SpaceX Super Heavy splashes down in the gulf, canceling chopsticks landing | Hacker News Reader

SpaceX Super Heavy splashes down in the gulf, canceling chopsticks landing

twitter.com

272 pointsalach11425 comments

They demonstrated the engines re-lighting in space, which is significant. There had been some questions about this because the engine is of a design that is said to be very tricky to start, and the tank pressurization system of the rocket has the risk of water and CO2 ice forming in the methane tanks, which had caused several failures in past tests flights. So this is a pretty good milestone.

So we might start seeing test flights actually entering orbit soon. Possibly even carrying some real payloads soon.

Why don't they already carry payloads? Is there anything worth taking up with the current expected value of it exploding ect?

they carried a banana this time :)

Also the structure behind it is the Starlink pez dispenser

https://ringwatchers.com/article/ship-pez-dispenser

Huh nice, missed that detail!

Is the Starship upper stage boosting itself up to full orbit yet?

No. This and all previous flights have intentionlly been barely sub-orbital, with less than one orbit. Launch in Texas, re-entry over Indian Ocean. A full orbit at that altitude takes about 90 minutes; this was over in a little over an hour.

The reason was safety. If it was orbital, then controlling the re-entry would require a sucessful relight of the engines. If that failed then the re-entry point would depend upon the vagaries of orbital decay from residual atmospheric drag. That's no doubt why today's relight was so brief; they didn't want to significantly alter the reentry point.

I don't believe this is quite correct. The last few trips are actually orbital, just not of the correct elliptical shape to do more than a half orbit as the perigee is less than the radius of earth. If earth was a point mass, it would have orbited.

This means you don't have to do anything to deorbit while proving you could have made a full orbit if you wanted to.

If the earth suddenly became a point mass except for all the humans, we'd all already be in orbit. At the "top" of a highly elliptical orbit that passes relatively close to that point mass, yes, but an orbit. Everything that was within the Earth's sphere of influence, not moving so fast to be on an escape trajectory, and not with 0 horizontal velocity relative to the point mass would be in an orbit.

Orbital means "on a trajectory that doesn't intersect (or escape from) the body you are orbiting", otherwise the word is meaningless.

A person standing at the north pole wouldn't be in orbit. They would fall directly down.

(Wouldn't they?)

I concur. Right up until they exhaled and gave themselves a little horizontal velocity.

I think it would also have to be at an equinox. Otherwise the pole would be tilted towards or away from the sun, meaning that it orbits at a slightly different velocity, so you would have some velocity relative to the center of mass.

If the earth were a point mass than almost any trajectory at all would be orbital.

Can’t hit a point mass on any trajectory.

Why not? If your starting point is completely static compared to the point mass and your aspect area isn’t zero, you’re going to fall directly down towards the point mass and are going to hit it.

If it was a point mass, and you had exactly zero horizontal motion relative to it, you'd go right through and out the other side.

Well, except for relativity turning it into a black hole with a Schwarzschild radius of 8.87 mm so it won't be "point-like".

But most of the disintegrate sheen of plasma that used to be your body would have had some horizontal motion compared to it, even if only due to you starting off as an extended body.

If the point mass is inside my body for some time, I would describe that as „hitting the point mass“

If you like.

But would you say you hit neutrinos that pass through you without interaction?

If pointlike was possible, it can be similar: nothing beyond the spaghetification that happens well before you reach the event horizon.

> the perigee is less than the radius of earth

Which is what we call "sub-orbital" :)

I believe that is called a ballistic trajectory.

That's an orbital-velocity ballistic trajectory.

And that's sub-orbital. Barely

Every time you throw a rock, it ends up on a trajectory that "would have orbited if the earth was a point mass". That's just not a very useful definition of "being in orbit".

The utility of test flights doesn't come from delivering a payload; but from collecting data. For example today's test involved intentionally weakening starship's heat shield to see if previous estimates of required shielding had been too conservative.

Well looks like you imposed a qualification on these types of flights and now by definition they cannot deliver payload.

The flights could deliver cheap payload for example.

"The payload is data." Elon The data they get from the test and they focus on getting the most and most valuable data. This is an explicit choice. A physical payload at this stage would reduce the overall value that they are able to get from a flight.

You can't deliver a payload to orbit if you're not planning on going to orbit. They have a launch licence for a particular mission plan.

The license for Falcon 9 and Falcon Heavy specifically says “Authorization: SpaceX is authorized to conduct flights of launch vehicles: […] (c) Transporting Dragon 2 to low Earth orbit or a payload to orbit;”

The license for Starship/Super Heavy Launch Vehicle does not include such an authorization.

https://www.faa.gov/media/69476

https://www.faa.gov/media/75501

Speculation:

Putting a starship in low earth orbit right now would be a bit reckless, because if the engines fail to relight it's going to come down at some point in a completely random spot along the trajectory, and it's quite a large piece of debris that is designed to not burn up. By contrast this test (which involved the first 0g relight of a raptor) was designed so that if that failed the ship would still come down in a designated keep out zone in the ocean.

Even ignoring the safety risk, the value SpaceX gets from this flight is largely testing the re-entry (heatshield, flaps, etc) of starship. Putting it in an orbital trajectory risks a failed engine relight making it impossible to test that, because the ship will be dead (out of power) by the time it comes back down. Whatever low-cost payload you could put up there for "free" (the cost of risking the payload being destroyed if the test flight goes wrong too early) might not be sufficient to pay for the risk stopping in an orbital trajectory imposes on the test objectives.

Now that they've successfully lit a raptor in 0g, I imagine they're a fair bit more likely to make the subsequent flights orbital.

> Putting a starship in low earth orbit right now would be a bit reckless, because if the engines fail to relight it's going to come down at some point in a completely random spot along the trajectory, and it's quite a large piece of debris that is designed to not burn up.

More relevantly—it's harder to make a marketing stunt out of a fallible mission.

Is it your position that flight 6, or the Starship program, or SpaceX is a marketing stunt?

What exactly do you think they're marketing?

And don't say launch services, 'cause you're using "it's a marketing stunt" to explain why they aren't taking payloads. "It's R&D" makes a heck of a lot more sense.

As if Space X needed more marketing than being the cheapest and more consistent launch provider for the past 10 years

> More relevantly—it's harder to make a marketing stunt out of a fallible mission.

SpaceX is well known for making a marketing stunt out of their failures (see "How Not to Land an Orbital Rocket Booster"). In fact, Elon Musk is known to make marketing stunts out of anything.

But that's not it, they could have launched a dummy payload if they wanted to, they have already done it for other rockets, and yeah, they made it a marketing stunt. Famously, they launched Elon Musk's Tesla Roadster in the direction of Mars. But here, launching a payload at this stage of development is just not the best thing to do.

In fact, IFT-6 had some payload. They put a banana into the payload bay.

That's what the flight termination system is for, and thus it'll be exploded remotely instead.

An FTS does not prevent 100t of debris of which a significant amount is designed to survive re-entry from impacting the surface. If you blow up 100t you still have 100t of debris, just in lots of bits (and honestly, still big chunks - an FTS does not atomise or even close - it punches a hole and then the vehicle collapses structurally)

All it really does is remove the explosive potential of the fuel.

So no, it's not designed to do this.

Once in orbit the FTS system is usually deactivated (safed).

Yeah, you do not want the FTS activated on orbit. It's not something you want going off where it can leave 100t of hazardous debris in orbit.

Debris in orbits that nearly intersect the atmosphere are practically harmless. The issues arise when you have an orbit that will intersect other orbits a billion times before decay.

While the reality is very complicated, you can make a rough handwave model for orbital debris in a circular orbit: At 100km it lasts 1 orbit (90 minutes) at most, and every ~100km you add after that increases orbital lifespan by ~10x.

It's designed to survive re-entry in a very particular, and repeatedly adjusted, orientation. It's unclear how much would survive re-entry in an uncontrolled tumble. But better safe than sorry.

You want to turn a single dead 100t object in orbit into 100t of randomly blasted debris in orbit?

Their payload door situation is complicated.

can you elaborate? https://ringwatchers.com/article/ship-pez-dispenser Seems like their door is made exactly for the purpose of dispensing starlink satelites, with minimal impact to the hull integrity..

The first time they tested it in space it didn't open and they haven't tested since.

I don't expect this to be a major showstopper but obviously they must figure it out before they can start making money off of starship.

It's exactly because they hadn't demonstrated engine relight in space yet. That means they couldn't guarantee they would be able to deorbit Starship in a controlled way. An uncontrolled deorbit would be bad because it could come down literally anywhere and large chunks would hit the ground.

Because they couldn't guarantee precise deorbiting, they never put it in orbit to begin with. Starship was on a ballistic trajectory that falls back to Earth. Any payloads they deployed would fall back too, unless they carried their own rockets to reach orbit themselves.

> Starship was on a ballistic trajectory that falls back to Earth

Actually Starship on this flight wasn't quite on a ballistic trajectory, the periapsis was actually above the ground so it counts as an orbital trajectory. Without the atmosphere it would keep going.

Lots of technical speculation in the sibling comments. I suspect the real answer is that any real payload would require at least FCC approval, and possibly modification of their FAA flight plan. The income from the payload would not be worth the delay.

they showed a banana in the payload bay, that was the testing payload:)

they pushed the rocket to the limits in this flight

From what I followed, its because: They already send payload to space with the falcon rockets (reliable cash cow) and the only point of starship system is proof of concept of full reusability. There is no point to the whole project if they dont achieve this. They are constrained in launches, either through regulatory (FCC) or engineering timeline and so far, every launch counted. They achieved a substantial improvement.

