Space Launch System#Development history

{{See also|Super heavy-lift launch vehicle#Comparison|l1=Comparison of super heavy-lift launch vehicles}}

The SLS is a Space Shuttle-derived launch vehicle. The rocket's first stage is powered by one central core stage and two outboard solid rocket boosters. All SLS Blocks share a common core stage design but differ in their upper stages and boosters.

{{main|Space Launch System core stage}}

File:Spacelaunchsystem-enginesection-jan2020.jpg for shipping to Stennis Space Center|left]]

Together with the solid rocket boosters, the core stage is responsible for propelling the upper stage and payload out of the atmosphere to near orbital velocity. It contains the liquid hydrogen and liquid oxygen tanks for the ascent phase, the forward and aft solid rocket booster attach points, avionics, and the Main Propulsion System (MPS), an assembly of the four RS-25 engines, associated plumbing and hydraulic gimbal actuators, and equipment for autogenous pressurization of the vehicle's tanks. The core stage provides approximately 25% of the vehicle's thrust at liftoff, the rest coming from the solid rocket boosters.

The stage measures {{cvt|65|order=flip|m|ft}} long by {{cvt|8.4|order=flip|m|ft}} in diameter and is visually similar to the Space Shuttle external tank. It is made mostly of 2219 aluminum alloy, and contains numerous improvements to manufacturing processes, including friction stir welding for the barrel sections, and integrated milling for the stringers. The first four flights will each use and expend four of the remaining sixteen RS-25D engines previously flown on Space Shuttle missions. Aerojet Rocketdyne refits these engines with modernized engine controllers, higher throttle limits, as well as insulation for the high temperatures the engine section will experience due to their position adjacent to the solid rocket boosters. Later flights will switch to an RS-25 variant optimized for expended use, the RS-25E, which will lower per-engine costs by over 30%. The thrust of each RS-25D engine has been increased from {{cvt|2188|order=flip|kN|lbf}}, as on the Space Shuttle, to {{cvt|2281|order=flip|kN|lbf}} on the sixteen modernized engines. The RS-25E will further increase per-engine thrust to {{cvt|2321|order=flip|kN|lbf}}.

Blocks 1 and 1B of the SLS will use two five-segment solid rocket boosters. They use casing segments that were flown on Shuttle missions as parts of the four-segment Space Shuttle Solid Rocket Boosters. They possess an additional center segment, new avionics, and lighter insulation, but lack a parachute recovery system, as they will not be recovered after launch. The propellants for the solid rocket boosters are aluminum powder, which is very reactive, and ammonium perchlorate, a powerful oxidizer. They are held together by a binder, polybutadiene acrylonitrile (PBAN). The mixture has the consistency of a rubber eraser and is packed into each segment.{{cite web |last1=Perry |first1=Beverly |title=We've Got (Rocket) Chemistry, Part 2 |url=https://blogs.nasa.gov/Rocketology/2016/04/21/weve-got-rocket-chemistry-part-2/ |website=Rocketology: NASA’s Space Launch System |publisher=National Aeronautics and Space Administration |access-date=30 September 2022 |date=21 April 2016}} The five-segment solid rocket boosters provide approximately 25% more total impulse than the Shuttle Solid Rocket Boosters.

The stock of SLS Block 1 to 1B boosters is limited by the number of casings left over from the Shuttle program, which allows for eight flights of the SLS. On 2 March 2019, the Booster Obsolescence and Life Extension program was announced, with the goal of developing new solid rocket boosters for SLS Block 2. These boosters will be built by Northrop Grumman Space Systems, and will be derived from the composite-casing solid rocket boosters then in development for the canceled OmegA launch vehicle, and are projected to increase Block 2's payload to {{cvt|130|order=flip|MT|lb}} to low Earth orbit (LEO) and at least {{cvt|46|order=flip|MT|lb}} to trans-lunar injection. {{As of|2021|7}}, the BOLE program is under development, with first firing expected in 2024.{{Needs update|date=March 2025}}

{{anchor|upper-stage-block-1}}

File:Interim Cryogenic Propulsion Stage.jpg ICPS under construction]]

The Interim Cryogenic Propulsion Stage (ICPS) is a temporary upper stage for Block 1 versions of SLS, built by United Launch Alliance, a joint venture of Boeing and Lockheed Martin. The ICPS is essentially an "off-the-shelf" Delta Cryogenic Second Stage, with minimal modifications for SLS integration. The ICPS is intended as a temporary solution and slated to be replaced on the Block 1B version of the SLS by the next-generation Exploration Upper Stage, under design by Boeing.

The ICPS used on the Artemis I mission was powered by a single RL10B-2 engine, while the ICPS for Artemis II and Artemis III will use the RL10C-2 variant.Rosenberg, Zach. [http://www.flightglobal.com/news/articles/delta-second-stage-chosen-as-sls-interim-371581/ "Delta second stage chosen as SLS interim"] {{Webarchive|url=https://web.archive.org/web/20120727084044/http://www.flightglobal.com/news/articles/delta-second-stage-chosen-as-sls-interim-371581/ |date=27 July 2012}}. Flight International, 8 May 2012. Block 1 is intended to be capable of lifting {{cvt|95|order=flip|t|lb}} to low Earth orbit (LEO) in this configuration, including the weight of the ICPS as part of the payload. At the time of SLS core stage separation, Artemis I was travelling on an initial {{cvt|1806|by|30|km}} transatmospheric orbital trajectory. This trajectory ensured safe disposal of the core stage. ICPS then performed orbital insertion and a subsequent translunar injection burn to send Orion towards the Moon. The ICPS will be human-rated for the crewed Artemis II and III flights.{{cite web |date=3 February 2020 |title=Upper Stage RL10s arrive at Stennis for upcoming SLS launches February 2020 |url=https://www.nasaspaceflight.com/2020/02/upper-stage-rl-10s-stennis-sls-launches/ |url-status=live |archive-url=https://web.archive.org/web/20200215153232/https://www.nasaspaceflight.com/2020/02/upper-stage-rl-10s-stennis-sls-launches/ |archive-date=15 February 2020 |access-date=15 February 2020 |publisher=NASASpaceFlight.com}}

The SLS Block 1 has a conical frustum-shaped interstage called the Launch Vehicle Stage Adapter between the core stage and the ICPS. It consists of sixteen aluminum-lithium panels made of 2195 aluminum alloy. Teledyne Brown Engineering is its builder.{{cite web | url=https://www.tbe.com/en-us/news-and-media/Pages/teledyne-to-build-nasa-60-million-launch-vehicle-stage-adapter.aspx | title=Teledyne to Build NASA's $60 Million Launch Vehicle Stage Adapter | access-date=1 April 2023 | archive-date=1 April 2023 | archive-url=https://web.archive.org/web/20230401232054/https://www.tbe.com/en-us/news-and-media/Pages/teledyne-to-build-nasa-60-million-launch-vehicle-stage-adapter.aspx | url-status=live}} The first one cost $60 million, and the next two cost $85 million together.{{Cite web|url=https://www.teledyne.com/en-us/news/Pages/Teledyne-Brown-Engineering-Awarded-$85-Million-NASA-Contract-to-Provide-Key-Stage-of-NASA%27s-Space-Launch-System-Vehicle-Ret.aspx|title=Teledyne Brown Engineering Awarded $85 Million NASA Contract to Provide Key Stage of NASA's Space Launch System Vehicle Returning Astronauts to the Moon|website=www.teledyne.com|access-date=31 May 2023|archive-date=1 April 2023|archive-url=https://web.archive.org/web/20230401232059/https://www.teledyne.com/en-us/news/Pages/Teledyne-Brown-Engineering-Awarded-%2485-Million-NASA-Contract-to-Provide-Key-Stage-of-NASA%27s-Space-Launch-System-Vehicle-Ret.aspx|url-status=live}}

The Exploration Upper Stage (EUS) is planned to first fly on Artemis IV. The EUS will complete the SLS ascent phase and then re-ignite to send its payload to destinations beyond LEO. It is expected to be used by Block 1B and Block 2. The EUS shares the core stage diameter of 8.4 meters, and will be powered by four RL10C-3 engines. It will eventually be upgraded to use four improved RL10C-X engines. {{As of|2022|3}}, Boeing is developing a new composite-based fuel tank for the EUS that would increase Block 1B's overall payload mass capacity to TLI by 40 percent. The improved upper stage was originally named the Dual Use Upper Stage (DUUS, pronounced "duce"), but was later renamed the Exploration Upper Stage (EUS).{{cite web |last1=Bergin |first1=Chris |title=SLS positioning for ARRM and Europa missions |url=http://www.nasaspaceflight.com/2014/03/sls-positioning-arrm-europa-missions/ |publisher=NASASpaceflight.com |date=28 March 2014 |access-date=8 November 2014 |archive-date=3 December 2021 |archive-url=https://web.archive.org/web/20211203181213/https://www.nasaspaceflight.com/2014/03/sls-positioning-arrm-europa-missions/ |url-status=live}}

File:SLS Evolution.jpg

During the joint Senate-NASA presentation in September 2011, it was stated that the SLS program had a projected development cost of US$18 billion through 2017, with $10 billion for the SLS rocket, $6 billion for the Orion spacecraft, and $2 billion for upgrades to the launch pad and other facilities at Kennedy Space Center.{{cite web|url=http://www.spacepolicyonline.com/news/new-nasa-crew-transportation-system-to-cost-18-billion-through-2017|title=New NASA Crew Transportation System to Cost US$18 Billion Through 2017|publisher=Space Policy Online|date=14 September 2011|access-date=15 September 2011|first=Marcia |last=Smith|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402133411/http://www.spacepolicyonline.com/news/new-nasa-crew-transportation-system-to-cost-18-billion-through-2017|url-status=live}}{{cite AV media |url=http://www.c-span.org/video/?301537-1/future-nasa-space-program |title=Future of NASA Space Program |date=14 September 2011 |language=en-us |publisher=Cspan.org |location=Washington, D.C. |people=Bill Nelson, Kay Bailey Hutchison, Charles F. Bolden |access-date=25 March 2015 |archive-date=2 April 2015 |archive-url=https://web.archive.org/web/20150402124545/http://www.c-span.org/video/?301537-1/future-nasa-space-program |url-status=live}} These costs and schedules were considered optimistic in an independent 2011 cost assessment report by Booz Allen Hamilton for NASA.{{cite web|url=http://www.nasa.gov/pdf/581582main_BAH_Executive_Summary.pdf|title=Independent Cost Assessment of the Space Launch System, Multi-purpose Crew Vehicle and 21st Century Ground Systems Programs: Executive Summary of Final Report|publisher=Booz Allen Hamilton|date=19 August 2011|access-date=3 March 2012|archive-date=2 March 2012|archive-url=https://web.archive.org/web/20120302191457/http://www.nasa.gov/pdf/581582main_BAH_Executive_Summary.pdf|url-status=live}} {{PD-notice}} An internal 2011 NASA document estimated the cost of the program through 2025 to total at least $41 billion for four {{cvt|95|order=flip|t|lb}} launches (1 uncrewed, 3 crewed),{{cite web |url=https://www.wsj.com/articles/SB10001424053111903648204576555010831469864|title=White House Experiences Sticker Shock Over NASA's Plans|newspaper=The Wall Street Journal|date=7 September 2011|access-date=22 February 2015|first=Andy |last=Paszior|archive-date=9 December 2017|archive-url=https://web.archive.org/web/20171209152249/https://www.wsj.com/articles/SB10001424053111903648204576555010831469864|url-status=live}}{{cite web|url=http://spacepolicyonline.com/pages/images/stories/SLS_budget_Integration_2011-08.pdf|title=ESD Integration, Budget Availability Scenarios|publisher=Space Policy Online |date=19 August 2011|access-date=15 September 2011|archive-date=9 December 2011|archive-url=https://web.archive.org/web/20111209072917/http://spacepolicyonline.com/pages/images/stories/SLS_budget_Integration_2011-08.pdf|url-status=live}} with the {{cvt|130|order=flip|t|lb}} version ready no earlier than 2030.{{cite web|url=http://www.spacepolicyonline.com/news/the-nasa-numbers-behind-that-wsj-article|title=The NASA Numbers Behind That WSJ Article|first=Marcia |last=Smith|publisher=Space Policy Online|date=9 September 2011|access-date=15 September 2011|archive-date=4 January 2013|archive-url=https://web.archive.org/web/20130104184900/http://www.spacepolicyonline.com/news/the-nasa-numbers-behind-that-wsj-article|url-status=live}} The Human Exploration Framework Team estimated unit costs for 'Block 0' at $1.6 billion and Block 1 at $1.86 billion in 2010.{{cite web |url=http://www.nasawatch.com/images/heft.presentation.pdf|title=HEFT Phase I Closeout|page=69|website=nasawatch.com|date=September 2010|access-date=25 March 2012|archive-date=30 September 2021|archive-url=https://web.archive.org/web/20210930001735/http://www.nasawatch.com/images/heft.presentation.pdf|url-status=live}} However, since these estimates were made, the Block 0 SLS vehicle was dropped in late 2011, and the design was not completed.

In September 2012, an SLS deputy project manager stated that $500 million is a reasonable target average cost per flight for the SLS program.{{cite web |url=http://www.nbcnews.com/id/49019843|title=NASA's huge new rocket may cost US$500 million per launch|publisher=NBC News|date=12 September 2012|access-date=13 November 2019|archive-date=12 August 2020 |archive-url=https://web.archive.org/web/20200812001859/http://www.nbcnews.com/id/49019843|url-status=dead}} In 2013, the Space Review estimated the cost per launch at $5 billion, depending on the rate of launches.{{cite web |author=Roop |first=Lee |date=29 July 2013 |title=NASA defends Space Launch System against charge it 'is draining the lifeblood' of space program |url=http://blog.al.com/breaking/2013/07/nasa_defends_space_launch_syst.html |url-status=live |archive-url=https://web.archive.org/web/20150218232702/http://blog.al.com/breaking/2013/07/nasa_defends_space_launch_syst.html |archive-date=18 February 2015 |access-date=18 February 2015 |website=al.com}}{{cite web|url=http://www.thespacereview.com/article/2330/1|title=Revisiting SLS/Orion launch costs|publisher=The Space Review|date=15 July 2013 |first=John |last=Strickland|access-date=18 February 2015|archive-date=18 February 2015 |archive-url=https://web.archive.org/web/20150218224343/http://www.thespacereview.com/article/2330/1|url-status=live}} NASA announced in 2013 that the European Space Agency will build the Orion service module.{{cite web|url=http://www.nasa.gov/exploration/systems/mpcv/orion_feature_011613.html|title=NASA Signs Agreement for a European-Provided Orion Service Module|archive-url=https://web.archive.org/web/20130118034139/https://www.nasa.gov/exploration/systems/mpcv/orion_feature_011613.html|publisher=NASA|url-status=dead|archive-date=18 January 2013|orig-year=2013|date=12 April 2015}} {{PD-notice}} In August 2014, as the SLS program passed its Key Decision Point C review and was deemed ready to enter full development, costs from February 2014 until its planned launch in September 2018 were estimated at $7.021 billion. Ground systems modifications and construction would require an additional $1.8 billion over the same time.{{cite web|last1=Davis|first1=Jason|title=NASA Budget Lists Timelines, Costs and Risks for First SLS Flight|url=http://www.planetary.org/blogs/jason-davis/2015/20150203-budget-maiden-sls-flight.html|archive-date=12 March 2015|archive-url=https://web.archive.org/web/20150312012014/http://www.planetary.org/blogs/jason-davis/2015/20150203-budget-maiden-sls-flight.html|url-status=live|publisher=The Planetary Society|access-date=11 March 2015}}

