back to article FAA gives SpaceX a bunch of homework to do before Starship flies again

The US Federal Aviation Administration (FAA) has closed its investigation into the case of another exploding SpaceX rocket with a list of corrective actions to be implemented before Starship can fly again. SpaceX led the investigation into the incident, which was overseen by the FAA. NASA and the National Transportation Safety …

  1. Zolko Silver badge

    payload ?

    If it had had a payload, it would have made it to orbit ... Starship was approximately 150 km up and traveling at around 24,000 kph at the time

    but if it indeed did have a 100T payload, then it would have been that much heavier and thus it wouldn't have made it to orbit either. Also, Oxygen doesn't burn by itself, it needs some fuel: where was that supposed to come from ?

    All-in-all, I persist in saying that this will never make it to orbit, let alone to the Moon.

    1. MichaelGordon

      Re: payload ?

      It's not as if SpaceX have a history of going from exploding, crashing prototypes to a massively reliable system that takes a substantial percentage of the market for satellite launches ...

    2. Flocke Kroes Silver badge

      Re: payload ?

      The flight profile was fixed so re-entry would occur near the military radars at Hawaii. To achieve that profile without a payload the engines were throttled down well below maximum thrust. The low thrust caused the rocket to use less propellant than was loaded. The excess had to be vented to get the mass low enough for re-entry.

      If SpaceX had started with less propellant then the required thrust to stay on trajectory would have been below the minimum thrust for all six engines. They could have done that by not lighting all of them but that would not have been a good match to real use. They could have used a dummy payload but the currently published limit is only 50t of payload down mass. They would have had to add some mechanism to push out at least 50t before re-entry.

      There is already hardware in place to unload propellant if a launch gets scrubbed. They decided to go with this equipment as it has worked reliably in ground tests. With hindsight we can see that this plan actually needed the quick disconnect arm attached and the ground support equipment that stores propellant after a scrub.

      1. Anonymous Coward
        Anonymous Coward

        If anyone is asking "why Oxygen?"

        For those of wondering why they would have loaded and vented oxygen, it's probably about twice as dense as the methane, and also has less environmental impact.

        As the poster above pointed out, a dummy load would have to be shed before the sections could prepare for return, and would increase the risk if the guidance or remote termination systems had an issue.

        1. CowHorseFrog Silver badge

          Re: If anyone is asking "why Oxygen?"

          What makes you think Musk gives a rats arse about the environment ?

          He doesnt even care about humans, his factories are full of abuse, racism and more, and you think he cares about the environment ?

          1. Persona

            Re: If anyone is asking "why Oxygen?"

            Maybe he doesn't care about the environment, but he/Tesla have produced roughly 5 million electric cars. Actions speak louder than words.

            1. CowHorseFrog Silver badge

              Re: If anyone is asking "why Oxygen?"

              You are making a lot of assumptions that Tesla cars are good for the environment. They are so good for the environment, that they were fined by the EPA for releasing toxic crap into the environment.

              Whats going to happen to all those batteries when they are worthless because there is new battery tech ?

      2. Zolko Silver badge

        Re: payload ?

        the engines were throttled down well below maximum thrust

        you mean that the rocket exploded despite not being at full power ? So when they decide that the rocket is "ready" then they'll launch it with full payload and full throttle, something they will never have tested before ? You can't be serious

        As for 100T payload, a 5x5x5m water ballast would do the job, no security or other dangers on re-entry.

        1. John Robson Silver badge

          Re: payload ?

          You do realise that engines are designed to throttle, and will do so throughout the flight... the explosion wasn't to do with the engines, but the fire which was caused by the venting of lox.

          So you're now designing a system to hold a 5m cube of water, and a way to pump that liquid overboard, and to prevent it from freezing, and to ensure that there is no slosh, and...

          Why not just load more of the propellant that you already load and vent it using existing hardware which has been tested (on the ground).