If they dont catch the starship (upper stage), the whole project is pointless so its important keep things simple (details like payload door, cargo dont matter) until they achieved the whole loop (land & catch starship)

They already have a cheap way of launching. Cheap for current market rate. Whole point of this project is to improve cost by / 1000.

They achieved substantial progress with every flight. 1. It flies, 2. hot staging 3. reach orbit 4. land both & heat shield, 5. catch booster, 6. extreme conditions & improve heat shield.

I'm curious if they will have enough fuel to carry (significant) payloads. Have they commented anything on the amount of fuel that they are taking today vs the capacity? Are they not flying with full tanks at the moment?

I would argue that IFT-6 was already orbital since the perigee was above the ground (albeit inside the atmosphere)

Although this is getting very nitpicky, while I'd agree a perigee above ground would count as an orbital _trajectory_, an orbital flight is usually considered as one that completes at least one full orbit around the planet.

By that logic Gagarin did not reach orbit, so I don't think that's a common definition.

Do you have a source for that? My understanding was that he completed a full orbit.

The insertion burn finished at 06:18 UTC and they started the deorbit burn at 07:25 UTC, while the period of the target orbit was 89 minutes.

There was also another issue - Gagarin did not land with the capsule, but ejected during the landing as expected & both the and the capsule landed under (separate) parachutes. This was because the capsule landing speed was higher than what could be achieved if only the kosmonaut parachuted down, making the landing safer.

But the FAI guidelines for for space records at the time were based on normal aircraft flights & expected the crew to board the craft & only disembark on landing.

So soviets just lied about Gagarin landing with the capsule up until 1971: https://en.wikipedia.org/wiki/Vostok_1#World_records

Also the orbital booster used (R7) was also still an active ICBM (even sometimes holding combat readiness with a live nuke on top on the same launch pad) so that was IIRC secret as well. :)

I think in a very technical sense you could say it wasn't an orbital flight because he didn't quite complete an entire orbit. Most people call his flight a complete orbit anyway though as his landing point was quite close to his launch point (unlike virtually all other sub-orbital flights).

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?

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.

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.

They also apparently already have a V3 in the works.

It's been announced, and is surely being designed, but they are only building hardware for V2 right now. Most likely V2 will continue as long as they need to get dialed in what they want V3 to be, then they will switch. V2 seems to be based on the learnings from V1, and I think V3 is the real design they want to fly-- but V3 depends on Raptor 3 and probably other advancements, and Raptor 3 is still at the testing stage in MacGregor.

For instance the V2 design seems to use Raptor 2.5 which is a Raptor 2 variant with Raptor 3 style interface with the ship. So they are testing the ship design to support Raptor 3 before they have Raptor 3.

The engines are really heart of these things and drive the development cadence.

That makes so much sense. Once you find the correct parameters for an optimal flight, use the rest of the rockets to map the state space of configurations to see how much they can deviate

Interesting, so if they do not intend to recover the rocket from the water here, then this was an effective waste-disposal method for their obsolete V1 design?

I was surprised to learn that, besides the environmental impact of the leftover fuel - though methane is the least toxic of them, and decomposing electronics, the metal rocket body itself can be a boost for marine life and corals by serving as shelter. Guess the outcome depends a lot on the design and materials used.

This is why I throw beer bottles into the sea, it's new habitat for sea creatures. Not really, but it makes a good excuse for littering.

True recycling.

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.

Which would be in direct conflict with the reason given originally above.

They might be happy to push hard enough to risk the booster, but be much less willing to risk the tower? Seems perfectly consistent to me.

I like SpaceX as much as the next nerd but that's not "intentionally crashing the booster" it's "doing the only other type of landing you can when you abort the first plan of landing it successfully". I'm sure they got useful data out of it (it's better than "booster blows up in mid air") but this is squarely in "2nd attempt to land with chopsticks wasn't as ready as they hoped" bucket, not "132nd attempt to land the booster was intentionally destroying it to see how much farther they could be pushing it" as was originally implied with the wording and prior example.

Oh, sure, I didn't want to make any comment on what they were actually doing or trying to accomplish. Only that the hypothetical we were talking about would have been consistent.

There's a lot of middle ground here. I suspect what's most accurate is "let's push the booster out of envelope a bit, if we get really nice numbers we'll go for the chopsticks landing, otherwise it's into the drink".

In other words, they were optimistic enough to think that another upright landing was within the realm of possibility, while also deliberately doing things which made that outcome less likely, to get the data they need.

If that's true, I wouldn't characterize it as a second attempt at a chopstick land, that would just be a stretch goal. Who knows if it is, but it's consistent with how SpaceX operates.

https://www.spacex.com/launches/mission/?missionId=starship-...

> During this phase, automated health checks of critical hardware on the launch and catch tower triggered an abort of the catch attempt.

Surely you aren't saying there is middle ground in the way the tower is being tested that caused the abort of the booster landing?

No, but I'm neither omniscient nor able to see into the future. It's not clear to me that the sentence you're referring to had been posted 18 hours ago, and in any case, I hadn't seen it.

One of the commentators said (roughly) "they can make another rocket real quick, but if they blow their one pad up then they are hosed for a long time."

During the livestream they did keep saying that they’re pushing it past its expected limits.

That was primarily said for the second stage. The primary stage I didn't hear them call out as often (if at all?)

was a stated objective before the launch: "faster/harder booster catch" https://x.com/elonmusk/status/1858867695233425734

I guess you are right! https://x.com/elonmusk/status/1859036912348262787

That is recovery of the top part he’s talking about not the bottom

You believe him?

Yes.

Do you have to pay to scrap old rockets?

I guess that could be an interesting cost savings measure, just lose/destroy your old inventory instead of paying disposal.

I have no idea, but my guess is that the cost of fuel would be an order of magnitude greater than any possible disposal costs.

Also, people pay good money for high-quality metals. The scrap value is probably greater than the logistics cost of getting it to a scrapyard.

You wouldn’t even need to scrap it. Cut it up and turn it into some mega silos for agriculture or materials suppliers. Or just set it aside and donated to the Smithsonian in a few decades…

And, I should add, but if anyone discovered that the fuel was being wasted for no benefit, it would be a PR nightmare, especially as there’s no end of people eager to find fault with the company’s founder and largest shareholder.

Why do you think that would be a PR nightmare?

This seems like the tail wagging the dog

It's running on natural gas and air. The fuel is actually really cheap.

Probably not as much as if you steer it toward the graveyard

https://en.wikipedia.org/wiki/Spacecraft_cemetery

You have to pay to get the rocket back anywhere near to a barge at all. If you don't want it back you just let it fall into the ocean without spending fuel on slowing it down (and more fuel bringing that fuel along so that it is there to slow it down). You don't pay for a barge. You don't pay for the engineering work associated with bringing it back.

Dropping rockets into the ocean was what everyone* did before SpaceX came along.

If you're already paying the cost to bring it back though, it's very hard to imagine that you would have to pay to scrap it. The thing is primarily a large metal tank, and some engines made up of a bunch of metal - people pay money for the privilege of scrapping metal, not the other way around.

* Technically some other countries dropped them on deserted land, or not so deserted land in the case of China.

They could probably get museums to pay them for their scrap. They would have some work to remove any confidential components before handing it over though.

Depending on what's in the rocket, just leaving it to decay in the environment would likely lead to contamination. Especially if you have any Hypergolic fuels lying around (explode on contact, and extremely harmful to humans / the environment). So you either pay to scrap it, or pay to clean up the site in X years.

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.

- 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?

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

Designing it for both is probably worse than either one separately

Being dunked in seawater while still being red/white hot from the plasma.

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.

A lot of the damage happens as soon as the spacecraft enters the water, because it's extremely hot, causing more chemical reactions than you might think. Even jet engines have trouble with corrosion from ingesting small amounts of aerosolized salt water.[1]

1. https://ntrs.nasa.gov/api/citations/19690007944/downloads/19...

This is the answer. Salt water destroys the engines.

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?

They’re much smaller and don’t have to move/deploy.

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.

It was pretty neat how Bezos explained to Everyday Astronaut how they were using 6 legs so the legs weren’t as long.

On the whole, pad catch is the way to go for non-expeditionary vehicles. For orbital uses each booster basically becomes a pyrotechnic elevator.

It would be good to see the numeric analysis of variants here. Legged landings are surely possible - say, with longer legs (twice as long as struts?), possibly static (legs are always deployed, even when launching), with shock absorbers which aren't that heavy... Would be good to see good and bad qualities next to each other.

I think it all just comes down to weight. If you can trim mass on the vehicle then you should do it.

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.

You can technically imagine two legs with really wide feet, allowing some perpendicular stability. I wonder if one-leg lander could be imagined. 3-legged landing scheme was used in Surveyors, first American automatic Moon landers, and was surely considered for Appolo LEMs, but rejected. So there could be additional, secondary reasons when choosing the number of legs.

The cost of one additional leg is pretty inexpensive for the redundancy it provides for the other three.

4 legs have no additional redundancy over 3. One leg failing will still result in the booster tipping over. They do push the maximum angle of tipping before your CG is no longer supported out farther though.

Useful for when you land on the rim of a crater like Apollo 12.

I think you are both using different meanings for the word 'least'.

Nitpick, I think the issue is different meanings for the word ‘require’. Practical/realistic minimum vs absolute/literal minimum.

> 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 tanks can surely be pressurized at landing, which greatly helps to avoid buckling.

Pressurized with what? They've already used their fuel for the landing. They can't put anything else in the tanks without worrying about contamination for the next flight.

