Tuesday, February 27, 2024

Starship Flight Test 3 Moves One Step Closer

SpaceX's Starship/Super Heavy Flight Test 3 moved closer in concept on Monday as the FAA closed its investigation of November's IFT-2.  A first date estimate would be in the second half of March, between the 17th and 31st (Easter). 

"SpaceX identified, and the FAA accepts, the root causes and 17 corrective actions documented in SpaceX’s mishap report," the federal agency said in a statement issued Monday. "Prior to the next launch, SpaceX must implement all corrective actions and receive a license modification from the FAA that addresses all safety, environmental and other applicable regulatory requirements."

SpaceX must still submit additional information to the FAA, which is responsible for the safety of people and property on the ground, before the agency completes its review of an application to launch Starship for a third time. The administrator for Commercial Space Transportation at the Federal Aviation Administration, Kelvin Coleman, said last week that early to mid-March is a reasonable timeline for the regulatory process to conclude.

I heard or read somewhere that the last flight was three weeks after the equivalent approval for that one, so we can figure two weeks later for this one.  Which is how the two week window I mentioned at the top was derived.  

SpaceX posted a summary of the technical findings they sent to the FAA on their Updates web page.  In big-picture overview, both the Super Heavy first stage and the Starship upper stage performed well except for a couple of problems that led to the loss of both parts of the vehicle.  

In the Super Heavy's case, the launch and flight through stage separation was flawless.  SpaceX describes it this way:

Following stage separation, Super Heavy initiated its boostback burn, which sends commands to 13 of the vehicle’s 33 Raptor engines to propel the rocket toward its intended landing location. During this burn, several engines began shutting down before one engine failed energetically, quickly cascading to a rapid unscheduled disassembly (RUD) of the booster.

"Failed energetically?" Cascading to a RUD?"  Love it!  You guys have been in Texas long enough to say, "It Done Blowed Up" or just "it blowed up."  The problem was linked to a problem with the liquid oxygen flow in the booster.  

The most likely root cause for the booster RUD was determined to be filter blockage where liquid oxygen is supplied to the engines, leading to a loss of inlet pressure in engine oxidizer turbopumps that eventually resulted in one engine failing in a way that resulted in loss of the vehicle. SpaceX has since implemented hardware changes inside future booster oxidizer tanks to improve propellant filtration capabilities and refined operations to increase reliability.

The six engines on Starship had ignited and burned completely nominally until what appears to have been an operational mistake over the Caribbean.  In an effort to simulate the extra fuel load required for some missions, they overfilled Starship with liquid oxygen, and decided they'd dump that extra LOX out there.  

A leak in the aft section of the spacecraft that developed when the liquid oxygen vent was initiated resulted in a combustion event and subsequent fires that led to a loss of communication between the spacecraft’s flight computers. This resulted in a commanded shut down of all six engines prior to completion of the ascent burn, followed by the Autonomous Flight Safety System detecting a mission rule violation and activating the flight termination system, leading to vehicle breakup. The flight test’s conclusion came when the spacecraft was as at an altitude of ~150 km and a velocity of ~24,000 km/h, becoming the first Starship to reach outer space.

SpaceX has implemented hardware changes on upcoming Starship vehicles to improve leak reduction, fire protection, and refined operations associated with the propellant vent to increase reliability. The previously planned move from a hydraulic steering system for the vehicle’s Raptor engines to an entirely electric system also removes potential sources of flammability.

The LOX didn't need to be released over the Caribbean, it just had to be dumped before the planned splashdown north of Hawaii. They could have released it later. Or, maybe, instead of LOX they could have put an equivalent weight of steel on the Starship?

Starship launches on its second flight on November 18, 2023.  Image credit: SpaceX

There was a story last week that SpaceX was asking for a way to "launch Starship at least nine times this year."  That would require a more streamlined response process from the FAA and everyone concerned, but we'd love to see it. March 18th will be four months since IFT-2.  Things would have to be moving much faster than we see for that to happen.


  1. "Rapid Unscheduled Disassembly"!!!

    Hilarious. Sheer comedic genius.

    The only thing that could have made it better was if it had been read, live, in a Ben Stein monotone.

    1. Have you been asleep, Aesop? ;-)
      We've all been using "RUD" for over a decade now.
      One of Musk's great contributions to humanity!

    2. Not Musk, Kerbal Space Program. Things will be fine as long as we don't get to use the other term KSP coined - lithobraking.

    3. Yes, but Musk made these terms famous. Very few people have ever heard of the Kerbals...

  2. SpaceX has already addressed some of those 17 items - I don't know the actual number. They are pushing forward, rapidly. They'll Git-R-Done!

  3. all the drama. sounds to me everything worked very well, swimmingly well.
    hope they have cams on both stages so we can watch them do their return to earth splash downs. the booster engines thrust must create quite the plume of water as it gets down to yards and feet in its landing sequence.
    got to say, those raptors produce quite a lot of high intensity light. they look pretty close to weld arc brightness. maybe its a function of their superb combustion efficiency. that said nothing like using pure clean LOX for oxidizer. particularly at the lbs per second flow rates the engines burn.