In October 2018, NASA's Inspector General reported that the Boeing core stage contract had made up 40% of the $11.9 billion spent on the SLS as of August 2018. By 2021, development of the core stage was expected to have cost $8.9 billion, twice the initially planned amount.{{cite web|url=https://oig.nasa.gov/docs/IG-19-001.pdf|title=NASA's Management of the Space Launch System Stages Contract |date=10 October 2018 |website=oig.nasa.gov|publisher=NASA Office of Inspector General Office of Audits|access-date=14 October 2018|archive-date=10 October 2018|archive-url=https://web.archive.org/web/20181010172919/https://oig.nasa.gov/docs/IG-19-001.pdf|url-status=live}} {{PD-notice}} In December 2018, NASA estimated that yearly budgets for the SLS will range from $2.1 to $2.3 billion between 2019 and 2023.{{Cite web|url=https://www.nasa.gov/sites/default/files/atoms/files/fy19_nasa_budget_estimates.pdf|title=NASA FY 2019 Budget Estimates|website=nasa.gov |page=BUD-2|archive-date=24 December 2018|archive-url=https://web.archive.org/web/20181224004339/https://www.nasa.gov/sites/default/files/atoms/files/fy19_nasa_budget_estimates.pdf|url-status=live|access-date=16 December 2018}} {{PD-notice}}

In March 2019, the Trump administration released its fiscal year 2020 budget request for NASA, which notably proposed dropped funding for the Block 1B and Block 2 variants of SLS. Congressional action ultimately included the funding in the passed budget.{{cite web |url=https://www.fool.com/investing/2019/03/26/is-nasa-preparing-to-cancel-its-space-launch-syste.aspx|title=Is NASA Preparing to Cancel Its Space Launch System?|last=Smith|first=Rich|date=26 March 2019 |website=The Motley Fool|access-date=15 May 2019 |archive-date=23 June 2019|archive-url=https://web.archive.org/web/20190623203841/https://www.fool.com/investing/2019/03/26/is-nasa-preparing-to-cancel-its-space-launch-syste.aspx|url-status=live}} One Gateway component that had been previously planned for the SLS Block 1B is expected to fly on the SpaceX Falcon Heavy rocket.{{Cite web|url=https://www.nasa.gov/sites/default/files/atoms/files/nasa_fy_2019_budget_overview.pdf|title=NASA FY 2019 Budget Overview|access-date=24 June 2019 |archive-date=4 December 2019|archive-url=https://web.archive.org/web/20191204033859/https://www.nasa.gov/sites/default/files/atoms/files/nasa_fy_2019_budget_overview.pdf|url-status=live}} Quote: "Supports launch of the Power and Propulsion Element on a commercial launch vehicle as the first component of the LOP–Gateway, (page 14) {{PD-notice}}{{update after|2023|3|15}}

On 1 May 2020, NASA awarded a contract extension to Aerojet Rocketdyne to manufacture 18 additional RS-25 engines with associated services for $1.79 billion, bringing the total RS-25 contract value to almost $3.5 billion.

{{anchor|SLS-total-budget-table}}NASA has spent $26.4 billion on SLS development since 2011, through 2023, in nominal dollars. This is equivalent to $32 billion in 2024 dollars using the NASA New Start Inflation Indices.

In 2024, the US Congress approved "up to" $2,600 million for the NASA Space Launch System.{{Cite web |title=NASA's FY 2024 Budget |url=https://www.planetary.org/space-policy/nasas-fy-2024-budget |access-date=7 June 2024 |website=The Planetary Society |language=en |archive-date=26 June 2024 |archive-url=https://web.archive.org/web/20240626133609/https://www.planetary.org/space-policy/nasas-fy-2024-budget |url-status=live}}

In January 2024 NASA announced plans for a first crewed flight of the Orion spacecraft on the SLS, the Artemis II mission, no earlier than March 2026.{{Cite web |last=Foust |first=Jeff |date=9 January 2024 |title=NASA delays Artemis 2 and 3 missions |url=https://spacenews.com/nasa-delays-artemis-2-and-3-missions/ |access-date=7 June 2024 |website=SpaceNews |language=en-US}}

Included in the above SLS costs above are (1) the Interim Cryogenic Propulsion Stage (ICPS), a $412 million contract{{Cite web |url=https://govtribe.com/award/federal-contract-award/definitive-contract-nnm12aa82c|title=Definitive Contract NNM12AA82C|website=govtribe.com|access-date=16 December 2018|archive-date=30 September 2021 |archive-url=https://web.archive.org/web/20210930001739/https://govtribe.com/award/federal-contract-award/definitive-contract-nnm12aa82c|url-status=live}} {{PD-notice}} and (2) the costs of developing the Exploration Upper Stage (below).

Excluded from the SLS cost above are the costs to assemble, integrate, prepare and launch the SLS and its payloads, funded separately in the NASA Exploration Ground Systems, currently at about $600 million per year, and anticipated to stay there through at least the first four launches of SLS. Also excluded are payloads that launch on the SLS, such as the Orion crew capsule, the predecessor programs that contributed to the development of the SLS, such as the Ares V Cargo Launch Vehicle project, funded from 2008 to 2010 for a total of $70 million, and the Ares I Crew Launch Vehicle, funded from 2006 to 2010 for a total of $4.8 billion{{Cite web |title=FY 2008 Budget Estimates |url=http://www.nasa.gov/pdf/168652main_NASA_FY08_Budget_Request.pdf |url-status=live |archive-url=https://web.archive.org/web/20160603152901/http://www.nasa.gov/pdf/168652main_NASA_FY08_Budget_Request.pdf |archive-date=3 June 2016 |access-date=23 June 2016 |publisher=NASA |page=ESMD-14}} {{PD-notice}} in development, including the 5-segment Solid Rocket Boosters used on the SLS.

File:Space Launch System Booster Passes Major Ground Test.webm's desert facility northwest of Ogden, Utah, March 2015]]

File:KSC-20210610-MH-FMX01-0001-Artemis I SLS Core Stage Lift Ops TIMELAPSE-3278141~orig-trimmed.webm

The SLS was created by an act of the U.S. Congress in the NASA Authorization Act of 2010, Public Law 111–267, in which NASA was directed to create a system for launching payloads and crew into space that would replace the capabilities lost with the retirement of the Space Shuttle. The act set out certain goals, such as being able to lift 70–100 tons into low earth orbit with evolvability to 130 tons, a target date of 31 December 2016 for the system to be fully operational, and a directive to use "to the extent practicable" existing components, hardware, and workforce from the Space Shuttle and from Ares I.{{rp|12}}

On 14 September 2011, NASA announced their plan to meet these requirements: the design for the SLS, with the Orion spacecraft as payload.{{Cite web|date=24 May 2011|title=NASA Announces Key Decision For Next Deep Space Transportation System|url=http://www.nasa.gov/home/hqnews/2011/may/HQ_11-164_MPCV_Decision.html|url-status=live|archive-url=https://web.archive.org/web/20160915182112/http://www.nasa.gov/home/hqnews/2011/may/HQ_11-164_MPCV_Decision.html|archive-date=15 September 2016|access-date=26 January 2012|publisher=NASA}} {{PD-notice}}{{Cite web|url=http://www.c-span.org/Events/Press-Conference-on-the-Future-of-NASA-Space-Program/10737424158/|title=Press Conference on the Future of NASA Space Program|publisher=C-Span|date=14 September 2011|access-date=14 September 2011|archive-date=8 February 2012|archive-url=https://web.archive.org/web/20120208145214/http://www.c-span.org/Events/Press-Conference-on-the-Future-of-NASA-Space-Program/10737424158/|url-status=live}}{{cite news |author=Chang |first=Kenneth |date=14 September 2011 |title=NASA Unveils New Rocket Design |url=https://www.nytimes.com/2011/09/15/science/space/15nasa.html |url-status=live |archive-url=https://web.archive.org/web/20170221195020/http://www.nytimes.com/2011/09/15/science/space/15nasa.html |archive-date=21 February 2017 |access-date=14 September 2011 |newspaper=The New York Times}}

The SLS has considered several future development routes of potential launch configurations, with the planned evolution of the blocks of the rocket having been modified many times. Many options, all of which just needed to meet the congressionally mandated payload minimums, were considered, including a Block 0 variant with three main engines, a variant with five main engines, a Block 1A variant with upgraded boosters instead of the improved second stage, and a Block 2 with five main engines plus the Earth Departure Stage, with up to three J-2X engines.

In the initial announcement of the design of the SLS, NASA also announced an "Advanced Booster Competition", to select which boosters would be used on Block 2 of the SLS.{{Cite web |author=Cowing |first=Keith |date=14 September 2011 |title=NASA's New Space Launch System Announced – Destination TBD |url=http://www.spaceref.com/news/viewnews.html?id=1567 |url-status=live |archive-url=https://archive.today/20120604021003/http://www.spaceref.com/news/viewnews.html?id=1567 |archive-date=4 June 2012 |access-date=26 January 2012 |publisher=SpaceRef}}{{Cite web |author=Morring |first=Frank |date=17 June 2011 |title=NASA Will Compete Space Launch System Boosters |url=http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/awx/2011/06/16/awx_06_16_2011_p0-337088.xml&headline=NASA%20Will%20Compete%20Space%20Launch%20System%20Boosters |url-status=live |archive-url=https://web.archive.org/web/20111011122336/http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news%2Fawx%2F2011%2F06%2F16%2Fawx_06_16_2011_p0-337088.xml&headline=NASA%20Will%20Compete%20Space%20Launch%20System%20Boosters |archive-date=11 October 2011 |access-date=20 June 2011 |publisher=Aviation Week}} Several companies proposed boosters for this competition, all of which were indicated as viable:{{Cite web|date=14 January 2013|title=SLS Block II drives hydrocarbon engine research|url=http://www.thespacereview.com/article/2217/1|url-status=live|archive-url=https://web.archive.org/web/20130902024820/http://www.thespacereview.com/article/2217/1|archive-date=2 September 2013|access-date=13 September 2013|work=thespacereview.com}} Aerojet and Teledyne Brown proposed three booster engines each with dual combustion chambers,{{Cite web|title=NASA's Space Launch System: Partnering For Tomorrow|url=http://www.asee.org/Crumbly_ASEE_Final.pdf|publisher=NASA|access-date=12 March 2013|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402114152/http://www.asee.org/Crumbly_ASEE_Final.pdf|url-status=live}} {{PD-notice}} Alliant Techsystems proposed a modified solid rocket booster with lighter casing, more energetic propellant, and four segments instead of five,{{Cite news|url=http://www.nasaspaceflight.com/2013/01/the-dark-knights-atks-advanced-booster-revealed-for-sls/|title=The Dark Knights – ATK's Advanced Boosters for SLS revealed|publisher=NASASpaceFlight.com|date=14 January 2013|access-date=10 September 2013|archive-date=12 September 2013|archive-url=https://web.archive.org/web/20130912223133/http://www.nasaspaceflight.com/2013/01/the-dark-knights-atks-advanced-booster-revealed-for-sls/|url-status=live}} and Pratt & Whitney Rocketdyne and Dynetics proposed a liquid-fueled booster named Pyrios.{{Cite news |author=Hutchinson |first=Lee |date=15 April 2013 |title=New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust |url=https://arstechnica.com/science/2013/04/new-f-1b-rocket-engine-upgrades-apollo-era-deisgn-with-1-8m-lbs-of-thrust/ |url-status=live |archive-url=https://web.archive.org/web/20171202064940/https://arstechnica.com/science/2013/04/new-f-1b-rocket-engine-upgrades-apollo-era-deisgn-with-1-8m-lbs-of-thrust/ |archive-date=2 December 2017 |access-date=15 April 2013 |publisher=Ars Technica}} However, this competition was planned for a development plan in which Block 1A would be followed by Block 2A, with upgraded boosters. NASA canceled Block 1A and the planned competition in April 2014, in favor of simply remaining with the Ares I's five-segment solid rocket boosters, themselves modified from the Space Shuttle's solid rocket boosters, until at least the late 2020s.{{Cite web|url=http://www.spacenews.com/article/civil-space/40647news-from-the-30th-space-symposium-second-sls-mission-might-not-carry-crew|archive-url=https://archive.today/20140727043122/http://www.spacenews.com/article/civil-space/40647news-from-the-30th-space-symposium-second-sls-mission-might-not-carry-crew|url-status=dead|archive-date=27 July 2014|title=Second SLS Mission Might Not Carry Crew|date=21 May 2014|publisher=SpaceNews|access-date=25 July 2014}} The overly powerful advanced booster would have resulted in unsuitably high acceleration, and would need modifications to Launch Complex 39B, its flame trench, and Mobile Launcher.{{cite web|url=http://www.nasaspaceflight.com/2012/07/wind-tunnel-testing-sls-configurations-block-1b/|title=Wind Tunnel testing conducted on SLS configurations, including Block 1B |date=July 2012|publisher=NASASpaceFlight.com|access-date=13 November 2012|archive-date=24 October 2012|archive-url=https://web.archive.org/web/20121024215052/http://www.nasaspaceflight.com/2012/07/wind-tunnel-testing-sls-configurations-block-1b/|url-status=live}}

On 31 July 2013, the SLS passed Preliminary Design Review. The review included not only the rocket and boosters but also ground support and logistical arrangements.{{Cite web|url=http://www.nasa.gov/exploration/systems/sls/sls-pdr.html|publisher=NASA|date=1 August 2013|title=NASA's Space Launch System Program PDR: Answers to the Acronym|access-date=3 August 2013|archive-date=4 August 2013|archive-url=https://web.archive.org/web/20130804050311/http://www.nasa.gov/exploration/systems/sls/sls-pdr.html|url-status=live}} {{PD-notice}}

On 7 August 2014, the SLS Block 1 passed a milestone known as Key Decision Point C and entered full-scale development, with an estimated launch date of November 2018.{{Cite web|url=http://www.nasa.gov/press/2014/august/nasa-completes-key-review-of-world-s-most-powerful-rocket-in-support-of-journey-to/#.U_5UAfl7Eeg|title=NASA Completes Key Review of World's Most Powerful Rocket in Support|date=15 April 2015 |publisher=NASA|access-date=26 October 2015|archive-date=27 May 2016 |archive-url=https://web.archive.org/web/20160527051013/http://www.nasa.gov/press/2014/august/nasa-completes-key-review-of-world-s-most-powerful-rocket-in-support-of-journey-to/#.U_5UAfl7Eeg|url-status=live}} {{PD-notice}}

In 2013, NASA and Boeing analyzed the performance of several Exploration Upper Stage (EUS) engine options. The analysis was based on a second-stage usable propellant load of 105 metric tons, and compared stages with four RL10 engines, two MARC-60 engines, or one J-2X engine.{{Cite web|url=http://www.nasaspaceflight.com/2013/11/sls-us-proposals-increasing-payload-destination-options/|title=SLS upper stage proposals reveal increasing payload-to-destination options|date=13 November 2013|publisher=NASASpaceFlight.com|first=Chris |last=Gebhardt|access-date=18 November 2013|archive-date=18 November 2013|archive-url=https://web.archive.org/web/20131118144209/http://www.nasaspaceflight.com/2013/11/sls-us-proposals-increasing-payload-destination-options/|url-status=live}}{{Cite web|url=http://seradata.com/SSI/2013/06/sls-may-change-upper-stage-eng/|title=SLS design may ditch J-2X upper stage engine for four RL-10 engines|archive-url=https://web.archive.org/web/20160304043940/http://seradata.com/SSI/2013/06/sls-may-change-upper-stage-eng/|archive-date=4 March 2016|first=David |last=Todd|date=3 June 2013|publisher=Seradata}} In 2014, NASA also considered using the European Vinci instead of the RL10, which offered the same specific impulse but with 64% greater thrust, which would allow for the same performance at a lower cost.{{Cite web|url=http://seradata.com/SSI/2014/11/next-steps-for-sls-europes-vinci-is-a-contender-for-exploration-upper-stage-engine/|title=Next Steps for SLS: Europe's Vinci is a contender for Exploration Upper-Stage Engine|first=David |last=Todd|date=7 November 2014|publisher=Seradata|archive-url=https://web.archive.org/web/20160304023658/http://seradata.com/SSI/2014/11/next-steps-for-sls-europes-vinci-is-a-contender-for-exploration-upper-stage-engine/|archive-date=4 March 2016}}

