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Starship's Fourth Flight Test [video]

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Re: Starship's Fourth Flight Test [video]

#121

Post by mpweiher »

pclmulqdq wrote: post #111
tekla wrote: post #105

Earlier quoted context omitted.

I'm always amazed at how wrong people on HN are. The orbital relight test was not a factor in the fact that Starship was not intended to reach orbital velocity. You may have noticed that the flight plan indicated that Starship was to land somewhere in the Indian ocean and usually reaching orbital velocity vastly increases the difficulty of doing a planned reentry. The flight plans had them turning off the engines bef…

The original IFT-3 flight plan had them reaching orbit and then doing the in-orbit relight as a de-orbit burn. At that altitude, there's enough drag that you will de-orbit pretty quickly if you are in orbit and your de-orbit burn fails, so there was no risk of a big piece of space junk. The disinformation I mentioned is why everyone keeps being "wrong" about SpaceX. It's incredibly difficult to be right. Here's the o…

No.

All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk.

100t of space junk that would then re-enter at some unpredictable time. Bad idea.

So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were fully inert.

Re: Starship's Fourth Flight Test [video]

#122

Post by kirksidlo »

kirksidlo wrote: post #114
rvnx wrote: post #110

Earlier quoted context omitted.

I don't understand one stuff, did the booster land on a drone ship or it just crashed into water ? At the end of the video feed for the booster, it looks like there is a huge fire and everything is destroyed, but the crowd is cheering

Drone ship was never the plan for this launch. They simulated a soft landing over the Indian ocean, which appeared to go relatively well.

Correction: Gulf of Mexico for the booster. Indian Ocean for the upper stage.

Re: Starship's Fourth Flight Test [video]

#123

Post by pclmulqdq »

mpweiher wrote: post #121
pclmulqdq wrote: post #111

Earlier quoted context omitted.

The original IFT-3 flight plan had them reaching orbit and then doing the in-orbit relight as a de-orbit burn. At that altitude, there's enough drag that you will de-orbit pretty quickly if you are in orbit and your de-orbit burn fails, so there was no risk of a big piece of space junk. The disinformation I mentioned is why everyone keeps being "wrong" about SpaceX. It's incredibly difficult to be right. Here's the o…

No. All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk. 100t of space junk that would then re-enter at some unpredictable time. Bad idea. So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were ful…

A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no propulsion within a few weeks. The ISS at ~400 km has to regularly burn their engines to stay in orbit.

Read the IFT-3 pre-flight materials, preferably from a source that comes from before the flight. They clearly intended to enter an orbital trajectory and then get out of it. SpaceX's historical revisionism muddies the waters. At the very least, they would not have announced (ie lied about) successful orbital insertion (which they didn't do) if they had no intention to get there.

Re: Starship's Fourth Flight Test [video]

#124

Post by MPSimmons »

pclmulqdq wrote: post #117
josephwegner wrote: post #89

Curious - I was watching the live stream, and noticed as the ship's rockets were on, there were a bunch of these "floaters" in the view. https://imgur.com/a/OrZTYxP I know nearly nothing about rocketry, so ELI5 (or give me a wikipedia link!)... anyone know what those floaters are? Is it some byproduct of the fuel? An artifact of the cameras? An illusion coming through the haze of the burning rocket?

I'm sort of surprised nobody has mentioned this. The ice is all gone at this altitude, and nothing seems to have started falling apart yet. Those might be satellites reflecting the light from the engines.

Ice is formed by vents on the rocket itself, too.

Re: Starship's Fourth Flight Test [video]

#125

Post by enslavedrobot »

pclmulqdq wrote: post #123
mpweiher wrote: post #121

Earlier quoted context omitted.

No. All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk. 100t of space junk that would then re-enter at some unpredictable time. Bad idea. So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were ful…

A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no…

You do not rely on drag to deorbit a stainless steel 10 story building partially covered in heat shielding in a random location.

They deliberately selected a suborbital trajectory with a velocity that matched orbital reentry... See 1:20 of this video.

