"433\" data-src=\"https:\/\/www.youtube.com\/embed\/bnl05iaftB0?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" data-load-mode=\"1\"><\/iframe><\/p>\n<p>La vid\u00e9o a \u00e9t\u00e9 faite rapidement et je ne voulais pas faire un truc trop long, donc je vous mets en prime quelques infos que je n&rsquo;ai pas cas\u00e9es mais qui sont quand m\u00eame int\u00e9ressante.<\/p>\n<h3>L&rsquo;orbite du t\u00e9lescope<\/h3>\n<p>J&rsquo;ai expliqu\u00e9 que le t\u00e9lescope \u00ab\u00a0se trouvait\u00a0\u00bb au point de Lagrange L2. Tout d&rsquo;abord pour ceux que \u00e7a int\u00e9resse, j&rsquo;avais \u00e9voqu\u00e9 la notion de point de Lagrange dans <a href=\"https:\/\/scienceetonnante.com\/2011\/09\/12\/l-asteroid-troyen-de-la-terre\/\">un vieux billet de blog.<\/a>\u00a0Ensuite, la trajectoire exacte du t\u00e9lescope n&rsquo;est pas de stationner au point L2, mais de r\u00e9aliser une orbite assez complexe autour de ce point, et pouvant l&#8217;emmener d&rsquo;ailleurs \u00e0 plusieurs centaines de milliers de kilom\u00e8tres de celui-ci.<\/p>\n<p><iframe title=\"Animation: The James Webb Space Telescope&#039;s Orbit\" width=\"770\" height=\"433\" data-src=\"https:\/\/www.youtube.com\/embed\/6cUe4oMk69E?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" data-load-mode=\"1\"><\/iframe><\/p>\n<h3>Capteurs et r\u00e9solution<\/h3>\n<p>J&rsquo;ai \u00e9voqu\u00e9 dans la vid\u00e9o le fait que l&rsquo;instrument NIRCam poss\u00e9dait 10 capteurs de 4 M\u00e9gapixels. Mais leur disposition est un peu particuli\u00e8re. On le voit sur le sch\u00e9ma suivant<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-large wp-image-9464 lazyload\" data-src=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.36.58-1024x514.png\" alt=\"\" width=\"770\" height=\"387\" data-srcset=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.36.58-1024x514.png 1024w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.36.58-300x151.png 300w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.36.58-1536x771.png 1536w\" data-sizes=\"(max-width: 770px) 100vw, 770px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 770px; --smush-placeholder-aspect-ratio: 770\/387;\" \/><\/p>\n<p>On a en r\u00e9alit\u00e9 deux groupes de capteurs qui couvrent chacun un champ de 2.2 x 2.2 arc-minutes, et chaque champ est imag\u00e9 par 4 capteurs (en bleu) pour les plus courtes longueurs d&rsquo;ondes (0.6 \u00e0 2.3 microns) et un capteur (en rouge) pour les plus grandes longueurs d&rsquo;onde (2.3 \u00e0 5 microns). Une image comme celle du champ profond imag\u00e9 avec NIRCam poss\u00e8de une r\u00e9solution \u00ab\u00a0native\u00a0\u00bb de 16 Mpx.<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-large wp-image-9465 lazyload\" data-src=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Deep-Field-NIRCam-1004x1024.png\" alt=\"\" width=\"770\" height=\"785\" data-srcset=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Deep-Field-NIRCam-1004x1024.png 1004w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Deep-Field-NIRCam-294x300.png 294w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Deep-Field-NIRCam-1505x1536.png 1505w\" data-sizes=\"(max-width: 770px) 100vw, 770px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 770px; --smush-placeholder-aspect-ratio: 770\/785;\" \/><\/p>\n<p>D&rsquo;ailleurs il existe aussi une image MIRI (infrarouge moyen) et la comparaison est int\u00e9ressante (MIRI est \u00e0 gauche, NIRCam \u00e0 droite)<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-large wp-image-9466 lazyload\" data-src=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.42.43-1024x700.png\" alt=\"\" width=\"770\" height=\"526\" data-srcset=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.42.43-1024x700.png 1024w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.42.43-300x205.png 300w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.42.43-1536x1050.png 1536w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/Capture-decran-2022-07-21-a-13.42.43.png 1606w\" data-sizes=\"(max-width: 770px) 100vw, 770px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 770px; --smush-placeholder-aspect-ratio: 770\/526;\" \/><\/p>\n<p>A propos de la cha\u00eene du traitement, je dis un truc impr\u00e9cis dans la vid\u00e9o quand je parle de 10mW de puissance. Le chiffre est correct mais il est pour 1 module de traitement., or il en faut un derri\u00e8re chaque capteur de 4Mpx.<\/p>\n<p><em>LOOSE, Markus, BELETIC, James, BLACKWELL, John, et al. <a href=\"https:\/\/www.researchgate.net\/profile\/Gregory-Winters\/publication\/228735600_The_SIDECAR_ASIC_focal_plane_electronics_on_a_single_chip\/links\/54fa0f5e0cf2040df21b1b15\/The-SIDECAR-ASIC-focal-plane-electronics-on-a-single-chip.pdf\" target=\"_blank\" rel=\"noopener\">The SIDECAR ASIC: focal plane electronics on a single chip<\/a>. In : Cryogenic Optical Systems and Instruments XI. SPIE, 2005. p. 293-302.<\/em><\/p>\n<h3>Spectroscopie<\/h3>\n<p>Sur la spectroscopie, je ne me suis pas vraiment \u00e9tendu sur les diff\u00e9rences entre les diff\u00e9rentes techniques. Cette image r\u00e9sume assez bien les choses<\/p>\n<p><img decoding=\"async\" class=\"aligncenter size-large wp-image-9467 lazyload\" data-src=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/spectroscopies-1024x585.png\" alt=\"\" width=\"770\" height=\"440\" data-srcset=\"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/spectroscopies-1024x585.png 1024w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/spectroscopies-300x171.png 300w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/spectroscopies-1536x877.png 1536w, https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/spectroscopies-900x515.png 900w\" data-sizes=\"(max-width: 770px) 100vw, 770px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 770px; --smush-placeholder-aspect-ratio: 770\/440;\" \/>On retrouve notamment la spectro multi-objet du NIR Spec, \u00e0 grand champ du NIRISS.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Une vid\u00e9o en r\u00e9action \u00e0 la sortie de l&rsquo;article qui \u00e9value les performances du t\u00e9lescope spatial James Webb \u00e0 l&rsquo;issue de la p\u00e9riode de mise en service La vid\u00e9o a \u00e9t\u00e9 faite rapidement et je ne voulais pas faire un truc trop long, donc je vous mets en prime quelques infos que je n&rsquo;ai pas<\/p>\n","protected":false},"author":1,"featured_media":9468,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[6],"tags":[40,132],"class_list":{"0":"post-9463","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physique","8":"tag-astronomie","9":"tag-astrophysique"},"jetpack_featured_media_url":"https:\/\/scienceetonnante.com\/blog\/wp-content\/uploads\/2022\/07\/teaser.png","jetpack_sharing_enabled":true,"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/posts\/9463","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/comments?post=9463"}],"version-history":[{"count":2,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/posts\/9463\/revisions"}],"predecessor-version":[{"id":9470,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/posts\/9463\/revisions\/9470"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/media\/9468"}],"wp:attachment":[{"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/media?parent=9463"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/categories?post=9463"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scienceetonnante.com\/blog\/wp-json\/wp\/v2\/tags?post=9463"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}