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by maccam94 22 days ago
Dang, they aren't catching the booster this time, but I guess V3 is practically a new vehicle and validating the next Starship launch is probably too critical to risk damage to the launch site for now.
3 comments

I think it's a few things:

They're already highly confident that if they have sufficient control over the booster trajectory they can execute the chopstick catch, so they don't particularly need to demonstrate that part more. Executing a pseudo-landing at sea lets them validate their booster flight controls perfectly fine without risking the launch tower and associated hardware. They can also do stuff like stretch the trajectory and control mechanisms to their limits to see how much they can handle, and not too big a deal if something goes wrong. Presumably any actual landings will be well within the known safe limits on all parameters.

I bet this first booster also has a lot of minor weird things associated with shaking out the manufacturing process, and they don't entirely mind testing to destruction the first one to get rid of it permanently and use the ones coming from a more proven manufacturing process for important work.

The booster catch is a useful trick but when the focus is just getting SS3 into orbit without incident, you can drop a few of the boosters in the ocean with the intent to fix at a later point.
Oh hey, you're right! Somehow I read "water landing" and interpreted it as landing on one of the barges (ocisly or jrti) any clue why that isn't the case? Is super heavy just too big for the barges maybe?
They won't use barges because the booster has no landing legs (to save weight), and because the booster is massive compared to Falcon 9. Also Starship is meant for rapid reusability, and it can take days to return a barge to port and unload the booster. Getting barge landings to work would be a distraction from the goal of Starship, and SpaceX already has Falcon 9 for current payloads.

And they won't attempt a catch with the first V3 booster because it's not worth the risk. They can build a new booster every couple of months. It takes much longer to build the launch/catch tower, and they don't have any spare towers yet. A catastrophe during a booster/ship catch would set them back a year, so they'll only attempt a catch if they're confident it will succeed.

I agree with everything but nitpick: SpaceX currently has two launch/catch towers in Texas, and they are building a third in Florida.
Only one of them is working right now. Their original tower needs to be overhauled to support Starship V3.
It doesn't have landing legs so it has to be caught by chopsticks. They're skipping the barges; either it lands back at the pad or it doesn't land.
Superheavy is 10x larger than the Falcon. Its thrust would sink the barge.
Yeah. Rocket first stage Approx. unfueled mass:

Super Heavy: 200000 to 280000 kg

Falcon 9 first stage (without Falcon Heavy side boosters): 25600 kg

So 200-280 tons. A standard barge can support 1500-3000 tons of cargo. Even with the added weight of a catch tower and a healthy factor of safety thrust isn't gonna sink the barge. Far more likely the major hurdle would be stability issues with how tall it is.
It's not 280 tons... it's a falling object with kinetic energy so that rocket thrust is going to be very problematic for that boat especially if it' hitting unevenly.

That and there's no way for it to stand without a catch tower.

Hypothetically, what's the effect of that much thrust close to a water surface?

I.e. if they cut a hole in the middle of a barge and it was burning at touchdown "against" the ocean

I imagine water doesn't have the kinetic problems that chunks of concrete do, but also that's a LOT of energy for even water, so maybe there'd be steam issues?

Well the idea would be to put a catch tower on a barge so those aren't actually issues.