Pressurization gases? The fuel goes from tanks to engines (engine pumps) because tanks are under pressure, right? Even if the liquids are spent - they are rarely spent in full - the gases remain.

Helium is a common pressure/purge gas in the fuel/oxidizer tanks.

They autogenously pressurize the tanks - they heat up the cryogenic propellants with the engines and use some of the gas to pressurize the tanks. In Starship’s case it’s methane and oxygen.

But why, if you don't need to

Aghm, sorry, I meant, the tanks actually are pressurized at landing and not at risk of buckling. Why depressurize?

The pressure is enough to help push out liquid fuel but I don't think that means the pressure can be fully relied upon to provide structural support.

That's literally how original Atlas rockets and modern Centaur stages work.

Starship is literally not an Atlas rocket or Centaur stage.

Starship uses autogenous pressurization, which is not what Atlas/Centaur used.

Sure, but I am quite sure pressure is expected to be in place & provides the necessary strength for all the maneuvers.

You know, that's completely unimportant. The important parts are that 1) Starship stage is under pressure when landing and 2) pressurization makes a thin-walled metal cylinder much stronger resisting buckling. Details of how Starship works and how pressurization is historically used to increase strength are just to support these two points. But if you already have these two points, you should admit that the argument "Starship can't land on legs because there's too big of a risk of buckling" has some counterarguments. And the overall decision isn't as clear as we'd like to have it.

Actually, it is very important. Autogenous pressurization has a much higher risk of pressurization loss than a system which uses inert gases, due to the potential for the ullage gases to mix with the liquid fuel and condense.

This is relevant when designing the landing system.

> surely

Rewrite:

"Why doesn't [huge successful project] do [simple thing]?"

At least link to some details of the design? Here's the best diagram of the tank design I could find:

https://www.elonx.net/wp-content/uploads/SpaceX-BFR-spaceshi...

Which doesn't show the design constraints but who wants those - edit and it's not an image of the booster? Elon mentions a design feature missing from the diagram: https://x.com/elonmusk/status/1093643894917492736 I would personally guess you'd need to be very careful with your implied load bearing connections between the tanks at x Kelvin and the skin at redhot reentry temperatures...

Good luck on buying spaceY.com and competing against those engineering fools at SpaceX ;)

I am mocking unreasonably, and I know I would find similar comments in my own internet history. I am hoping you will learn to be a little less thoughtless in your armchair. We all assume other rocket-science engineers must not know what they are doing but usually that just shows our own ignorance.

Nah, misses. We discuss technical possibilities, not flame on forums. The previous post was an answer itself.

Or you're implying that tank pressurization isn't a standard practice and not a simple thing?..

Let me explain once more :) . The original post which I was replying to was

----- > So the struts (plus supporting structure) are lighter than the legs? Why is that?

Note how the author says that a thin-shelled tube is limited in compression strength by buckling. Technically it's correct, but practically if you put some extra pressure in that tube - which, after all, has also airtight caps on both ends - then the tube becomes much stronger, and is able to withstand reasonable forces during landing.

That's what I noted, and I can repeat that. I am quite sure SpaceX engineers considered that possibility, and I think they rejected that because they felt they see an even better result. I'm trying to see that here.

I also suspect that you don't know my qualifications in the area, and referring to armchair ones just so. It's interesting how many different and widely qualified people participate in HN discussions.

What is the booster’s body in during launch/flight?

Tension from internal pressure -- these aren't really balloon tanks, but they absolutely benefit from internal pressure.

What about during the slow-down burn?

The same, its just a much higher proportion of gas rather then liquid. Basically on the pad its mostly full with liquid, as it launches, it pumps back part of the gas created in the engine back into the tank. That called 'Autogenous pressurization'. So they don't need an extra gas like helium, as for example Falcon 9 needs.

The big issue during landing is that you need to make sure that the engine doesn't suck in gas. That causes bubbles and can destroy the engine. This was actually the failure that caused some of the earlier SN flights to explode or not produce enough power from the engine.

You need to either have header tanks, like the booster. Or some kind of method to push the liquids into the right place.

If you want to deep dive into the whole problem, 'CSI Starbase' on youtube has a brilliant series on all the engineering problems with all of this. Its a very complex problem.

Ok, so I was right: Does this end up being more efficient because more of the loading is in tension instead of compression?

This bugged me because everyone was saying the deletion of legs was key, but to me the struts are basically legs mounted up high. It's taking advantage of tensile loading that promotes the weight reduction.

the other big difference is that legs need to extend below the engine which means they need up move, which makes them much bigger and more complicated than the catch pins

Also, the struts are much smaller than the legs, and there's no need for moving parts or hydraulic mechanisms.

The booster is already strong enough to support itself in compression, because that's what it does during ascent and the landing burn. The entire bottom structure of a rocket (the "octaweb" for F9) is basically made to transfer the thrust compression loads of the engines into the tanks.

The "struts" are needed anyway to lift/move the rocket using cranes, they aren't optional.

One of the things that came up in one of the livestreams was that some of the changes to the starship heat shielding were to test a couple of different spots for those struts - because the booster doesn't do orbital-speed reentry, starship itself does, so to catch that, you need to avoid burning off the struts...

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.

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

> 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.

This is a pic of the top of the booster. You can see the landing lugs between the grid fins.

https://x.com/TrainOfError/status/1846030879602209054

I've never understood this, because the economics of hourly launches just don't make sense. There's not nearly enough demand, even assuming they drive prices down and induce demand.

Today, there are about ~1,100 metric tons of satellites launched into orbit annually. Starship is aiming for $100/kilogram cost per kilo to orbit. Let's get absolutely wild and assume that Starship takes over the entire world's launches. It would earn what, 1,100 tons * 1000 kilos/ton * $100/kilo = $110,000,000. $110M is... not a tremendous amount of money. It's definitely not enough to be building a fleet of rockets up.

Only about 20% of satellite costs are due to launch (and that was found in a pre-SpaceX era), so it's not likely satellite builders are going to optimize solely on cost. It's not an order of magnitude cost savings for builders. So SpaceX will have to find other means to compete -- reliability, capability, etc.

The US puts up <100 orbital launches per year. Even if Starship took all of those (and it won't), they'd need to have 10x the number of launches for an hour level restack and refuel to make a difference. And that's not even counting the differences in payload capacity. Add several whole integer multipliers to account for that. For starship to need an "hours-scale" relaunch time, you'd need something like 50x+ the number of launches we currently have AND every launch in the nation to be on the platform.

It's a cool engineering target, but it's total nonsense for now.

I think they have a "build it and they will come" attitude. While their own Mars goals will need 100s if not 1000s of launches they also see new customers that would want launch and even recover much larger payloads than what are feasible today

I think that's a reasonable attitude to a point, but like, it doesn't scale infinitely. Build it and it will come to 50-100x today's launch capacity? And Mars is still a laughable pipedream. Doing 100s of launches will cost SpaceX so much more than they are making selling launches to the rest of the world, it simply makes no sense.

And like, I'm a space enthusiast. I think we should be out mining asteroids and setting up space living quarters. I just... hourly starship launches don't make any sort of logical sense.

What they do make sense as is a marketing gimmick for Elon to get on stage to appeal to emotions of investors and nerds online. It's a gorgeous dream! I want it to be! But it's just a clever emotional appeal to get you to not think too hard or too critically.

The asteroid belt is even further than Mars so you need rapid reusability for that too.

The asteroid belt doesn't have nearly the gravity well to send payloads back from, but it seems much harder to make propellant there in situ.

You don't need to go to the asteroid belt to get to meaningful asteroids, and in fact many fantastic candidate asteroids come much, much closer than Mars.

They don’t come as close as LEO though so you still need rapid reusability.

> Build it and it will come to 50-100x today's launch capacity

Yes, because Starship promises 50-100 times cheaper delivery of kg to LEO.

Read https://caseyhandmer.wordpress.com/2021/10/28/starship-is-st... on the subject.

Let's take the pessimistic estimates of Falcon 9 Heavy, which are about $3000/kg to LEO. (The optimistic estimates put it closer to $1500.)

You are suggesting that pessimistically, Starship is aiming at $30-60/kg to LEO. (Or, using the optimistic estimates, $15-$30/kg to LEO).

I don't think in even Elon Musk's wildly optimistic press conferences he pushed a number below ~$100/kg to LEO. I don't know where you get the idea that launch costs are going to come down 50-100x.

Back-of-the-envelope calculations look like this: fully reusable Starship's flight costs roughly the cost of fuel, which is 1-2 million dollars per flight, both stages. If the Starship carries 150 tons to orbit per flight, and it costs $1.5e6, then we have the price of 1 kg on orbit equal to $1.5e6 / 150e3 = $10. Which is rather comfortably 100 times cheaper than SOTA.

Wildly optimistic would seem to be even lower estimations. If both oxygen and methane we can get from atmosphere - and we have both efficient detanders and demonstrations of e.g. Terraform Industries which use solar panels and oxygen to pull CO2 from atmosphere and produce CH4 - then the question is of optimization, and we're just starting here for this application. So, a flight of Starship might get cheaper than $1 million - the question is, how much and how soon?

I haven't seen anywhere suggesting a $1-2m launch cost is a reasonable target. Sure, maybe $10m is achievable, but $1m is so far off it's not useful as a cost estimate.

I think it's just you didn't see such estimates. Here's what I found first. https://www.space.com/spacex-starship-flight-passenger-cost-...

It depends on what you are thinking critically about - what is your frame of mind. You don't see a viable business here.

