I remember there was a phase of Falcon design where it looked like they had perfected barge landing, and then they had a rash of failures. Later on they admitted to intentionally crashing older boosters so they could find the limits of the hardware. They were iterating at such a pace that the data was worth more than a recovered booster. I wonder if that was the case today?
During the livestream they did keep saying that they’re pushing it past its expected limits.
To give an example of this, the Starship they've been flying on the last few flights is already obsolete. There's a newer V2 but they wanted to burn through the rest of the V1s they had already built and get more data before flying V2.
Why would they plan to catch it and then divert mid flight if they didn’t want to reuse it?
It's possible to plan for multiple eventualities. They may have pushed it to its limits (or beyond) and decided the best destination based on how it handled it
I believe they diverted to save the tower from being potentially damaged/destroyed by a failed landing.
Yes Musk said before one of the first flights, that they are making changes and building new hardware at a much faster rate than they could ever hope to fly it right now. pretty much something to the effect that by the time they get to fly hardware a lot of it is obsolete.
What's the advantage of the chopsticks landing over splashing the thing down in the ocean?
Does an ocean landing cause significant damage that's not present with an on-land chopsticks landing?
Presumably there are pretty big advantages considering how much it must have cost to develop the chopsticks approach.
The booster is destroyed when it tips over after "landing" vertically on the water. It's like a 20 story building falling over.
If you're asking why they don't land it on a floating barge like Falcon 9, there are two reasons. One is that landing back on the launchpad lets them refuel and relaunch immediately. The other is that landing legs are big and heavy and significantly reduce the payload capacity. If you're already landing on the launchpad you might as well add arms to catch it. The mass of the arms is free because they're on the tower instead of the rocket, and the rocket only needs tiny nubs to catch on the arms instead of giant legs. Also the arms double as a crane to lift and stack the rocket on the launchpad.
So is it cheaper to dump the booster in the ocean then land it back at the tower and then have to dispose of it?
No, it seems like what happened is the booster failed one of its automated safety checks before landing which caused it to abort into the ocean. It's cheaper to dump the booster in the ocean than to build a new launch tower when it's destroyed in a failed landing.
Also, a rocket that hangs doesn’t need near the structural beef as one that is designed to withstand landing on its feet.
>immediately
So far this hasn't been shown even on much simpler Falcons. The barge gives quite some energy advantage for not having to boost back.
Ideally they'd build a capesize kinda barge with chopsticks to catch it in the ocean, then perhaps service what they have to while it's steaming back.
Hasn't been shown because they're not meant to be immediately reusable.
Spaceship and/or super heavy are (I don't remember the details).
I'll believe it when I see it.
There are several advantages:
- Turnaround time is a major one for SpaceX. They want to stack a new Starship on top of it and launch the booster again in hours, not weeks. By catching the booster they can simply lower it back onto the launch mount, refuel and relaunch.
- No need for landing legs. The legs add significant weight, especially on something as large as Super Heavy. Leaving these out means more usable payload to orbit.
If the chopsticks are catching the rocket by the grid fins, doesn't that mean the grid fins (and associated structure) have to be strengthened (weight added) to support the entire weight of the vehicle? That would negate some of the weight savings of removing the legs. Does this end up being more efficient because more of the loading is in tension instead of compression?
The chopsticks actually don't catch the booster by the grid fins, there are little struts that stick out from the rocket that don't stick out nearly as far.
I thought the same thing before the first catch, if you go look at the catch footage you can see the booster resting those on the chopsticks.
So the struts (plus supporting structure) are lighter than the legs? Why is that?
> So the struts (plus supporting structure) are lighter than the legs? Why is that?
Besides the other answers you've received, the lugs hold the booster from (near) the top. This means that the body of the booster is in tension during and after landing. Legs, on the other hand, support the landing load and weight after loading in compression. The booster is basically a thin-shelled tube, which is limited in compression strength (for a given wall thickness) by buckling; in tension, the strength approaches the strength of the material, so less additional reinforcement is needed in the structure to support landing loads.
The legs would need to be much longer (because you can’t push the engine nozzles all the way into the ground and still hope for good things.) Longer structure means more mass, but also larger torque which need to be handled with the support of the structure.
Legs need to move to deploy. The struts are just there, static things are much simpler. Simpler things weigh less.
Legs need to contain shock absorbers. With the struct solution the shock absorber is in the chopsticks. It doesn’t matter how much the shock absorber weighs when you don’t need to carry it up with you.