In 2018, Blue Origin submitted a proposal to replace the EUS with a cheaper alternative to be designed and fabricated by the company, but it was rejected by NASA in November 2019 on multiple grounds; these included lower performance compared to the existing EUS design, incompatibility of the proposal with the height of the door of the Vehicle Assembly Building being only {{convert|390|ft|m}}, and unacceptable acceleration of Orion components such as its solar panels due to the higher thrust of the engines being used for the fuel tank.{{Cite news |last1=Berger|first1=Eric|title=NASA rejects Blue Origin's offer of a cheaper upper stage for the SLS rocket|url=https://arstechnica.com/science/2019/11/nasa-rejects-blue-origins-offer-of-a-cheaper-upper-stage-for-the-sls-rocket/|work = Ars Technica|access-date=19 December 2019|date=5 November 2019|archive-date=19 December 2019|archive-url=https://web.archive.org/web/20191219042903/https://arstechnica.com/science/2019/11/nasa-rejects-blue-origins-offer-of-a-cheaper-upper-stage-for-the-sls-rocket/|url-status=live}}{{Cite web |title=Redacted_EUS.pdf |url=https://sam.gov/opp/957d857a579a9c13c26c64825f82a5d5/view |website=sam.gov |access-date=6 October 2021 |date=31 October 2019 |archive-url=https://web.archive.org/web/20211006030858/https://iae-fbo-attachments.s3.amazonaws.com/fbo/files/b3a/b3a26357ad9cd1ca8bf7e370e7459804.pdf?response-content-disposition=attachment%3B%20filename%3DRedacted_EUS.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20211006T030858Z&X-Amz-SignedHeaders=host&X-Amz-Expires=9&X-Amz-Credential=AKIAY3LPYEEX5FRGIQ4E%2F20211006%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=1697246eac19e0b7f799a6d9a048d3c583cecf12e1ee7213e4e5a254fae3a876 |url-status=live |archive-date=6 October 2021}}{{rp|7–8}}

From 2009 to 2011, three full-duration static fire tests of five-segment solid rocket boosters were conducted under the Constellation Program, including tests at low and high core temperatures, to validate performance at extreme temperatures.{{Cite web|url=http://www.nasa.gov/mission_pages/constellation/ares/dm1_success.html|title=NASA and ATK Successfully Test Ares First Stage Motor|publisher=NASA|date=10 September 2009|access-date=30 January 2012|archive-date=24 December 2018|archive-url=https://web.archive.org/web/20181224004602/https://www.nasa.gov/mission_pages/constellation/ares/dm1_success.html|url-status=live}} {{PD-notice}}{{Cite web|url=http://www.nasa.gov/mission_pages/constellation/ares/10-202.html|title=NASA and ATK Successfully Test Five-Segment Solid Rocket Motor|publisher=NASA|date=31 August 2010|access-date=30 January 2012|archive-date=19 December 2011|archive-url=https://web.archive.org/web/20111219022208/http://www.nasa.gov/mission_pages/constellation/ares/10-202.html|url-status=live}} {{PD-notice}}{{Cite web|url=http://www.nasa.gov/exploration/features/dm3.html|title=NASA Successfully Tests Five-Segment Solid Rocket Motor|publisher=NASA|date=31 August 2010|access-date=8 September 2011|archive-date=24 September 2011|archive-url=https://web.archive.org/web/20110924091505/http://www.nasa.gov/exploration/features/dm3.html|url-status=live}} {{PD-notice}} The 5-segment solid rocket booster would be carried over to SLS. Northrop Grumman Innovation Systems has completed full-duration static fire tests of the five-segment solid rocket boosters. Qualification Motor 1 was tested on 10 March 2015.{{Cite news|last1=Bergin|first1=Chris|title=QM-1 shakes Utah with two minutes of thunder|url=http://www.nasaspaceflight.com/2015/03/qm-1-shake-utah-two-minutes-thunder/|access-date=10 March 2015|publisher=NASASpaceFlight.com|date=10 March 2015|archive-date=13 March 2015|archive-url=https://web.archive.org/web/20150313223625/http://www.nasaspaceflight.com/2015/03/qm-1-shake-utah-two-minutes-thunder/|url-status=live}} Qualification Motor 2 was successfully tested on 28 June 2016.{{Cite web|url=https://news.northropgrumman.com/news/features/orbital-atk-successfully-tests-the-world-s-largest-solid-rocket-motor |title=Orbital ATK Successfully Tests the World's Largest Solid Rocket Motor |publisher=Northrop Grumman |date=28 June 2016 |access-date=11 October 2021 |archive-url=https://web.archive.org/web/20210615100406/https://news.northropgrumman.com/news/features/orbital-atk-successfully-tests-the-world-s-largest-solid-rocket-motor |archive-date=15 June 2021 |url-status=live}}

On 7 February 2025, Boeing, the primary contractor for the SLS, informed its employees working on the rocket program that they may face layoffs when the company's contract expires in March. The announcement coincided with the anticipated release of the presidential budget, suggesting the Trump administration might propose canceling the SLS program.{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=7 February 2025 |title=Boeing has informed its employees that NASA may cancel SLS contracts |url=https://arstechnica.com/space/2025/02/boeing-has-informed-its-employees-that-nasa-may-cancel-sls-contracts/ |access-date=7 February 2025 |work=Ars Technica |language=en-US}}

On 2 May 2025, the Trump administration released its fiscal year 2026 budget proposal for NASA, which calls for terminating the SLS and Orion spacecraft programs after Artemis III.{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=2 May 2025 |title=White House budget seeks to end SLS, Orion, and Lunar Gateway programs |url=https://arstechnica.com/space/2025/05/white-house-budget-seeks-to-end-sls-orion-and-lunar-gateway-programs/ |access-date=2 May 2025 |work=Ars Technica}}{{Cite press release |title=President Trump's FY26 Budget Revitalizes Human Space Exploration |date=2 May 2025 |publisher=NASA |url=https://www.nasa.gov/news-release/president-trumps-fy26-budget-revitalizes-human-space-exploration/ |last1=Dooren |first1=Jennifer M. |last2=Stevens |first2=Bethany |access-date=2 May 2025 |id=25-035}} The budget proposal described the SLS as "grossly expensive", noting that it costs $4 billion per launch and has exceeded its budget by 140 percent. The budget allocates funding for a program to transition to "more cost-effective commercial systems", a move projected to save NASA $879 million.{{Cite web |date=2 May 2025 |title=Fiscal Year 2026 Discretionary Budget Request |url=https://www.whitehouse.gov/wp-content/uploads/2025/05/Fiscal-Year-2026-Discretionary-Budget-Request.pdf |access-date=2 May 2025 |website=United States Office of Management and Budget |page=37}}

NASA has been reluctant to provide an official per-flight cost estimate for the SLS.{{Cite web |url=https://arstechnica.com/science/2017/10/nasa-chooses-to-not-tell-congress-how-much-deep-space-missions-cost/|title=NASA chooses not to tell Congress how much deep space missions cost |last=Berger|first=Eric|date=20 October 2017|website=arstechnica.com|access-date=16 December 2018|archive-date=17 December 2018|archive-url=https://web.archive.org/web/20181217062648/https://arstechnica.com/science/2017/10/nasa-chooses-to-not-tell-congress-how-much-deep-space-missions-cost/|url-status=live}} However, independent agencies, such as the White House Office of Management and Budget and the NASA Office of Inspector General, have offered their own estimates.

A White House Office of Management and Budget letter to the Senate Appropriations Committee in October 2019 estimated that SLS's total cost to the taxpayer was estimated at "over $2 billion" per launch.{{refn|name=totalcost|group=note|See the budget table for yearly inflation-adjusted figures.}} When questioned by a journalist, a NASA spokesperson did not deny this per-flight cost estimate.

The NASA Office of Inspector General has conducted several audits of the SLS program. A November 2021 report estimated that, at least for the first four launches of Artemis program, the per-launch production and operating costs would be $2.2 billion for SLS, plus $568 million for Exploration Ground Systems. Additionally, the payload would cost $1 billion for Orion and $300 million for the European Service Module.{{rp|23}} An October 2023 report found that recurring production costs for SLS, excluding development and integration costs, are estimated to be at least $2.5 billion per launch.

NASA has said that it is working with Boeing to bring down the cost of SLS launches and that a higher launch frequency could potentially lead to economies of scale, and would allow fixed costs to be spread out over more launches. However, the NASA Office of Inspector General has called NASA's cost savings goals highly unrealistic and other potential government customers have made it clear they have no interest in using SLS.

File:NASA Readies Artemis II Liquid Hydrogen Tank for Next Phase of Manufacturing.jpg tank for Artemis II under construction, August 2020]]

File:MAF 20210609 CS2 BoatTail2CellA09.jpg for Artemis II under construction, June 2021]]

File:NASA Readies Artemis III (MAF 20210401 ARTIII ESLift14).jpg under construction, April 2021]]

{{as of|2020}}, three SLS versions are planned: Block 1, Block 1B, and Block 2. Each will use the same Core stage with its four main engines, but Block 1B will feature the Exploration Upper Stage (EUS), and Block 2 will combine the EUS with upgraded boosters.{{cite web|url=http://commerce.senate.gov/public/index.cfm?p=Legislation&ContentRecord_id=8d7c1465-f852-4835-ba84-25faf56bbb36&ContentType_id=03ab50f5-55cd-4934-a074-d6928b9dd24c&Group_id=6eaa2a03-6e69-4e43-8597-bb12f4f5aede|work=Featured Legislation|title=The NASA Authorization Act of 2010|date=15 July 2010 |publisher=U.S. Senate|archive-url=https://web.archive.org/web/20110410161657/https://www.commerce.senate.gov/public/index.cfm?p=Legislation&ContentRecord_id=8d7c1465-f852-4835-ba84-25faf56bbb36&ContentType_id=03ab50f5-55cd-4934-a074-d6928b9dd24c&Group_id=6eaa2a03-6e69-4e43-8597-bb12f4f5aede|archive-date=10 April 2011|url-status=dead|access-date=26 May 2011}} {{PD-notice}}{{cite web|url=http://www.space.com/12957-nasa-giant-rocket-space-launch-system-infographic.html|title=Space Launch System: NASA's Giant Rocket Explained|first=Karl |last=Tate|date=16 September 2011|publisher=Space.com|access-date=26 January 2012|archive-date=27 January 2012|archive-url=https://web.archive.org/web/20120127120812/http://www.space.com/12957-nasa-giant-rocket-space-launch-system-infographic.html|url-status=live}}

The ICPS for Artemis 1 was delivered by ULA to NASA about July 2017{{cite web|url=https://www.nasaspaceflight.com/2017/07/sls-upper-stage-residency-former-home-iss-modules/|title=SLS Upper Stage set to take up residence in the former home of ISS modules July 2017|date=11 July 2017 |access-date=15 February 2020|archive-date=7 August 2020|archive-url=https://web.archive.org/web/20200807132155/https://www.nasaspaceflight.com/2017/07/sls-upper-stage-residency-former-home-iss-modules/|url-status=live}} and was housed at Kennedy Space Center as of November 2018.{{cite web|title=Meet the Interim Cryogenic Propulsion Stage for SLS |url=http://www.nasa.gov/exploration/systems/sls/interim-cryogenic-propulsion-stage-infographic-for-sls.html|url-status=dead|last=Harbaugh|first=Jennifer|date=8 November 2018|publisher=NASA|archive-url=https://web.archive.org/web/20200807130817/https://www.nasa.gov/exploration/systems/sls/interim-cryogenic-propulsion-stage-infographic-for-sls.html|archive-date=7 August 2020}} {{PD-notice}}

In mid-November 2014, construction of the first core stage hardware began using a new friction stir welding system in the South Vertical Assembly Building at NASA's Michoud Assembly Facility. Between 2015 and 2017, NASA test fired RS-25 engines in preparation for use on SLS.

The core stage for the first SLS, built at Michoud Assembly Facility by Boeing, had all four engines attached in November 2019,{{cite web |url=https://www.nasa.gov/exploration/systems/sls/multimedia/four-engines-attached-to-sls-core-stage-for-artemis-I-mission.html|title=All Four Engines Are Attached to the SLS Core Stage for Artemis I Mission |date=8 November 2019 |publisher=NASA|access-date=12 November 2019|archive-date=12 November 2019|archive-url=https://web.archive.org/web/20191112214328/https://www.nasa.gov/exploration/systems/sls/multimedia/four-engines-attached-to-sls-core-stage-for-artemis-I-mission.html|url-status=live}} {{PD-notice}} and it was declared finished by NASA in December 2019.{{cite web|last1=Clark|first1=Stephen|title=NASA declares first SLS core stage complete|url=https://spaceflightnow.com/2019/12/15/nasa-declares-first-sls-core-stage-complete/|publisher=Spaceflight Now|access-date=7 October 2021|date=15 December 2019|archive-date=11 May 2022|archive-url=https://web.archive.org/web/20220511091912/https://spaceflightnow.com/2019/12/15/nasa-declares-first-sls-core-stage-complete/|url-status=live}}

The first core stage left Michoud Assembly Facility for comprehensive testing at Stennis Space Center in January 2020.{{cite news|url=https://www.bbc.com/news/science-environment-51048986|title=Nasa Moon rocket core leaves for testing|last=Rincon|first=Paul|publisher=BBC News|date=9 January 2020|access-date=9 January 2020|archive-date=9 January 2020|archive-url=https://web.archive.org/web/20200109151551/https://www.bbc.com/news/science-environment-51048986|url-status=live}} The static firing test program at Stennis Space Center, known as the Green Run, operated all the core stage systems simultaneously for the first time.{{cite web|url=https://www.nasaspaceflight.com/2019/12/boeing-nasa-sls-core-stage-green-run-campaign-stennis/|title=Boeing, NASA getting ready for SLS Core Stage Green Run campaign ahead of Stennis arrival|date=14 December 2019|publisher=NASASpaceFlight.com|access-date=9 January 2020|archive-date=30 September 2021|archive-url=https://web.archive.org/web/20210930001752/https://www.nasaspaceflight.com/2019/12/boeing-nasa-sls-core-stage-green-run-campaign-stennis/|url-status=live}}{{cite web |url=https://www.nextbigfuture.com/2019/08/nasa-will-have-8-minute-hold-down-test-in-2020.html|title=NASA Will Have 8 Minute Hold Down Test in 2020|publisher=Next Big Future|access-date=2 August 2019|archive-date=2 August 2019|archive-url=https://web.archive.org/web/20190802192558/https://www.nextbigfuture.com/2019/08/nasa-will-have-8-minute-hold-down-test-in-2020.html|url-status=live}} Test 7 (of 8), the wet dress rehearsal, was carried out in December 2020 and the fire (test 8) took place on 16 January 2021, but shut down earlier than expected,{{cite web|last1=Foust|first1=Jeff|title=Green Run hotfire test ends early|url=https://spacenews.com/green-run-hotfire-test-ends-early/|publisher=SpaceNews|access-date=17 January 2021|date=16 January 2021|archive-date=3 October 2021|archive-url=https://web.archive.org/web/20211003032149/https://spacenews.com/green-run-hotfire-test-ends-early/|url-status=live}} about 67 seconds in total rather than the desired eight minutes. The reason for the early shutdown was later reported to be because of conservative test commit criteria on the thrust vector control system, specific only for ground testing and not for flight. If this scenario occurred during a flight, the rocket would have continued to fly normally. There was no sign of damage to the core stage or the engines, contrary to initial concerns.{{Cite web|last1=Rincon|first1=Paul|title=SLS: NASA finds cause of 'megarocket' test shutdown|url=https://www.bbc.co.uk/news/science-environment-55727686|publisher=BBC News|access-date=20 January 2021|date=20 January 2021|archive-date=20 January 2021 |archive-url=https://web.archive.org/web/20210120041016/https://www.bbc.co.uk/news/science-environment-55727686|url-status=live}}

The second fire test was completed on 18 March 2021, with all four engines igniting, throttling down as expected to simulate in-flight conditions, and gimballing profiles. The core stage was shipped to Kennedy Space Center to be mated with the rest of the rocket for Artemis I. It left Stennis on 24 April and arrived at Kennedy on 27 April.{{cite web|url=http://www.nasa.gov/image-feature/space-launch-system-core-stage-arrives-at-the-kennedy-space-center|title=Space Launch System Core Stage Arrives at the Kennedy Space Center|first=Brian|last=Dunbar|date=29 April 2021|publisher=NASA|access-date=1 June 2021|archive-date=7 May 2021|archive-url=https://web.archive.org/web/20210507205846/http://www.nasa.gov/image-feature/space-launch-system-core-stage-arrives-at-the-kennedy-space-center/|url-status=live}} {{PD-notice}} It was refurbished there in preparation for stacking.{{cite web|title=SLS Core Stage thermal protection system refurbishment in work at Kennedy for Artemis 1|url=https://www.nasaspaceflight.com/2021/05/tps-repairs-core-stage-work-updatei/|last=Sloss|first=Philip|publisher=NASASpaceFlight.com|archive-date=26 May 2021|archive-url=https://web.archive.org/web/20210526143900/https://www.nasaspaceflight.com/2021/05/tps-repairs-core-stage-work-updatei/|url-status=live|date=20 May 2021|access-date=26 May 2021}} On 12 June 2021, NASA announced the assembly of the first SLS rocket was completed at the Kennedy Space Center. The assembled SLS was used for the uncrewed Artemis I mission in 2022.