          Simple is usually better - and this is one case where despite the result I suspect they'll do similar for IFT3. When they decide the rocket is "ready" they'll test it with payloads - but that's the same with basically any rocket, the first loaded flight is always the first loaded flight. In fact I'd suggest that the SS/SH will have had *more* testing than the majority of first launch rockets.

      3. Ian Johnston Silver badge

        Re: payload ?

        The concept of "ballast" might be useful here.

    3. John Robson Silver badge
      Mushroom

      Re: payload ?

      That would have been from the methane tank.

      But you absolutely don't vent both at the same time...

      1. Graham Dawson Silver badge

        Re: payload ?

        When you're leaking enough pure oxygen, it really doesn't matter all that much if there's methane in the air. Anything remotely reactive will start oxidising in a sufficiently rich oxygen atmosphere.

        1. Anonymous Coward Silver badge
          Flame

          Re: payload ?

          Especially when there's heat around too, say from a hot engine or several

        2. John Robson Silver badge

          Re: payload ?

          They were at in excess of 100km altitude when they vented, so "in the air" is a bit of a stretch.

          Lox will oxidise basically anything, but if you actively vent both methane and oxygen then you end up with close to a stoichiometric mix which is guaranteed to be ignited by the heat from the exhaust system.

          They weren't "leaking" they were venting, for the purposes of "oops, the oxygen did some oxidising" that's not a big difference, but from the perspective of "what do we need to change" it's completely different - maybe they need to load a little more of their engine bay fire suppressant to flood the bay whilst the oxygen is being dumped.

    4. imanidiot Silver badge

      Re: payload ?

      gaseous oxygen is really good at making things not normally all that flammable, very flammable. Hot metal, insulation material, wiring, electronics, o-rings, all of it becomes flammable when you introduce pure oxygen into an environment not designed for it. And enough fire or fire in the wrong place then releases the fuel and KABOOM!

  2. Andy 73 Silver badge

    Moon landing

    Should a Starship ever make it to the moon, the plan appears to be to land it upright on bare regolith. Given the height of the thing, and a large number of engines that would probably not be very happy eating moon dust, the recent Intuitive Machines' landing failure makes this particular idea seem very... brave.

    1. Anonymous Coward
      Anonymous Coward

      Re: Moon landing

      Intuitive Machines apparently missed the lesson about spacecraft height-to-width aspect ratio's used in the Surveyor program & Apollo Lunar Lander missions.

    2. Yet Another Anonymous coward Silver badge

      Re: Moon landing

      >Given the height of the thing, and a large number of engines that would probably not be very happy eating moon dust

      Have you told them this? They might not have thought about it as deeply as you, they aren't exactly rocket scientists

      1. stiine Silver badge

        Re: Moon landing

        And? They are and they still managed to put it on its side. By the way, its still able to receive power and to communicate, in a limited manner, so having it land vertically seems to have been an unnecessary action.

        1. Anonymous Coward
          Anonymous Coward

          Re: Moon landing

          Obviously, this was why Thunderbird 2 landed the way it did.

      2. Andy 73 Silver badge

        Re: Moon landing

        Great appeal to authority there. It would carry more weight if two groups of exactly rocket scientists hadn't both independently failed to land rockets upright on the moon.

        Turns out some jobs are difficult - who knew?

    3. Flocke Kroes Silver badge

      Re: Moon landing

      Yet again:

      Most of the mass of Starship is at the bottom. During a Moon landing the propellant will be at the bottom of the tank. Most of the propellant mass comes from the liquid oxygen which is stored in the lower tank. Starship HLS is as stable as an empty egg shell glued to a 1cm thick stone plinth.

      Superheavy takes off from Earth with 33 engines to lift a booster and ship both fully loaded with propellant and a payload on top. Starship HLS lands on the Moon (1/6 of Earth gravity) with the propellant tanks mostly depleted. Current speculation is the tanks extend further into the payload volume than cargo Starship partly to get enough delta V for the entire mission and partly because NASA cannot afford to build enough payload mass to reach Starship's limit with their current (late) Artemis budget.