    1. "sounds to me everything worked very well, swimmingly well."

      When you get down to it, yeah.

      The first stage experienced some slosh of fuel doing something no one in history has done with a vehicle that size. They found they need to add some more filtering in the fuel system.

      The second stage dumped LOX around some really effin' hot engines and the LOX found something to oxidize. Maybe they could vent the extra LOX in orbit? Or let it coast a bit longer before they dump it?

    2. yeah exactly. well said about it getting into uncharted territory.

      imagine how quickly all that pure concentrated oxygen oxidized say a copper engine bell or a section of super hot 718 Inconel or 321 SST.
      be like an oxygen lance or using oxegen instead of regular air with a carbon arc gouge.
      (my first job in my first employment as a kid welder was they put me on this bog ol' plasma cutter table. back then they where these 1000amp vdc machines, mostly for cutting heavy plate, this one up to 12 inches, but you had to pierce the plate first, use a 12 volt car battery, a carbon arc rod, with a bottle of oxygen hooked to it, take all of maybe ine second to pierce a twelve inch piece of hot rolled mild steel, but oh Lord the sparks come out of that hole before it cut thru. had to wear a asbestos fire suit with a clean air full head welding hood, massive fire proof gauntlets too, and sparks still got thru and burn the sheet out of you.
      eat up a half inch OD carbon rod, sometimes needed two rods to punch thru. pretty basic idea, 2 wheel dolly with a battery and oxygen bottle strapped to it, ground clamp, gouger stinger and a regulator, turn it up to 150psi. full current straight off the battery.

      that was 48 years ago. funny thing, i got one even now, nifty tool, incredible for busting something loose.
      cut the threaded stub of a rusted together trailer ball in a couple seconds. lot cheaper than using up oxy-acetelyne these days for burning, with welding gas prices tripled and higher. its not the neatest method but it gets the job done lickety split.
      rigged a lever valve on a gouger stinger, soon as you get a scratch spark hit the 02 and poof! very handy.

  4. It really bothers me that the media (and some of the people I know) keep harping that all SpaceX can do is fail. Fail, fail, FAIL! In truth, IFT-2 was very nearly a complete success. One issue restarting engines for boostback ("restarting engines" wasn't even a thing until SpaceX), and one stupid decision to dump oxidizer (that won't ever be done again anyway).

    But the whole thing FAILED! Musk is an evil con artist who steals everybody's money! Musk Man Bad!!

    There are times I could just bishslap this whole generation of self-important, entitled pussies.

    1. SpaceX operates by a totally different philosophy than pretty much the whole world. Get as close as reasonable with analysis and instead of doing more analysis for another year, test it and see how close to the analysis it ends up being.

      No analysis software is right all situations. Read that again. Then there are things they need to model that are mathematically impossible to solve in every situation, like Fluid Dynamics (Navier-Stokes).

      Be "hardware rich" so you can experiment and re-start quickly when you learn what doesn't work.

      In a way, it's kind of a positive interpretation of FAFO.

    2. There's another point that can be hard to express. If you design by modeling until you think everything is fixed, you will fix anticipated problems that turn out will never happen. Engineers are fantastic at coming up with potential problems that just don't show up in the real world. By breaking things, you learn what is really a problem.

      Method A: Probably works first time, not likely to keep working due to unimagined issues, takes forever and costs much moola.

      Method B: Quick, cheap if your hardware is inexpensive, results in robust and reliable system with no issues that haven't been shaken out.

      This is the same reason that war pushes technology so far forward so fast.

      Compare the two methods directly, recently: Dragon capsule has worked perfectly, was on time, and is relatively cheap. Boeing Starliner capsule failed twice so far when they were sure it was ready, and is vastly behind schedule and extremely expensive.

      All the media got wet and happy when Blue Origin rolled out its half-mockup New Glenn rocket. SpaceX will be building out an intrasolar transportation system before Bezos gets to orbit.

  5. Eric Berger has a great article on the IM-1 mission, though I'm pretty sure you've already read it. For others here, they landed the thing without altimetry. They have data, and images, and they will be releasing the latter sometime today:


    1. Yeah, it's a rather neat article, and in today's press conference they talk about expecting Odie to make it to the lunar night and then try to contact it after sunrise. That'll be around three weeks from now. For now, they've downloading data whenever the moon is up over Australia - the biggest dish on the DSN. Actually, not on the DSN, but a 60 (64?) meter diameter dish.

      For everyone else who sees this, that Ars Technica article is a good read. Quite interesting. I left a clickable link to it in the comments to the Monday article "Interesting Developments from the Moon."

    2. Sorry, I missed that link. Didn't mean to double-post it.

    3. Not a problem. Everyone who might be interested in it should know about it.