Exploration Upper Stage Explained

Exploration Upper Stage
Manufacturer:Boeing[1]
Country:United States
Rockets:Space Launch System (Block 1B/2)[2]
Height:[3]
Empty:[4]
Stagedata:
Engine details
Engines:4 × RL10C-3
Si:[5]
Burntime:1,275 seconds

The Exploration Upper Stage (EUS) is a rocket stage under development that will be used for future flights of NASA's Space Launch System (SLS). Used on SLS Block 1B and Block 2, it will replace the SLS Block 1's Interim Cryogenic Propulsion Stage. The stage will be powered by four RL10C-3 engines burning liquid oxygen and liquid hydrogen to produce a total thrust of . The EUS is expected to first fly on Artemis IV in 2028.[6]

Development

The Block 1 configuration of SLS, which first flew the Artemis I mission, has a core stage powered by four RS-25 engines, two Space Shuttle-derived five-segment solid rocket boosters, and an Interim Cryogenic Propulsion Stage (ICPS) upper stage.[7] [8]

NASA will develop the EUS to increase SLS performance for trans-lunar injection beyond Block 1 specifications. The improved upper stage was originally named the Dual Use Upper Stage (DUUS, pronounced "duce"),[9] but was later renamed the Exploration Upper Stage (EUS) due to DUUS sounding like a profanity in Japanese.[10]

In 2014, NASA announced that it would proceed with development of Block 1B with the EUS[11] and would use it on Exploration Mission 2, now referred to as Artemis II.[12] In April 2016, it was reported that NASA has chosen to use a design based on four RL10-C3 engines for the EUS, and in October 2016 NASA confirmed they had ordered 10 of the engines.[13]

In 2018, it was decided to optimize EUS for payload to lunar missions, by using smaller tanks.[14]

By February 2020, the development contract for EUS had been delayed, and NASA was planning to use ICPS for the first three launches of the SLS.[15]

Boeing announced on 21 December 2020 that the EUS of the SLS completed a critical design review (CDR) with NASA. That review confirmed the design of the EUS, allowing Boeing to proceed with development of the stage, including hardware fabrication.[16]

In March 2022, Boeing discussed the possibility of using a carbon composite liquid oxygen tank on the EUS, offering mass savings of up to 30%.[17]

Funding history

Fiscal yearNominal
(in millions)		Inflation adjusted
(FY24, in millions)[18]
2016$77.0$98.9
2017$300.0[19] $377.4
2018$300.0[20] $368.1
2019$150.0[21] $180.6
2020$300.0[22] $353.4
2021$400.0[23] $454.0
2022$636.7[24] $684.4
2023$648.3[25] $669.0
2024$600.0[26] $600.0
Total$3,412.0$3,785.9