      One Raptor engine at low thrust is sufficient to land Starship HLS including payload and return propellant. Intuitive machines' lander was intended to land vertically. It came down diagonally and tripped over. I am sure IM's recent mission will be very educational for everyone planning to land on the Moon. It is almost as if a bunch of rocket scientists planned to get up to date experience of Moon landings before committing to a final design for sending humans.

      1. CowHorseFrog Silver badge

        Re: Moon landing

        That may be all true, but that doesnt solve the problem of the fine particles of moon dust being sucked into those engines and causing havok.

        1. S4qFBxkFFg

          Re: Moon landing

          > the problem of the fine particles of moon dust being sucked into those engines

          That's not really an accurate way to think of the situation. These are rocket engines; they don't have external intakes, so nothing is getting "sucked" in. The high speed dust may very well cause damage to the hardware (some scientists have even expressed concern that the dust could achieve lunar escape velocity, and cause problems for orbiting spacecraft), but that's more of a sandblasting effect. ISTR a plan to have engines near the nose, pointing outwards/downwards for the last part of the descent (and subsequent initial ascent), which would cause cosine losses, but may be better overall for the health of the vehicle.

          1. CowHorseFrog Silver badge

            Re: Moon landing

            > That's not really an accurate way to think of the situation. These are rocket engines; they don't have external intakes, so nothing is getting "sucked" in.

            THey have openings where al lthe exhaust gases escape, stuff will get sucked in which is exactly what happened when in that Starship failure not that long ago, rocks got sucked in and destroyed numerous engines and it eventually was unbalanced and failed.

            1. cray74

              Re: Moon landing

              THey have openings where al lthe exhaust gases escape, stuff will get sucked in which is exactly what happened when in that Starship failure not that long ago

              Rather longer ago, the largest rocket engines used on the moon did so without damage from flying debris. The Apollo LM descent engines and descent module never experienced dust/debris damage, though they did sandblast nearby structures (e.g., Apollo 12's damage to Surveyor 3). Apollos 12 and 15 had very dusty landings, with the crew commenting it felt like they were making instrument flight rules descents rather than visual. Despite that: no dust/debris damage.

              Apollo 15 did experience engine damage but not from blown dust/debris. Apollo 15's LM was the first to use an extended engine nozzle to deliver more payload to the lunar surface. The nozzle extension was crumpled (as it was designed to do) when it crunched into the uneven lunar surface.

      2. Andy 73 Silver badge

        Re: Moon landing

        I'm not sure if you've fully grasped the physics here.

        3 tonnes of mass (random figure for illustration) around the nose of Starship (50 meters up) has the same rotational inertia as it does on Earth. 20 tonnes of fuel at the bottom has one sixth the weight (and therefore exerts 1/6th the stabilising force). In essence, Starship acts like a rocket six times taller when it comes to trying to balance it on the moon. That's exactly the problem the two recent landers have had, and they didn't go for the Buck Rogers 'tall thin tube' design.

        IMs design and learnings have nothing to do with SpaceX's own design - other than to point out that this is a non trivial task, where basic design can make things significantly easier or harder. Pointing out that the Starship geometry is intrinsically less stable (no matter what the distribution of fuel is) is not to say they cannot do it, just that they have chosen a design that makes the task more difficult. How many times has SpaceX successfully landed Starship on Earth so far?

        1. John Robson Silver badge

          Re: Moon landing

          Huh?

          Are you trying to suggest that starship will be landing with significant lateral velocity?

          Stability isn't determined by "mass" at the nose and "weight" at the tail - it's determined by CoG.

          The aim is to land the thing vertically - and to use RCS to ensure that it lands vertically with zero velocity.

          "How many times has SpaceX successfully landed Starship on Earth so far?"

          Several, though most of those exploded - the more interesting question is: How many Falcon 9 boosters have the landed on a barge sitting in the middle of the ocean, moving with the waves?