The first SLS, for Artemis I, launched an Orion spacecraft into a lunar orbit on a test flight in fall 2022,{{cite news |title=Former NASA Official: Moon launch this month may be "embarrassing" |url=https://futurism.com/the-byte/lori-garver-sls-moon-launch |work=The Byte |date=25 August 2022 |access-date=15 September 2022 |archive-date=16 September 2022 |archive-url=https://web.archive.org/web/20220916001826/https://futurism.com/the-byte/lori-garver-sls-moon-launch |url-status=live}} and NASA and Boeing are constructing the next three rockets for Artemis II, Artemis III, and Artemis IV. Boeing stated in July 2021 that while the COVID-19 pandemic had affected their suppliers and schedules, such as delaying parts needed for hydraulics, they would still be able to provide the Artemis II SLS core stage per NASA's schedule, with months to spare. The spray-on foam insulation process for Artemis II was automated for most sections of the core stage, saving 12 days in the schedule. The Artemis II forward skirt, the foremost component of the core stage, was affixed on the liquid oxygen tank in late May 2021. By 25 September 2023 the core stage was functionally complete, as all sections were assembled and the four RS-25 engines had been installed.{{cite web | last=Mohon | first=Lee | title=All Engines Added to NASA's Artemis II Moon Rocket Core Stage – Artemis | website=NASA Blogs | date=25 September 2023 | url=https://blogs.nasa.gov/artemis/2023/09/25/all-engines-added-to-nasas-artemis-ii-moon-rocket-core-stage/ | access-date=25 September 2023 | archive-date=25 September 2023 | archive-url=https://web.archive.org/web/20230925202615/https://blogs.nasa.gov/artemis/2023/09/25/all-engines-added-to-nasas-artemis-ii-moon-rocket-core-stage/ | url-status=live}} {{As of|2023|May}}, the complete core stage was set to ship to NASA in late fall 2023,{{cite web | last=Clark | first=Stephen | title=Rocket Report: Iran launches satellite; Artemis II boosters get train ride | website=Ars Technica | date=29 September 2023 | url=https://arstechnica.com/space/2023/09/rocket-report-iran-launches-satellite-artemis-ii-boosters-get-train-ride/ | access-date=2 October 2023 | archive-date=29 September 2023 | archive-url=https://web.archive.org/web/20230929111259/https://arstechnica.com/space/2023/09/rocket-report-iran-launches-satellite-artemis-ii-boosters-get-train-ride/ | url-status=live}}{{cite web | last=Sloss | first=Philip | title=Artemis II Moon mission transitioning from planning to preparation | website=NASASpaceFlight.com | date=2 May 2023 | url=https://www.nasaspaceflight.com/2023/05/artemis-ii-update/ | access-date=6 June 2023 | archive-date=2 May 2023 | archive-url=https://web.archive.org/web/20230502201704/https://www.nasaspaceflight.com/2023/05/artemis-ii-update/ | url-status=live}} eight months later than was predicted originally.{{Cite web |last=Sloss |first=Philip |date=25 July 2022 |title=Boeing aiming to deliver second SLS Core Stage to NASA in March |url=https://www.nasaspaceflight.com/2022/07/boeing-second-sls-core-march/ |access-date=30 July 2022 |website=NASASpaceFlight.com |language=en-US |archive-date=31 August 2022 |archive-url=https://web.archive.org/web/20220831222158/https://www.nasaspaceflight.com/2022/07/boeing-second-sls-core-march/ |url-status=live}} The complete core stage was delivered in July 2024.{{cite web | url=https://aerospaceglobalnews.com/news/boeing-delivers-second-stage-of-sls-rocket-to-nasa/ | title=Boeing delivers second stage of SLS rocket to NASA - AGN Boeing delivers second stage of SLS rocket to NASA | date=17 July 2024 }} For Artemis III, assembly of elements of the thrust structure began at Michoud Assembly Facility in early 2021. The liquid hydrogen tank for Artemis III was originally planned to be the Artemis I tank, but it was set aside as the welds were found to be faulty.{{rp|2}} Repair techniques were developed, and the tank re-entered production and will be proof tested for strength, for use on Artemis III.{{rp|2}}

{{Asof|2021|7|post=,}} Boeing is also preparing to begin construction of the Exploration Upper Stage (EUS), which is planned to be used on Artemis IV.

{{main|List of Space Launch System launches}}

Originally planned for late 2016, the uncrewed first flight of SLS slipped more than twenty-six times and almost six years.{{refn|group=note|name=slips|1={{anchor|first-launch-slips}}

{{(!}}class{{=}}"wikitable alternation"

{{!}}+Then-planned launch date history

! Date

! Planned launch date

{{!}}-

{{!}} October 2010

{{!}} 31 December 2016

{{!}}-

{{!}} September 2011

{{!}} 2017

{{!}}-

{{!}} February 2012–August 2014

{{!}} 17 December 2017{{cite web |last1=Bergin |first1=Chris |title=Exploration Mission 1: SLS and Orion mission to the Moon outlined |url=https://www.nasaspaceflight.com/2012/02/exploration-mission-1-sls-orion-debut-mission-moon-outlined/ |website=NASASpaceFlight.com |publisher=NASASpaceFlight |access-date=2 September 2022 |date=29 February 2012 |archive-date=24 August 2022 |archive-url=https://web.archive.org/web/20220824104014/https://www.nasaspaceflight.com/2012/02/exploration-mission-1-sls-orion-debut-mission-moon-outlined/ |url-status=live}}

{{!}}-

{{!}} December 2014

{{!}} June–July 2018

{{!}}-

{{!}} 13 April 2017{{inconsistent|date=June 2022|reason=Ref TPS-20170517 implies that Nov 2018 launch date existed as early as 2015? Need to find when the slip to Nov 2018 really happened}}

{{!}} November 2018

{{!}}-

{{!}} 28 April 2017

{{!}} 2019

{{!}}-

{{!}} November 2017

{{!}} June 2020

{{!}}-

{{!}} December 2019

{{!}} November 2020

{{!}}-

{{!}} 21 February 2020

{{!}} 18 April 2021

{{!}}-

{{!}} 28 February 2020

{{!}} Mid- to late 2021

{{!}}-

{{!}} May 2020

{{!}} 22 November 2021

{{!}}-

{{!}} August 2021

{{!}} December 2021

{{!}}-

{{!}} 22 October 2021

{{!}} 12 February 2022

{{!}}-

{{!}} 17 December 2021

{{!}} March–April 2022

{{!}}-

{{!}} February 2022

{{!}} May 2022

{{!}}-

{{!}} March 2022

{{!}} June 2022

{{!}}-

{{!}} 26 April 2022

{{!}} 23 August 2022

{{!}}-

{{!}} 20 July 2022

{{!}} 8:33 am ET (12:33 UTC), 29 August 2022

{{!}}-

{{!}} 29 August 2022

{{!}} 12:48 pm ET (16:48 UTC), 2 September 2022{{cite news |author1=Anthony Cuthbertson |author2=Vishwam Sankaran |author3=Johanna Chisholm |author4=Jon Kelvey |title=Nasa scrambles to fix Moon rocket issues ahead of Artemis launch – live |url=https://www.independent.co.uk/space/artemis-launch-nasa-live-stream-watch-b2154809.html |access-date=29 August 2022 |work=The Independent |date=29 August 2022 |language=en |archive-date=29 August 2022 |archive-url=https://web.archive.org/web/20220829160436/https://www.independent.co.uk/space/artemis-launch-nasa-live-stream-watch-b2154809.html |url-status=live}}{{cite news |author=Ashley Strickland |title=Today's Artemis I launch has been scrubbed after engine issue |url=https://edition.cnn.com/2022/08/29/world/nasa-artemis-1-launch-scn/index.html |access-date=29 August 2022 |work=CNN |date=29 August 2022 |archive-date=29 August 2022 |archive-url=https://web.archive.org/web/20220829140305/https://edition.cnn.com/2022/08/29/world/nasa-artemis-1-launch-scn/index.html |url-status=live}}{{cite web | last=Foust | first=Jeff | title=First Artemis 1 launch attempt scrubbed | website=SpaceNews | date=29 August 2022 | url=https://spacenews.com/?p=131026&preview=true&preview_id=131026 | access-date=29 August 2022 | archive-date=29 August 2022 | archive-url=https://web.archive.org/web/20220829160434/https://spacenews.com/first-artemis-1-launch-attempt-scrubbed/?preview_id=131026 | url-status=live}}

{{!}}-

{{!}} 30 August 2022

{{!}} 2:17 pm ET (18:17 UTC), 3 September 2022

{{!}}-

{{!}} 3 September 2022

{{!}} 19 September–4 October 2022{{cite web | last=Foust | first=Jeff | title=Second Artemis 1 launch attempt scrubbed | website=SpaceNews | date=3 September 2022 | url=https://spacenews.com/second-artemis-1-launch-attempt-scrubbed/ | access-date=4 September 2022 | archive-date=17 November 2022 | archive-url=https://wayback.archive-it.org/all/20221117061214/https://spacenews.com/second%2Dartemis%2D1%2Dlaunch%2Dattempt%2Dscrubbed/ | url-status=live}}

{{!}}-

{{!}} 8 September 2022

{{!}} 23 September–4 October 2022

{{!}}-

{{!}} 12 September 2022

{{!}} 27 September–4 October 2022{{cite web|title=NASA Adjusts Dates for Artemis I Cryogenic Demonstration Test and Launch; Progress at Pad Continues|date=12 September 2022|last=Kraft|first=Rachel|access-date=16 September 2022|publisher=NASA|url=https://blogs.nasa.gov/artemis/2022/09/12/nasa-adjusts-dates-for-artemis-i-cryogenic-demonstration-test-and-launch-progress-at-pad-continues/|archive-date=12 September 2022|archive-url=https://web.archive.org/web/20220912224450/https://blogs.nasa.gov/artemis/2022/09/12/nasa-adjusts-dates-for-artemis-i-cryogenic-demonstration-test-and-launch-progress-at-pad-continues/|url-status=live}}

{{!}}-

{{!}} 24 September 2022

{{!}} Late October 2022

{{!}}-

{{!}} 30 September 2022

{{!}} 12–27 November 2022

{{!}}-

{{!}} 13 October 2022

{{!}} 12:07 am ET (5:07 UTC), 14 November 2022

{{!}}-

{{!}} 8 November 2022

{{!}} 1:04 am ET (6:04 UTC), 16 November 2022

{{!}}-

{{!)}}}} As of earlier that month, the first launch was originally scheduled for 8:30 am EDT, 29 August 2022.{{cite web| url=https://blogs.nasa.gov/artemis/2022/08/26/weather-remains-70-favorable-teams-on-track-to-begin-countdown-saturday/| title=Weather remains 70% Favorable, Teams on Track to Begin Countdown Saturday – Artemis| date=26 August 2022| access-date=27 August 2022| archive-date=27 August 2022| archive-url=https://web.archive.org/web/20220827132349/https://blogs.nasa.gov/artemis/2022/08/26/weather-remains-70-favorable-teams-on-track-to-begin-countdown-saturday/| url-status=live}} It was postponed to 2:17 pm EDT (18:17 UTC), 3 September 2022, after the launch director called a scrub due to a temperature sensor falsely indicating that an RS-25 engine's hydrogen bleed intake was too warm. The 3 September attempt was then scrubbed due to a hydrogen leak in the tail service mast quick disconnect arm, which was fixed; the next launch option was at first a period in late October and then a launch in mid-November, due to unfavorable weather during Hurricane Ian.{{cite web | title=Artemis I Launch Attempt Scrubbed | last=Kraft | first=Rachel | website=NASA Blogs | date=3 September 2022 | url=https://blogs.nasa.gov/artemis/2022/09/03/artemis-i-launch-attempt-scrubbed/ | access-date=3 September 2022 | archive-date=28 December 2022 | archive-url=https://web.archive.org/web/20221228161944/https://blogs.nasa.gov/artemis/2022/09/03/artemis-i-launch-attempt-scrubbed/ | url-status=live}} It launched on 16 November.{{Cite web |date=16 November 2022 |title=SLS Artemis I Mission |url=https://rocketlaunch.org/mission-sls-block-1-artemis-i |website=RocketLaunch.org |access-date=27 March 2024 |archive-date=1 September 2024 |archive-url=https://web.archive.org/web/20240901012834/https://rocketlaunch.org/mission-sls-block-1-artemis-i |url-status=live}}{{Cite news |last1=Roulette |first1=Joey |last2=Gorman |first2=Steve |date=16 November 2022 |title=NASA's next-generation Artemis mission heads to moon on debut test flight |language=en |work=Reuters |url=https://www.reuters.com/lifestyle/science/nasas-artemis-moon-rocket-begins-fueling-debut-launch-2022-11-15/ |access-date=16 November 2022 |archive-date=16 November 2022 |archive-url=https://web.archive.org/web/20221116115602/https://www.reuters.com/lifestyle/science/nasas-artemis-moon-rocket-begins-fueling-debut-launch-2022-11-15/ |url-status=live}}

NASA originally limited the amount of time the solid rocket boosters can remain stacked to "about a year" from the time two segments are joined. The first and second segments of the Artemis I boosters were joined on 7 January 2021. NASA could choose to extend the time limit based on an engineering review. On 29 September 2021, Northrop Grumman indicated that the limit could be extended to eighteen months for Artemis I, based on an analysis of the data collected when the boosters were being stacked; an analysis weeks before the actual launch date later extended that to December 2022 for the boosters of Artemis I, almost two years after stacking.{{cite web|url=https://spacenews.com/sls-returns-to-the-pad-for-next-artemis-launch-attempt/|title=SLS returns to the pad for next Artemis launch attempt|date=4 November 2022|access-date=16 November 2022}}

