{"id":263325,"date":"2022-01-25T21:49:58","date_gmt":"2022-01-26T02:49:58","guid":{"rendered":"https:\/\/www.nasa.gov\/?migration=converted-node-476839"},"modified":"2023-12-15T14:43:08","modified_gmt":"2023-12-15T19:43:08","slug":"frequently-asked-questions","status":"publish","type":"topic","link":"https:\/\/www.nasa.gov\/cara\/frequently-asked-questions\/","title":{"rendered":"Frequently Asked Questions (FAQs)"},"content":{"rendered":"<div id=\"\" class=\" hds-module hds-module-full wp-block-nasa-blocks-secondary-navigation\"><div class=\"hds-secondary-navigation-wrapper z-top width-100 padding-0\"><div id=\"\" class=\"hds-secondary-navigation width-full border-bottom-1px text-center hds-color-mode-light hds-module hds-module-full wp-block-nasa-blocks-hdsnav\"><button type=\"button\" class=\"hds-secondary-nav-mobile-button display-flex tablet:display-flex desktop:display-none width-full flex-align-center bg-carbon-90 border-color-carbon-80 color-spacesuit-white\" aria-expanded=\"false\" aria-controls=\"hds-secondary-nav-track\"><span>CARA<\/span><svg width=\"16\" height=\"16\" alt=\"\" enable-background=\"new 0 0 400 400\" viewBox=\"0 0 400 400\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"m4.2 122.2 195.1 195.1 196.5-196.6-37.9-38-157.8 157.8-156.8-156.8z\" \/><\/svg><\/button><div class=\"hds-secondary-nav-track grid-container grid-container-extrawide padding-0 tablet:padding-x-3 desktop:padding-x-2 \"><div class=\"hds-secondary-navigation-menu-items\"><nav><ul class=\"usa-nav__primary usa-accordion flex-justify-center margin-0\"><li class=\"usa-nav__primary-item \"><a class=\"usa-nav__link\" href=\"https:\/\/www.nasa.gov\/cara\/\">CA Home<\/a><\/li><li class=\"usa-nav__primary-item \"><a class=\"usa-nav__link\" href=\"https:\/\/www.nasa.gov\/conjunction-assessment\/\">NASA CARA<\/a><\/li><li class=\"usa-nav__primary-item\"><button type=\"button\" class=\"usa-accordion__button usa-nav__link\" aria-expanded=\"false\" aria-controls=\"basic-nav-section-one\"><span>Conjunction Event Prediction<\/span><svg class=\"hds-desktop-submenu-toggle-icon display-none tablet:display-none desktop:display-block\" width=\"16\" height=\"16\" alt=\"\" enable-background=\"new 0 0 400 400\" viewBox=\"0 0 400 400\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"m4.2 122.2 195.1 195.1 196.5-196.6-37.9-38-157.8 157.8-156.8-156.8z\" \/><\/svg><svg class=\"hds-mobile-submenu-toggle-icon display-block tablet:display-block desktop:display-none\" width=\"16\" height=\"16\" viewBox=\"0 0 16 16\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><circle cx=\"8\" cy=\"8\" r=\"7.5\" fill=\"#0B3D91\" stroke=\"white\"\/><rect x=\"4\" y=\"7.6001\" width=\"8\" height=\"0.8\" fill=\"white\"\/><rect class=\"hds-mobile-submenu-toggle-icon-line-vertical\" x=\"7.59998\" y=\"12\" width=\"8\" height=\"0.8\" transform=\"rotate(-90 7.59998 12)\" fill=\"white\"\/><\/svg><\/button><ul id=\"basic-nav-section-one\" class=\"usa-nav__submenu\" hidden><li class=\"usa-nav__submenu-item \"><a class=\"usa-nav__link\" target=\"_self\" href=\"https:\/\/www.nasa.gov\/cara\/step-1-conjunction-event-prediction\/\">Step 1<\/a><\/li><li class=\"usa-nav__submenu-item \"><a class=\"usa-nav__link\" target=\"_self\" href=\"https:\/\/www.nasa.gov\/cara\/step-2-close-approach-risk-assessment\/\">Step 2 <\/a><\/li><li class=\"usa-nav__submenu-item \"><a class=\"usa-nav__link\" target=\"_self\" href=\"https:\/\/www.nasa.gov\/cara\/step-3-close-approach-risk-mitigation\/\">Step 3<\/a><\/li><\/ul><\/li><li class=\"usa-nav__primary-item \"><a class=\"usa-nav__link\" href=\"https:\/\/www.nasa.gov\/cara\/unique-conjunction-events\/\">Unique Conjunction Events<\/a><\/li><li class=\"usa-nav__primary-item\"><button type=\"button\" class=\"usa-accordion__button