But SpaceX does see several possibilities. One is supplying a US Moon base and US space stations. Since Starship/Superheavy rockets are so inexpensive to build (about 100M in expendable configuration [1] even doing something like that would be profitable for SpaceX.

For Mars colonization, Elon Musk has said his target for Starship to Mars cost per flight was USD 10M. If it can take 100 people, and they each pay USD 200K per person, that's USD 20M, a 10M profit for SpaceX.

It might also be that a nation state might want to fund something like that to establish a base there.

Again, you may see a viable business in Mars colonization. But SpaceX does. So do other people. It was conventional wisdom that Starlink would not work, but it is now quite profitable. [2]

[1] https://en.wikipedia.org/wiki/SpaceX_Starship

[2] https://www.nasdaq.com/articles/billionaire-elon-musks-new-s...

> For Mars colonization, Elon Musk has said his target for Starship to Mars cost per flight was USD 10M. If it can take 100 people, and they each pay USD 200K per person, that's USD 20M, a 10M profit for SpaceX.

Musk has lied many times about many things. This one in particular makes less than 0 sense - Starship has nowhere near the capacity to take 100 humans to Mars even just including the provisions needed for the trip, unless you assume that those people will essentially sit in their own little cell for 2 months.

Thank you. I was timed out, but I was going to say there's 0% chance of Starship taking 100 people. Do you have any concept of how much water, oxygen, C02 scrubbing, food, shielding, medicine, and infrastructure you need to support 100 people?! Imagine the device they have on the ISS, multiply it by 20, and then pack all the water it uses in a year in advance onto the ship. Then pack 100 warm bodies in there too?

It's simply not possible in the ship they've designed.

You seemingly ignored the cost of the return ticket, which even with your fantasy numbers would cost many millions of dollars.

Cramming one hundred people into a starship is eerily reminiscent of overloaded slave ships. The assumption is that you will die on the journey or at your destination.

They don't really plan for people coming back from Mars, for most of them its a one way ticket...

It's not nonsense. To refuel Starship to land on the Moon like the NASA HLS program proposes [1], it will take 16 Starship Tanker flights [2][3]. So 16 launch, transfer propellant, land, refuel and refill propellant on the ground, and repeat.

For Mars launches, which is what Starship is mainly designed for, it's also 8-16 Tanker flights to fully fuel a Mars Starship. But SpaceX anticipates sending fleets of ships each synodic period (2 years), when Earth and Mars are closest. For a fleet of 10 Starships, that would be 10 launches of the Mars Starships, then 160 launches of Tanker Starships to fuel them.

You might debate whether Mars colonization is possible or desirable, but Starship and the high launch rate is designed for refueling Moon and Mars landing vehicles.

[1] https://en.wikipedia.org/wiki/Human_Landing_System

[2] https://en.wikipedia.org/wiki/SpaceX_Starship#Planned_launch...

[3] https://en.wikipedia.org/wiki/Starship_HLS

I think you are being taken for a ride, but hey, if SpaceX does this in the next 15 years come find me.

I think a big part of the motivation to have many launches within hours is because in order for Starship to deliver anything beyond low earth orbit it will need refueling by many other Starships acting as tankers.

This means that for one mission to the Moon for example you might need >10 Starships to launch, and it's better to have them closer together so that you don't have fuel in space being heated by the sun for days.

It remains to be seen if they will actually reuse a booster on the same day, but there is a use case for it.

> it's better to have them closer together so that you don't have fuel in space being heated by the sun for days.

A hydrogen stage for Soviet N-1 rocket was designed so that it would be used near the Moon. The shelf life was going to be about 11 days (I think astronautix.com has this datapoint).

Starship is bigger, and methane/LOX is hotter than liquid hydrogen. Will it be storable for a month?..

http://astronautix.com/n/n1blocksr.html

I wonder how much improvement a "sunshade" type thing could make in reducing boil-off.

EDIT: or even just orienting the heat shield itself towards the sun, it probably has a fair amount of insulation ability at normal temperatures too.

Starship is intended to be human-rated. It’s possible to get anywhere on Earth in an hour. One possible use of Starship is to compete with long-haul aircraft routes. Rapid reusability becomes very important in that situation.

For Mars and Moon missions multiple Starships have to launch to refuel the Starship that will actually take the trip. Like, a dozen or more. Again, rapid reusability of the booster is appealing in this situation.

The Starship Earth-to-Earth idea is a complete non-starter. Landing what amounts to an ICBM anywhere near a populated area is not something that’ll be allowed for multiple lifetimes, if ever. Maybe in the US because Musk is the government now. Just risk aversion will inhibit it, plus the economics for it will never make sense either.

Just because Musk says some things doesn’t mean they should (or will) exist. His predictions are mostly marketing.

Just setup oil-rig style landing terminals in the various oceans.

He's already landing Starships in oceans.

People today pay $15,000+ USD per seat now for 1st class, and it still takes them 18+ hours.

1st class is 18h of extreme comfort. Starship would be a few hours of extreme discomfort. It's very likely much of the target audience wouldn't even survive the accelerations if they were allowed to attempt it.

It's 60 minutes to any point on the planet. 100 people fitting comfortably with a lot more room than a current airliner. The G forces are meant for humans. Very different considerations. No need to bring food or have bathrooms when the flight is that quick.

The G forces are meant for astronauts, not for regular people rich enough to buy this flight. And the whole point of first class is that you pay for luxury. The duration of the flight barely matters, the luxury is the point, and a rocket just can't offer that. There are very few situations where rich people would be willing to put up with the discomfort for a shorter trip.

Especially given that the total trip time will likely be much longer than the flight itself. Consider that you can't take off or land Starship anywhere near a densely populated area, it has to be at least a few hours away by car from anywhere that people actually live.

So you can take a chauffeur to the airport, go trough priority and special luxuries as a first class passenger until your flight for say 1h total, board your 15h flight spent in luxury, and then a limo waits to take you to your destination 30m away from the landing airport.

Or, you can get driven for 3 hours out to the Starship launch site, board the rocket, probably in a special life support suit, wait some hours on the ship for it to be filled (humans are never allowed to approach an already full rocket), fly for one hour in an extremely bare bones flight that literally feels like a roller-coaster (so forget any kind of phone access, you'll be lucky not to puke while just holding on). Then you'll arrive at your destination landing area, ready for some limo to take you on another three hour trip back to civilization.

So you've saved maybe 8-10 hours, being extremely generous and only for the longest haul flights possible, but got none of the luxuries you'd expect. And you get to pay much more for the whole deal.

Remember that the Concorde halved or less the Paris-New York trip, and gave all the luxury you could want, and still went out of business.

Have you actually bothered to look it up? I have.

https://preview.redd.it/b9f14da6y0ac1.png?width=1105&format=...

You only experience anything over 1.5 Gs for 180 seconds.

Please stop making stuff up and look at the data.

According to SpaceX themselves [0], the axial acceleration can reach up to 6g, though they do say it can be throttled, so what can be achieved in practice remains to be seen. Some graph on reddit with no other context is hard for me to trust.

[0] https://www.spacex.com/media/starship_users_guide_v1.pdf

The link I provided sources the data from an actual Starship flight. Just cause it's hosted on Reddit doesn't change the data. The link you provided was put together before flights even started from simulations.

Concorde stopped flying for lots of reasons, not the least of which is that BA was the only one flying them by the end. In a different world, had there been a robust cargo program (and a reason for one), it would not have been on British Airways to run the program by themselves and the program would have continued. This is hypothetical, of course, but the rockets are flying to deliver cargo (and people) to space anyway, so there's a lot of expertise being built up that doesn't depend on a passenger service.

I don't know if rocket passenger service will ever happen or become routine, but there's just so much to the Concorde story that simplifying it like that isn't a good case study that does the program justice.

How is a starship in anyway like an ICBM?

ICBMs are weapons, and are dangerous because you target them at specific targets and they explode.

How is starship coming down significantly more dangerous than a plane? If they can demonstrate similar levels or reliability (a huge ask), then I don't see a problem.

ICBM’s take a payload (warhead) and deliver it from the launch point to somewhere on the earth very far away (on another continent).

If you don’t see how earth to earth starship use couldn’t be construed as a type of ICBM, I suspect you’re thinking branding means a lot more than capability.

Two paratroopers and some electronics can turn a passenger jet into a bomb carrying many kilotons of conventional explosive.

Trucks have blown up buildings. Anything is a weapon if you arm it.

Conversely...

> Two paratroopers and some electronics can turn a passenger jet into a bomb carrying many kilotons of conventional explosive.

A fully fueled 747 only carries about 190 tons of fuel and 140 tons of cargo. How do electronics turn that into kilotons of explosives?

Centitons of explosive then. Much like a Starship.

I don’t think jet fuel is as explosive as TNT so these two paratroopers would have to fill the cargo hold with tens of tons of explosives.

Jet fuel has significantly more total energy per unit of mass than TNT. 46 MJ/kg for Kerosene [https://en.m.wikipedia.org/wiki/Heat_of_combustion], and 14.5 MJ/KG for TNT [https://en.m.wikipedia.org/wiki/TNT].

Kerosene can be used to make a thermobaric bomb in the right conditions. It’s just just trickier to actually do than detonating TNT. Notably, TNT can certainly help accomplish making a thermobaric bomb.

Either way, the cargo capacity by weight for a 747 is still the same.

More energy =/= more explosive. Are the fuel tanks of a 747 conducive to creating a thermobaric bomb? By two paratroopers?

With some TNT or cutting charges and an electronic device (timer/detonator)?