In late 2015, the SLS program was stated to have a 70% confidence level for the first Orion flight that carries crew, the second SLS flight overall, to happen by 2023;{{cite web |url=http://spacenews.com/first-crewed-orion-mission-may-slip-to-2023/|title=First Crewed Orion Mission May Slip to 2023|last=Foust|first=Jeff|date=16 September 2015|publisher=SpaceNews|access-date=23 June 2016|archive-date=30 September 2021|archive-url=https://web.archive.org/web/20210930001748/https://spacenews.com/first-crewed-orion-mission-may-slip-to-2023/|url-status=live}}{{cite web |url=https://spaceflightnow.com/2015/09/16/orion-spacecraft-may-not-fly-with-astronauts-until-2023/|title=Orion spacecraft may not fly with astronauts until 2023|last=Clark|first=Stephen|publisher=Spaceflight Now|date=16 September 2015|access-date=23 June 2016|archive-date=1 July 2016|archive-url=https://web.archive.org/web/20160701155403/https://spaceflightnow.com/2015/09/16/orion-spacecraft-may-not-fly-with-astronauts-until-2023/|url-status=live}}{{cite web|url=http://www.spacepolicyonline.com/news/mikulski-deeply-troubled-by-nasas-budget-request-sls-wont-use-70-percent-jcl|title=Mikulski "Deeply Troubled" by NASA's Budget Request; SLS Won't Use 70 Percent JCL|last=Clark|first=Smith|date=1 May 2014|website=spacepolicyonline.com|access-date=23 June 2016|archive-date=5 August 2016|archive-url=https://web.archive.org/web/20160805085633/http://www.spacepolicyonline.com/news/mikulski-deeply-troubled-by-nasas-budget-request-sls-wont-use-70-percent-jcl|url-status=live}} {{as of|November 2021|lc=y}}, NASA delayed Artemis II from 2023 to May 2024.{{cite web |last=Foust |first=Jeff |url=https://spacenews.com/nasa-delays-human-lunar-landing-to-at-least-2025/ |title=NASA delays human lunar landing to at least 2025 |work=SpaceNews |date=9 November 2021 |access-date=9 November 2021 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901052905/https://spacenews.com/nasa-delays-human-lunar-landing-to-at-least-2025/ |url-status=live}} In March 2023, NASA announced they had delayed Artemis II to November 2024,{{cite web |url=https://phys.org/news/2023-03-nasa-artemis-mission-moon-november.html |title=NASA's Artemis 2 mission around Moon set for November 2024 |work=Phys.org |date=7 March 2023 |access-date=10 March 2023 |archive-date=7 March 2023 |archive-url=https://web.archive.org/web/20230307211934/https://phys.org/news/2023-03-nasa-artemis-mission-moon-november.html |url-status=live}} in January 2024 the mission was further delayed to September 2025,{{cite web |last=Tingley |first=Brett |url=https://www.space.com/nasa-artemis-2-moon-mission-delay-september-2025 |title=Astronauts won't walk on the moon until 2026 after NASA delays next 2 Artemis missions |website=Space.com |date=9 January 2024 |access-date=9 January 2024 |archive-date=11 January 2024 |archive-url=https://web.archive.org/web/20240111220629/https://www.space.com/nasa-artemis-2-moon-mission-delay-september-2025 |url-status=live}} and in December 2024 it was announced that the launch was pushed back to April 2026.{{Cite web |last=Donaldson |first=Abbey A. |date=5 December 2024 |title=NASA Shares Orion Heat Shield Findings, Updates Artemis Moon Missions |url=https://www.nasa.gov/news-release/nasa-shares-orion-heat-shield-findings-updates-artemis-moon-missions/ |access-date=2024-12-05 |website=NASA |language=en-US}}

{{SLS launches/future}}

{{main|List of Space Launch System launches#Proposed launches}}

Efforts have been made to expand the Artemis missions to launching NASA's robotic space probes and observatories. However, SLS program officials have noted that between the launch cadence of Artemis missions and supply chain constraints, it is unlikely that rockets could be built to support science missions before the late 2020s or early 2030s.{{Cite web |last=Foust |first=Jeff |date=8 July 2021 |title=Supply chain, Artemis program limit SLS use for science missions |url=https://spacenews.com/supply-chain-artemis-program-limits-sls-use-for-science-missions/ |access-date=27 November 2024 |publisher=SpaceNews}}

Another challenge is that the large solid-rocket boosters produce significant vibrations, which can damage sensitive scientific instruments. During wind-tunnel testing, torsional load values (a measurement of twisting and vibration) were nearly double initial estimates.{{cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=23 July 2021 |title=SpaceX to launch the Europa Clipper mission for a bargain price |url=https://arstechnica.com/science/2021/07/spacex-to-launch-the-europa-clipper-mission-for-a-bargain-price/ |access-date=28 November 2021 |work=Ars Technica}} Although program officials later acknowledged the issue, they expressed confidence in their ability to mitigate it.

{{asof|2024|10|post=,}} NASA has studied using SLS for Neptune Odyssey,{{cite web |last1=Carter |first1=Jamie |date=27 September 2021 |title=The $3.4 Billion Plan For NASA To Explore 'Pluto's Twin' And The Rings Of Neptune Then Execute A 'Death Dive' |url=https://www.forbes.com/sites/jamiecartereurope/2021/09/27/the-34-billion-plan-for-nasa-to-explore-plutos-twin-and-the-rings-of-neptune-then-do-a-death-dive/ |url-status=live |archive-url=https://web.archive.org/web/20211005012246/https://www.forbes.com/sites/jamiecartereurope/2021/09/27/the-34-billion-plan-for-nasa-to-explore-plutos-twin-and-the-rings-of-neptune-then-do-a-death-dive/ |archive-date=5 October 2021 |access-date=13 October 2021 |work=Forbes}}{{cite journal |last1=Rymer |first1=Abigail M. |last2=Runyon |first2=Kirby D. |last3=Clyde |first3=Brenda |last4=Núñez |first4=Jorge I. |last5=Nikoukar |first5=Romina |last6=Soderlund |first6=Krista M. |last7=Sayanagi |first7=Kunio |last8=Hofstadter |first8=Mark |last9=Quick |first9=Lynnae C. |last10=Stern |first10=S. Alan |last11=Becker |first11=Tracy |last12=Hedman |first12=Matthew |last13=Cohen |first13=Ian |last14=Crary |first14=Frank |last15=Fortney |first15=Jonathan J. |display-authors=1 |date=8 September 2021 |title=Neptune Odyssey: A Flagship Concept for the Exploration of the Neptune–Triton System |journal=The Planetary Science Journal |volume=2 |issue=5 |page=184 |bibcode=2021PSJ.....2..184R |doi=10.3847/PSJ/abf654 |s2cid=237449259 |doi-access=free |last16=Vertesi |first16=Janet |last17=Hansen |first17=Candy |last18=De Pater |first18=Imke |last19=Paty |first19=Carol |last20=Spilker |first20=Thomas |last21=Stallard |first21=Tom |last22=Hospodarsky |first22=George B. |last23=Smith |first23=H. Todd |last24=Wakeford |first24=Hannah |last25=Moran |first25=Sarah E. |last26=Annex |first26=Andrew |last27=Schenk |first27=Paul |last28=Ozimek |first28=Martin |last29=Arrieta |first29=Juan |last30=McNutt |first30=Ralph L.}} Europa Lander,{{cite web |last=Foust |first=Jeff |date=31 March 2017 |title=Europa lander work continues despite budget uncertainty |url=http://spacenews.com/europa-lander-work-continues-despite-budget-uncertainty/ |access-date=31 March 2017 |publisher=SpaceNews}}{{cite news |last=Foust |first=Jeff |date=17 February 2019 |title=Final fiscal year 2019 budget bill secures US$21.5 billion for NASA |url=https://spacenews.com/final-fiscal-year-2019-budget-bill-secures-21-5-billion-for-nasa/ |publisher=SpaceNews}}[https://www.jpl.nasa.gov/missions/web/absscicon/02-AbsSciCon-Mission-Overview-13Jun2019-no-BU.pdf Europa Lander Mission Concept Overview] {{Webarchive|url=https://web.archive.org/web/20210131175314/https://www.jpl.nasa.gov/missions/web/absscicon/02-AbsSciCon-Mission-Overview-13Jun2019-no-BU.pdf|date=31 January 2021}} Grace Tan-Wang, Steve Sell, Jet Propulsion Laboratory, NASA, AbSciCon2019, Bellevue, Washington. 26 June 2019 {{PD-notice}} Enceladus Orbilander, Persephone,{{cite web |last1=Clark |first1=Stephen |date=14 July 2020 |title=Five years after New Horizons flyby, scientists assess next mission to Pluto |url=https://spaceflightnow.com/2020/07/14/five-years-after-new-horizons-flyby-scientists-assess-next-mission-to-pluto/ |url-status=live |archive-url=https://web.archive.org/web/20211006140822/https://spaceflightnow.com/2020/07/14/five-years-after-new-horizons-flyby-scientists-assess-next-mission-to-pluto/ |archive-date=6 October 2021 |access-date=13 October 2021 |publisher=Spaceflightnow}} HabEx,{{Cite web |date=25 August 2019 |title=Habitable Exoplanet Observatory Final Report |url=https://www.jpl.nasa.gov/habex/pdf/HabEx-Final-Report-Public-Release.pdf |url-status=live |archive-url=https://web.archive.org/web/20191211194309/https://www.jpl.nasa.gov/habex/pdf/HabEx-Final-Report-Public-Release.pdf |archive-date=11 December 2019 |access-date=11 May 2020 |website=Jet Propulsion Laboratory |ref={{SfnRef|"Habitable Exoplanet Observatory Final Report"|2019 {{PD-notice}}}}}} Section 9-11 9.4.1 Basis of estimate, p. 281. Origins Space Telescope,{{Cite web |date=11 October 2019 |title=Origins Space Telescope Mission Concept Study Report |url=https://asd.gsfc.nasa.gov/firs/docs/OriginsVolume1MissionConceptStudyReport_11Oct2019.pdf |url-status=live |archive-url=https://web.archive.org/web/20200712204108/https://asd.gsfc.nasa.gov/firs/docs/OriginsVolume1MissionConceptStudyReport_11Oct2019.pdf |archive-date=12 July 2020 |access-date=14 May 2020 |page=ES-11 |quote=The launch cost (US$500 million for the SLS launch vehicle, as advised by NASA Headquarters) is also included.}} {{PD-notice}} LUVOIR,{{cite web |last1=Siegel |first1=Ethan |date=19 September 2017 |title=New Space Telescope, 40 Times The Power Of Hubble, To Unlock Astronomy's Future |url=https://www.forbes.com/sites/startswithabang/2017/09/19/new-space-telescope-40-times-the-power-of-hubble-to-unlock-astronomys-future/ |url-status=live |archive-url=https://web.archive.org/web/20210705073027/https://www.forbes.com/sites/startswithabang/2017/09/19/new-space-telescope-40-times-the-power-of-hubble-to-unlock-astronomys-future/ |archive-date=5 July 2021 |access-date=13 October 2021 |work=Forbes}} Lynx,{{cite web |title=Lynx X-Ray Observatory |url=https://wwwastro.msfc.nasa.gov/lynx/docs/LynxConceptStudy.pdf |url-status=live |archive-url=https://web.archive.org/web/20210416101032/https://wwwastro.msfc.nasa.gov/lynx/docs/LynxConceptStudy.pdf |archive-date=16 April 2021 |access-date=13 October 2021 |publisher=NASA}} and Interstellar probe.{{cite web |last1=Billings |first1=Lee |title=Proposed Interstellar Mission Reaches for the Stars, One Generation at a Time |url=https://www.scientificamerican.com/article/proposed-interstellar-mission-reaches-for-the-stars-one-generation-at-a-time1/ |publisher=Scientific American |access-date=13 October 2021 |date=12 November 2019 |archive-url=https://web.archive.org/web/20210725054502/https://www.scientificamerican.com/article/proposed-interstellar-mission-reaches-for-the-stars-one-generation-at-a-time1/ |archive-date=25 July 2021 |url-status=live}}

Initially, Congress mandated that NASA use the SLS to launch the Europa Clipper probe. However, concerns about the SLS's availability led NASA to seek congressional approval for competitive launch bids. SpaceX ultimately won the contract, saving the agency an estimated US$2 billion in direct launch costs over SLS, albeit at the cost of a longer flight.

After the launch of Artemis IV, NASA plans to transfer production and launch operations of SLS to Deep Space Transport LLC, a joint venture between Boeing and Northrop Grumman. The agency hopes the companies can find more buyers for flights on the rocket to bring costs per flight down to $1 billion. However, finding a market for the large and costly rocket will be difficult. Reuters reported that the US Department of Defense, long considered a potential customer, stated in 2023 that it has no interest in the rocket as other launch vehicles already offer them the capability that they need at an affordable price.

The SLS has been criticized based on program cost, lack of commercial involvement, and non-competitiveness of legislation requiring the use of Space Shuttle components "where possible".{{Cite news |last=Davenport |first=Christian |date=16 November 2022 |title=Relief and pride as NASA's huge SLS rocket finally flies |language=en-US |newspaper=The Washington Post |url=https://www.washingtonpost.com/technology/2022/11/16/artemis-moon-mission-launch/ |access-date=29 July 2023 |issn=0190-8286}}

File:NASA_OIG_20-012_Figure_7.png report, showing how NASA used accounting to "mask" a cost increase by moving the boosters (which cost $889 million) from the SLS to another cost center, without updating the SLS budget to match{{rp|iv,22}}|alt=A diagram showing two bars on both sides]]

As the Space Shuttle program drew to a close in 2009, the Obama administration convened the Augustine Commission to assess NASA's future human spaceflight endeavors. The commission's findings were stark: NASA's proposed Ares V rocket, intended for lunar and Martian missions, was unsustainable and should be canceled. The administration further advocated for a public-private partnership, where private companies would develop and operate spacecraft, and NASA would purchase launch services on a fixed-cost basis.

The recommendations faced fierce opposition from senators representing states with significant aerospace industries. In response, in 2011, Congress mandated the development of the SLS. The program was characterized by a complex web of political compromises, ensuring that various regions and interests benefited, maintaining jobs and contracts for existing space shuttle contractors.{{Cite news |last=Brown |first=David W. |date=17 March 2021 |title=NASA's Last Rocket |url=https://www.nytimes.com/2021/03/17/science/nasa-space-launch-system.html |access-date=29 August 2024 |work=The New York Times |language=en-US |issn=0362-4331 |archive-date=18 December 2023 |archive-url=https://web.archive.org/web/20231218144333/https://www.nytimes.com/2021/03/17/science/nasa-space-launch-system.html |url-status=live}}{{Cite news |last=Davenport |first=Christian |date=16 November 2022 |title=Relief and pride as NASA's huge SLS rocket finally flies |url=https://www.washingtonpost.com/technology/2022/11/16/artemis-moon-mission-launch/ |access-date=29 August 2024 |newspaper=Washington Post |language=en-US |issn=0190-8286 |archive-date=7 February 2023 |archive-url=https://web.archive.org/web/20230207113355/https://www.washingtonpost.com/technology/2022/11/16/artemis-moon-mission-launch/ |url-status=live}} Utah Senator Orrin Hatch ensured the new rocket used the Shuttle's solid boosters, which were manufactured in his state. Alabama Senator Richard Shelby insisted that the Marshall Space Flight Center design and test the rocket. Florida Senator Bill Nelson brought home billions of dollars to Kennedy Space Center to modernize its launch facilities.{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=9 September 2016 |title=How I learned to stop worrying and love the big $60B NASA rocket |url=https://arstechnica.com/science/2016/09/how-i-learned-to-stop-worrying-and-love-the-big-nasa-rocket/ |access-date=28 August 2024 |work=Ars Technica |language=en-us |archive-date=26 July 2024 |archive-url=https://web.archive.org/web/20240726084001/https://arstechnica.com/science/2016/09/how-i-learned-to-stop-worrying-and-love-the-big-nasa-rocket/ |url-status=live}}{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=10 July 2024 |title=Congress apparently feels a need for "reaffirmation" of SLS rocket |url=https://arstechnica.com/space/2024/07/congress-apparently-feels-a-need-for-reaffirmation-of-sls-rocket/ |access-date=28 August 2024 |work=Ars Technica |language=en-us |archive-date=27 August 2024 |archive-url=https://web.archive.org/web/20240827213859/https://arstechnica.com/space/2024/07/congress-apparently-feels-a-need-for-reaffirmation-of-sls-rocket/ |url-status=live}}

Almost immediately, Representative Tom McClintock called on the Government Accountability Office to investigate possible violations of the Competition in Contracting Act, arguing that the requirement that Shuttle components be used on SLS were non-competitive and assured contracts to existing suppliers.

