{"id":394415,"date":"2026-03-27T06:12:30","date_gmt":"2026-03-26T20:12:30","guid":{"rendered":"https:\/\/www.nasa.gov\/?p=978168"},"modified":"2026-03-27T06:12:30","modified_gmt":"2026-03-26T20:12:30","slug":"nasa-releases-artemis-ii-moon-mission-launch-countdown","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=394415","title":{"rendered":"NASA Releases Artemis II Moon Mission Launch Countdown"},"content":{"rendered":"<div id=\"\" class=\"hds-media hds-module wp-block-image\">\n<div class=\"margin-left-auto margin-right-auto nasa-block-align-full\">\n<div class=\"hds-media-wrapper margin-left-auto margin-right-auto\">\n<figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-fit \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg\"><img decoding=\"async\" width=\"1152\" height=\"2048\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?w=1152\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" loading=\"lazy\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg 3840w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=169,300 169w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=768,1365 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=576,1024 576w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=864,1536 864w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=1152,2048 1152w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=225,400 225w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=338,600 338w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=506,900 506w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=675,1200 675w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/03\/countdown.jpg?resize=1125,2000 1125w\" sizes=\"auto, (max-width: 1152px) 100vw, 1152px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\">\n<div class=\"hds-caption-text p-sm margin-0\">NASA&#8217;s crawler-transporter carries the powerful SLS (Space Launch System) rocket and Orion spacecraft on the Mobile Launcher from the Vehicle Assembly Building to Launch Pad 39B at Kennedy Space Center in preparation for the Artemis II mission on Jan. 17, 2026.<\/div>\n<div class=\"hds-credits\">Credit: NASA\/Brandon Hancock<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n<p>Before NASA sends its astronauts Reid Wiseman, Victor Glover, Christina Koch, and CSA (Canadian Space Agency) astronaut Jeremy Hansen on their Artemis II mission around the Moon, the launch team at NASA\u2019s Kennedy Space Center in Florida and teams across the country will begin counting down about two days before liftoff.&nbsp;<\/p>\n<p>A launch countdown contains \u201cL Minus\u201d and \u201cT Minus\u201d times. The \u201cL minus\u201d indicates how far away liftoff is in hours and minutes. The \u201cT minus\u201d time is a sequence of events built into the launch countdown.&nbsp;Pauses in the countdown, or \u201cholds,\u201d are built in to allow the launch team to target a precise launch window, and to provide a cushion of time for certain tasks and procedures without impacting the overall schedule. During planned holds in the countdown process,&nbsp;the countdown clock is intentionally stopped and the T- time also stops. The L- time, however, continues to advance. &nbsp;<\/p>\n<p>Below are some of the key events that take place at each milestone after the countdown begins.<\/p>\n<p>All times are approximate for when these milestones occur.&nbsp;<\/p>\n<p><strong>L-49&nbsp;hours 50 minutes and counting&nbsp;<\/strong>&nbsp;<\/p>\n<ul class=\"wp-block-list\">\n<li>L-49H50M \u2013 Launch team arrives to stations<\/li>\n<li>L-49H40M &#8211; Countdown clock begins<\/li>\n<li>L-49H40M \u2013 L-42H30M: Liquid oxygen (LOX)\/Liquid hydrogen (LH2) system<br \/>preparations for vehicle loading<\/li>\n<li>L-45H30M \u2013 L-44H: Orion spacecraft powered up<\/li>\n<li>L-42H20M \u2013 L-41H: Core stage powered up<\/li>\n<li>L-42H10M \u2013 L-40H30M: Interim cryogenic propulsion stage (ICPS) powered up<\/li>\n<li>L-39H45M \u2013 L-35H30M: Final preparations of the four RS-25 engines<\/li>\n<\/ul>\n<p><strong>L-35 hours and counting<\/strong><strong><\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li>L-34H45M \u2013 L-34H10M: ICPS is powered down<\/li>\n<li>L-33H30M \u2013 L-29H30M: Charge Orion flight batteries to 100%<\/li>\n<li>L-31H30M \u2013 L-24H30M: Charge core stage flight batteries<\/li>\n<li>L-20H15M \u2013 L-18H45M: