Explosion during static fire test of SpaceX’s Starship-SN1 prototype

Chronological Encyclopedia of Discoveries in Space cover

After being in print for twenty years, the Chronological Encyclopedia of Discoveries in Space, covering everything that was learned on every single space mission in the 20th century, has finally gone out of print.

I presently have my last four hardback copies available for sale. The book sold new for about $90. To get your own autographed copy of this now rare collector's item, please send a $120 check (which includes shipping) payable to Robert Zimmerman to

Behind The Black, c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

"Useful to space buffs and generalists, comprehensive but readable, Bob Zimmerman's Encyclopedia belongs front and center on everyone's bookshelf." -- Mike Collins, Apollo 11 astronaut


"The Chronological Encylopedia of Discoveries in Space is no passionless compendium of information. Robert Zimmerman's fact-filled reports, which cover virtually every spacecraft or probe to have ventured into the heavens, relate the scientific and technical adventure of space exploration enthusiastically and with authority." -- American Scientist

Capitalism in space: It appears that about two seconds into a static fire engine test tonight of SpaceX’s Starship-SN1 prototype, something went wrong, there was an explosion, the prototype suddenly lifted into the air and then crashed to the ground in a bigger explosion.

The video below shows the event three times. We shall have to await word from SpaceX as to what happened. So far it appears that no one was hurt.



  • mkent

    I don’t think this was a static fire test.
    It was just a pressurization test with the tanks
    filled with liquid nitrogen instead of propellant.

  • Scott M.

    Agreed, from everything I’ve read it was a pressure test. I don’t think they’d even mounted an engine to it yet.

    The move to stainless steel eliminated a Very Hard Problem, namely how to make cryogenic-compatible carbon fiber composite tanks of the proper size.

    However, it appears that the move to that material created a (Less?) Hard Problem, namely how to get ultra-strong welds in thin stainless steel sheeting. My understanding is that making the steel thicker would make proper welding easier, but that would in turn create too much of a weight penalty.

    My own two cents is that they’ll solve this problem faster than they would have solved the issues with composite tanks.

  • All: You are right. In my hurry to post last night I forgot this was only a tank pressure test. I have corrected the post.

  • Fredrik Perman

    You should correct the post and title, is it’s not yet corrected.

  • sippin_bourbon


    Set backs are expected.
    No one hurt. Makes it easier to watch.

    A few weeks ago, someone stated that SpaceX has no desire to improve the Crewed Dragon to allow landing on ground (as opposed to splash downs), because they have Starship coming next.

    Things like this make me think they should revisit the decision.

    Starship will be a massive leap, but I see more setbacks, just as they had with Falcon.
    I suspect that Crew Dragon, Starliner, and maybe even Orion with be the standard methods of getting up there for a while.

    Dont get me wrong, I am rooting for all of them. But Rome… Construction… Time… some assembly required.

  • Cotour

    I never liked this retro 1950’s / Flash Gordon / “Destination Moon” design with the welded stainless panels. The stainless steel solves the weight and heat resistance problem but those solutions appear to introduce several new design and material performance problems, which is expected.

    Just found this, look familiar? https://youtu.be/7N_Eghin6pM

    I think maybe Musk saw this “Destination Moon” movie when he was a child and he is determined to manifest it, will it into being. Like all good willful masters of the universe billionaires would do.

    I say can the stainless steel (No pun intended).

    Im not saying it cant be done, not at all, but there has to be a new way found to accomplish it.

  • Cotour

    This guy has a more optimistic take then I https://youtu.be/Bv9rTdFC1dg

    And I will have to bow to the more informed Space X nerds and optimistic among us on this subject. I have to admit that the roll stainless steel segments as opposed to the panels are an improvement.

    “Test fast and fail quickly”

  • Scott M.

    The next Starship tank prototype (SN2) has several improvements to its welding which aren’t in this one, particularly in the areas of automation and weld quality. I hope it will do better than SN1.

    As I said earlier, I think this will be an easier problem to solve than that of trying to get a composite tank to work. My very limited experience with composites is that they’re nowhere near as easy to rework and test as straight metal.

    In either case, I find SpaceX’s open failures refreshing when contrasted with their competitor’s behavior. We still haven’t heard the final word on Boeing’ s issues with that first Starliner test. The unofficial word (as yet) is that there was never any end-to-end test of software+hardware, which to me seems unbelievably reckless.

  • Scott M.