          1. Andy 73 Silver badge

            Re: Moon landing

            Quote of the day "Several, though most of those exploded".

            And yet again - the recent landers have shown that zero lateral velocity on a remote body with very mobile regolith is not as easy as neatly marked, perfectly flat landing platforms surrounded by telemetry and sensors. Or do you think calculating relative velocity can be done entirely on-board with no external reference?

            1. Anonymous Coward Silver badge
              Facepalm

              Re: Moon landing

              > "Or do you think calculating relative velocity can be done entirely on-board with no external reference?"

              There's a helicopter on Mars that has demonstrated that this is perfectly feasible, using commercial off-the-shelf hardware.

              Nav cam + lidar appears to be all that's needed, but I suspect SpaceX will do a bit more than that.

              1. CowHorseFrog Silver badge

                Re: Moon landing

                A helicopter is not a rocket, they are completely different vehicles, If a rocket was as simple as a helicopter they wouldnt need to special empty places to blast off.

            2. John Robson Silver badge

              Re: Moon landing

              SpaceX have more experience with powered landing of spacecraft than... well everyone else in history combined.

              So yes, I do think they can manage it from on board sensors - since that's what most landings do.

              The two recent landings on the moon:

              - One had an engine nozzle fail and separate from the vehicle whilst still a way off the ground.

              - The other had a complete failure (human error) of the primary ranging system, and ended up landing fast and not in complete control.

              All the Apollo landers managed to land without any external reference - so yes, I have every confidence that we can calculate relative velocity without previously landing a pad on the moon. The regolith isn't that mobile, it's far less mobile than for example the sea.

              Depending on the chosen engine configuration there might not even be any dust being kicked up.

    4. Brian 3

      Re: Moon landing

      You apparently missed the whole "moon lander starship is a bit non-standard" what with the whole "engines at the top", "fewer engines needed to land on the moon" and that they'll all be vacuum engines etc. Pretty sure they have a plan that goes something like "we'll test this first before installing live crew", too

    5. CowHorseFrog Silver badge

      Re: Moon landing

      Most people have no clue just how terrible moon dust is. It sticks to everything just ask the moon landers. Theres no way rockets will be reusable and able to launch from a bare surface of the moon, just like its basically impossible from earth where the dust is considerably nicer.

      1. I don't know, stop asking me.

        Re: Moon landing

        > Theres no way rockets will be reusable and able to launch from a bare surface of the moon

        You do realise that that is exactly what they did six times between 1969 and 1972?

        1. John Robson Silver badge

          Re: Moon landing

          Calling the lunar lander reusable is a bit of a stretch, the ascent stage and descent stages were completely separate.

        2. Zolko Silver badge

          Re: Moon landing

          The Apollo Lunar landers didn't "launch from a bare surface of the moon " but from the platform that they brought down with them : only a small part of the lander launched the 2 astronauts back into Monn orbit. And they were not reusable.

        3. CowHorseFrog Silver badge

          Re: Moon landing

          The lunar landers did not return the entire vehicle. The return vehicle with the astronauts sacrificed the lower half as a base. Less than a 1/4 of the vehicle actually returned.

          How is that resuable when only a 1/4 returns ?

        4. CowHorseFrog Silver badge

          Re: Moon landing

          Brainy one, go watch the video on wiki, you can clearly see there is a base with raised legs and the return vehicle uses that to return to the coammand module.

    6. Anonymous Coward
      Anonymous Coward

      Re: eating moon dust

      These are rockets, not jets. Everything they eat* comes from sealed tanks.

      * drink is probably more apt.

  3. Bitsminer Silver badge

    ...and a large number of engines that would probably not be very happy eating moon dust

    These are rocket engines, not jet engines.

    But dust is indeed a problem. On landing the rocket engines will be blowing a significant amount of dust into lunar orbit.

    You can count on the fingers of no hands how many people will like that.

    I expect the next major private mission will be a dust-proof parking lot. Parking: $1300 per hour. Half price on weekends.