The Obama administration's 2014 budget called for canceling SLS and turning over space transportation to commercial companies. The White House sent Lori Garver, the NASA deputy administrator, along with astronaut Sally Ride and other experts to defend the proposal, saying the SLS program was too slow and wasteful. However, Senators Shelby and Nelson quickly moved to fight efforts to cut the program and were ultimately victorious. After retirement from NASA, Garver would go on to recommend cancellation of the SLS.{{cite journal |last1=Foust |first1=Jeff |title=Garver: NASA Should Cancel SLS and Mars 2020 Rover |journal=SpaceNews |date=Jan 3, 2014 |url=https://spacenews.com/38912garver-nasa-should-cancel-sls-and-mars-2020-rover/}}

During the Trump administration, NASA administrator Jim Bridenstine suggested to a Senate committee that the agency was considering using the Falcon Heavy or Delta IV Heavy rocket to launch Orion instead of SLS. Afterward, the administrator was reportedly called into a meeting with Senator Shelby, who told Bridenstine he should resign for making the suggestion in a public meeting.

In 2023, Cristina Chaplain, former assistant director of the GAO, expressed doubts about reducing the rocket's cost to a competitive threshold, "just given the history and how challenging it is to build."

In 2019, the Government Accountability Office (GAO) noted that NASA had assessed the performance of contractor Boeing positively, though the project had experienced cost growth and delay. A March 2020 report by Office of Inspector General found NASA moved out $889 million of costs relating to SLS boosters, but did not update the SLS budget to match. This kept the budget overrun to 15% in FY 2019;{{rp|22}} an overrun of 30% would have required NASA to request additional funding from the U.S. Congress{{rp|21–23}} The Inspector General report found that were it not for this "masking" of cost, the overrun would have been 33% by FY 2019.{{rp|iv,23}} The GAO stated "NASA's current approach for reporting cost growth misrepresents the cost performance of the program".{{rp|19–20}}

In 2009, the Augustine commission proposed a commercial {{cvt|75|t|lb|order=flip}} launcher for lunar exploration. In 2011–2012, the Space Access Society, Space Frontier Foundation, and The Planetary Society called for the cancellation of the project, arguing that the SLS would consume the funds for other projects from the NASA budget. U.S. Representative Dana Rohrabacher and others{{Who|date=June 2023}} proposed the development of an orbital propellant depot and the acceleration of the Commercial Crew Development program as an alternative to the SLS program.

An unpublished NASA study and another from the Georgia Institute of Technology found these approaches could have lower costs. In 2012, United Launch Alliance also suggested using existing rockets with on-orbit assembly and propellant depots as needed. In 2019, a former ULA employee alleged that Boeing viewed orbital refueling technology as a threat to the SLS and blocked investment in the technology. In 2010, SpaceX's CEO Elon Musk claimed that his company could build a launch vehicle in the {{cvt|140–150|order=flip|t|lb}} payload range for $2.5 billion, or $300 million (in 2010 dollars) per launch, not including a potential upper-stage upgrade.

Former NASA Administrator Charlie Bolden, expressed that the SLS could be replaced in the future in an interview with Politico in September 2020. Bolden said that the "SLS will go away ... because at some point commercial entities are going to catch up." Bolden further stated, "They are really going to build a heavy-lift launch vehicle sort of like SLS that they will be able to fly for a much cheaper price than NASA can do SLS. That's just the way it works."

{{Portal|Spaceflight

}}

• Austere Human Missions to Mars
• Comparison of orbital launch systems
• Criticism of the Space Shuttle program
• DIRECT, proposals prior to SLS
• Shuttle-Derived Heavy Lift Launch Vehicle, a 2009 concept launch vehicle
• Ares V, a 2000s cargo vehicle design for the Constellation Program
• National Launch System, 1990s
• Saturn rocket family, 1960s
• Starship HLS, lunar variant of super heavy-lift vehicle Starship
• Studied Space Shuttle Variations and Derivatives

{{reflist|group=note}}

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{{Cite news|last=Berger|first=Eric|date=8 November 2019|title=NASA does not deny the "over US$2 billion" cost of a single SLS launch|url=https://arstechnica.com/science/2019/11/nasa-does-not-deny-the-over-2-billion-cost-of-a-single-sls-launch/|work = Ars Technica | publisher = Condé Nest | access-date=13 November 2019|archive-date=11 November 2019|archive-url=https://web.archive.org/web/20191111232104/https://arstechnica.com/science/2019/11/nasa-does-not-deny-the-over-2-billion-cost-of-a-single-sls-launch/|url-status=live|quote=The White House number appears to include both the "marginal" cost of building a single SLS rocket as well as the "fixed" costs of maintaining a standing army of thousands of employees and hundreds of suppliers across the country. Building a second SLS rocket each year would make the per-unit cost "significantly less"}}

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{{Cite web|url=http://www.nasaspaceflight.com/2011/06/managers-sls-announcement-after-sd-hlv-victory/|publisher=NASASpaceFlight.com|date=16 June 2011|author=Bergin, Chris|title=Managers SLS announcement after SD HLV victory|access-date=26 January 2012|archive-date=29 January 2012|archive-url=https://web.archive.org/web/20120129022555/http://www.nasaspaceflight.com/2011/06/managers-sls-announcement-after-sd-hlv-victory/|url-status=live}}

{{Cite news|url=http://www.nasaspaceflight.com/2012/02/acronyms-ascent-sls-managers-create-developmental-milestone-roadmap/|title=Acronyms to Ascent – SLS managers create development milestone roadmap|publisher=NASASpaceFlight.com|first=Chris|last=Bergin|date=23 February 2012|access-date=9 April 2012|archive-date=30 April 2012|archive-url=https://web.archive.org/web/20120430013811/http://www.nasaspaceflight.com/2012/02/acronyms-ascent-sls-managers-create-developmental-milestone-roadmap/|url-status=live}}

{{Cite web|title=Public Law 111–267 111th Congress, 42 USC 18322. SEC. 302 (c) (2) 42 USC 18323. SEC. 303 (a) (2)|url=https://www.nasa.gov/pdf/649377main_PL_111-267.pdf|access-date=14 September 2020|date=11 October 2010|pages=11–12|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112003142/https://www.nasa.gov/pdf/649377main_PL_111-267.pdf|url-status=live |quote=42 USC 18322. SEC. 302 SPACE LAUNCH SYSTEM AS FOLLOW-ON LAUNCH VEHICLE TO THE SPACE SHUTTLE [...] (c) MINIMUM CAPABILITY REQUIREMENTS (1) IN GENERAL – The Space Launch System developed pursuant to subsection (b) shall be designed to have, at a minimum, the following: (A) The initial capability of the core elements, without an upper stage, of lifting payloads weighing between 70 tons and 100 tons into low-Earth orbit in preparation for transit for missions beyond low Earth orbit [...] (2) FLEXIBILITY [...] (Deadline) Developmental work and testing of the core elements and the upper stage should proceed in parallel subject to appro-priations. Priority should be placed on the core elements with the goal for operational capability for the core elements not later than December 31, 2016 [...] 42 USC 18323. SEC. 303 MULTI-PURPOSE CREW VEHICLE (a) INITIATION OF DEVELOPMENT (1) IN GENERAL – The Administrator shall continue the development of a multi-purpose crew vehicle to be available as soon as practicable, and no later than for use with the Space Launch System [...] (2) GOAL FOR OPERATIONAL CAPABILITY. It shall be the goal to achieve full operational capability for the transportation vehicle developed pursuant to this subsection by not later than December 31, 2016. For purposes of meeting such goal, the Administrator may undertake a test of the transportation vehicle at the ISS before that date.}}

{{Cite web|url=https://www.congress.gov/bill/111th-congress/senate-bill/3729|title=S.3729 – National Aeronautics and Space Administration Authorization Act of 2010|date=11 October 2010|publisher=United States Congress|access-date=14 September 2020|archive-date=28 April 2021|archive-url=https://web.archive.org/web/20210428040539/https://www.congress.gov/bill/111th-congress/senate-bill/3729|url-status=live}} {{PD-notice}}

{{Cite web|last1=Davis|first1=Jason|title=To Mars, with a monster rocket: How politicians and engineers created NASA's Space Launch System|url=https://www.planetary.org/articles/20161003-horizon-goal-part-4|publisher=The Planetary Society|access-date=14 September 2020|date=3 October 2016|archive-date=25 September 2020|archive-url=https://web.archive.org/web/20200925041839/https://www.planetary.org/articles/20161003-horizon-goal-part-4|url-status=live}}

{{Cite web|last1=Harwood|first1=William|title=NASA unveils new super rocket for manned flights beyond Earth orbit|url=https://www.cbsnews.com/network/news/space/home/spacenews/files/8ef7f2e7f3ddec1c1a67085fd26c335b-336.html|publisher=CBS News|access-date=14 September 2020|date=14 September 2011|archive-date=10 August 2020|archive-url=https://web.archive.org/web/20200810070346/http://www.cbsnews.com/network/news/space/home/spacenews/files/8ef7f2e7f3ddec1c1a67085fd26c335b-336.html|url-status=live}}

{{Cite web|last1=Foust|first1=Jeff|title=NASA inspector general foresees additional SLS/Orion delays|url=https://spacenews.com/nasa-inspector-general-foresees-additional-slsorion-delays/|publisher=SpaceNews|access-date=14 September 2020|date=13 April 2017|archive-date=3 October 2021|archive-url=https://web.archive.org/web/20211003032203/https://spacenews.com/nasa-inspector-general-foresees-additional-slsorion-delays/|url-status=live}}

{{Cite news|url=https://spaceflightnow.com/2017/04/28/nasa-confirms-first-flight-of-space-launch-system-will-slip-to-2019/|title=NASA confirms first flight of Space Launch System will slip to 2019|work=Spaceflight Now|first=Stephen|last=Clark|date=28 April 2017|access-date=29 April 2017|archive-date=26 December 2017|archive-url=https://web.archive.org/web/20171226172916/https://spaceflightnow.com/2017/04/28/nasa-confirms-first-flight-of-space-launch-system-will-slip-to-2019/|url-status=live}}

{{Cite news|url=https://spaceflightnow.com/2017/11/20/nasa-expects-first-space-launch-system-flight-to-slip-into-2020/|title=NASA expects first Space Launch System flight to slip into 2020|last=Clark|first=Stephen|work=Spaceflight Now|date=20 November 2017|access-date=24 May 2018|archive-date=9 August 2018|archive-url=https://web.archive.org/web/20180809131110/https://spaceflightnow.com/2017/11/20/nasa-expects-first-space-launch-system-flight-to-slip-into-2020/|url-status=live}}

{{Cite web|last=Gebhardt|first=Chris|url=https://www.nasaspaceflight.com/2020/02/sls-debut-april-2021-ksc-teams-launch-sims/|title=SLS debut slips to April 2021, KSC teams working through launch sims|work=NASASpaceFlight|date=21 February 2020|access-date=21 February 2020|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806231409/https://www.nasaspaceflight.com/2020/02/sls-debut-april-2021-ksc-teams-launch-sims/|url-status=live}}

{{Cite web|last=Clark|first=Stephen|url=https://spaceflightnow.com/2020/05/01/hopeful-for-launch-next-year-nasa-aims-to-resume-sls-operations-within-weeks/|title=Hopeful for launch next year, NASA aims to resume SLS operations within weeks|date=1 May 2020|access-date=3 May 2020|archive-date=13 September 2020|archive-url=https://web.archive.org/web/20200913103626/https://spaceflightnow.com/2020/05/01/hopeful-for-launch-next-year-nasa-aims-to-resume-sls-operations-within-weeks/|url-status=live}}

{{Cite web |last1=Berger |first1=Eric |title=NASA's big rocket misses another deadline, now won't fly until 2022 |url=https://arstechnica.com/science/2021/08/nasas-sls-rocket-will-not-fly-until-next-spring-or-more-likely-summer/ |work=Ars Technica |access-date=1 September 2021 |date=31 August 2021 |archive-date=1 September 2021 |archive-url=https://web.archive.org/web/20210901021015/https://arstechnica.com/science/2021/08/nasas-sls-rocket-will-not-fly-until-next-spring-or-more-likely-summer/ |url-status=live}}

{{Cite web |publisher=nasaspaceflight |title=New Artemis 1 schedule uncertainty as NASA EGS ready to continue SLS Booster stacking |url=https://www.nasaspaceflight.com/2020/12/artemis-1-schedule-uncertainty-sls-booster-stacking |first=Philip |last=Sloss |date=4 December 2020 |access-date=28 September 2021 |archive-date=28 September 2021 |archive-url=https://web.archive.org/web/20210928194436/https://www.nasaspaceflight.com/2020/12/artemis-1-schedule-uncertainty-sls-booster-stacking/ |url-status=live}}

{{Cite web |last1=Clark |first1=Stephen |title=Stacking complete for SLS boosters |url=https://spaceflightnow.com/2021/03/09/stacking-complete-for-sls-boosters/ |work=Spaceflight Now |access-date=28 September 2021 |date=9 March 2021 |archive-date=3 June 2021 |archive-url=https://web.archive.org/web/20210603230506/https://spaceflightnow.com/2021/03/09/stacking-complete-for-sls-boosters/ |url-status=live}}

{{Cite web |url=https://spaceflightnow.com/2021/01/15/nasa-continues-stacking-boosters-for-first-sls-test-flight |work = Spaceflight Now |title=NASA proceeds with SLS booster stacking in Florida before core stage arrives |date=15 January 2021 |last=Stephen |first=Clark |access-date=28 September 2021 |archive-date=7 March 2021 |archive-url=https://web.archive.org/web/20210307000536/https://spaceflightnow.com/2021/01/15/nasa-continues-stacking-boosters-for-first-sls-test-flight/ |url-status=live}}

{{Cite web |last=Harbaugh |first=Jennifer |date=9 July 2018 |title=The Great Escape: SLS Provides Power for Missions to the Moon |url=https://www.nasa.gov/exploration/systems/sls/to-the-moon.html |url-status=dead |archive-url=https://web.archive.org/web/20191211052148/https://www.nasa.gov/exploration/systems/sls/to-the-moon.html |archive-date=11 December 2019 |access-date=4 September 2018 |publisher=NASA}}