    Oh, and Cotour when it comes to rocket aesthetics I”m afraid we’ll have to agree to disagree ;)

    I personally love the retro-futuristic look of a chromed rocket.

  • sippin_bourbon

    re: Cotour’s link.

    “Never before has any woman sent her man on such an exploit!”

    I think my ex tried…

  • Diane Wilson


    Update on Starliner. It’s pretty direct in how their testing missed the two software problems, and what they will do about it. No word yet on whether another unmanned test flight will be required.

  • Ryan Lawson

    That looked more like an implosion than an explosion. Do they do a vacuum test on the tanks?

  • Dick Eagleson

    I suspect SpaceX had more than an inkling SN01’s lower half was not likely flight-worthy once it had been fabricated. The piece transported to the test stand was pretty much just the tankage. Giving it a pressure test – whether to deliberate destruction or not – was just a way to gather some additional data to feed back into the rapidly iterating build process. SN02 is hard on SN01’s heels. It won’t be long before one of these test articles passes pressure testing and gets the rest of its bits installed to enable hot fire, short hop and tall hop tests. That may well happen before DM-2 lifts off. Given that the now-late SN01 took only a month to build vs. six months for the late Mk1, the build cadence is certainly ramping up quickly.

  • Scott M.

    Diane, thank you very much for the link…even though I had to wait awhile after reading it for my blood pressure to abate.

    I might just barely give Boeing a pass on ‘chunking’ the software; that meant they missed the first big error, where Starliner didn’t ‘grab’ the correct time from the Atlas.

    But that second error, the thruster-mapping issue? They didn’t test the software for that portion ‘because it was legacy’? That is absolutely inexcusable. If NASA doesn’t make Boeing re-fly the entire test mission without crew, that will be a certain sign of political pressure. And it might result in yet more dead astronauts.

  • Diane Wilson

    Scott, I can’t give them a pass for either test failure. Errors happen at interfaces, or in this case, between chunks. Legacy software in a new environment is also a red flag.

  • Diane Wilson

    I watched part of an interview with Elon Musk with an Air Force (Space Force?) audience. He talked about solving the hard problems first (yes!) and developing the manufacturing process and facilities in tandem with developing the Starlink satellites. He said that the production line was finished before the Starlink design was complete, and that they’re now producing Starlink satellites faster than they can launch them.

    He also said that they need Starship to stay on schedule for Starlink deployment.

  • Ray Van Dune

    It is astounding that Boeing took the testing shortcuts they did, considering the 737 MAX debacle, and hopefully Dennis Muillenberg’s head was only one among many that rolled!

    Boeing’s testing of the software in “chunks” was reasonable, to avoid the unworkable situation where every test is a full end-to-end test! But, the chunk boundaries should have been selected, and varied, so that no hand-off or interface is left un-exercised (which in highly complex code can be non-trivial to insure). All that being said, at least several full end-to-end tests should have been run, and now MUST BE run, prior to final acceptance.

  • jburn

    Ryan Lawson, here’s a link which describes the mechanics that likely took place.

    Scott Manley provides a nice explanation..


  • Edward

    Ray Van Dune suggested: “Boeing’s testing of the software in “chunks” was reasonable, to avoid the unworkable situation where every test is a full end-to-end test!

    This “chunking” of the software seems similar to the separate mechanical testing that doomed Mars Polar Lander, when the legs opened up, over stretched due to momentum, and tripped the landing switch that shut down the engine prematurely. The leg opening test had occurred separately from the part with the switch on it, so that system was not properly tested to ensure the switch was not tripped when the legs opened from the stowed position.

    It looks like yet another lesson that was not properly learned.

  • Col Beausaber

    To Engineer is Human, The Role of Failure in Successful Design https://www.goodreads.com/book/show/271495.To_Engineer_Is_Human

  • pzatchok

    I would like to see if it was the weld that failed, the sheet of metal itself, or the boundary between the weld and the sheet metal. An area that takes some stress during the weld.

    Each problem would take a different fix.

  • Andi

    Seems like they missed out on Software Development 101:

    It’s quite advisable to test complex software in “chunks” to be sure that each piece works by itself, but good QA would demand that, once assured that each piece works as designed, a test of the entire system is required to be sure that all the pieces work properly together.

  • David Scott

    FWIW SpaceX did two engine tests this week. One last night about 8 pm. We’re about 10 miles from the test sight in central Texas

Leave a Reply

Your email address will not be published. Required fields are marked *