I didn’t propose the initial idea, but it actually could probably work if the plane was flying [https://www.sciencedirect.com/science/article/pii/S001021802...], and [https://tetrazolelover.at.ua/WpnryInTheWoods/Zhang2015_Artic...]. You’d want to run some significant calculations first to get the airspeed/timing just right, but yeah.

It would be one hell of a show. Like a tactical nuke, probably.

Edit: did the math because I was curious. A fully fueled 747 contains approximately 9 trillion joules of energy worth of fuel (not counting any payload, or the energy in its aluminum fuselage - which would be significant). A ton of TNT equivalent is 4.181 gigajoules. So the fuel load of a 747, if properly detonated, would be “equivalent” to a 2KT nuclear bomb.

A 747 has a maximum payload capacity of an additional 100-120 tons.

The B-2 famously bombed Afghanistan from Missouri. That doesn’t make the 747 a weapon.

If you don’t think a 747 should be considered a potential weapon, then…. 9/11. Literally.

Same as trucks/cars and carbombs.

For the same reason, anything like we’re discussing will also be considered a potential weapon by any country paying attention at all. And counter measures and restrictions will be installed.

> If you don’t think a 747 should be considered a potential weapon, then…. 9/11. Literally.

Yet we still have airplanes, boats, cars, sports equipment, lawn tools, and kitchen utensils. Nothing about Starship makes it more likely to be weaponized than anything else we already account for in our daily lives.

> For the same reason, anything like we’re discussing will also be considered a potential weapon by any country paying attention at all. And counter measures and restrictions will be installed.

Is “potential weapon” really the way countries view vehicles crossing borders? I have never gotten that impression. Border crossings maintain some healthy skepticism but not because a Camry is similar to an M1 Abrams if you squint really hard.

I’m honestly not sure what relation your comment has to what I wrote or this part of the thread.

ICBMs and M1 Abrams also exist? They also are used carefully and heavily regulated.

Heavy aircraft are also heavily regulated, and their presence near occupied areas is heavily controlled - including with fighter jets and AA installations on standby in many areas.

Car bombs are a huge issue in many parts of the world, and approaching some facilities in a car in those places without going through exactly the right procedures will get you shot before you can get too close.

I’m not saying it shouldn’t be built, rather that if you expect it to be able to be allowed to go anywhere and do anything without significant security measures and/or even bans, that isn’t how this works. Because it wouldn’t be hard for it to be defacto a ICBM, just like it wasn’t hard to turn those planes on 9/11 into massive cruise missiles.

You can’t really turn a car into an ICBM the same way, correct?

> I’m not saying it shouldn’t be built, rather that if you expect it to be able to be allowed to go anywhere and do anything without significant security measures and/or even bans, that isn’t how this works.

Why would I expect this? Did I say something to make you think I believe this? Clearly rocket travel would be regulated, is that not obvious?

ICBMs are scary because of their payloads. A weaponized Starship wouldn’t do anywhere near the damage of an ICBM’s nuclear payload.

Per your comment above. “The B-2 famously bombed Afghanistan from Missouri. That doesn’t make the 747 a weapon.”

Then later I pointed out that 747’s literally had already been used as weapons to commit one of the most notorious crimes in modern history.

Then later you said “Nothing about Starship makes it more likely to be weaponized than anything else we already account for in our daily lives”.

Except it does - because it literally can be trivially turned into an ICBM way easier that anything in our normal daily lives. Just like an airliner being hijacked can give a terrorist a huge cruise missile they otherwise would not.

And ICBMs are not just dangerous because of nukes. But would also allow a non-state actor who somehow gets ahold of a nuke, or dirty bomb, or anthrax, or whatever to potentially deliver it in an ICBM way.

But they could also be targeted at someone with actual nukes to force them into a response which could potentially kick off an actual nuclear war, yes?

None of which is feasible with what anyone normally experiences in their daily lives.

> Then later I pointed out that 747’s literally had already been used as weapons to commit one of the most notorious crimes in modern history.

I see, you aren’t differentiating between something created as a weapon and weaponizing otherwise peaceful objects.

> Except it does - because it literally can be trivially turned into an ICBM way easier that anything in our normal daily lives. Just like an airliner being hijacked can give a terrorist a huge cruise missile they otherwise would not.

I don’t think a Starship could be turned into an ICBM at all. Anyone who tried to replicate that trajectory in a Starship would be turned into jelly by G forces shortly before being incinerated by atmospheric drag.

> And ICBMs are not just dangerous because of nukes. But would also allow a non-state actor who somehow gets ahold of a nuke, or dirty bomb, or anthrax, or whatever to potentially deliver it in an ICBM way.

This is already possible with existing rockets. Is your concern that a terrorist would sneak a WMD onto a rocket? Because if they can do that they can also sneak it onto an airliner and do the same damage.

> But they could also be targeted at someone with actual nukes to force them into a response which could potentially kick off an actual nuclear war, yes?

How does Starship uniquely make this a possibility? Like someone hijacks a Starship in Texas and then suicide bombs Beijing in some kind of false flag operation? Starship is clearly not an ICBM. It doesn’t have the same flight characteristics and doesn’t originate at an ICBM site. China can see that.

Given the proposed capabilities of Starship I don’t see a novel threat. Our existing defense mechanisms remain effective.

wow.

Starship is to an ICBM what a 747 is to an F/A 18.

Noise is a major concern for sure. But when the competition takes 18 hours you can put the launch and landing sites in very remote places where that’s less of a concern then feed them with planes or trains.

Regardless of how practical you think this is it is the reason SpaceX is pushing rapid reusability.

> The Starship Earth-to-Earth idea is a complete non-starter. Landing what amounts to an ICBM anywhere near a populated area is not something that’ll be allowed for multiple lifetimes

The US military actually has a contract with SpaceX to develop this to enable cargo drops, and in a later stadium even personnel, in 1 hour anywhere on the planet.

I suspect that if you're at the point where the US military intents to drop cargo or soldiers into your country within an hour, they're not going to be too concerned with asking for permission.

> One possible use of Starship is to compete with long-haul aircraft routes.

The per pax price here would be astronomical. Starship launches are in the tens of millions of dollars per launch, and human rated spacecraft vehicles cost even more. Even if you are putting a thousand people onto the spacecraft (which is a stretch), you are looking at 10s to 100s of thousands of dollars per ticket.

Then you'd need the infrastructure to actually operate the rockets. That includes refurbishment, grounds crews, basically a whole Kennedy Space Center operating to launch these things.

And on top of that, you'd need an urban area willing to deal with constant sonic booms. Even one launch/landing cycle from these rockets is multiple sonic booms. The noise would be unbelievable. No urban center is going to allow regular starship launches out of it, so you'd have to go a loooong ways out. Which then means either a long boat ride or a short flight back to the city center. Which entails baggage transfer and potentially significant delays.

On top of that, space flight is not easy on the body. You can't just put grandma on a rocket and trust that it'd be a comfortable experience. Both the exit, zero-g, and re-entry portions of spaceflight are significant w.r.t. the forces they exert on the body.

It's a neat idea, but like all the neat ideas in the thread mentioned so far it's all marketing. Run the numbers yourself, think through the externalities. It's not like air transport at all.

> The per pax price here would be astronomical. Starship launches are in the tens of millions of dollars per launch, and human rated spacecraft vehicles cost even more. Even if you are putting a thousand people onto the spacecraft (which is a stretch), you are looking at 10s to 100s of thousands of dollars per ticket.

That’s the case today but they’re essentially all disposable so far. If it meets expectations the cost will be much lower, approaching the cost of fuel.

According to Quora (yuck, I know) fully fueling a Starship snd Super Heavy costs about $1m [1] and a 747 is about $200k [2]. If Starship can carry 1,000 people that’s $1,000 per passenger in fuel. A 747-8 can carry up to about 600 people for $333.00 per passenger.

3x the price in fuel is something but Starship can get to orbit on that fuel load which means anywhere on earth. The 747-8 can “only” go about a third of the way around the earth on a full tank. So it’s within the realm of economic possibility especially considering the enormous time savings.

If all we cared about was fuel efficiency we’d use trains and boats for long distance travel. Time is money.

> It's a neat idea, but like all the neat ideas in the thread mentioned so far it's all marketing. Run the numbers yourself, think through the externalities. It's not like air transport at all.

Correct. The difference is more like an airplane vs an ocean liner or train.

I agree it is impractical but it is a reason for rapid reusability.

A smaller version of something like Starship could be more practical for earth-to-earth service.

It’s already the case that some people can’t fly for health reasons. Space travel won’t be for everyone but the fact is availability will continue to expand.

[1]: https://www.quora.com/What-does-it-cost-to-fully-fuel-a-Spac...

[2]: https://www.quora.com/How-much-does-it-cost-to-fill-a-747-je...

Great, now we can subject millions of people to hearing loss for the benefit of billionaires being too petty for international flights.

The ticket price would be more like first class airfare so not limited to billionaires.

I don’t think anyone is suggesting operating Starship anywhere near populated areas so hearing loss also isn’t a concern.

Starbase is like 10km/6mi from Port Isabel (5 000 people) and 30km/18mi from Brownsville/Matamoros (700 000 people). That's not that far.

If you don't operate it near populated areas then that negates the faster transport. People don't pay a lot of money to fly to the middle of nowhere, they pay a lot of money to go between populated areas. If Starship has to land 200km from its destination city, then you need to plan for several hours of onward travel.

It doesn’t negate the faster transport because it’s 18x faster. That leaves time to take a short flight on both sides.

