this post was submitted on 25 May 2024
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[–] [email protected] 167 points 7 months ago* (last edited 7 months ago) (3 children)

the explosion, which took place at its Boca Chica Starbase facilities

The raptor testing stand at McGregor experienced an anomaly

Well, which is it? I'm going to trust NASASpaceflight over this article and go with it was a McGregor. No where near Starbase. And that means it will likely have no effect on IFT4 as this article says.

edit: Adding to this, the author of this article has no idea what they are talking about.

The Raptor engines that are currently undergoing testing are SpaceX’s Raptor 2 engines

So clearly nothing to do with IFT4, as Ship 29 and Booster 11 are already outfitted with their engines, non of which are Raptor 2s.

On its last flight test, IFT-3, Starship finally reached orbital velocity and it soared around Earth before crashing down into the Indian Ocean. On the next flight, SpaceX aims to perform a reentry burn, allowing Starship to perform a soft landing in the ocean.

IFT3 burned up on reentry, maybe parts of it made it to the ocean, but it was not crashing into the ocean that was the problem. IFT4 does not plan on doing a reentry burn. No one does a reentry burn from orbit. Starship uses a heat shield like every other orbital space craft. They are planning to attempt a landing burn, that is probably what they are talking about.

[–] [email protected] 74 points 7 months ago (1 children)

It waw McGregor. And while the explosion was spectacular, it happened on the test stand, so not much damage was done actually.

[–] [email protected] 42 points 7 months ago* (last edited 7 months ago) (3 children)

Yeah anyone following space YouTube has seen this a dozen times already and knows that it was a deflagration likely due to busted lines and not a detonation. The test stand is likely undamaged (In anysignificant way at least) and it was just an engine test of likely raptor 2 design. This has nothing to do with IFT4 or starbase as far as we can tell.

[–] [email protected] 14 points 7 months ago

Indeed. We don't know the conditions of the test. Maybe it was running the engines through a simulated flight. Or they were testing the engine in different failure modes to see if it shuts itself down or takes care of the problem correctly. Or they were doing a deliberate test to failure where a RUD is the expected result.

[–] [email protected] 10 points 7 months ago

Seriously!

OMG THE SPACEX ENGINE BLEW UP.

Brother yeah, it's a ground up redesign. It's brand new. Shit breaks. This article is a big fat nothing burger. and other comments on here being like SEE SPACEX IS DOG SHIT.... Just telling the world how uninformed they are with no regard for their own dignity lmao

[–] [email protected] 5 points 7 months ago

But the headline promised me a "massive explosion" and I'm only reacting to those words. Didn't read the article, nor did I watch the video to see what actually happened.

"Down with Musk!"

[–] sp3tr4l 12 points 7 months ago* (last edited 7 months ago) (2 children)

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.

[–] [email protected] 18 points 7 months ago (1 children)

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.

[–] [email protected] 9 points 7 months ago* (last edited 7 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.

[–] [email protected] 0 points 7 months ago* (last edited 7 months ago) (1 children)

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.

[–] [email protected] 5 points 7 months ago* (last edited 7 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.

[–] [email protected] 3 points 7 months ago (1 children)

The re-entry burn is the burn to slow down your spacecraft below orbital speeds, initiating re-entry.
Every spacecraft that wants to land back on earth after orbiting it needs to do a re-entry burn.
The only exception, theoretically, are spacecraft that return from outside earth's orbit. They could in theory re-enter by steering towards the atmosphere at the right angle. I don't know if they actually do that in practice or slow down to orbital speeds first, though.

[–] [email protected] 11 points 7 months ago (1 children)

What you're talking about is usually referred to as a de-orbit burn. Sure somebody could call it a reentry burn, but not SpaceX. What SpaceX calls a reentry burn is the maneuver when a Falcon 9 booster lights its engines as it first hits the atmosphere to slow down and move the heating away from it's body. Neither the super heavy booster nor the ship make a maneuver like this.

IFT3 did not make a de-orbit burn, and there is not one planned for IFT4 either.

[–] [email protected] 8 points 7 months ago

Thanks for the correction and clarification. Looks like I'll have to return my degree from KSP academy.