ICPS is powered up for launch<\/li>\n<\/ul>\n<p><strong>L-16 hours and counting<\/strong><strong><\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li>L-15H30M \u2013 L-14H: All non-essential personnel leave Launch Complex 39B<\/li>\n<li>L-14H15M \u2013 L-12H05M: Air-to-gaseous nitrogen (GN2) changeover and rocket<br \/>cavity inerting<\/li>\n<li>L-13H15M \u2013 L-11H45M: Ground launch sequencer (GLS) activation<\/li>\n<\/ul>\n<p><strong>L-13 hours and counting<\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li>L-12H35M \u2013 L-9H50M: 2-hour 45-minute built in countdown hold begins<\/li>\n<li>L-10H50M \u2013 Launch team decides \u201cgo\u201d or \u201cno-go\u201d to begin tanking<\/li>\n<li>L-10H50M \u2013 L-9H35M: Orion cold soak<\/li>\n<li>L-10H40M \u2013 L-10H35M: Core stage LOX transfer line chilldown<\/li>\n<li>L-10H40M \u2013 L-9H55M: Core stage LH2 chilldown<\/li>\n<li>L-10H25M \u2013 L-9H40M: Core stage LOX main propulsion system chilldown<\/li>\n<\/ul>\n<p><strong>L-10 hours and counting<\/strong><strong><\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li>L-9H55M \u2013 L-9H25M: Core stage LH2 slow fill start<\/li>\n<li>L-9H50M \u2013 Resume T-Clock from T-8H10M<\/li>\n<li>L-9H40M \u2013 L-9H30M: Core stage LOX slow fill<\/li>\n<li>L-9H30M \u2013 L-6H40M: Core stage LOX fast fill<\/li>\n<li>L-9H25M \u2013 L-8H: Core stage LH2 fast fill<\/li>\n<li>L-9H05M \u2013 L-8H30M: ICPS LH2 chilldown<\/li>\n<li>L-8H30M \u2013 L-7H45M: ICPS LH2 fast fill start<\/li>\n<li>L-8H \u2013 L-7H55M: Core stage LH2 topping<\/li>\n<li>L-7H55M \u2013 terminal count: Core stage LH2 replenish<\/li>\n<li>L-7H45M \u2013 L-7H20M: ICPS LH2 vent and relief test<\/li>\n<li>L-7H20M \u2013 L-7H10M: ICPS LH2 tank topping start<\/li>\n<li>L-7H05M \u2013 terminal count: ICPS LH2 replenish<\/li>\n<li>L-6H40M \u2013 L-6H10M: Orion communications system activated (radio frequency to mission control)<\/li>\n<li>L-6H40M \u2013 L-6H05M: Core stage LOX topping<\/li>\n<li>L-6H40M \u2013 L-6H30M: ICPS LOX main propulsion system chilldown<\/li>\n<li>L-6H30M \u2013 L-5H45M: ICPS LOX fast fill<\/li>\n<li>L-6H10M \u2013 Stage pad rescue<\/li>\n<li>L-6H10M: \u2013 Closeout crew assemble<\/li>\n<li>L-6H05M \u2013 terminal count: Core stage LOX replenish<\/li>\n<\/ul>\n<p><strong>L-6 hours and counting<\/strong><strong><\/strong><\/p>\n<ul class=\"wp-block-list\">\n<li>L-6H \u2013 Flight crew weather brief<\/li>\n<li>L-5H45M \u2013 L-5H30M: ICPS LOX vent and relief test<\/li>\n<li>L-5H30M \u2013 L-5H10M: ICPS LOX topping<\/li>\n<li>L-5H10M \u2013 terminal count: ICPS LOX replenish<\/li>\n<li>L-5H10M \u2013 All stages replenish<\/li>\n<li>L-5H10M \u2013 Start 1-hour 10-minute built in hold<\/li>\n<li>L-5H10M \u2013 L-4H55M: Closeout crew to white room<\/li>\n<li>L-4H40M \u2013 L-4H10M: Flight crew deployment to pad<\/li>\n<li>L-4H: Flight crew board Orion<\/li>\n<li>L-3H40M \u2013 L-3H10M: Crew module hatch preps and closure<\/li>\n<li>L-3H10M \u2013 L-2H45M: Counterbalance mechanism hatch sealpress decay<br \/>checks<\/li>\n<li>L-2H20M \u2013 L-1H40M: Crew module hatch service panel install\/closeouts<\/li>\n<li>L-1H40M \u2013 L1H30M: Launch abort system (LAS) hatch closure for flight<\/li>\n<li>L-1H10M \u2013 Launch director brief \u2013 rocket &amp; thermal protection system scan results with the imagery console<\/li>\n<li>L-50M \u2013 L-40M: Closeout crew departs Launch Complex 39B<\/li>\n<li>L-50M \u2013 Final NASA test director briefing is held&nbsp;<\/li>\n<\/ul>\n<p><strong>L-40 minutes and holding&nbsp;<\/strong>&nbsp;<\/p>\n<ul class=\"wp-block-list\">\n<li>L-40M \u2013 Built in 30-minute countdown hold begins&nbsp;<\/li>\n<\/ul>\n<p><strong>L-25 minutes and holding&nbsp;&nbsp;<\/strong>&nbsp;<\/p>\n<ul class=\"wp-block-list\">\n<li>L-25M \u2013 Transition team to Orion to Earth communication loop following final NTD briefing<\/li>\n<li>L-17M \u2013 Launch director polls team to ensure they are \u201cgo\u201d for launch<\/li>\n<li>L-15M \u2013 Flight crew visors down<\/li>\n<li>L-14M \u2013 Flight crew short purge verification&nbsp;<\/li>\n<\/ul>\n<p><strong>T-10 minutes and counting&nbsp;<\/strong>&nbsp;<\/p>\n<ul class=\"wp-block-list\">\n<li>T-10M \u2013 GLS initiates terminal count<\/li>\n<li>T-8M \u2013 Crew Access Arm retract<\/li>\n<li>T-6M \u2013 GLS go for core stage tank pressurization &nbsp;<\/li>\n<li>T-6M \u2013 Orion ascent