The pins/struts are a 2 point system that double as the booster lift points in general operations. The booster mostly hangs in tension which the existing tank structure can support. I would guess they share some of the structure beefiness with the grid fins.
Legs require at least 4 points, probably more. Shock absorption hardware, ability to unfurl to an acceptable width. Require reinforcement (cross bracing) near the base of the tanks to handle the loads pushing inwards toward the center of the tanks.
Legs require at least 3, not 4 points.
The "struts" are needed anyway to lift/move the rocket using cranes, they aren't optional.
They’re much smaller and don’t have to move/deploy.
This is a pic of the top of the booster. You can see the landing lugs between the grid fins.
> If the chopsticks are catching the rocket by the grid fins
The chopsticks don't catch the rocket by the grid fins. There are dedicated supports (pins) sticking out the sides of Super Heavy that support the load. It does negate some of the savings from removing the legs, but by returning not only near the launch site like Falcon 9 but literally to the launch tower itself, they can save a whole bunch of time on transporting the stage back to where it will be launched again. They want to launch these things at such a rapid pace that every hour they can save in the refurb / repair / refuel part after landing matters.
I thought it was the grid fins initially too until I saw that there are actually just two pins that the entire thing rests on. Check this clip around 19:30. https://youtu.be/dpxB1S-ohEU?si=yozlCWmDCNeEFO4B&t=1169
Sort of. They need to lift the rocket to put it in place on the launch structure so that is already built into the design.
>They want to stack a new Starship on top of it and launch the booster again in hours, not weeks.
I want a castle in the mountains, a helicopter with unlimited range and a submarine to boot.
I don't understand this take. Are you saying it's in-principle impossible for them to accomplish these goals?
If you think of a way to make that happen, I guess you should do it then.
If you had spacex’s budget you could make all of these things happen
Didn't they already burn through their Starship development budget?
That's what they said about landing a booster
Keep in mind, splashing the booster down in the ocean almost always results in rapid unscheduled disassembly (explosion) of the booster. It lands upright but has no ability to stay upright on its own, so usually makes a soft water landing and then immediately tips over. The shock of the side of the booster hitting the water usually ruptures one or more pressure vessels, resulting in a nice fireball and destruction of the vehicle.
Even the Falcon 9 when it lands "at sea" is actually landing on a barge that is able to keep it upright (usually) and out of the water, but any booster vehicle that SpaceX (or anyone) launches that does a soft water landing is a write-off. The only real exception to this is return capsules with astronauts in them which are explicitly designed to land in the water and deploy buoys to keep themselves afloat while they wait for the Coast Guard to come pick them, and the capsule (which is a one-time-use component) up.
> The only real exception to this is return capsules with astronauts in them which are explicitly designed to land in the water and deploy buoys to keep themselves afloat while they wait for the Coast Guard to come pick them, and the capsule (which is a one-time-use component) up.
With SpaceX Dragon (both crew and cargo variants), the capsule is designed to be reusable, so it is no longer a “one-time-use” component. The same is true of Boeing Starliner and NASA/LockheedMartin Orion. “One-time-use” was true of previous ocean-landing capsules, such as Apollo’s Command Module, with the sole exception of the Jan 1965 Gemini 2 uncrewed testflight’s capsule, which was reused for another uncrewed testflight the next year, as part of USAF’s Manned Orbital Laboratory program (which was cancelled in 1969)
Of course, reuse after a spaceflight and ocean landing requires significant refurbishment. Also, both Starliner and Orion are only partially reusable, since both (like Apollo) have a service module designed to burn up on re-entry. Dragon likewise has a trunk, but Dragon’s trunk contains fewer spacecraft systems than Starliner or Orion’s service modules, making it more reusable overall.
tiny correction, but I believe the capsules are also re-used
- salt water is horrific for anything
- time to transport, move back into initial position.
That makes sense - sending out barges / recovery vehicles into the ocean can't be cheap.
The environmental impact of a chopsticks landing is likely a whole lot less damaging too.
What do you figure is worse for chemical changes to materials, being engulfed in a big call of plasma, or being dunked in the ocean?
I don’t know any chemistry but there seem to be a lot of smart people round here. What say you?
Dunked in the ocean. There just isn't a ton of plasma and it's not very good at transferring heat to things it isn't being pressed up against. So heat shields and the like function very well. Seawater by contrast gets everywhere, and if it does even a little damage, keeps doing it for a long time.
