SLS saves itself with successful full-duration engine firing but its career may still be short

by | Mar 19, 2021 | Blue Origin, Launches, NASA, Seradata News, SpaceX, Technology

NASA’s much delayed and very expensive SLS heavy-lift launch vehicle (HLV) has coming under renewed criticism as SpaceX’s partly reusable commercial HLV has advanced into its stage testing programme (the main super-booster stage is nearly constructed while the Starship upper stage is already flying atmospheric landing tests). Thus, the knives were out when an engine test firing of the SLS rocket’s core stage failed after only 67 seconds, at the Stennis Space Center in Mississippi on 16 January. It was feared the maiden flight would be further delayed until next year.

The second “green run” test of SLS core stage RS-25 engines was successful. Courtesy; NASA TV

In the end, the failure turned out to have been due to a minor issue. An automatic shutdown was caused by Engine No 2’s hydraulic generating core stage auxiliary power units (CAPUs) exceeding pre-set limits related to the actual test stand being used.

And so, it provided some relief to NASA and the rocket engine maker, Aerojet Rocketdyne, when the four RS-25 main engine core managed to burn for over eight minutes during a second test at Stennis on 18 March. This success cleared the way for the core stage to be taken back to the Kennedy Space Centre so that it could be stacked, along with its current Delta IV-rocket derived ICPS (interim cryogenic propulsion stage) upper-stage,and fitted with solid rocket boosters ready for its unmanned (uncrewed) maiden flight at the end of the year.

However, all is not well for SLS. Many are wondering if NASA would not be wise to cancel the more powerful Block 1B and Block 2 versions of the SLS and the exploration upper stage (EUS). The EUS has recently been given the technical green light and has the budget funding to proceed.

It has been recently revealed that NASA is mounting a study to examine whether it really needs the later versions of SLS. There is particular concern over its per flight cost – at US$2 billion a shot – compared with commercial alternatives, which might be able to fly similar sized payloads for one tenth of the price.

Doubts about whether SLS will ever be cost-effective have led to the loss of some of its key “pork barrel” political backing in the US Senate. Even its supporters are beginning to leave the stage. Republican Senator Richard Shelby, a strong advocate of SLS given that much of the work is done in his Alabama constituency, is no longer Chair of the Senate Appropriations Committee and does not intend to stand for office again.

Computer image of SLS Block 1. Courtesy: NASA

Nevertheless, SLS may yet get a stay of execution. This is because former Democrat Senator and strong proponent of SLS, Bill Nelson, is now likely to be appointed as NASA’s next Administrator. Even so, SLS is now likely to fly on only a handful of Project Artemis missions – in effect as an interim HLV rocket and, quite possibly, with commercial rockets backing it up. The previous NASA Administrator, Jim Bridenstine, mooted a plan involving the already operational SpaceX Falcon Heavy equipped with an ICPS as a possible alternative to SLS. While that idea was shot down by Senate pressure, there may yet be a role for the SpaceX rocket.

For example, NASA’s initial Project Artemis lunar landings could employ an ICPS-equipped Falcon Heavy to carry a lunar landing craft to lunar orbit, and just use the human-rated SLS Block 1 for the Orion spacecraft carrying the astronauts. More advanced commercial heavy-lift rockets, such as SpaceX’s Starship/Superbooster combination and Blue Origin’s New Glenn, could be used for later Artemis missions. A more detailed rundown of the NASA study into the future of SLS, by Eric Berger (Ars Technica), can be found here






About Seradata

Seradata produce the renowned Seradata database. Trusted by over 100 of the world’s leading Space organisations, Seradata is a fully queryable database used for market analysis, failure/risk assessment, spectrum analysis and space situational awareness (SSA).

For more information go to

Related Articles

Iran launches Noor 3 (Nour 3) satellite using Qased rocket launch

A Qased rocket launch at 0558 GMT on 27 September from the Qased Shahroud Test Centre, Iran, carried the Noor Read more

Soyuz MS-23 undocks from ISS and returns to Earth

With the hatch closed at 0441 GMT on 27 September 2023, Soyuz MS-23 undocked from the Prichal module of the Read more

China launches second Yaogan 33 mission in a month

In a near repeat of a mission which took place earlier this month on 6 September 2023, China has launched Read more

OSIRIS REx returns its Bennu asteroid sample capsule to Earth then heads for new asteroid on OSIRIS-APEx mission

Having been launched in September 2016, the main sample return pat of the OSIRIS-REx mission to the asteroid Bennu has Read more

Falcon 9 launches Starlink Group 6-18 from Cape Canaveral, then one puts Starlink Group 7-3 up from Vandenberg

SpaceX successfully launched a Falcon 9v1.2FT Block 5 rocket from Cape Canaveral, Florida, USA at 0338 GMT on 24 September Read more

Galactic Energy of China suffers first launch failure of its Ceres-1 rocket losing insured Jilin 1 Gaofen 04B-01

Having been launched at 0459 GMT on the morning of 21 September it later filtered out that the Ceres-1 Y11 Read more

Starlink Group 6-17 is launched by Falcon 9

SpaceX successfully launched a Falcon 9v1.2FT Block 5 rocket from Cape Canaveral, Florida, USA at 0338 GMT on 20 September Read more

Electron KS rocket has another failure losing Acadia 2 radar Earth observation satellite

Rocket Lab launched Electron KS from Māhia Peninsula, New Zealand, at 0655 GMT on 19 September 2023. The Electron was Read more

China launches Long March 2D carrying Yaogan 39 trio

China successfully launched a Long March 2D/2 (CZ-2D/2) from Xichang Satellite Launch Centre, Sichuan Province, China at 0312 GMT on Read more




nasaspacexecoreviewsissesaArianespacevideochina25virgin galacticfalcon 9ULAFalcon 9v1.2FT Block 5RoscosmosevaDGAspacewalkaviation weekaressoyuzIGTInternational Space StationBeidouawardsspaceBlue OriginSatellite broadcastingRocket LabStarlinkrussiamoonCargo Return VehicleboeingOneWebAirbus DSmarsblogISROresearchorionspaceshiptwojaxaimpacthyperboladelaymarsEutelsatdemocratrocketobamahypertextgoogle lunar prizelunarlaunchVegabarack obamaconstellationSEStourismnorthfiguresthales alenia spacespaceflightnode 2fundedRaymond LygoIntelsat2009Lockheed MartinExpress MD-2Atlas Vromess2Elon Muskdassault aviationaviationLucy2008wk2sstlukradiotestmissilesuborbitaldocking portexplorationAriane 5 ECAVirgin OrbitinternetChina Manned Space EngineeringAriane 5SLSsts-1222010flightspace tourismNorthrop Grummancotsnewspapermissile defensegalileospaceportExpress AMU 1Long March 4CLong March 2D/2Electronbuildspace stationaltairinternational astronautical congresssoyuz 2-1ashuttleProton MEuropean Space AgencyLauncherOneCosmosIntelsat 23scaled compositeshanleybudgetrulesnew yorkAriane 6shenzhouspace shuttleatvVietnamcongressMojaveboldenLong March 2COrbital ATKnew shepardInmarsatGuiana Space Centeriaccneslunar landerksclawsSpace Systems/LoralUK Space AgencyLong March 4BILSUS Air ForceprotonTalulah RileyApollodarpaFalcon 9v1.2 Block 5Kuaizhou 1AVega CSkylonAstriumeupicturebaseusaastronautdragonlanderfiveeventTelesatSSLElectron KSNorth KoreaAprilSNCWednesdayinterviewSea Launchfalcon50thcustomerlinkLong Marchatlantissuccessor