pyros are armed<\/li>\n<li>T-6M \u2013 Orion set to internal power<\/li>\n<li>T-5M57S \u2013 Core stage LH2 terminate replenish<\/li>\n<li>T-5M20S \u2013 LAS capability is available<\/li>\n<li>T-5M20S \u2013 NTD lets commander knows LAS capability is available<\/li>\n<li>T-4M40S \u2013 GLS&nbsp;go for LH2 high flow bleed check<\/li>\n<li>T-4M30S \u2013 Flight termination system&nbsp;armed<\/li>\n<li>T-4M \u2013 GLS&nbsp;is go for core stage&nbsp;auxiliary power unit (APU)&nbsp;start<\/li>\n<li>T-4M \u2013 Core Stage&nbsp;APU starts<\/li>\n<li>T-4M \u2013 Core stage LOX&nbsp;terminate replenish<\/li>\n<li>T-3M30S \u2013 ICPS LOX&nbsp;terminate replenish &nbsp;<\/li>\n<li>T-3M10S \u2013 GLS go for purge sequence 4&nbsp;<\/li>\n<li>T-2M02S \u2013 ICPS switches to internal battery power<\/li>\n<li>T-2M \u2013 Booster switches to internal batter power<\/li>\n<li>T-1M30S \u2013 Core stage switches to internal power &nbsp;<\/li>\n<li>T-1M20S \u2013 ICPS enters terminal countdown mode &nbsp;<\/li>\n<li>T-50S \u2013 ICPS LH2 terminate replenish<\/li>\n<li>T-33S \u2013 GLS sends \u201cgo for automated launch sequencer\u201d command<\/li>\n<li>T-30S \u2013 Core stage flight computer to automated launching sequencer &nbsp;<\/li>\n<li>T-12S \u2013 Hydrogen burn off igniters initiated &nbsp;<\/li>\n<li>T-10S \u2013 GLS sends the command for core stage engine start&nbsp;<\/li>\n<li>T-6.36S\u2013 RS-25 engines startup &nbsp;<\/li>\n<\/ul>\n<p>&nbsp;<strong>T-0<\/strong>&nbsp;&nbsp;<\/p>\n<ul class=\"wp-block-list\">\n<li>Booster ignition, umbilical separation, and liftoff&nbsp;<\/li>\n<\/ul>\n<p>Inside the terminal countdown, teams have a few options to hold the count if needed.<\/p>\n<ul class=\"wp-block-list\">\n<li>The launch team can hold at 6 minutes for the duration of the launch window, less the 6 minutes needed to launch, without having to recycle back to 10 minutes.<\/li>\n<li>If teams need to stop the clock between T-6 minutes and T-1 minute, 30 seconds, they can hold for up to 3 minutes and resume the clock to launch. If they require more than 3 minutes of hold time, the countdown would recycle back to T-10.<\/li>\n<li>If the clock stops after T-1 minute and 30 seconds, but before the automated launch sequencer takes over, then teams can recycle back to T-10 to try again, provided there is adequate launch window remaining.<\/li>\n<li>After handover to the automated launch sequencer, any issue that would stop the countdown would lead to concluding the launch attempt for that day.<\/li>\n<\/ul>\n<p>Launching the Artemis II Moon rocket will lift off the agency\u2019s first crewed mission under the Artemis program, testing the systems that will return astronauts to the Moon for an enduring presence, and paving the way to human exploration of Mars.<\/p>\n<p>To learn more about the Artemis program, visit:<\/p>\n<p class=\"has-text-align-center\"><a href=\"https:\/\/www.nasa.gov\/artemis\"><strong>https:\/\/www.nasa.gov\/artemis<\/strong><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Before NASA sends its astronauts Reid Wiseman, Victor Glover, Christina Koch, and CSA (Canadian Space Agency) astronaut Jeremy Hansen on their Artemis II mission around the Moon, the launch team at NASA\u2019s Kennedy Space Center in Florida and teams across the country will begin counting down about two days before liftoff.\u00a0 A launch countdown contains [\u2026]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[15595,15741,15606,15703,15653],"tags":[],"class_list":["post-394415","post","type-post","status-publish","format-standard","hentry","category-artemis","category-artemis-2","category-general","category-humans-in-space","category-missions"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/posts\/394415","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=394415"}],"version-history":[{"count":1,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/posts\/394415\/revisions"}],"predecessor-version":[{"id":394416,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=\/wp\/v2\/posts\/394415\/revisions\/394416"}],"wp:attachment":[{"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=394415"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=394415"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vibewire.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=394415"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}