usa-nav__link\" aria-expanded=\"false\" aria-controls=\"basic-nav-section-one\"><span>More<\/span><svg class=\"hds-desktop-submenu-toggle-icon display-none tablet:display-none desktop:display-block\" width=\"16\" height=\"16\" alt=\"\" enable-background=\"new 0 0 400 400\" viewBox=\"0 0 400 400\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"m4.2 122.2 195.1 195.1 196.5-196.6-37.9-38-157.8 157.8-156.8-156.8z\" \/><\/svg><svg class=\"hds-mobile-submenu-toggle-icon display-block tablet:display-block desktop:display-none\" width=\"16\" height=\"16\" viewBox=\"0 0 16 16\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><circle cx=\"8\" cy=\"8\" r=\"7.5\" fill=\"#0B3D91\" stroke=\"white\"\/><rect x=\"4\" y=\"7.6001\" width=\"8\" height=\"0.8\" fill=\"white\"\/><rect class=\"hds-mobile-submenu-toggle-icon-line-vertical\" x=\"7.59998\" y=\"12\" width=\"8\" height=\"0.8\" transform=\"rotate(-90 7.59998 12)\" fill=\"white\"\/><\/svg><\/button><ul id=\"basic-nav-section-one\" class=\"usa-nav__submenu\" hidden><li class=\"usa-nav__submenu-item \"><a class=\"usa-nav__link\" target=\"_self\" href=\"https:\/\/www.nasa.gov\/cara\/cara-services\/\">CARA Overview<\/a><\/li><\/ul><\/ul><\/nav><\/div><\/div><\/div><\/div><\/div>\n\n<div id=\"\" class=\"nasa-gb-align-full maxw-full width-full padding-0 hds-module hds-module-full wp-block-nasa-blocks-page-intro\">\n\t<div class=\"padding-0 bg-spacesuit-white wp-block-nasa-blocks-page-intro\">\n\t\t\t<div class=\"hds-page-intro hds-page-intro-banner width-full maxw-full padding-0 hds-cover-wrapper minh-tablet\">\n\t\t<div class=\"hds-foreground-wrapper display-flex\">\n\t\t\t<div class=\"grid-row grid-container grid-container-block margin-top-auto margin-bottom-auto width-full maxw-desktop-lg padding-top-9 padding-x-3 z-400\">\n\t\t\t\t<div class=\"grid-col-12 desktop:grid-col-6 desktop:padding-right-4 margin-bottom-3 desktop:margin-bottom-0\">\n\t\t\t\t\t<div class=\"margin-bottom-2\">\n\t\t\t\t\t\t<h1 class=\"page-heading-md line-height-sm color-spacesuit-white-important\">\n\t\t\t\t\t\t\tFrequently Asked Questions\t\t\t\t\t\t<\/h1>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<p class=\"p-lg color-carbon-30-important\">\n\t\t\t\t\t\tConjunction Risk Assessment\t\t\t\t\t<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"grid-col-12 desktop:grid-col-6 desktop:padding-right-4 margin-bottom-3 desktop:margin-bottom-0\">\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div>\n\t\t<div class=\"skrim-overlay skrim-left mobile-skrim-top z-200\"><\/div>\n\t\t<figure class=\"hds-media-background  \"><img fetchpriority=\"high\" decoding=\"async\" width=\"1200\" height=\"630\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?w=1200\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"Conjunction Risk Assessment\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg 1200w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=300,158 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=768,403 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=1024,538 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=400,210 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=600,315 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/07\/cara-web-banner-wp-jul23.jpg?resize=900,473 900w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" loading=\"eager\" \/><\/figure>\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\n<h3 class=\"wp-block-heading\">What is the difference between 18 SDS* and CARA?<\/h3>\n\n\n\n<p>The 18th SDS (Space Defense Squadron) is a tactical squadron under United States Space Command (USSPACECOM), located at Vandenberg Space Force Base (VSFB), CA. Their primary mission is to provide and advance a continuous, comprehensive, and combat-relevant understanding of the space situation. This includes executing command and control of the U.S. Space Surveillance Network (SSN), a global collection of both ground and space-based sensors that tracks man-made resident space objects (RSOs), enabling them to maintain the high-accuracy space catalog (Source sited).