Bill Gates once complained that independent developers, other software companies aren't keen about building software for Microsoft's modern graphical environment, Windows, so he had to put his own engineers to work on that. Legend then goes that it's how Office application suit was born :) .

With SpaceX Musk surely understands he's aiming way higher than the capacity of the modern space launch market. Your, whaaaaat, reasoning was - and unfortunately even now sometimes is - the standard among the industry professionals. That's why rather early on Starlink - the project which was going to employ Falcon's capacities - was born.

With Starship we see some obvious uses for launches - orbital tankers - because Starship doesn't really fly anywhere from LEO without refueling, Solar system probes - we probably going to see many, space telescopes, unmanned satellites of many kinds, manned orbital stations. I hope a Moon base - or several - would be another customer of Starship launches. Elon was talking about picking some slice of the world market of cargo and passenger transportation. Maybe we'll see some other uses which we don't see today.

The point, roughly is that, yes, here we have "build and they'll come", and SpaceX will help them to come in all possible ways. So I disagree that it's total nonsense, it might be actually a very good idea.

> Legend then goes that it's how Office application suit was born :) .

Legend indeed. All the main Office applications either started on the Mac and/or were bought from third-party developers.

This is a legend :) some apps were running under DOS even before porting to Windows... But still a legend no worse than some others :) .

No Office application came from DOS to Windows. They either came from the Mac (Word, Excel, PowerPoint) or directly started as Windows apps (Access). Word for DOS was a completely different application with no relation to the Mac and Windows versions.

I guess the Word for Windows is as related to Word for DOS as Atlas V is related to Atlas II. Thanks.

Vertical integration has always been a key aspect of SpaceX (and Tesla for that matter). Starlink is perfectly in line with that strategy.

Doesn't this argument prove too much? Long ago, compute was extremely expensive. The cost of compute went down, but people made tons of money selling more and more computers. The same was true for most technologies when they were first invented.

Yes, satellites are expensive compared to launches, but that's because launch costs are so high and launches are so infrequent. If you're spending the money to launch something into space, you'll also spend lots of money making sure that satellite is as reliable and as capable as possible. For example: The James Webb Space Telescope required a complex origami folding mechanism, but it could fit unfolded in Starship's payload bay. Removing that constraint would have saved the program hundreds of millions of dollars.

If the cost of something goes down, people buy more of it. This is basic economics, and it would be foolish to assume it doesn't apply to space launches. There are quite a few potential markets that would become viable if launch costs went down: space tourism, rapid point-to-point Earth transport (this would be especially useful for the military), cheap and rapid deployment of new satellite constellations, single module space stations, cheaper satellites due to fewer mass constraints, orbital radio telescopes, beamed power, space infrastructure such as asteroid harvesting, and so on. I doubt all of these things will exist in the future, but a 20x reduction in launch costs would make quite a few of them profitable. Just as how people 50 years ago couldn't have predicted all the future uses of cheap, fast computers, we can't predict all the uses of cheap, fast launches. What we can predict is that lower costs will increase demand.

More satellites == more space debris pollution, not really something I'm interested in supporting. Eventually we won't be able to safely get off this rock if there's too much space trash orbiting.

https://en.wikipedia.org/wiki/Space_debris

This https://en.wikipedia.org/wiki/Kessler_syndrome

Thanks! This is the link I was searching for but didn't find.

Unless you specifically send satellites to hunt for debris and bring it back. We have NORAD database of flying objects and Starship possibilities... hmm, I wonder if more satellites == less space debris pollution with such an approach...

What's a database going to do for you when your craft runs into debris? Nothing.

These databases (which include collision risks) are public. Satellite owners use them to make maneuvers so they can avoid getting too close to debris or other satellites. Since these collision risks can be predicted days in advance, it takes very little thrust to prevent them. Even cubesats without propulsion systems can change their orbits, as their orientation affects how much drag they experience.

Agreed, this will generally work up until the Kessler Threshold is reached.

I was addressing the comment about the economics of lower launch costs, not space debris. Similar to past pollution issues, I think it will be a problem but not a show stopper. There are already global standards for satellite end of life procedures. Most governments require that satellites be able to passivate themselves so that pressure vessels or batteries don't explode and create more debris. Geosynchronous satellites are required to have extra propellant so they can move to a graveyard orbit. Many satellites are put into low orbits so that atmospheric drag will cause them to deorbit within a known time frame. And lower launch costs will make it easier to launch spacecraft that can clean up debris.

Also, reusable spacecraft such as Starship actually reduce the amount of debris created per launch, as most space debris comes from spent upper stages. Of the 25 recent debris producing events listed on Wikipedia[1], 16 were caused by debris that would not be created by a reusable spacecraft (either an upper stage, a payload adapter, or a fairing).

1. https://en.wikipedia.org/wiki/List_of_space_debris_producing...

By that same logic you think humans should not use ships right? I mean, more ships, means more ocean debris?

The 80% cost of satellites is in large part optimizing them for infrequent high cost launches. Bringing the cost of launch down means we can launch a lot more stuff and that stuff doesn't have to built to the same quality as e.g. the James Webb or even an Intelsat GEO satellite.

This kind of launch capacity is going to change the entire economics of building stuff for space. https://caseyhandmer.wordpress.com/2021/10/28/starship-is-st... has some interesting writing on this.

$100/kg is the cost, not what they are charging. The only missions that will be launched at cost are SpaceX's own payloads (Starlink satellites / Mars colony shenanigans).

>I've never understood this, because the economics of hourly launches just don't make sense. There's not nearly enough demand, even assuming they drive prices down and induce demand.

There's no demand for travel that would take you to the other side of the earth in 1-2 hours?

> The US puts up <100 orbital launches per year. Even if Starship took all of those (and it won't), they'd need to have 10x the number of launches for an hour level restack and refuel to make a difference

There's an interesting post[1] on r/enoughmuskspam drawing some conclusions (based on well documented history) that SpaceX is just an extension of the 80s Star Wars/SDI program. Little easter eggs like the fact that the Falcon rockets are named after the DARPA FALCON Project, Musk's ties to directors of the SDI program, etc.

If the real goals of the SDI program are to be realized, i.e. winning WWIII by knocking down all the enemy ballistic nukes, the US would have to put a lot of mass into orbit. You'd need some kind of cheap heavy launch system to put Brilliant Pebbles[2] up there, or as we're calling it these days, Starshield[3].

I think this is 100% the plan, and Musk has gone so hard right because the Heritage Foundation was the original proponent of SDI/"Let's start and win WWIII" and they're still the power players behind the republican party. (Fun fact, SDI and Brilliant Pebbles were heavily pushed by Dr. Strangelove himself, Edward Teller.) The stuff about populating Mars is just an exciting story to tell the rubes so they don't go asking questions about your massive space-based weapons platform.

[1] https://www.reddit.com/r/EnoughMuskSpam/comments/1gdx11x/elo...

[2] https://en.wikipedia.org/wiki/Brilliant_Pebbles

[3] https://en.wikipedia.org/wiki/SpaceX_Starshield

As if I needed more things to worry about...

Your claims are simply incorrect.

First, Musk has been talking about Mars since before he founded SpaceX. Other people such as Adeo Ressi, Robert Zubrin, and Reid Hoffman have reported Musk talking about colonizing Mars as early as 2001. It was only after that that he went to Russia to try and buy old rockets, thinking that landing a greenhouse on Mars would excite people about space again.

Second, Falcon 1 was named 18 months before the DARPA FALCON project existed. And the contract that SpaceX was awarded was less than half a million dollars. Nine other companies got similar contracts, including AirLaunch and Orbital Sciences Corp. Only Andrews Space, Lockheed Martin, and Northrup Grumman got phase two contracts.

Third, the Starshield program is almost entirely a product of the Biden administration, and its capabilities are nothing like SDI. Current Starshield satellites are similar to that of Starlink, but owned and operated by the US government. They have better encryption and probably some observational capabilities, but they are incapable of intercepting ICBMs. An SDI program would require technologies very different from what SpaceX has been developing. For example: SpaceX uses liquid fuels, while interceptors would have to be solid boosters.

And finally, SDI is unworkable for several reasons. It takes time to launch a satellite constellation, and during that time an adversary would be incentivized to launch their nukes (since it becomes a use it or lose it situation). Or they would build more anti-satellite weapons and ground based lasers, allowing them to take out enough interceptors to launch a devastating nuclear exchange. And even if the system remained intact, it would do nothing to stop hypersonics, bombers, submarine launched ballistic missiles, and nukes being smuggled into the country. People realized this long ago, which is why (in addition to cost) SDI was cancelled.

The only way your model of the world could be correct is if Musk was a brilliant con man who has spent the past quarter century risking his fortune to develop reusable rockets for the sole purpose of building a system that everyone knows would not protect the US in a global thermonuclear war. And he's somehow kept this secret from the public this entire time, even though he's leaked many other embarrassing secrets. Musk is far from the sanest person around, but such a claim stretches credulity to the breaking point.

You might think SDI is unworkable but Mike Griffin doesn’t[1], and he’s been working with Musk for decades now. Meanwhile Starshield started launching in 2020 under the Trump administration.

You were right about Falcon though, it wasn’t DARPA but the actual SDI Falcon laser program [2].

I don’t claim to know everything and I could be wrong, but it is very unlikely that we’d know all the details the super secret weapons system if SpaceX is actually building it. The parts they wouldn’t be able to hide, however, are definitely visible.

[1] https://spacenews.com/space-development-agency-a-huge-win-fo...

