{"id":9599,"date":"2026-03-07T23:17:12","date_gmt":"2026-03-07T15:17:12","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/nasa-contract-confirms-selection-of-ulas-centaur-5-as-new-upper-stage-for-the-sls-rocket\/"},"modified":"2026-03-07T23:17:12","modified_gmt":"2026-03-07T15:17:12","slug":"nasa-contract-confirms-selection-of-ulas-centaur-5-as-new-upper-stage-for-the-sls-rocket","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/nasa-contract-confirms-selection-of-ulas-centaur-5-as-new-upper-stage-for-the-sls-rocket\/","title":{"rendered":"NASA contract confirms selection of ULA\u2019s Centaur 5 as new upper stage for the SLS rocket"},"content":{"rendered":"<figure id=\"attachment_72856\" aria-describedby=\"caption-attachment-72856\" style=\"width: 678px\" class=\"wp-caption aligncenter\"><img fetchpriority=\"high\" decoding=\"async\" class=\"size-full wp-image-72856\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-V_Cert-1_pressure_testing.jpeg\" alt=\"\" width=\"678\" height=\"509\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-V_Cert-1_pressure_testing.jpeg 678w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-V_Cert-1_pressure_testing-300x225.jpeg 300w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-V_Cert-1_pressure_testing-326x245.jpeg 326w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-V_Cert-1_pressure_testing-80x60.jpeg 80w\" sizes=\"(max-width: 678px) 100vw, 678px\"><figcaption id=\"caption-attachment-72856\" class=\"wp-caption-text\">United Launch Alliance\u2019s (ULA\u2019s) Centaur 5 upper stage for the Vulcan Certification-1 (Cert-1) flight heads into pressure cell testing. Image: United Launch Alliance<\/figcaption><\/figure>\n<p>NASA officially selected United Launch Alliance\u2019s Centaur 5 as the upper stage for its Space Launch System rocket starting with the Artemis 4 mission, scheduled to launch no earlier than early 2028.<\/p>\n<p>The Centaur 5 was developed as the upper stage of ULA\u2019s Vulcan rocket. The launch vehicle flew four times since its debut in January 2024 and the upper stage performed well across all flights.<\/p>\n<p>The news, disclosed in contract documents published on Friday, comes one week after NASA Administrator Jared Isaacman announced that the agency would move towards a \u201cstandardization of the [Space Launch System rocket] fleet to\u2026 a near-Block 1 configuration.\u201d<\/p>\n<p>\u201cThe idea is we want to reduce complexity to the greatest extent possible,\u201d Isaacman said during a briefing at the Kennedy Space Center on Feb. 27. \u201cWe want to accelerate manufacturing, pull in the hardware, and increase launch rate, which obviously has a direct safety consideration to it as well.\u201d<\/p>\n<p><iframe loading=\"lazy\" title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/oVyaDyUPZPg?si=edIakD4HqlLAgeE3\" width=\"678\" height=\"381\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><span data-mce-type=\"bookmark\" style=\"display: inline-block; width: 0px; overflow: hidden; line-height: 0;\" class=\"mce_SELRES_start\">\ufeff<\/span><\/iframe><\/p>\n<p>Originally, NASA planned to launch the first three missions for the Artemis program using ULA\u2019s Interim Cryogenic Propulsion Stage (ICPS), a modified version of its Delta 4 Cryogenic Second Stage, and then transition to the Exploration Upper Stage (EUS), built by Boeing, beginning with the Artemis 4 mission.<\/p>\n<p>NASA, under Isaacman\u2019s leadership, decided to move away from those plans due to cost and schedule overruns.<\/p>\n<p>Long before this decision, Tory Bruno, ULA\u2019s President and CEO at the time, was asked during a reporter roundtable in December 2024 about how the company would handle a theoretical change in the architecture for the SLS rocket. The question came up a month after President Donald Trump was elected to a second term, which sparked discussions of whether or not the SLS plans at the time might change.<\/p>\n<p>\u201cThe Exploration Upper Stage is a very, very large upper stage. It\u2019s much larger than the Interim Cryogenic Upper Stage that we\u2019re providing now. It\u2019s larger than a Centaur 5,\u201d Bruno said. \u201cIf the government wants to change something in the architecture of SLS, they would tell us and we would tell them what we could do.\u201d<\/p>\n<p>That \u2018what if?\u2019 scenario is now reality.