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Comment by baq | Hacker News Reader

99% chance that they lost attitude control hence couldn't point the business end towards wherever they wanted to. we know they can relight the engine on the booster and we know they can relight for landing burns.

no surprise if the next launch has a couple pre-production big starlink birds.

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On the contrary, they absolutely had attitude control. Otherwise reentry would have seen the ship tumbling out of control and quickly breaking up. Instead, SpaceX was able to begin a controlled reentry in the upright position, indicating nominal orientation performance.

My bet on the re-entry failure is that they have really poor attitude control. They definitely had some, but you can also see at different points that the plasma was shifting directions. At T+46, it was doing a spin as the first plasma started to show. At T+47, it was going down on the edge of the heat shields. At T+47:40 it appears to be going down engine first.

Moreover, I'm guessing the reason they skipped the mock re-entry burn was due to not being able to settle the propellant. Though it's really hard to tell if the turning of the Starship was to rotate which side was getting heating from the sun, or if it was spinning out of (or with less than desired) control.

Tim Todd noticed that the gas thrusters were icing over and then releasing the ice. So it's a reasonable guess that this was part of the issue, but that's leaning even more into speculation territory.

I just noticed that I typed "Tim Todd" instead of "Tim Dodd". It's past the edit period so I shall forever live with this shame. In my defense, I was on 5 hours of sleep so I could watch the launch.

You are a contemporary yet timeless sort of gentleman. Well done.

I'm no so sure, it at least looked like it was tumbling before and throughout re-entry. If they had attitude control, I think they would have at least stopped the visible rotation at some point before re-entry?

I'm not sure why the ship not immediatly breaking up, but eventually breaking up is proof that they at attitude control - especially against what the live feed showed - rotation.

  > If they had attitude control, I think they would have at least stopped the visible rotation at some point before re-entry?

Maybe they thought the flaps would help stabilize once hitting some atmosphere. In fact, that seemed to happen though not before quite a bit of plasma cooked the unshielded side.

I'd speculate one of main tank bulkheads breached and gas kept leaking from payload door which overpowered RCS. Then, during reentry, the vehicle briefly managed to regain attitude by aerodynamic forces on the flaps, but became north-northwest aligned and broke up.

they were tumbling, just slowly. they started reentering side first. that it broke at 65km was unsurprising - shuttle experienced peak heating about there.

> know they can relight the engine on the booster and we know they can relight for landing burns.

Do we know that? Booster crashed into the water at full speed; landing reignition failed.

They did demonstrate this during their Starship-only bellyflop/landing tests a couple of years ago. This wasn't in space, though, obviously, and wasn't after an extended coast period. So... we know they can relight them under at least some circumstances, but whether or not they can under _these_ circumstances is maybe unclear.

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