• sp3tr4l@lemmy.zip
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    5 months ago

    Just to be pedantic:

    IFT 3 was a suborbital flight, so… either it did not reach orbital velocity, or the upper stage careened so wildly out of control that it borked it.

    Its kind of confusing as in the live stream of it they keep saying the phrase orbital velocity, reached orbit, but also say it was intended to be a suborbital flight.

    Edit: Yeah as best I can tell it was not even intended to be an orbital flight. https://x.com/planet4589/status/1765586241934983320

    Also, the lower stage crashed into the ocean at around mach 2, so maybe that is what they are referring to? Looked like many of the engines did not relight, in addition to significant instability as it traversed back through the atmosphere.

    Also also, the ‘re entry’ burn may be referring to attempting to relight the engines while in space? You are probably correct that they mean the landing burn / belly flop???

    Edit 2: If they intend to do a suborbital flight, but also reach orbital velocity, this would entail a trajectory leading to a fairly steep descent path, which could need a … basically a pre reentry burn, to lessen velocity and/or change the descent path to something more shallow.

    Its pretty hard to tell actual info about these Starship flights, partially because SpaceX outright lies during their live feeds, is tight lipped about other things, and many sources of coverage are often confused and/or simping for Musk.

    One last thing: Does… Starship, the upper stage… even have monopropellant thrusters, or gyros, or anything for out of atmosphere orientation adjustments?

    From the IFT3 vid it seemed like either no, or they malfunctioned.

    • rImITywR@lemmy.world
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      5 months ago

      IFT3 was technically suborbital, but only barely. Like a couple hundred km/h short. Literally a couple of seconds longer second stage burn would have put it into a stable orbit. Or the same velocity just with a lower apogee. They intentionally left the perigee just inside the atmosphere so a deorbit burn was not required. This is also the plan for IFT4, iirc. I think they are talking about the bellyflop/suicide burn. It was not planned on IFT3, but is for IFT4.

      Both the booster and the ship have attitude control thrusters that you could see firing during the live stream of IFT3. Early prototypes used nitrogen cold-gas thrusters, but were planned to be upgraded to methane/oxygen hot-gas thrusters at some point. I don’t recall if/when they were.

      • NotMyOldRedditName@lemmy.world
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        5 months ago

        Just to further clarify this…

        They did the suborbital thing because they wanted to ensure it came in over the ocean.

        If they went orbital, and anything went wrong, they’d have lost control of where it would deorbit and land, potentially putting people at risk.

        So sure the rocket did not reach orbit.

        No one with even a pinch of knowledge on the topic would ever try to dispute they could have if they wanted.

        It was for our saftey that they didn’t.

    • Buffalox@lemmy.world
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      5 months ago

      IFT3 began to tumble shortly after launch, at least before they opened the “door” where it was obvious. The tumble may have been caused by a leak, and the “reentry” was simply a chaotic mess where the engine(s) began to burn up in the atmosphere, and it was absolutely 100% out of control.

      • FaceDeer@fedia.io
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        5 months ago

        IFT3 finished most of the goals that had been set for that test flight. It was highly successful and they learned a lot that is being applied to IFT4.