<\/p>\n<figure id=\"attachment_64554\" aria-describedby=\"caption-attachment-64554\" style=\"width: 678px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-64554\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2023\/11\/Vulcan_Centaur_graphic-678x524.jpg\" alt=\"\" width=\"678\" height=\"524\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2023\/11\/Vulcan_Centaur_graphic-678x524.jpg 678w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2023\/11\/Vulcan_Centaur_graphic-300x232.jpg 300w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2023\/11\/Vulcan_Centaur_graphic-768x594.jpg 768w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2023\/11\/Vulcan_Centaur_graphic.jpg 876w\" sizes=\"(max-width: 678px) 100vw, 678px\"><figcaption id=\"caption-attachment-64554\" class=\"wp-caption-text\">An infographic illustrating the differences between the Centaur 3 and the Centaur 5 upper stages. Graphic: ULA<\/figcaption><\/figure>\n<p>In its procurement statement, NASA said its intention is to issue a sole source contract to ULA, meaning it\u2019s the only upper stage being considered for this new iteration of the SLS rocket. An eight-page supporting document from NASA\u2019s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, was published to document the reasoning for its decision.<\/p>\n<p>Among the stated reasons are the decades-long heritage of the RL10 engine, which has matured over time; the ability of the Centaur 5 to use the interfaces available on the Mobile Launcher 1 (ML1) along with the propulsion commodities of liquid oxygen and liquid hydrogen; and the experience of ULA\u2019s teams working with NASA\u2019s Exploration Ground Systems (EGS) at the Kennedy Space Center and elsewhere in the country.<\/p>\n<p>They also noted that with the Centaur 3 upper stage achieving certification to launch humans as part of the Commercial Crew Program, there are a lot of common features with the Centaur 5.<\/p>\n<p>\u201cThis approach leverages current support infrastructure and will use, with relatively minor modifications, an existing ULA upper stage,\u201d NASA said. \u201cAll other alternative solutions fail to meet the performance requirements, would require significant modifications to hardware that is still under-development, or would require the development of new hardware that does not currently exist.\u201d<\/p>\n<p>NASA also said a time constraint to this decision caused them to select ULA as its sole choice.<\/p>\n<p>\u201cThe NASA Kennedy Space Center (KSC) need date for processing is projected to be nine months prior to a launch,\u201d NASA said. \u201cAward to another source would cause unacceptable delays to current launch schedules.<\/p>\n<p>\u201cThese delays would derive from the procurement process, on\/off ramping of new contractor personnel, the potential need for reworked activities, as well as efforts necessary to satisfy SLS technical and programmatic drivers.\u201d<\/p>\n<figure id=\"attachment_72857\" aria-describedby=\"caption-attachment-72857\" style=\"width: 678px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-72857\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-5_USSF-87.jpeg\" alt=\"\" width=\"678\" height=\"452\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-5_USSF-87.jpeg 678w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_Centuar-5_USSF-87-300x200.jpeg 300w\" sizes=\"auto, (max-width: 678px) 100vw, 678px\"><figcaption id=\"caption-attachment-72857\" class=\"wp-caption-text\">A zoomed in shot of the Centaur 5 upper stage on United Launch Alliance\u2019s Vulcan rocket that flew the USSF-87 mission for the United States Space Force on Feb. 12, 2026. Image: Adam Bernstein\/Spaceflight Now<\/figcaption><\/figure>\n<p>The other upper stage that may have been in contention was from Blue Origin\u2019s New Glenn rocket. Besides not having the previously stated advantages from NASA\u2019s perspective, the agency also expressed concerns with the modifications needed to adopt Glenn Stage 2 for the ML1.<\/p>\n<p>\u201cUsing the NGUS would require significant modifications to both the stage and the EGS infrastructure. For example, using NGUS would require relocating the Mobile Launcher Crew Access Arm and modification to the upper stage umbilical retraction mechanism,\u201d NASA said.<\/p>\n<p>\u201cThe stage could be shortened to meet VAB height constraints but would require full scale development and testing to qualify the stage for the shorter configuration. Full scale testing\/requalification would result in unacceptable schedule impacts and additional cost risk to the SLS Program.\u201d<\/p>\n<p><iframe id=\"twitter-widget-0\" scrolling=\"no\" frameborder=\"0\" allowtransparency=\"true\" allowfullscreen=\"true\" class=\"\" style=\"position: absolute; visibility: hidden; width: 0px; height: 0px; display: block; flex-grow: 1;\" title=\"X Post\" src=\"https:\/\/platform.twitter.com\/embed\/Tweet.html?dnt=false&amp;embedId=twitter-widget-0&amp;features=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%3D%3D&amp;frame=false&amp;hideCard=false&amp;hideThread=false&amp;id=1999575473563844646&amp;lang=en&amp;origin=https%3A%2F%2Fspaceflightnow.com%2F2026%2F03%2F07%2Fnasa-contract-confirms-selection-of-ulas-centaur-5-as-new-upper-stage-for-the-sls-rocket%2F&amp;sessionId=c165339b0bdd234d9b7020a036c38419fdbcdd4e&amp;theme=light&amp;widgetsVersion=6a3ad42b224df%3A1778106238597&amp;width=550px\" data-tweet-id=\"1999575473563844646\"><\/iframe><\/p>\n<blockquote class=\"twitter-tweet\" data-twitter-extracted-i1782461358795397017=\"true\">\n<p dir=\"ltr\" lang=\"en\">Another GS2 ready to fly. We completed a 15-second hotfire with serial number 4 today. Incredible work by our New Glenn team ramping GS2 production. pic.twitter.com\/Ltjq3psFwK<\/p>\n<p>\u2014 Dave Limp (@davill) December 12, 2025<\/p>\n<\/blockquote>\n<p><script async=\"\" src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script><\/p>\n<h4>What happened to the Exploration Upper Stage?