[2] https://www.osti.gov/biblio/12982617

Mike Griffin is one of the most involved people in US space for many decades. Of course he has some connection to many companies including SpaceX. And of course he wanted to encourage and create a more dynamic space company environment in the US.

But to see all this as some sort of linear story is just a conspiracy.

Yes people in the 80s who were part of Starwars continued to exist and continue in many place in the US government. And they still believe in many of the ideas in the 80s, specially Missile defense.

Many of them are space nerds, and simply want to see more space development in general. And they are not secretive about that, there are plenty of interviews you can look up. The whole OpenStack project came about because somebody from Starwars wanted to bring in young people to NASA. The whole company Plant came out of that too.

Specifically in regards to the early 2000s, the reason for DoD support for launch was that after 2001 they realised that they didn't have enough sat capacity over the middle east, and then they realised it would take far to long to launch new sats. Since then DoD has supported various programs for small and rapid launch. DoD has continued this, most recently with the company Firefly. That was the reason for early support for SpaceX and others, not any great dreams of Starwars ideas.

SpaceX however wasn't really able to get in with DoD much, the whole Starwars grand scale idea had no real power at DoD. NASA and the needs to supply station that made SpaceX able to continue to exist and develop. That built Falcon 9.

SpaceX themselves then pushed for Falcon 9 reusability and cheaper price. That then in turn made many old-heads at DoD dust off old plans that were shelved in the 80s and started to look into what could be done with the new capabilities that SpaceX dropped into their labs.

Remember, SpaceX wasn't the only company talking about reusability. Rocketplane Kistler had far more support from 'the establishment'. So Musk was just one of many people who want to do things in space, and most people thought he was likely gone fail.

Starlink was a natural thing for SpaceX to do. LEO internet, was a thing people had been wanting to do since the 90s. And SpaceX jumped on it with private funding. They for sure knew they would likely be able to sell to the government, but they also knew that it wouldn't be easy or fast, so they designed it as a consumer system primarily.

Now that SpaceX the largest producers of rockets and sats, of course DoD would look to them for various other projects. And SpaceX wants to make money, so if DoD asks for bids on some projects, then SpaceX will likely bid if they think they can make money.

Mike Griffin has worked with Musk, but they have also fought each other quite a bit. Even in the early days. Just recently Mike Griffin was the spearhead in the anti-SpaceX lunar lander campaign.

Basically, there is no real story here. Literally everything in modern US spaceflight was influenced by the money that flowed into the space industry in the 80s under Reagan. Many of the same people and same ideas are still around and as the space industry develops, many old ideas are warmed up, and new ideas are developed.

I don’t look at it as being a conspiracy but as the DoD doing its job (with different political groups having different ideas about what that job is) and building technologies and systems to win wars. My take on Musk is that he’s hyperfixated on what one political group wants to do with SDI, and that’s why he’s suddenly obsessing over supporting them. Republicans certainly don’t care about any science nonsense happening with taxpayer money. They want weapons.

I don't think Musk cares much about winning wars or these Starwars DoD projects. He wants to get to Mars. If DoD pays SpaceX to build something, he might do it, but that's about it.

His all-in for republicans is partly because he is anti-regulation and because he has always been a free-speech all the way guy, even before he was more directly political.

He really turned more MAGA during the pandemic when in California, the politicians didn't want to allow him to reopen the Tesla factory.

> I don't think Musk cares much about winning wars or these Starwars DoD projects. He wants to get to Mars. If DoD pays SpaceX to build something, he might do it, but that's about it.

If he's involved in a neo-SDI program I would not expect any of his public statements about his motivations to mean anything at all. He most assuredly has a TS-SCI clearance and probably handlers who are watching his every word and ready to haul him to jail for running his mouth. If I were in that position, I too would be a good soldier and frequently monologue about the agreed-upon cover story of settling Mars.

He is involved because DoD asked for people to bid on projects and DoD pays well. SpaceX is part of a contract for missile defense, this is public information. SpaceX delivers the sat bus, as far as I know. But this isn't all that big of a contract. I would have to look up the details again, but this is public, you can go find it.

Why would he since 20+ years talk about Mars? He went to Mars Society conventions long before he wasn't even remotely famous. If he cared about SDI, why not talk about it, its not that controversial. If it was an interest of his, nothing stops him from talking about it. You think he openly talks about Ukraine, trans issues, Israel and almost everything else that's controversial. But mentioning SDI is somehow to controversial? What?

> probably handlers who are watching his every word

You are disagreeing with every journalist who has interacted with Musk. And tons of other people who have interacted with him. In fact its the opposite, its a whole thing that Musk can't shut the fuck up even if he should by any reasonable definition. Have you done literally any research on this topic?

> If I were in that position, I too would be a good soldier and frequently monologue about the agreed-upon cover story of settling Mars.

What the fuck are you even talking about? 'Agreed up on' with who? People from the Starwars days are very open about what they want and thinking that its a good idea to continue that. They talk openly about it.

Musk talking and pushing these ideas publicly that would be a good thing for them. Because the people that need to be convinced are the decision makers at DoD and the congress. If Musk used his lobbying power to push these ideas, people like Griffin would welcome that. But Musk doesn't, because he doesn't really care. And he rather lobbies for Mars.

Of course if he is part of an ongoing DoD project then he would be under NDA for that project and couldn't talk about it. That's not a conspiracy, that just how DoD contracting works. But SpaceX has not started bidding on such contracts until recently.

You just creating a conspiracy where non exists. The whole conspiracy doesn't even make sense. You don't need Mars as a smoke-screen, you can just say 'we build rockets in order to support DoD and NASA and gain commercial contracts as to make money', that is what other rocket companies do. Talking about Mars in 2002 made Musk look like a delusional idiot.

> People from the Starwars days are very open about what they want and thinking that its a good idea to continue that. They talk openly about it.

Big picture yes, but definitely not the actual details. And maybe you're right, maybe Musk is a true believer. I just think that I can't possibly know what's the truth or not when, if this project is real it would be treated like the biggest state secret in history with plenty of efforts to obfuscate what's actually happening. In WWII we intentionally let people die to protect the fact that Enigma had been cracked, and keeping this program secret would be at least as important to national security.

> But SpaceX has not started bidding on such contracts until recently.

Literally the first thing that SpaceX ever tried to launch was for a DoD contract[1]. Maybe not a big one, but they go way back with the DoD, before they had any serious prospects. So they started out with DoD, and the second they got a single solitary atom into orbit they got a 1.6 billion dollar contract with NASA. Who was the NASA administrator when they got that contract? Oh that's right: Michael D. Griffin.

[1] https://ntrs.nasa.gov/api/citations/20060048219/downloads/20...

> Literally the first thing that SpaceX ever tried to launch was for a DoD contract[1]

I was talking about sat contracts, not rockets.

This was the first and so far only one (outside of Starshield): https://spacenews.com/spacex-l3harris-win-space-development-...

And again, non of this is secret, so I have no idea what you are talking about.

And SpaceX just delivers the sat bus, not any of the other missile related stuff.

This is a minor sideshow for SpaceX.

> Big picture yes, but definitely not the actual details.

People don't talk in detail about national security projects ... shocker.

Everything you are arguing is just typical conspiracy theory 'coincidence I THINK NOT' type of argument. You have absolutely nothing even remotely solid. So Ill show you how its done:

> In 1991, Griffin was the president and CTO of Orbital Sciences

and then

> in December 2008, NASA awarded SpaceX and Orbital Sciences

COINCIDENCE? I THINK NOT! Orbital got 300 million $ more then SpaceX for doing LESS!!!!!!

Northrop Grumman has since absorbed Orbital.

> SDA industry partners now include SpaceX, L3Harris Technologies, Northrop Grumman, Ball Aerospace and General Dynamics.

AHAHAHAHAH COINCIDENCE? I THINK NOT!

They’ll need something like 8 or 10 tanker launches to fully refuel an orbiting starship that will then depart Earth orbit. That’s the initial use case for quick turnaround at the launch pad.

Hard to have a spaceport if your vehicle needs to land in the ocean.

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.

tiny correction, but I believe the capsules are also re-used

> 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.

Rocketlab seems to be able to recover their boosters intact after a sea landing.

But they haven't reused one yet AFAIK. They have reused an engine.

The space shuttle solid rocket boosters were also recovered after a sea landing and reused, but solid rockets are more like simple big metal tubes than liquid fueled rockets are

I don't think they reuse the boosters that they do a splashdown with. So reuse vs trash.

Rocketlab is working in it. They have sent the first one or two to the production line for refurb.

https://www.rocketlabusa.com/updates/rocket-lab-announces-re...

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.

>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.

It would be good because there are many people who, roughly, refuse to believe their own eyes and keep moving goalposts, misrepresenting what they said or meant earlier, inventing additional conditions, changing their mind etc. If you would honestly believe that Starship can fly frequently when you see it flying frequently, you're already ahead of some.

I remember when people doubted that the full-flow staged combustion methalox engines could work... until SpaceX showed over a hundred of them working now.

Then the ULA CEO Tory Bruno claiming that the SpaceX photos of the first Raptor 3 were “partially assembled”, to which Gwynne Shotwell replied with this: https://x.com/Gwynne_Shotwell/status/1821674726885924923?t=v...

I'd consider that cheating on the Gwynne side. It could be argued if chamber tilting mechanism is part of the engine - after all, it was added separately to NK-33 - but surely for Raptors it's considered an integral part, the fire test was then a test of chamber, not the engine :) . Though Gwynne had to answer positively, having little good choice.

The outer ring of engines on Superheavy do not tilt. They're rigidly mounted and exclude even the engine start hardware which is contained in the launch mount, further reducing weight. And they're only used during liftoff, not for boostback or landing.