    1. John Robson Silver badge

      Re: ...and a large number of engines that would probably not be very happy eating moon dust

      Did you not look at the plans for the lunar lander - you know the ones which specifically deal with the potential for kicking up dust, and make design decisions to minimise that possibility?

      1. Anonymous Coward
        Anonymous Coward

        In the Reg forum?

        Nah, the house rules are that if you have a question about if, why, or how something works with aerospace stuff you phrase it in the form of a declarative statement.

        Doing otherwise denies the remaining engineers and Ballocket enthusiasts here a chance you point out how wrong someone is.

        People that assume that highly paid and trained engineers didn't think about our couldn't solve these issues without checking before posting are the main thing keeping the trolls from dying of boredome or god forbid the place backsliding into civility.

        1. Zolko Silver badge

          Re: In the Reg forum?

          highly paid and trained engineers

          1) they might not be those deciding

          2) I'd be interested in the "highly paid" figures

          3) didn't all other failed aeronautical and space projects have those highly paid engineers ?

          All-in-all, mistakes happen. I think there was a recent aircraft carrier that was designed and built too short for the aircraft that it was designed to carry, they had to "extend" the ship. And think of the 737 Max fiasco, or the Piaggion Avanti with its noise due to the propellers on the trailing edge. The world of (aerospace) engineering is full of "oh sh***t didn't think of that " moments.

        2. I ain't Spartacus Gold badge
          Devil

          Re: In the Reg forum?

          or god forbid the place backsliding into civility.

          We'll have none of that nonsense round here! Now fuck off!

      2. CowHorseFrog Silver badge

        Re: ...and a large number of engines that would probably not be very happy eating moon dust

        The text clearly says that Starships will land on the moon and take off. Look at the artist renderings...THere clearly are rockets on the bottom with nothing between them and the surface.

        https://en.wikipedia.org/wiki/SpaceX_Starship

        >A planned lunar lander variant of Starship was contracted by NASA to land astronauts on the Moon as part of the Artemis program for at least two Artemis lunar landings, starting with Artemis 3 in 2026.[5]

        https://en.wikipedia.org/wiki/Starship_HLS

  4. rcxb Silver badge

    Almost there...

    "If it had had a payload, it would have made it to orbit. Because the reason it didn't quite make it to orbit was we vented the liquid oxygen, and the liquid oxygen ultimately led to fire and an explosion ..."

    "Look! I barely exploded at all."

    "We can control that with medication."

    -- Malfunctioning Eddie in Futurama Season 3, Episode 12: Insane in the Mainframe

  5. Anonymous Coward
    Anonymous Coward

    They'll make it boring soon.

    Falcon 9 launches used to be exciting and the landings were full of explosions Hollywood would be proud of. Now they happen every few days and nobody notices. I'm pretty confident that this rocket will be like that one day.

    1. captain veg Silver badge

      Re: They'll make it boring soon.

      OK, both were before my time, but so far as I'm aware neither the first train ride from Stockton to Darlington nor the trip by Mrs Benz from Mannheim to Pforzheim resulted in any kind of explosion in space.

      Not blowing up in ordinary operation is not a very high requirement.

      -A.

      1. John Robson Silver badge

        Re: They'll make it boring soon.

        And tell me - exactly how many production ready starships have blown up so far?

        Oh, wait that would be none, because they are still prototyping the thing.

        There are quite a few cases of boiler failure (which gets *very* nasty, very fast because all the water flash boils when the pressure vessel is breached) in the steam engine era - often killing people.

      2. Julz

        Even

        The first train journeys were dangerous too.

        https://www.theguardian.com/theguardian/from-the-archive-blog/2011/may/06/newspapers-national-newspapers2?CMP=twt_gu

      3. John Brown (no body) Silver badge

        Re: They'll make it boring soon.

        "the first train ride from Stockton to Darlington" was after many attempts to make a reliable steam locomotive, many of which previously exploded. They were pretty confident by the time the started letting people on, having run freight first since that was the primary objective. Carrying people was a "nice to have". And even then, life was cheap and a fair number of people died because steam locomotives exploded.

