Exploration Upper Stage
 Diagram of the Exploration Upper Stage | |
| Manufacturer | Boeing[1] |
|---|---|
| Country of origin | United States |
| Used on | SLS Block 1B[2] |
| General characteristics | |
| Height | not to exceed 18 m (59 ft) |
| Diameter | 8.4 m (28 ft) |
| Propellant mass | up to 129,000 kg (284,000 lb) |
| Engine details | |
| Powered by | 4 RL10-C3[3][4] |
| Maximum thrust | 440 kN (99,000 lbf) |
| Propellant | LOX / LH2 |
The Exploration Upper Stage (EUS) is being developed as a large second stage for Block 1B of the Space Launch System (SLS), succeeding Block 1's Interim Cryogenic Propulsion Stage. It will be powered by four RL10-C3 [4] engines burning liquid oxygen and liquid hydrogen to produce a total of 440 kN (99,000 lbf) thrust. As of February 2015[update], the SLS Block 1B will provide thrust of 105 t (103 long tons; 116 short tons).[5] The EUS is expected to first fly on Artemis IV in March 2026.[6][7]
Development
The Block 1 configuration of SLS will have 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.[8][9]
NASA will develop the EUS to increase SLS performance beyond Block 1 specifications. The improved upper stage was originally named the Dual Use Upper Stage (DUUS, pronounced "duce")[10] but was later renamed the Exploration Upper Stage (EUS) due to DUUS sounding like a profanity in Japanese.[11]
In 2014, NASA announced that it would proceed with development of Block 1B with the EUS,[12] and would use it on EM-2.[2] In April 2016, it was reported that NASA has chosen to use a design based on four RL10-C3 engines for the EUS,[3] and in October 2016 NASA confirmed they had ordered 10 of the engines.[4]
By February 2020, the development contract for EUS had been delayed and NASA was planning to use ICPS for the first three launches of SLS.[13]
Boeing announced on 21 December 2020 that the Exploration Upper Stage (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.[14]
Role and comparable stages
The EUS is to complete the SLS's ascent phase and then re-ignite to send its payload to destinations beyond low Earth orbit. This is a similar function to the S-IVB stage of the old Saturn V rocket.
Cost concerns and alternatives
Due to the possible cost of EUS (about US$800 million each), NASA invited proposals for alternatives, but in May 2019 rejected Blue Origin's proposal.[15] NASA ordered eight EUS's from Boeing.[15]
See also
References
- ^ "NASA, Boeing Finalize US$2.8 billion SLS Core Stage Contract". SpaceNews. 4 July 2014. Retrieved 25 July 2014.
- ^ a b "NASA confirms EUS for SLS Block IB design and EM-2 flight". NASASpaceflight.com. 6 June 2014. Retrieved 25 July 2014.
- ^ a b Bergin, Chris (7 April 2016). "MSFC propose Aerojet Rocketdyne supply EUS engines". NASASpaceflight.com. Retrieved 8 April 2016.
- ^ a b c Proven Engine Packs Big, In-Space Punch for NASA's SLS Rocket. October 2016
This article incorporates text from this source, which is in the public domain.
- ^ "Advanced Boosters progress towards a solid future for SLS". NasaSpaceflight.com. 20 February 2015. Retrieved 12 March 2015.
- ^ "NASA's Management of the Gateway Program for Artemis Missions" (PDF). OIG. NASA. 10 November 2020. p. 3. Retrieved 4 January 2021.
Artemis IV is scheduled to launch in March 2026 (as of August 2020).
- ^ Loff, Sarah (16 October 2019). "NASA Commits to Future Artemis Missions With More SLS Rocket Stages". NASA. Retrieved 4 January 2021.
NASA aims to use the first EUS on the Artemis IV mission.
- ^ "SLS". Gunter's Space Page. Retrieved 25 July 2014.
- ^ "Space Launch System Data Sheet". SpaceLaunchReport.com. Retrieved 25 July 2014.
- ^ "SLS prepares for PDR – Evolution eyes Dual-Use Upper Stage". NASASpaceflight.com. June 2013. Retrieved 25 July 2014.
- ^ Bergin, Chris (28 March 2014). "SLS positioning for ARRM and Europa missions". NASASpaceflight.com. Retrieved 8 November 2014.
- ^ Bergin, Chris (30 July 2012). "Wind Tunnel testing conducted on SLS configurations, including Block 1B". NASASpaceFlight.com. Retrieved 12 March 2015.
- ^ Upper Stage RL10s arrive at Stennis for upcoming SLS launches February 2020
- ^ "SLS Exploration Upper Stage passes review". SpaceNews. 22 December 2020. Retrieved 22 December 2020.
- ^ a b NASA rejects Blue Origin's offer of a cheaper upper stage for the SLS rocket May 2019