<\/h4>\n<p>The original plan to use an EUS-enabled rocket would\u2019ve enabled what NASA called \u201cmore ambitious missions\u201d to the Moon, given that it would allow for the delivery of up to 11 metric tons more mass to the lunar surface under the Block 1B configuration as compared to the ICPS-powered Block 1 rocket.<\/p>\n<p>However, a 2024 report from NASA\u2019s Office of Inspector General found that, despite the SLS Block 1B being in development since 2014 and moving the first flight from Artemis 3 to Artemis 4, it continued to be behind schedule due in part to what the OIG called \u201cquality control issues\u201d at the Michoud Assembly Facility (MAF) in Louisiana.<\/p>\n<p>\u201cWe project SLS Block 1B costs will reach approximately $5.7 billion before the system is scheduled to launch in 2028,\u201d the report stated. \u201cThis is $700 million more than NASA\u2019s 2023 Agency Baseline Commitment, which established a cost and schedule baseline at nearly $5 billion.<\/p>\n<p>\u201cEUS development accounts for more than half of this cost, which we estimate will increase from an initial cost of $962 million in 2017 to nearly $2.8 billion through 2028.\u201d<\/p>\n<figure id=\"attachment_72858\" aria-describedby=\"caption-attachment-72858\" style=\"width: 678px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-72858\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_EUS_rendering.jpg\" alt=\"\" width=\"678\" height=\"452\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_EUS_rendering.jpg 678w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2026\/03\/20260306_EUS_rendering-300x200.jpg 300w\" sizes=\"auto, (max-width: 678px) 100vw, 678px\"><figcaption id=\"caption-attachment-72858\" class=\"wp-caption-text\">An artist\u2019s rendering of the Exploration Upper Stage (EUS), a four-engine liquid hydrogen\/liquid oxygen in-space stage on the Space Launch System (SLS) Block 1B and Block 2 rockets. Image: NASA<\/figcaption><\/figure>\n<p>The mid-2024 report also noted that at the time, delivery of the EUS to NASA was \u201cdelayed from February 2021 to April 2027.\u201d That put the Artemis 4 flight, then projected for September 2028, to become further delayed.<\/p>\n<p>Back in late September 2025, Spaceflight Now spoke with Sharon Cobb, the Associate Program manager for SLS at Boeing, about the Artemis 2 mission as well as the progress on the EUS.<\/p>\n<p>\u201cWe\u2019ve been working very diligently on Exploration Upper Stage. I was just at MAF last week and was able to see the liquid oxygen tank has been welded and tested,\u201d Cobb said. \u201cWe\u2019ve also got barrels in work there that are about to be welded for the flight unit. The LOX tank is a structural test article. So, we\u2019re making really good progress on developing that Exploration Upper Stage.<\/p>\n<p>Like with the core stage that launched the Artemis 1 mission, the plan was to perform what\u2019s called a \u2018green run\u2019 with the EUS at NASA\u2019s Stennis Space Center in Mississippi. That would include a full fueling of the upper stage and a full duration static fire test of the four RL10 engines as well.<\/p>\n<p>Presumably, with this new direction for the SLS rocket, that will no longer take place, though NASA hasn\u2019t specifically commented on what will happen with the EUS hardware currently in flow.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>United Launch Alliance\u2019s (ULA\u2019s) Centaur 5 upper stage for the Vulcan Certification-1 (Cert-1) flight heads into pressure cell testing. Image: United Launch Alliance NASA officially selected United Launch Alliance\u2019s Centaur 5 as the upper stage for its Space Launch System rocket starting with the Artemis 4 mission, scheduled to launch no earlier than early 2028. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[],"class_list":["post-9599","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/9599"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=9599"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/9599\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=9599"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=9599"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=9599"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}