        Living, and having been born, within a few miles of Stevensons locomotive works and only about 35-40 miles from the Stockton Darling railway, we learned a LOT about the invention of the steam locomotive at school, including the failures, explosions and disasters along the way. It was nothing like plain sailing or NASA-like development processes leading to a first time success.

  6. tyrfing

    What I'm amazed at is that SpaceX is much more interested than the FAA in how to make the rocket launch successfully and make it to orbit.

    But SpaceX has to wait for the FAA to make its recommendations before it can do anything.

    I suspect that SpaceX probably told the bureaucrats what things needed to be fixed, then the bureaucrats sat on it, p*ssed in it, decided this made the flavour better, then issued it as their report.

    Why do they have the FAA again? Oh yes, it's so when *Boeing* messes up, they might actually have to fix things.

    1. ecarlseen

      Corporations have life cycles just like people do

      As every organization - governments, corporations, and even nonprofits - grows and ages they tend to become corrupt, both in purpose and in ethics. This happens to the organizations as a whole, but it tends to be exceptionally pronounced at the departmental level. Slowing / ameliorating this is a function of leadership that we have not yet been able to adequately define, let alone duplicate. The academic managerialist push in the mid-20th century to make organizations as large as possible has horribly exacerbated this problem, and the latest push of notions like DEI and ESG as replacements for the lack of genuine purpose in huge organizations is transforming them from soulless abominations into absolute hellscapes.

      Boeing is a very old, and very decrepit corporation that has become deeply corrupt. Instead of being kept alive with Darth Vadar-levels of government life support, it should be allowed to whither, die, and be replaced by something new.

      SpaceX is something new. They're doing amazing stuff right now. But one day SpaceX, too, will become old. I'm willing to enjoy what they're doing in the present.

  7. Oneman2Many

    As per last time, FAA didn't write the report or really have any input. The report is spacex reporting on issues they found and will correct and I suspect most of have already been implemented as there are things like design changes which would take months to implement (or years if you are Boeing). All the FAA are doing is agreeing with SpaceX findings. I can understand why is works this way as SpaceX are the SME on Starship so will know the most about what happened and how to prevent it in future but it does seem to make FAA rather toothless.

    1. John Robson Silver badge

      " it does seem to make FAA rather toothless."

      Not really - it means that they don't need to employ as many people as the rest of the aeronautics industry combined.

      The report has to satisfy them that SpaceX know what went wrong and that they have a decent plan to prevent it happening again.

      If you want the FAA to look toothless then take a look at Boeing, at that point you realise that they are toothless - you just can't infer that from the fact that SpaceX wrote most of the report.

      1. Oneman2Many

        My issues is that effectly SpaceX are self-certifying the clearance. I don't have any knowledge of what the behind the scenes discussions are but SpaceX and FAA have said many times that they are continously in contact so I doubt the publish report is the first itteration of it. How many times did FAA push back and get SpaceX to make changes ?

        1. John Robson Silver badge

          We'll likely never know - but there is no way the FAA can do all the engineering calculations required, though they should be able to verify the report... one would hope.

          On the other hand I have far less expectation of the FAA with SpaceX here, than with Boeing. Only one of those companies is risking lives with their certifications.

          When we've had sufficient launches for a trial HLS - then we need to expect more detailed FAA approvals and calculations - but even then we're looking at a very different scale of risk to life - if they aim to do point to point transport then they need more analysis than even Boeing... at least the aircraft industry has some decent history.

  8. Whyohwhy
    Holmes

    Sooo they require "...hardware changes to reduce leaks". Brilliant. Let's award the FAA chap who came up with that the Silver Ducttape Award.

    Golden one would have been for "...hardware changes to reduce explosions."

    1. Oneman2Many

      FAA didn't come up with. That is what SpaceX told the FAA what they plan to do There will be more details that SpaceX will have given to FAA.

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