Everyone who actually follows SpaceX knows this. You are confidently and totally wrong.https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb

Re: Starship's Fourth Flight Test [video]

#126

Post by 2OEH8eoCRo0 »

TiredOfLife wrote: post #120
2OEH8eoCRo0 wrote: post #97

Earlier quoted context omitted.

I'm aware. What does SpaceX gain from the exclusivity?

The CEO of SpaceX owns Twitter.

Im sure SpaceX's investors love being used to promote a single private social media platform. Sounds like another case of the CEO enriching themselves to the detriment of investors.

Re: Starship's Fourth Flight Test [video]

#127

Post by mpweiher »

pclmulqdq wrote: post #123
mpweiher wrote: post #121

Earlier quoted context omitted.

No. All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk. 100t of space junk that would then re-enter at some unpredictable time. Bad idea. So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were ful…

A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no…

Nope.

> Read the IFT-3 pre-flight materials

I did.

> They clearly intended to enter an orbital trajectory and then get out of it

Nope, they very clearly did not.

Even the graphic you linked to earlier shows this very clearly.

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi...

1. At step 4 for Starship, they write "Once S28 has reached orbital velocity..." Not trajectory. Not orbit.

2. At step 8, we have the "relight demo". Note the last sentence, the one in parentheses: "for an actual deorbit burn, the ship would need to yaw 180º first".

So there is no deorbit burn in the flight plan. The relight demo was just supposed to show that they could relight, and thus hopefully could do a deorbit burn. Note also that the ship deorbited despite the fact that there was no relight demo (never mind no deorbit burn).

Re: Starship's Fourth Flight Test [video]

#128

Post by pclmulqdq »

enslavedrobot wrote: post #125
pclmulqdq wrote: post #123

Earlier quoted context omitted.

A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no…

You do not rely on drag to deorbit a stainless steel 10 story building partially covered in heat shielding in a random location. They deliberately selected a suborbital trajectory with a velocity that matched orbital reentry... See 1:20 of this video. Everyone who actually follows SpaceX knows this. You are confidently and totally wrong. https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb

All I see is a video from after IFT-3 that parrots SpaceX's post-hoc rationalization about the fact that their craft could not reach orbital velocity. If you look at the GAO report on Artemis, one of the big issues they mentioned is that Starship has not proven that it can reach orbit, and SpaceX is very interested in making sure that the narrative is that it can and did. It was only after the fact that they said that the never intended to reach an orbital trajectory with IFT-3.

And actually, people rely on drag to deorbit huge objects in space in a controlled manner all the time. It's the preferred way to do it, and is basically the only way it's done - any satellite with fuel left will just stay in orbit. They have it down to a science. Usually they aim for the middle of an ocean. Sometimes they miss and chunks fall in a backyard.

Re: Starship's Fourth Flight Test [video]

#129

Post by pclmulqdq »

mpweiher wrote: post #127
pclmulqdq wrote: post #123

Earlier quoted context omitted.

A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no…

Nope. > Read the IFT-3 pre-flight materials I did. > They clearly intended to enter an orbital trajectory and then get out of it Nope, they very clearly did not. Even the graphic you linked to earlier shows this very clearly. https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi... 1. At step 4 for Starship, they write "Once S28 has reached orbital velocity ..." Not trajectory . Not orbit . 2. At step 8, we ha…

Orbital velocity = orbital speed + orbital trajectory. Velocity is a vector. Orbital velocity + orbital altitude means orbit. That is, unless you think that everyone at SpaceX misspoke and they were only aiming for orbital speed (which they did not achieve with IFT3), and just wanted that speed in any direction.

Sounds like the plan to de-orbit was then to just go belly forward and let drag take you out of orbit. That is pretty much how every object in LEO de-orbits.

Re: Starship's Fourth Flight Test [video]

#130

Post by kolinko »

openmarmot wrote: post #91

the video from the booster simulated landing in the ocean was incredible! It came in and did a soft landing vertically just touching the ocean, engines cut, it appeared to be floating for a second and then just kind of slowly fell over. I did not think they would nail the booster landing this flight, as it was not stable all the way down on the last flight. Absolutely incredible watching this live edit : video clip :…

Boster was awesome, but the ship itself and watching heat dig through the fin slowly - that was one of the craziest moments I’ve seen out if all the launches :)
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