{{Cite web|title=NASA'S MANAGEMENT OF SPACE LAUNCH SYSTEM PROGRAM COSTS AND CONTRACTS|url=https://oig.nasa.gov/docs/IG-20-012.pdf|publisher=NASA – Office of Inspector General – Office of Audits|access-date=14 September 2020|date=10 March 2020|archive-date=28 August 2020|archive-url=https://web.archive.org/web/20200828034618/https://oig.nasa.gov/docs/IG-20-012.pdf|url-status=live|quote=Based on our review of SLS Program cost reporting, we found that the Program exceeded its Agency Baseline Commitment (ABC) by at least 33 percent at the end of FY 2019, a figure that could reach 43 percent or higher if additional delays push the launch date for Artemis I beyond November 2020. This is due to cost increases tied to Artemis I and a December 2017 replan that removed almost $1 billion of costs from the ABC without lowering the baseline, thereby masking the impact of Artemis I’s projected 19-month schedule delay from November 2018 to a June 2020 launch date. Since the replan, the SLS Program now projects the Artemis I launch will be delayed to at least spring 2021 or later. Further, we found NASA’s ABC cost reporting only tracks Artemis I-related activities and not additional expenditures of almost $6 billion through FY 2020 that are not being reported or tracked through the official congressional cost commitment or the ABC. [...] as a result of delaying Artemis I up to 19 months to June 2020, NASA conducted a replan of the SLS Program in 2017 and removed $889 million in Booster and RS-25 Engine-related development costs because SLS Program officials determined those activities were not directly tied to Artemis I. [...] In our judgement, the removal of these costs should have reduced the SLS Program’s ABC development costs from $7.02 billion to $6.13 billion. [...] SLS Program and HEOMD officials disagreed with our assessment and stated the SLS Program’s change in cost estimates for the Booster and Engines element offices were not a removal of costs but rather a reallocation of those activities to appropriately account for them as non-Artemis I costs. [...] Federal law requires that any time Agency program managers have reasonable knowledge that development costs are likely to exceed the ABC by more than 30 percent, they must notify the NASA Administrator. Once the Administrator determines the SLS Program will exceed the development cost baseline by 30 percent or more, NASA is required to notify Congress and rebaseline program costs and schedule commitments. If the Administrator notifies Congress of the need to rebaseline, NASA is required to stop funding program activities within 18 months unless Congress provides approval and additional appropriations. In our judgement, using NASA’s cost estimates from October 2019 and accounting for the removed costs from the replan, the SLS Program was required to rebaseline when the program exceeded its ABC by 33 percent at the end of FY 2019, an increase that could reach 43 percent or higher by the Artemis I launch date.}}

{{Cite web|title=NASA HUMAN SPACE EXPLORATION: Persistent Delays and Cost Growth Reinforce Concerns over Management of Programs|url=https://www.gao.gov/assets/700/699923.pdf|publisher=GAO|access-date=15 September 2020|archive-date=3 October 2021|archive-url=https://web.archive.org/web/20211003032148/https://www.gao.gov/assets/700/699923.pdf|url-status=live|quote=NASA’s current approach for reporting cost growth misrepresents the cost performance of the program and thus undermines the usefulness of a baseline as an oversight tool. NASA’s space flight program and project management requirements state that the agency baseline commitment for a program is the basis for the agency’s commitment to the Office of Management and Budget (OMB) and the Congress based on program requirements, cost, schedule, technical content, and an agreed-to joint cost and schedule confidence level. Removing effort that amounts to more than a tenth of a program’s development cost baseline is a change in the commitment to OMB and the Congress and results in a baseline that does not reflect actual effort. [...] Further, the baseline is a key tool against which to measure the cost and schedule performance of a program. A program must be rebaselined and reauthorized by the Congress if the Administrator determines that development costs will increase by more than 30 percent. Accounting for shifted costs, our analysis indicates that NASA has reached 29.0 percent development cost growth for the SLS program. [...] In addition, as we previously reported in May 2014, NASA does not have a cost and schedule baseline for SLS beyond the first flight. As a result, NASA cannot monitor or track costs shifted beyond EM-1 against a baseline. We recommended that NASA establish cost and schedule baselines that address the life cycle of each SLS increment, as well as for any evolved Orion or ground systems capability. NASA partially concurred with the recommendation, but has not taken any action to date. [...] By not adjusting the SLS baseline to account for the reduced scope, NASA will continue to report costs against an inflated baseline, hence underreporting the extent of cost growth. NASA’s Associate Administrator and Chief Financial Officer stated that they understood our rationale for removing these costs from the EM-1 baseline and agreed that not doing so could result in underreporting of cost growth. Further, the Associate Administrator told us that the agency will be relooking at the SLS program’s schedule, baseline, and calculation of cost growth.}}

{{cite web |last1=Sloss |first1=Philip |title=Boeing working on multiple Cores, first EUS hardware for Artemis missions 2–4 |url=https://www.nasaspaceflight.com/2021/07/sls-maf-update-july-2021/ |publisher=NASASpaceFlight.com |access-date=11 October 2021 |date=19 July 2021 |archive-url=https://web.archive.org/web/20210812130259/https://www.nasaspaceflight.com/2021/07/sls-maf-update-july-2021/ |archive-date=12 August 2021 |url-status=live}}

{{cite web |url=https://www.boeing.com/features/2021/07/shields-up-spray-foam-evolving-to-protect-nasa-sls.page |publisher=Boeing |title=Shields up! Spray foam evolving to protect NASA SLS |access-date=11 October 2021 |date=14 July 2021 |archive-url=https://web.archive.org/web/20210815153218/https://www.boeing.com/features/2021/07/shields-up-spray-foam-evolving-to-protect-nasa-sls.page |archive-date=15 August 2021 |url-status=live}}

{{cite web |url=https://www.nasa.gov/sites/default/files/atoms/files/sls_monthly_highlights_feb_2020_web.pdf |title=SLS Monthly Highlights February 2020 |publisher=NASA |access-date=11 October 2021 |date=February 2020 |archive-url=https://web.archive.org/web/20211011055206/https://www.nasa.gov/sites/default/files/atoms/files/sls_monthly_highlights_feb_2020_web.pdf |archive-date=11 October 2021 |url-status=live}} {{PD-notice}}

{{cite web |url=https://ntrs.nasa.gov/api/citations/20205000944/downloads/Askins%20JANNAF%202020%20PAPER%2004152020.docx.pdf |title=NASA'S SPACE LAUNCH SYSTEM BEGINS MOVING TO THE LAUNCH SITE |publisher=NASA | access-date=12 October 2021 |date=15 April 2020 |archive-url=https://web.archive.org/web/20211013024817/https://ntrs.nasa.gov/api/citations/20205000944/downloads/Askins%20JANNAF%202020%20PAPER%2004152020.docx.pdf |archive-date=13 October 2021 |url-status=live}}

{{cite web |last1=Evans |first1=Ben |title=NASA Orders 18 More RS-25 Engines for SLS Moon Rocket, at $1.79 Billion |url=https://www.americaspace.com/2020/05/02/nasa-orders-18-more-rs-25-engines-for-sls-moon-rocket-at-1-79-billion/ |publisher=AmericaSpace |access-date=13 October 2021 |date=2 May 2020 |archive-url=https://web.archive.org/web/20210831221158/https://www.americaspace.com/2020/05/02/nasa-orders-18-more-rs-25-engines-for-sls-moon-rocket-at-1-79-billion/ |archive-date=31 August 2021 |url-status=live}}

{{cite web |last1=Sloss |first1=Philip |title=NASA, Aerojet Rocketdyne plan busy RS-25 test schedule for 2021 |url=https://www.nasaspaceflight.com/2020/12/nasa-aerojet-plan-busy-2021-test-schedule/ |publisher=NASASpaceFlight |access-date=13 October 2021 |date=31 December 2020 |archive-url=https://web.archive.org/web/20210409190926/https://www.nasaspaceflight.com/2020/12/nasa-aerojet-plan-busy-2021-test-schedule/ |archive-date=9 April 2021 |url-status=live}}

{{cite web |last1=Ballard |first1=Richard |title=Next-Generation RS-25 Engines for the NASA Space Launch System |url=https://ntrs.nasa.gov/api/citations/20170008946/downloads/20170008946.pdf |publisher=NASA Marshall Space Flight Center |access-date=13 October 2021 |date=2017 |archive-url=https://web.archive.org/web/20211013061547/https://ntrs.nasa.gov/api/citations/20170008946/downloads/20170008946.pdf |archive-date=13 October 2021 |url-status=live |page=3}}

{{cite web |url=https://oig.nasa.gov/docs/IG-22-003.pdf |title=NASA'S MANAGEMENT OF THE ARTEMIS MISSIONS |work=Office of Inspector General (United States) |publisher=NASA |date=15 November 2021 |access-date=15 November 2021 |archive-date=15 November 2021 |archive-url=https://web.archive.org/web/20211115213313/https://oig.nasa.gov/docs/IG-22-003.pdf |url-status=live|quote=SLS/Orion Production and Operating Costs Will Average Over $4 Billion Per Launch [...] We project the cost to fly a single SLS/Orion system through at least Artemis IV to be $4.1 billion per launch at a cadence of approximately one mission per year. Building and launching one Orion capsule costs approximately $1 billion, with an additional $300 million for the Service Module supplied by the ESA [...] In addition, we estimate the single-use SLS will cost $2.2 billion to produce, including two rocket stages, two solid rocket boosters, four RS-25 engines, and two stage adapters. Ground systems located at Kennedy where the launches will take place—the Vehicle Assembly Building, Crawler-Transporter, Mobile Launcher 1, Launch Pad, and Launch Control Center—are estimated to cost $568 million per year due to the large support structure that must be maintained. The $4.1 billion total cost represents production of the rocket and the operations needed to launch the SLS/Orion system including materials, labor, facilities, and overhead, but does not include any money spent either on prior development of the system or for next-generation technologies such as the SLS’s Exploration Upper Stage, Orion’s docking system, or Mobile Launcher 2. [...] The cost per launch was calculated as follows: $1 billion for the Orion based on information provided by ESD officials and NASA OIG analysis; $300 million for the ESA’s Service Module based on the value of a barter agreement between ESA and the United States in which ESA provides the service modules in exchange for offsetting its ISS responsibilities; $2.2 billion for the SLS based on program budget submissions and analysis of contracts; and $568 million for EGS costs related to the SLS/Orion launch as provided by ESD officials.|page=numbered page 23, PDF page 29}}

{{cite web|title=NASA FY2021 budget estimates|url=https://www.nasa.gov/sites/default/files/atoms/files/fy_2021_budget_book_508.pdf|url-status=live|archive-url=https://web.archive.org/web/20200727051233/https://www.nasa.gov/sites/default/files/atoms/files/fy_2021_budget_book_508.pdf|archive-date=27 July 2020|publisher=NASA|access-date=14 September 2020}} {{PD-notice}}

{{Cite web|title=NASA's Ground Systems Development and Operations Program Completes Preliminary Design Review| date=27 March 2014 |url=https://www.youtube.com/watch?v=yd_Bg7K6Jt0|url-status=live|archive-url=https://web.archive.org/web/20210930001739/https://www.youtube.com/watch?v=yd_Bg7K6Jt0|archive-date=30 September 2021|access-date=23 June 2016|publisher=NASA}}

{{cite web |last=Wall |first=Mike |url=https://www.space.com/nasa-rollout-artemis1-sls-orion-ready |title=NASA's Artemis 1 moon mission, 1st flight of new megarocket, won't launch until May |work=Space.com |date=24 February 2022 |access-date=25 February 2022 |archive-url=https://web.archive.org/web/20220318005729/https://www.space.com/nasa-rollout-artemis1-sls-orion-ready |archive-date=18 March 2022 |url-status=live}}

{{cite web |last=Sloss |first=Philip |url=https://www.nasaspaceflight.com/2021/10/artemis-1-stack-complete/ |title=Artemis 1 Orion joins SLS to complete vehicle stack |work=NASASpaceFlight |date=21 October 2021 |access-date=22 October 2021 |archive-url=https://web.archive.org/web/20211230171116/https://www.nasaspaceflight.com/2021/10/artemis-1-stack-complete/ |archive-date=30 December 2021 |url-status=live}}

{{cite web |last1=Barker |first1=Nathan |last2=Gebhardt |first2=Chris |title=NASA moon rocket SLS rolls out to "rebuilt" LC-39B ahead of Artemis 1 rehearsal |url=https://www.nasaspaceflight.com/2022/03/sls-rollout-wet-dress-rehearsal/ |date=17 March 2022 |access-date=18 March 2022 |work=NASASpaceFlight |archive-url=https://web.archive.org/web/20220317181610/https://www.nasaspaceflight.com/2022/03/sls-rollout-wet-dress-rehearsal/ |archive-date=17 March 2022 |url-status=live}}

{{cite web |last1=Gebhardt |first1=Chris |title=With all-composite cryogenic tank, Boeing eyes mass-reducing space, aviation applications |url=https://www.nasaspaceflight.com/2022/03/boeing-all-composite-cryo-tank/ |access-date=18 March 2022 |date=5 March 2022 |archive-url=https://web.archive.org/web/20220307235518/https://www.nasaspaceflight.com/2022/03/boeing-all-composite-cryo-tank/ |archive-date=7 March 2022 |url-status=live}}

{{cite web|url=https://spaceflightnow.com/2021/10/22/nasa-targets-february-launch-for-artemis-1-moon-mission/|title=NASA targets February launch for Artemis 1 moon mission|last=Clark|first=Steven|publisher=Spaceflight Now|date=22 October 2021|access-date=18 March 2022 |archive-url=https://web.archive.org/web/20220113080223/https://spaceflightnow.com/2021/10/22/nasa-targets-february-launch-for-artemis-1-moon-mission/ |archive-date=13 January 2022 |url-status=live}}

{{cite web |url=https://www.space.com/16762-nasa-deep-space-rocket-passes-milestone.html |title=NASA's Giant Rocket for Deep-Space Travel Passes Key Review |publisher=Space.com |date=26 July 2012 |access-date=18 March 2022 |archive-url=https://web.archive.org/web/20210513212133/https://www.space.com/16762-nasa-deep-space-rocket-passes-milestone.html |archive-date=13 May 2021 |url-status=live}}

{{cite web |url=https://spacenews.com/nasa-says-sls-and-orion-will-slip-to-2018-despite-additional-funding/ |title=NASA Says SLS and Orion Will Slip to 2018 Despite Extra Funding |date=10 December 2014 |first=Jeff |last=Foust |publisher=SpaceNews}}

{{cite web |url=https://spacenews.com/first-sls-launch-now-expected-in-second-half-of-2021/ |title=First SLS launch now expected in second half of 2021 |date=2 March 2020 |first=Jeff |last=Foust |publisher=SpaceNews |access-date=19 March 2022 |archive-date=9 September 2023 |archive-url=https://web.archive.org/web/20230909185245/https://spacenews.com/first-sls-launch-now-expected-in-second-half-of-2021/ |url-status=live}}

{{cite web |url=https://www.technologyreview.com/2019/12/31/131052/the-seven-most-exciting-space-missions-of-2020/ |title=The seven most exciting space missions of 2020 |date=31 December 2019 |first=Neel |last=Patel |publisher=MIT Technology Review |access-date=18 March 2022 |archive-url=https://web.archive.org/web/20200808054330/https://www.technologyreview.com/2019/12/31/131052/the-seven-most-exciting-space-missions-of-2020/ |archive-date=8 August 2020 |url-status=live}}

{{cite web |url=https://www.planetary.org/articles/20170515-anatomy-of-delay-sls-orion |title=The anatomy of a delay: Here's a timeline of twists and turns for NASA's SLS and Orion programs |date=17 May 2017 |first=Jason |last=Davis |publisher=The Planetary Society |access-date=18 March 2022 |archive-url=https://web.archive.org/web/20200807133444/https://www.planetary.org/articles/20170515-anatomy-of-delay-sls-orion |archive-date=7 August 2020 |url-status=live}}

{{cite web |url=https://spaceflightnow.com/2022/06/22/nasa-not-planning-another-artemis-1-countdown-dress-rehearsal/ |title=NASA not planning another Artemis 1 countdown dress rehearsal |date=22 June 2022 |first=Stephen |last=Clark |publisher=Spaceflightnow |access-date=24 June 2022 |archive-url=https://web.archive.org/web/20220623133905/https://spaceflightnow.com/2022/06/22/nasa-not-planning-another-artemis-1-countdown-dress-rehearsal/ |archive-date=23 June 2022 |url-status=live}}