See also

Notes and References

  1. Web site: 4 July 2014 . NASA, Boeing Finalize US$2.8 billion SLS Core Stage Contract . dead . https://archive.today/20140727032517/http://www.spacenews.com/article/civil-space/41139nasa-boeing-finalize-28b-sls-core-stage-contract . 27 July 2014 . 25 July 2014 . SpaceNews.
  2. Web site: Space Launch System Fact Sheet . 16 May 2023 . NASA.
  3. News: 9 September 2018 . Space Launch System . live . https://web.archive.org/web/20211005011936/https://www.spaceflightinsider.com/hangar/sls/ . 5 October 2021 . 4 October 2021 . Spaceflight Insider.
  4. Donahue . Benjamin . Sigmon . Sheldon . Cooper . Darby . 9 July 2018 . The NASA SLS Exploration Upper Stage Development & Mission Opportunities . 2018 Joint Propulsion Conference . en . Cincinnati, Ohio . American Institute of Aeronautics and Astronautics . 10.2514/6.2018-4639 . 978-1-62410-570-8.
  5. Web site: RL10 Engine . dead . https://web.archive.org/web/20211107110702/https://www.rocket.com/space/liquid-engines/rl10-engine . 7 November 2021 . 18 November 2021 . Aerojet Rocketdyne.
  6. Web site: Foust . Jeff . 30 October 2022 . Lunar landing restored for Artemis IV mission . 31 October 2022 . SpaceNews.
  7. Web site: SLS . 25 July 2014 . Gunter's Space Page.
  8. Web site: Space Launch System Data Sheet . usurped . https://archive.today/20130411204255/http://www.spacelaunchreport.com/sls0.html . 11 April 2013 . 25 July 2014 . SpaceLaunchReport.com.
  9. Web site: June 2013 . SLS prepares for PDR – Evolution eyes Dual-Use Upper Stage . 25 July 2014 . NASASpaceflight.com.
  10. Web site: Bergin . Chris . 28 March 2014 . SLS positioning for ARRM and Europa missions . 8 November 2014 . NASASpaceflight.com.
  11. Web site: Bergin . Chris . 30 July 2012 . Wind Tunnel testing conducted on SLS configurations, including Block 1B . 12 March 2015 . NASASpaceFlight.com.
  12. Web site: 6 June 2014 . NASA confirms EUS for SLS Block IB design and EM-2 flight . 25 July 2014 . NASASpaceflight.com.
  13. Web site: 21 October 2016 . Proven Engine Packs Big, In-Space Punch for NASA's SLS Rocket . 18 November 2021 . NASA.
  14. https://www.nasaspaceflight.com/2021/02/nasa-completes-exploration-upper-stage-cdr-focuses-new-office-on-sls-block-1b-development/ NASA completes Exploration Upper Stage CDR, focuses new office on SLS Block 1B development
  15. https://www.nasaspaceflight.com/2020/02/upper-stage-rl-10s-stennis-sls-launches/ Upper Stage RL10s arrive at Stennis for upcoming SLS launches
  16. Web site: 22 December 2020 . SLS Exploration Upper Stage passes review . 22 December 2020 . SpaceNews.
  17. Web site: 28 January 2016 . With all-composite cryogenic tank, Boeing eyes mass-reducing space, aviation applications . 2 June 2024.
  18. Web site: NASA FY24 Inflation Tables – to be utilized in FY24 . 2 June 2024 . NASA . Inflation Table.
  19. Web site: 1 May 2019 . NASA outlines plan for 2024 lunar landing . live . https://web.archive.org/web/20210930001738/https://spacenews.com/nasa-outlines-plan-for-2024-lunar-landing/ . 30 September 2021 . 15 May 2019 . SpaceNews.
  20. Web site: Berger . Eric . 20 May 2019 . NASA's full Artemis plan revealed: 37 launches and a lunar outpost . live . https://web.archive.org/web/20190523032200/https://arstechnica.com/science/2019/05/nasas-full-artemis-plan-revealed-37-launches-and-a-lunar-outpost/ . 23 May 2019 . 20 May 2019 . Ars Technica.
  21. Web site: Sloss . Philip . 18 December 2019 . Amid competing priorities, Boeing redesigns NASA SLS Exploration Upper Stage . live . https://web.archive.org/web/20200807073655/https://www.nasaspaceflight.com/2019/12/amid-priorities-boeing-redesigns-nasa-sls-eus/ . 7 August 2020 . 25 July 2020 . NASASpaceFlight.com.
  22. Web site: July 2020 . NATIONAL AERONAUTICS AND SPACE ADMINISTRATION FY 2020 SPENDING PLAN FOR APPROPRIATIONS PROVIDED BY P.L. 116-93 and P.L. 116-136 . 2 June 2024.
  23. Web site: June 2021 . NATIONAL AERONAUTICS AND SPACE ADMINISTRATION FY 2021 SPENDING PLAN FOR APPROPRIATIONS PURSUANT TO P.L. 116-260 . 2 June 2024.
  24. Web site: July 2022 . NATIONAL AERONAUTICS AND SPACE ADMINISTRATION FY 2022 SPENDING PLAN FOR APPROPRIATIONS PROVIDED BY P.L. 117-103 . 2 June 2024.
  25. Web site: March 2023 . NATIONAL AERONAUTICS AND SPACE ADMINISTRATION FY 2023 SPENDING PLAN FOR APPROPRIATIONS PROVIDED BY P.L. 117-328 . 2 June 2024.
  26. Web site: March 2024 . COMMERCE, JUSTICE, SCIENCE, AND RELATED AGENCIES APPROPRIATIONS ACT, 2024 . 2 June 2024.

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