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NASA postpones second SLS static fire test

NASA today announced that it was postponing the second SLS static fire test of the rocket’s core stage due to a valve issue in its main engines.

NASA said it was postponing the Green Run static-fire test, which had been scheduled for Feb. 25, after discovering a problem with one of eight valves called “prevalves” associated with the stage’s four RS-25 main engines. The valve, which supplies liquid oxygen, was “not working properly,” NASA said in a statement, but didn’t elaborate on the problem.

Engineers identified the problem during preparations over the weekend for the test. NASA said it will work with Boeing, the prime contractor for the core stage, to “identify a path forward in the days ahead and reschedule the hot fire test” but did not set a new date for the test.

This was not the first time Boeing and NASA has had valve problems with the rocket, though this problem appears unrelated to the previous issue.

Either way, the continuing technical problems — such as the two previous aborts during testing — does not build confidence in the rocket. First, the schedule is very tight, and is getting tighter. Its first unmanned test flight was supposed to happen by the end of this year, and right now that looks very unlikely. Yet, it must happen within the next twelve months because they have begun stacking the strap-on solid rocket boosters, and those have a sell-by date.

More important, these issues raise big red flags as to the overall trustworthiness of the rocket. I certainly would not want to fly on it, at least not until I see it fly at least a half dozen times successfully. The problems however suggest that achieving such a track record is going to be quite difficult.

And if SLS has any major failures during any launch, be prepared for Congress’s support to finally collapse, especially with the on-going spectacular progress being achieved by SpaceX with Starship along with two Falcon Heavy launches planned for this year.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

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  • Jeff Wright

    All rockets have these problems. Musk’s workers at least get respect with no one attacking them

  • john hare

    You are right Jeff. It normally takes a few launches to get it right. Let’s see how much refurbishment an SLS takes after a launch before going up again.

  • Jeff Wright

    Better to have an SLS core as a wet workshop like the ET tank station concept. No need of heat shields or legs.

  • Ray Van Dune

    I think the SLSS (Single Launch Space Station) is a winning concept, potentially combining the function of habitat and Earth orbit – Lunar orbit ferry.

  • John hare

    Good idea there. Gets around the problem of pretending the SLS is a launch vehicle.

  • Col Beausabre

    Wait a second, folks. SLS is supposed to be constructed of proven technology. Those valves should be 30-40 year old designs, proven by dozens of flights. SLS was purposefully supposed to be cheap and easy because it used technology “proven” on the Shuttle. So what’s the deal with these valves….

  • Dick Eagleson


    If an SLS core stage can actually make it into LEO, your idea may be the only really useful one as to a mission for SLS. I presume SLS would have to be launched with neither a 2nd stage nor any other payload in order for a core stage to make orbit.

    That would, of course, require either using no SLSes for Artemis missions or fewer of them. The Artemis schedule seems all but certain to be stretched out anyway so that may not be a problem. The Artemis 1 mission looks as though it is likely to be flown more or less as planned, with an unmanned Orion payload, but will likely be delayed into 1Q or perhaps even 1H 2022. That pretty well guarantees Artemis 2, the notional first manned flight of SLS-Orion, can’t happen before 2024. By that time, Starship, in HLS form, is likely to have landed, unmanned, on the Moon at least once and SpaceX should have flown manned Starships both into Earth orbit and around the Moon (Dear Moon) as well. That would allow the Orion and upper stage Artemis contracts to be cancelled and all crew flights to the Moon, done on Starships. That would also free up all but the first SLS core stage to fly to orbit, ala your wet workshop notion.

    Something else that could be canceled at that point would be the AJR contract for expendable RS-25s. With SLS core stages – as of the second one built – now getting to orbit, crews could be sent up on Starships to remove the SLS core stage engines and bring them back for reuse on new core stages. The same crews could also fit out the core stages with PV power arrays, airlocks and ECLSS systems needed to make them functioning stations or subsets of a larger station. This would be good work for SpaceX and could end the long-simmring SLS-Starship “war.” With a dozen reusable RS-25s still on-hand in slow rotation, a new wet workshop core stage could be launched every year or two for quite a long time. The SLS SRBs would still be expendable, but at least NorGrum would get to make a new set every year or two to go with the Boeing core stages.

    So LockMart and ULA would find themselves with no further SLS business and Boeing would lose the EUS contract. But two of the big SLS contractors would still keep significant work going and that would certainly be better than outright program cancellation so far as they would be concerned.

    SLS core stages are still pretty pricey as rocket hardware goes, but as space station hardware, SLS becomes a relative bargain. An SLS core stage costs about $2 billion and would provide approx. 3,500 cu. meters of enclosed volume. On a $/cu. meter basis, SLS core stages are way cheaper than ISS and might even be competitive with the station Axiom plans to build.

    Faced, as they may soon be, with a choice between the wet workshop idea and outright cancellation, it would seem that Boeing and NorGrum, at least, would be receptive to the former alternative. LockMart and ULA would be left out in the cold, but that simply lowers the amount of political headwind that would need to be bucked to make your notion happen. And you would have countervailing political wind at your back from the contractors who would still have chairs when the music stops.

  • Patrick Underwood

    SLS wet workshop? Why not speculate about something more likely, such as unicorns that hand out free candy?

  • Dick Eagleson


    I don’t consider the idea likely to come to pass, just interesting to kick around as it’s one of the vanishingly rare scenarios in which SLS might actually be salvaged for a useful purpose. But, where government programs are concerned, the most useful ideas are the ones least likely to be taken up.

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