{{cite web |last=Clark |first=Stephen |url=https://spaceflightnow.com/2022/04/26/nasas-moon-rocket-rolls-back-to-vehicle-assembly-building-for-repairs/ |title=NASA's moon rocket rolls back to Vehicle Assembly Building for repairs |work=Spaceflight Now |date=26 April 2022 |access-date=26 April 2022 |archive-date=26 April 2022 |archive-url=https://web.archive.org/web/20220426202127/https://spaceflightnow.com/2022/04/26/nasas-moon-rocket-rolls-back-to-vehicle-assembly-building-for-repairs/ |url-status=live}}

{{cite web|url=https://blogs.nasa.gov/artemis/2021/12/17/artemis-i-integrated-testing-update/|title=Artemis I Integrated Testing Update|publisher=NASA|date=17 December 2021|access-date=18 December 2021|archive-date=11 December 2022|archive-url=https://web.archive.org/web/20221211224645/https://blogs.nasa.gov/artemis/2021/12/17/artemis-i-integrated-testing-update/|url-status=live}}

{{cite web |url=https://arstechnica.com/science/2022/07/nasa-sets-a-late-august-launch-date-for-sls-and-it-may-actually-happen/ |title=The SLS rocket finally has a believable launch date, and it's soon |work=Ars Technica |date=20 July 2022 |access-date=20 July 2022 |archive-url=https://web.archive.org/web/20220720185717/https://arstechnica.com/science/2022/07/nasa-sets-a-late-august-launch-date-for-sls-and-it-may-actually-happen/ |archive-date=20 July 2022 |url-status=live}}

{{cite web |url=https://blogs.nasa.gov/artemis/2022/10/12/nasa-sets-date-for-next-launch-attempt-for-artemis-i-moon-mission/ |title=NASA Sets Date for Next Launch Attempt for Artemis I Moon Mission |work=NASA |date=12 October 2022 |access-date=13 October 2022 |archive-date=12 October 2022 |archive-url=https://web.archive.org/web/20221012130404/https://blogs.nasa.gov/artemis/2022/10/12/nasa-sets-date-for-next-launch-attempt-for-artemis-i-moon-mission/ |url-status=live}}

{{cite web |url=https://blogs.nasa.gov/artemis/2022/09/30/teams-confirm-no-damage-to-flight-hardware-focus-on-november-for-launch/ |title=Teams Confirm No Damage to Flight Hardware, Focus on November for Launch |work=NASA |date=30 September 2022 |access-date=30 September 2022 |archive-date=6 October 2022 |archive-url=https://web.archive.org/web/20221006095400/https://blogs.nasa.gov/artemis/2022/09/30/teams-confirm-no-damage-to-flight-hardware-focus-on-november-for-launch/ |url-status=live}}

{{cite web |url=https://blogs.nasa.gov/artemis/2022/11/08/nasa-prepares-rocket-spacecraft-ahead-of-tropical-storm-nicole-re-targets-launch/ |title=NASA Prepares Rocket, Spacecraft Ahead of Tropical Storm Nicole, Re-targets Launch |work=NASA |date=8 November 2022 |access-date=8 November 2022 |archive-date=8 November 2022 |archive-url=https://web.archive.org/web/20221108231240/https://blogs.nasa.gov/artemis/2022/11/08/nasa-prepares-rocket-spacecraft-ahead-of-tropical-storm-nicole-re-targets-launch/ |url-status=live}}

{{cite web |author=Chris Bergin |date=4 October 2011 |title=SLS trades lean towards opening with four RS-25s on the core stage |url=http://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/ |access-date=26 January 2012 |publisher=NASASpaceflight.com |archive-date=16 July 2019 |archive-url=https://web.archive.org/web/20190716022841/https://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/ |url-status=live}}

{{cite web | last=Payne | first=Martin | title=SLS takes on new buckling standards, drops Super Light alloy | website=NASASpaceFlight.com | date=18 February 2013 | url=https://www.nasaspaceflight.com/2013/02/sls-new-buckling-standards-drops-super-light-alloy/ | access-date=26 June 2023 | archive-date=26 June 2023 | archive-url=https://web.archive.org/web/20230626195544/https://www.nasaspaceflight.com/2013/02/sls-new-buckling-standards-drops-super-light-alloy/ | url-status=live}}

{{cite web | last=Burkey | first=Martin | title=A (much) Closer Look at How We Build SLS – Rocketology: NASA's Space Launch System | website=NASA Blogs | date=2 June 2016 | url=https://blogs.nasa.gov/Rocketology/2016/06/02/a-much-closer-look-at-how-we-build-sls/ | access-date=26 June 2023}}

{{cite web|url=http://www.nasaspaceflight.com/2013/06/sls-pdr-evolved-rocket-dual-upper-stage/|title=SLS prepares for PDR – Evolution eyes Dual-Use Upper Stage|date=June 2013|archive-date=14 September 2013|archive-url=https://web.archive.org/web/20130914154418/http://www.nasaspaceflight.com/2013/06/sls-pdr-evolved-rocket-dual-upper-stage/|url-status=live|publisher=NASASpaceFlight.com|access-date=12 March 2015}}

“[https://www.nasa.gov/sites/default/files/atoms/files/2022_nasa_new_start_inflation_index_for_fy23_final.xlsx NASA FY22 Inflation Tables – to be utilized in FY23] {{Webarchive|url=https://web.archive.org/web/20221031195649/https://www.nasa.gov/sites/default/files/atoms/files/2022_nasa_new_start_inflation_index_for_fy23_final.xlsx |date=31 October 2022}}” (Excel). NASA. Retrieved 31 October 2022. This article incorporates text from this source, which is in the public domain.

{{Cite web |title=Fiscal Year 2010 Budget Estimates |url=http://www.nasa.gov/pdf/345225main_FY_2010_UPDATED_final_5-11-09_with_cover.pdf |url-status=live |archive-url=https://web.archive.org/web/20160806211200/http://www.nasa.gov/pdf/345225main_FY_2010_UPDATED_final_5-11-09_with_cover.pdf |archive-date=6 August 2016 |access-date=23 June 2016 |publisher=NASA |page=v}} {{PD-notice}}

{{Cite web|url=http://www.nasa.gov/home/hqnews/2011/sep/HQ_11-301_SLS_Decision.html|title=NASA Announces Design For New Deep Space Exploration System|publisher=NASA|date=14 September 2011|access-date=14 September 2011|archive-date=21 September 2011|archive-url=https://web.archive.org/web/20110921160158/http://www.nasa.gov/home/hqnews/2011/sep/HQ_11-301_SLS_Decision.html|url-status=live}} {{PD-notice}}

{{Cite web|last1=Bergin|first1=Chris|title=Advanced Boosters progress towards a solid future for SLS|date=20 February 2015 |url=http://www.nasaspaceflight.com/2015/02/advanced-boosters-towards-solid-future-sls/|publisher=NasaSpaceFlight.com|access-date=25 February 2015|archive-date=23 February 2015|archive-url=https://web.archive.org/web/20150223033632/http://www.nasaspaceflight.com/2015/02/advanced-boosters-towards-solid-future-sls/|url-status=live}}

{{Cite news|last1=Foust|first1=Jeff|title=SLS Debut Likely To Slip to 2018|url=http://spacenews.com/41690sls-debut-likely-to-slip-to-2018/|access-date=12 March 2015|publisher=SpaceNews|date=27 August 2014|archive-date=30 September 2021|archive-url=https://web.archive.org/web/20210930001748/https://spacenews.com/41690sls-debut-likely-to-slip-to-2018/|url-status=live}}

"[https://oig.nasa.gov/wp-content/uploads/2023/10/ig-24-001.pdf NASA’s Transition of the Space Launch System to a Commercial Services Contract] {{Webarchive|url=https://web.archive.org/web/20240725014246/https://oig.nasa.gov/wp-content/uploads/2023/10/ig-24-001.pdf|date=25 July 2024}}" oig.nasa.gov. 12 October 2023. Retrieved 7 June 2024.

{{cite web|url=http://www.nasa.gov/sls/14-171.html#.VGfrNb4_ypc|title=SLS Engine Section Barrel Hot off the Vertical Weld Center at Michoud|publisher=NASA|access-date=16 November 2014 |archive-date=19 November 2014|archive-url=https://web.archive.org/web/20141119072126/http://www.nasa.gov/sls/14-171.html#.VGfrNb4_ypc|url-status=live}} {{PD-notice}}

{{cite web|last1=Campbell|first1=Lloyd|title=NASA conducts 13th test of Space Launch System RS-25 engine |url=http://www.spaceflightinsider.com/space-centers/stennis-space-center/nasa-conducts-13th-test-space-launch-system-rs-25-engine/|publisher=SpaceflightInsider.com|date=25 March 2017|access-date=29 April 2017 |archive-date=26 April 2019|archive-url=https://web.archive.org/web/20190426153013/https://www.spaceflightinsider.com/space-centers/stennis-space-center/nasa-conducts-13th-test-space-launch-system-rs-25-engine/|url-status=live}}

{{cite web |last=Foust |first=Jeff |url=https://spacenews.com/next-artemis-1-launch-attempt-set-for-sept-3/ |title=Next Artemis 1 launch attempt set for Sept. 3 |work=SpaceNews |date=30 August 2022 |access-date=31 August 2022 |archive-date=3 September 2022 |archive-url=https://web.archive.org/web/20220903145954/https://spacenews.com/next-artemis-1-launch-attempt-set-for-sept-3/ |url-status=live}}

{{Cite web |last=Strickland |first=Ashley |website=CNN |publisher=Warner Bros Discovery |title=Artemis I launch team is ready for another 'try' on Saturday |url=https://www.cnn.com/2022/09/01/world/nasa-artemis-1-saturday-launch-update-scn/index.html |date=1 September 2022 |access-date=2 September 2022 |archive-date=3 September 2022 |archive-url=https://web.archive.org/web/20220903145954/https://www.cnn.com/2022/09/01/world/nasa-artemis-1-saturday-launch-update-scn/index.html |url-status=live}}

{{cite web|last=Gebhardt|first=Chris|website=NASASpaceflight|access-date=8 September 2022|url=https://www.nasaspaceflight.com/2022/09/artemis-i-update-sept8/|title=NASA discusses path to SLS repairs as launch uncertainty looms for September, October|date=8 September 2022|archive-date=8 September 2022|archive-url=https://web.archive.org/web/20220908171739/https://www.nasaspaceflight.com/2022/09/artemis-i-update-sept8/|url-status=live}}

{{cite web | last=Kraft | first=Rachel | title=Artemis I Managers Wave Off Sept. 27 Launch, Preparing for Rollback – Artemis | website=NASA Blogs | date=24 September 2022 | url=https://blogs.nasa.gov/artemis/2022/09/24/artemis-i-managers-wave-off-sept-27-launch-preparing-for-rollback/ | access-date=24 September 2022 | archive-date=24 September 2022 | archive-url=https://web.archive.org/web/20220924135858/https://blogs.nasa.gov/artemis/2022/09/24/artemis-i-managers-wave-off-sept-27-launch-preparing-for-rollback/ | url-status=live}}

{{Cite web |title=NASA to Roll Artemis I Rocket and Spacecraft Back to VAB Tonight – Artemis |url=https://blogs.nasa.gov/artemis/2022/09/26/nasa-to-roll-artemis-i-rocket-and-spacecraft-back-to-vab-tonight/ |access-date=26 September 2022 |website=blogs.nasa.gov |date=26 September 2022 |language=en-US |archive-date=26 September 2022 |archive-url=https://web.archive.org/web/20220926142032/https://blogs.nasa.gov/artemis/2022/09/26/nasa-to-roll-artemis-i-rocket-and-spacecraft-back-to-vab-tonight/ |url-status=live}}

{{cite web | last=Foust | first=Jeff | title=SLS to roll back to VAB as hurricane approaches Florida | website=SpaceNews | date=26 September 2022 | url=https://spacenews.com/sls-to-roll-back-to-vab-as-hurricane-approaches-florida/ | access-date=27 September 2022 | archive-date=16 January 2023 | archive-url=https://web.archive.org/web/20230116232552/https://spacenews.com/sls-to-roll-back-to-vab-as-hurricane-approaches-florida/ | url-status=live}}

{{cite news |last=Potter |first=Sean Sean |date=27 July 2022 |title=NASA Prepares for Space Launch System Rocket Services Contract |publisher=NASA |url=https://www.nasa.gov/press-release/nasa-prepares-for-space-launch-system-rocket-services-contract |access-date=10 August 2022 |archive-date=10 August 2022 |archive-url=https://web.archive.org/web/20220810221823/https://www.nasa.gov/press-release/nasa-prepares-for-space-launch-system-rocket-services-contract/ |url-status=live}}

{{Cite news |last=Roulette |first=Joey |date=8 June 2023 |title=Analysis: Boeing, Northrop face obstacles in commercializing flagship US rocket |url=https://www.reuters.com/technology/space/boeing-northrop-face-obstacles-commercializing-flagship-us-rocket-2023-06-07/ |access-date=8 June 2023 |work=Reuters |language=en}}

{{Cite news |last=Berger |first=Eric |author-link=Eric Berger (journalist) |date=9 February 2021 |title=So long Senator Shelby: Key architect of SLS rocket won't seek reelection |url=https://arstechnica.com/science/2021/02/so-long-senator-shelby-key-architect-of-sls-rocket-wont-seek-reelection/ |access-date=28 August 2024 |work=Ars Technica |language=en-us |archive-date=28 August 2024 |archive-url=https://web.archive.org/web/20240828163729/https://arstechnica.com/science/2021/02/so-long-senator-shelby-key-architect-of-sls-rocket-wont-seek-reelection/ |url-status=live}}

{{Cite web|url=https://www.nasa.gov/sites/default/files/atoms/files/sls_core_stage_fact_sheet_01072016.pdf|title=SLS Core Stage Fact Sheet|publisher=NASA|access-date=4 October 2021|archive-date=20 February 2021|archive-url=https://web.archive.org/web/20210220131734/https://www.nasa.gov/sites/default/files/atoms/files/sls_core_stage_fact_sheet_01072016.pdf|url-status=live}}

{{Cite web|title=RS-25 Engine|url=https://www.rocket.com/space/liquid-engines/rs-25-engine|access-date=12 June 2021|archive-date=12 August 2021|archive-url=https://web.archive.org/web/20210812044245/https://rocket.com/space/liquid-engines/rs-25-engine|url-status=live}}

{{Cite web|url=https://www.flickr.com/photos/ulalaunch/51266939305/in/album-72157690220351103/|title=What is ICPS?|date=23 June 2021|publisher=United Launch Alliance|access-date=4 October 2021|archive-date=23 June 2021|archive-url=https://web.archive.org/web/20210623140346/https://www.flickr.com/photos/ulalaunch/51266939305/in/album-72157690220351103/|url-status=live}}

{{Cite web|title=RL10 Engine|url=https://rocket.com/space/liquid-engines/rl10-engine|access-date=5 July 2021|archive-date=9 July 2021|archive-url=https://web.archive.org/web/20210709183437/https://rocket.com/space/liquid-engines/rl10-engine|url-status=live}}

}}

{{Commons category|Space Launch System}}

• [http://www.nasa.gov/exploration/new_space_enterprise/sls_mpcv/index.html Space Launch System and Multi-Purpose Crew Vehicle page on NASA.gov] {{Webarchive|url=https://web.archive.org/web/20110427020225/http://www.nasa.gov/exploration/new_space_enterprise/sls_mpcv/index.html |date=27 April 2011 }}
• [http://www.nasa.gov/pdf/510449main_SLS_MPCV_90-day_Report.pdf "Preliminary Report on Multi-Purpose Crew Vehicle and Space Launch System" (PDF), NASA]
• [http://www.nasa.gov/multimedia/videogallery/index.html?collection_id=73621&media_id=131955371 SLS Future Frontiers video]
• [http://www.beyondearth.com/ Video animations of mission to asteroid, the Moon, and Mars, beyondearth.com]
• [http://www.spacepolicyonline.com/news/nasa-continues-journey-to-mars-planning "NASA Continues Journey to Mars Planning", spacepolicyonline.com]

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