<\/p>\n\n\n\n<p>18 SDS operators support the Conjunction Assessment mission by screening the predicted trajectory of spacecraft (computed non-cooperatively using SSN tracking to obtain an orbit determination solution, and\/or predictions provided by the Owner\/Operator (O\/O) that include planned maneuvers) against the trajectories of all other objects in the catalog, to determine when close approaches occur.  These predictions are provided to O\/Os in the form of Conjunction Data Messages (CDMs).  These CDMs are then analyzed by the O\/Os to determine the risk posed by the close approach.    <\/p>\n\n\n\n<p>The CARA team performs this risk analysis of close approach prediction data on behalf of the O\/Os we support. CARA also assists O\/Os with maneuver planning to mitigate high interest events identified in the screenings.<\/p>\n\n\n\n<p><a href=\"https:\/\/www.jtf-spacedefense.mil\/About-Us\/Fact-Sheets\/Display\/Article\/3155799\/18th-space-defense-squadron\/\" target=\"_blank\" rel=\"noreferrer noopener\">* 18 SDS Source information<\/a><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What is the Probability of Collision?<\/h3>\n\n\n\n<p>The Probability of Collision (Pc) represents the likelihood that the miss distance between two objects may become less than some protected radius during the encounter time interval. CARA uses the Hard Body Radius (HBR), which is the sum of the hard body radii (sizes, essentially) of both the primary and secondary object. Pc employs miss distance, event covariance, and hard body radius in its calculation.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What is an AnalystSat?<\/h3>\n\n\n\n<p>An Analyst, or sometimes AnalystSat, is simply an object for which the 18 SDS has tracking observations and an elset but cannot determine from which launch it originated. Because the ownership of the object cannot be attributed, the object is not officially cataloged. These objects are given a SatID in the 80,000 object number range. These objects are screened in the CARA process, but no TLEs are available for them in the public catalog on SpaceTrack.org.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What is Space-Track.org?<\/h3>\n\n\n\n<p>Space-Track is a website (<a href=\"https:\/\/www.space-track.org\/\" rel=\"noopener\">https:\/\/www.space-track.org\/<\/a>) hosted and maintained by the 18th Space Defense Squadron. The site\u2019s primary purpose is to disseminate space situational awareness (SSA) data to approved users. Examples of SSA data available on Space-Track are Two-Line Elements (TLEs) of publicly-cataloged objects and satellite reentry predictions. Access to Space-Track.org requires an account with login credentials. Entities desiring to request support and\/or data from 18 SDS can find a template Orbital Data Request form on Space-Track.org. For NASA, these ODRs are collected and submitted via CARA who ensures that data requests are correct, complete, and understood by both parties. ODR submissions should be sent to <a href=\"mailto:odr-liaison@lists.nasa.gov\">odr-liaison@lists.nasa.gov<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>What is the difference between 18 SDS* and CARA? The 18th SDS (Space Defense Squadron) is a tactical squadron under United States Space Command (USSPACECOM), located at Vandenberg Space Force Base (VSFB), CA. Their primary mission is to provide and advance a continuous, comprehensive, and combat-relevant understanding of the space situation. This includes executing command [...]