Talk:Exploration Upper Stage

RL10 variant

Not in citation given. "-C" (sdsds - talk) 23:41, 10 December 2016 (UTC)

• To be clear Bergin's article is a very good source to cite. It just doesn't support the (presumed correct) assertion that the RL10 variant that will be used on EUS is the new RL10-C. Maybe https://www.nasa.gov/exploration/systems/sls/proven-engine-packs-big-in-space-punch-for-nasa-s-sls-rocket.html ? (sdsds - talk) 23:45, 10 December 2016 (UTC)

That says "The EUS will use four RL10C-3 engines, ... NASA recently contracted with Aerojet Rocketdyne of West Palm Beach, Florida for the production of 10 RL10C-3 engines for the rockets second and third flights with Orion, as well as two spare engines." (Oct 2016)

Bergin (April 2016) says "Per the EUS POD, the definitions called for the stage to utilize four RL-1OC-3 engines" - I'll change the cite to the later Oct ref. - Rod57 (talk) 10:27, 10 January 2018 (UTC)

Is there a construction and test schedule we can mention ?

What tests are planned before the flight hardware is built or flown ? - Rod57 (talk) 13:34, 12 February 2018 (UTC)

Need to mention Blue Origins proposed alternative, and NASA's rejection of it

Need to mention Blue Origins proposed alternative, and NASA's rejection of it. - I'll look for some sources ... - Rod57 (talk) 14:10, 9 November 2019 (UTC)

Made a brief mention, with source. - Rod57 (talk) 13:42, 17 October 2020 (UTC)

Delayed development - waiting on NASA technical decision ?

EUS development delays are not mentioned. It was to have been used on the first manned SLS/Orion (EM-2?) but funding delays in 2019, 2020, and maybe earlier, seem to have pushed the first planned use of EUS out to Artemis-4 ! (find RS - maybe Upper Stage RL10s arrive at Stennis for upcoming SLS launches Feb 2020 or Amid competing priorities, Boeing redesigns NASA SLS Exploration Upper Stage Dec 2019) - Rod57 (talk) 15:42, 15 February 2020 (UTC)

I went with the first ref; 2nd ref also confirms. 2nd ref also says that NASA asked Boeing for more performance from EUS, and Boeing had responded with about 10 options for NASA to decide between. Development progress seems to be costing about $150 M per annum. - Rod57 (talk) 18:12, 16 April 2020 (UTC)

Will need an interstage to fit on SLS

Looking at the image of EUS, it might need an interstage to fit on the top of the SLS core stage unless the core stage cylinder is lengthened to extend above the main tanks. (SLS block 1 has a substantial conical interstage to support the ICPS.) Is either part of the EUS contracts ? - Rod57 (talk) 01:02, 14 December 2020 (UTC)

• SLS configuration images show a substantial Interstage between SLS core and EUS hydrogen tank. - Rod57 (talk) 11:51, 30 June 2024 (UTC)

The interstage is being built currently at Michoud. I don't remember if it has a qual article or not but there were some photos released of it in the VWC here: https://www.facebook.com/photo?fbid=861241042702385&set=pcb.861276362698853 Sub31k (talk) 15:20, 5 July 2024 (UTC)

Ref for more detail on development schedule

NASA completes Exploration Upper Stage CDR, focuses new office on SLS Block 1B development Feb 2021 has dates for structural test article and first flight article, build and test. - Rod57 (talk) 16:07, 23 February 2021 (UTC)

Uneeded section in lead paragraph

is this part really needed in the lead paragraph anymore?

However, the Trump administration has proposed terminating the SLS program after Artemis III, which would eliminate the need for the EUS, though Congress in July 2025 provided funding for Artemis IV anyway in the One Big Beautiful Bill Act.

its covered in the development section and sounds irrelavent for the lead paragraph as it is still being funded for the time being. WP:RECENTISM ~2026-79251-1 (talk) 04:55, 5 February 2026 (UTC)

Funding

I have updated the funding to include all information up to and including the current budget. The 2016 budget is uncited still - looking at the 2016 NASA budget, only overall SLS costs were given, with no upper stage breakdown. If there are no objections in the next week or so I will remove this row. BennBluee (talk) 16:33, 14 June 2026 (UTC)

Also the second column (the inflation adjusted figure) might count as original research / synthesis? Looks like someone has calculated this themself using the 2024 inflation figures (unfortunately I cannot find the NASA spreadsheet for years after 2025). Is this allowed / standard on funding sections? Or should it be removed? BennBluee (talk) 16:37, 14 June 2026 (UTC)

Yes adjusting for inflation is fine WP:CALC and especially fine if done with NASA's official figures. There's even templates to do it automatically: Template:Inflation Leijurv (talk) 18:40, 14 June 2026 (UTC)

Thanks! I've just updated the table to use that template. BennBluee (talk) 19:34, 14 June 2026 (UTC)

Also just a quick note: I removed the "Totals" row as I think its not particularly useful, since 4 of the years listed are for Block 1B, and not just EUS. Instead, I've added in the EUS total that NASA gives in a sentence below. Maybe this can be moved to a row, but then it might be confusing that the above cells don't sum to that $1.9 billion figure. BennBluee (talk) 19:41, 14 June 2026 (UTC)