Seagoing ships are good at being in salt water but don't deal as well with being engulfed in plasma. Starship is pretty good at being engulfed in plasma but doesn't handle being engulfed in salt water very well. Making a single ship that can handle both is a very tall order, even just doing one or the other is hard.
Seagoing ships are pretty good at floating on top of salt water for a while, but they're not very good at being "dunked" in it (i.e. sunken). It is possible to raise sunken ships and rehabilitate them to regular service, and this has been before, but it generally destroys everything inside, and requires a ton of work. Salt water is one of the most corrosive substances we know of.
Ocean is worse. (For rockets.)
- used to be an engineer in aerospace
Being dunked in seawater while still being red/white hot from the plasma.
Designing it for both is probably worse than either one separately
I don't think they reuse the boosters that they do a splashdown with. So reuse vs trash.
Hard to have a spaceport if your vehicle needs to land in the ocean.
Hypothetically speaking (asking for a friend), can you intercept the Starship with standard AA missiles as it re-enters?
Is this due to the higher incidence angle ? Seemed like the main 'difficulty' factor that was upped in the mission description
I think these were two different things. It was Starship that reentered (successfully) at a lower angle of attack, but it was the Super Heavy Booster that was supposed to attempt the chopsticks landing.
I haven't seen anything for sure, but there was a significantly bent antenna on the launch tower that may have been the cause.
Yeah Elon described it as a "harder" and "faster" landing. So maybe things were a little outside of the safe parameters, necessitating the change in plans. I wonder if we'll get to find out what that was.
That was the upper stage, not the booster.
It was, in fact, the booster ("coming in harder and faster"). The upper stage's orientation was being tested (nose down until final flip) as was the removal of 2,100 heat shield tiles.
Why can't the tower/chopsticks be as portable as the booster?
Probably for similar reasons that your average apartment tower isn't portable.
Transporting empty big rockets is already really hard and finicky. Transporting something even bigger and heavier than the largest known rockets is harder. Then you need to anchor it to the ground strongly enough to take the weight and dynamic forces of a fully loaded rocket and subsequent landing, but weakly enough you can move it again later. Overall it's really a situation that benefits from a permanent concrete foundation.
Oil rigs are transportable and massive. I don't think it'd be unfeasible to convert one of those into a rocket catcher.
That was the plan for a bit, but it didn't pan out.
https://spacenews.com/spacex-drops-plans-to-covert-oil-rigs-...
Transportable over land? I assumed that was the question.
The main argument from SpaceX is that they want to be able to refuel, restack, and relaunch this thing in just a few hours.
If it's returning to the launch site for relaunch, the tower doesn't really need to be portable.
We finally found a great use for those heavy lift dirigibles.
Think you are going to need more than a few. Also really don’t want your apartment tower to fall down if anything goes wrong. Maybe safer to just build multiple.
I forget that sf novel with mobile cities on crawlers.
It was Mortal Engines by Philip Reeve. Was an ok book. (Better than the film)
Mortal Engines?
Then you have to have something to catch the tower.
You can drive the tower
Seems like fts failed and the booster is still floating in the sea right now.
> Seems like fts failed and the booster is still floating in the sea right now.
FTS is designed for flight termination, not sinking the booster after ocean soft touchdown. So if FTS detonation fails to terminate the flight sufficiently quickly, that counts as an FTS failure which FAA will require to be investigated as a safety mishap, grounding the launch vehicle in the meantime. But if FTS fails to sink the booster after ocean soft touchdown, it wasn’t designed to do that anyway, so I don’t think the FAA will consider it a “failure”. If the flight plan lists this outcome as a possibility, and SpaceX has a backup plan to respond to it, it isn’t a failure as far as the FAA is concerned.
Did they want to sink it? I'd think they want to recover it for investigation purposes.
There's likely minimal value to recovering it given how much telemetry they already have, plus having launched very similar boosters (test flights 5 and below, plus Starhopper) for a similar launch profile. Additionally, based on previous comments SpaceX engineers have made when towing an in-the-water booster back to land, making it safe for transport to active commercial waterways is a huge pain in the ass. There's also considerations to be made for protection of intellectual property: much harder for other companies to steal your trade secrets from the bottom of the gulf of mexico.
Sad, but makes sense I guess.
> think they want to recover it for investigation purposes
These are V1s. Not worth the effort.