<\/p>\n","protected":false},"author":93,"featured_media":526303,"parent":401428,"menu_order":0,"template":"","meta":{"nasa_hds_core_meta_l10n":"en-US","nasa_hds_core_meta_article_editor":"","nasa_hds_core_meta_article_contacts":[],"nasa_hds_core_meta_article_topic":"","nasa_hds_core_meta_linked_locations":[],"nasa_hds_core_meta_article_related_articles":[],"hds_migrate_meta_pr_release_id":"","hds_migrate_meta_pr_release_type":"","nasa_hds_core_meta_location_x":"","nasa_hds_core_meta_location_y":"","nasa_hds_core_meta_gallery_images":[]},"categories":[11813],"news-tags":[],"internal-terms":[10636],"coauthors":[9510],"parsely":{"version":"1.1.0","meta":{"@context":"https:\/\/schema.org","@type":"WebPage","headline":"Frequently Asked Questions (FAQs)","url":"https:\/\/www.nasa.gov\/cara\/frequently-asked-questions\/","mainEntityOfPage":{"@type":"WebPage","@id":"https:\/\/www.nasa.gov\/cara\/frequently-asked-questions\/"},"thumbnailUrl":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/06\/scan-faq.png?w=150&h=150&crop=1","image":{"@type":"ImageObject","url":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/06\/scan-faq.png"},"articleSection":"Organizations","author":[{"@type":"Person","name":"Garrett Shea"}],"creator":["Garrett Shea"],"publisher":{"@type":"Organization","name":"NASA","logo":"https:\/\/www.nasa.gov\/wp-content\/themes\/nasa\/assets\/images\/nasa-logo.svg"},"keywords":["Organizations","Conjunction Assessment Risk Analysis Team (CARA)"],"dateCreated":"2022-01-26T02:49:58Z","datePublished":"2022-01-26T02:49:58Z","dateModified":"2023-12-15T19:43:08Z"},"rendered":"<meta name=\"parsely-title\" content=\"Frequently Asked Questions (FAQs)\" \/>\n<meta name=\"parsely-link\" content=\"https:\/\/www.nasa.gov\/cara\/frequently-asked-questions\/\" \/>\n<meta name=\"parsely-type\" content=\"index\" \/>\n<meta name=\"parsely-image-url\" content=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/06\/scan-faq.png?w=150&h=150&crop=1\" \/>\n<meta name=\"parsely-pub-date\" content=\"2022-01-26T02:49:58Z\" \/>\n<meta name=\"parsely-section\" content=\"Organizations\" \/>\n<meta name=\"parsely-tags\" content=\"Organizations,Conjunction Assessment Risk Analysis Team (CARA)\" \/>\n<meta name=\"parsely-author\" content=\"Garrett Shea\" \/>","tracker_url":"https:\/\/cdn.parsely.com\/keys\/nasa.gov\/p.js"},"read_time":3,"time_ago":"2 years","featured_image":{"id":526303,"file":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/06\/scan-faq.png","title":"scan-faq","alt":"Image of question mark","caption":""},"_links":{"self":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/topic\/263325"}],"collection":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/topic"}],"about":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/types\/topic"}],"author":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/users\/93"}],"version-history":[{"count":7,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/topic\/263325\/revisions"}],"predecessor-version":[{"id":581198,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/topic\/263325\/revisions\/581198"}],"up":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/topic\/401428"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media\/526303"}],"wp:attachment":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media?parent=263325"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/categories?post=263325"},{"taxonomy":"news-tags","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/news-tags?post=263325"},{"taxonomy":"internal-terms","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/internal-terms?post=263325"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/coauthors?post=263325"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}