Raptor is non-functional without tilting. That is, it's possible to build rocket where all Raptors are fixed, but that defeats some ideas of Raptors. And I haven't seen tilt mechanisms considered parts of the rocket.

So, while engines without tilting have been used - e.g. NK-15 - Raptors aren't from that category.

Raptor is used in a non-tilting configuration on both the booster and ship. You could certainly design a rocket to get to space with only non-tilting raptors, if you wanted. It would be silly to consider it incomplete without tilt, even if Starship does have some tilting ones too. Consider it two variants if you like, both complete on their own.

Differential thrust has been used to steer rockets for decades, and raptor has the sort of deep throttling capability required for it. Tilting is absolutely not required for anything but landing.

Yeah - you would still need roll-control, but given there are huge potato smashers already bolted on, it should not be an issue while in enough atmosphere. ;-)

Yup. In addition to the grid fins, there is the warm gas RCS which could perform roll control.

I'd like to suggest the idea that had they been able to operate it "well" without tilting, they wouldn't have added the mass for it.

There's clearly a huge advantage somewhere.

Yeah, landing. As was mentioned.

Not necessary for launch.

Also catching a booster, also landing boosters at all, also achieving cost reduction via landings, also cheap enough phased arrays to make Starlink viable, also also also... SpaceX has a long history of proving doubters wrong.

I remember talking about landing booster when I was in college in the 1980s. Super awesome I got to see it in my lifetime!

And yeah, Starlink was a great purchase by SpaceX.

What part of Starlink was purchased?

It’s fake news, SpaceX built Starlink internally. Even Wikipedia says so: https://en.m.wikipedia.org/wiki/Starlink

Not every piece of misinformation floating around is “fake news”

There's people on the Internet always arguing SpaceX was purchased. Starlink as an idea within SpaceX is older than it's first launch

Reread my comment.

I have but it's a spreading meme. Usually mixed with other falsehoods

Falcon 9 wasn't designed for immediate reuse. Immediate reuse is just a theory right now, but SpaceX has an excellent track record of turning their theories into reality.

SpaceX did purchase some oil rigs with the intention to turn them into launch platforms, but later abandoned the idea. It's probably something they will return to later once Starship is flying regularly. You're right that avoiding the boostback burn is a big advantage. But maybe they don't need to bring the booster back after it lands on a platform, it can just launch again from there. Maybe they could have a bucket brigade of launch platforms ringing the Earth!

The oil rig idea is brilliant, especially for cargo flights.

I.e. the bulk of near / intermediate term launches

Far fewer people care if you "oops" an unmanned rig in the ocean.

The issue is logistics, and in this case isnt an easy solve.

You have to get fuel, and the rocket, out to a pad in the ocean, and have to deal with a rocket lift on varying conditions.

If you dont want to do most of that, then the only option is putting your manufacturing on the rig too, which negates lifting a rocket, but instead makes the rig huge, and requires having a train of ships in and out 24/7 to keep it supplied.

There was even a company in the late 90s that tried oil rig launch platforms and ultimately abandoned it.

Most heavy lift is transported by barge over water anyway.

Since the 2 stages of Starship aren't intended to be road mobile, due to size, there's no transportation benefit to being land-accessible.

So really the main concern is piping propellant... but afaik some rigs off the shallow coast of Texas are directly piped to land?

The main benefit you get is terrifying the FAA et al. less, as the consequences of a missed catch are now out in the ocean.

Musk spoke of 24-hour Falcon turnaround as early as 2011 and as late as 2019.

Immediate reuse means significantly less than 24 hours. Falcon 9's current cadence is fast enough to meet their current launch demand and doesn't need to improve, especially with Starship on the horizon. On the other hand, Starship will need to launch repeatedly in a short amount of time for orbital refueling to work.

So it was declared as a target, was possible but wasn't done because no demand? Knowing SpaceX they'd do it just for bragging.

The fact that it's required for Artemis to work, and the amount (nobody knows exactly but lower bound is like 15) of Starships required to launch in quick succession just highlights how risky, to the point of unsoundness, the project is.

They don’t need rapid reuse for Artemis. It would certainly help but Starship can just hang out in orbit for a few weeks while they do what they need to do to launch all their rockets.

I wonder what the boil-off rate is on the cryogenic propellants.

It really depends - you can do direct injection to GEO now with cryogenic stages. And IIRC Soviets did some tests with kerolox stage (that should eventually launch on the ill fated N1) around the Moon, meaning multi-day flight times with liquid oxygen on board.

If you do the thermal design right, possibly use a sun shade (space is a large thermos bottle after all) or even use active cooling to remove the little heat that gets through, then it should work just fine. :)

The heat shield probably provides some degree of insulation from the solar radiation as well, and it's only needed on one side if you're far from Earth.

Yeah, I was thinking about the orientation during the coast phase & how thermal management could explain the Starship orientation at that point. :)

Also, a rocket that hangs doesn’t need near the structural beef as one that is designed to withstand landing on its feet.

Not convinced about this argument; wouldn't the forces during the slow-down burn be applied much the same as the from the feet?

Actually no - the forces travel inside the "tank" of the rocket, and push against the top of it.

The force doesn't push against the nozzle of the engine.

Same pressure in the tank as in the nozzle? That doesn’t sound right. It would burst.

Same force, not same pressure. The nozzles are relatively small.

I wouldn't want to try to intuit what the force distribution would be and how much is carried through each component of the structure, though — that's what simulations are for.

> The force doesn't push against the nozzle of the engine.

I’m not sure what you are saying here. The force pushes against the nozzle, (and of course the walls of the combustion chamber.) That is the purpose of the rocket engine, to push the rocket forward. They are not just there to provide mood-lights.

I said "nozzle", as in the side walls of the engine.

The force doesn't transfer via those walls, rather it goes through the full tank of the rocket and pushes against the top.

> I said "nozzle", as in the side walls of the engine.

Ok? I seem to have said the same.

> The force doesn't transfer via those walls

Where do you think the force starts on a rocket? What pushes the rocket forward?

The chopsticks on the tower can absorb a lot of the impact, I'd guess.

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?

The booster always follows a trajectory for an ocean landing until it passes a bunch of safety checks, and then it diverts to the launchpad. This way a failure early on can't cause it to crash on land.

What probably happened is it failed a safety check (e.g. a sensor read out of range) and so it didn't divert to the launchpad. It's cheaper to dump the booster in the ocean than to build a new launch tower if it's destroyed in a failed landing. They have an assembly line for boosters, but only one fully complete launch tower at the moment.

The launch tower takes multiple months to build. The orbital launch mount and launch tower and quick disconnect hardware is all custom and expensive and huge. They call it “Stage 0”. Losing that is an order of magnitude more of a setback than losing a Stage 1.

I guess they didn't optimize the towers to be fast-buildable :) because there are several obvious ideas.

The 2nd tower at Starbase is much more modular than the first and is being built at quite a rapid rate.

They’re building one at the Cape, too, but they’re still a multi-month process.

Construct additional pylons?

Why not to use the Mechazilla for adding the next section of tower on top of existing one? So we transport parts to the tower, assemble relatively thin sections of tower nearby, the lifter moving along the tower brings the sections on top of existing ones, and we have a few places for optimizations here. The proponents of The Boring Company may see some parallels here.

have they tried a giant net? lol

Yes: https://youtu.be/oTH3mq7SsK4?t=14

> One is that landing back on the launchpad lets them refuel and relaunch immediately.

How do they structurally, electrically, etc. checkout the rocket after landing?

An ops problem for later. At least now its possible!

It seems like a pretty expensive assumption that landing the rocket is enough. Relaunching the rocket, which requires inspection and validation procedures and technology, is just as important as landing it.

They haven't done it yet and nobody outside of SpaceX knows their specific plans. Of course we can speculate that they will design sensors and cameras to replace any previously required manual inspections.

Like a falling chimney (google it), it breaks because the top can't fall fast enough.

Are they going to need legs when they land the Starship on the moon or Mars?

the booster does not need legs, only starship does

Yes, also the lunar variant won't need a heat shield so that will compensate for the extra leg mass. Not sure what their plans are for a heat shield for Mars.

They're planning on catching starship as well however, as the in-orbit refueling will require a lot of starship launches that aren't going anywhere except orbit and back.

Yes, Starship needs legs to land on the Moon or Mars. They will be lighter than legs for Earth landings, as Moon/Mars have lower gravity.

Not sure about the amount of fuel needed to land, as there is much less atmosphere on Mars, and none on the Moon. I would still guess that it needs less fuel there as well.

Don't they also need fuel to lift off again?

I think Elon has said that it's going to be a one way trip to Mars.

That will have to happen through in-situ resource utilization. aka making the fuel on Mars.

An atmosphere reduces the amount of fuel needed to land, because you can use aerobraking to slow down rather than carry fuel to do it. See the Apollo return capsule, which landed without any rockets, only parachutes and a heat shield.

Yes. Starship HLS will have them.

But the other Starships don't and adding them would make a big difference.

Since you need a huge fuel tank in orbit that needs to be refilled by multiple starships to refuel Starship HLS to actually land on the moon adding legs on those refueling Starships would decrease payload capacity, and thus you'd need even more Starships to refuel the tank for a single lunar landing.

Also, a ship big enough to carry Starship booster would be huge. And then what port infrastructure do you use to bring it to land and transport it to your launch pad? You would basically need your own port right next to the launch site.

Why do people ask the same questions every time? Can’t you search?

Ability to re-launch the same day.

Efficiency. If you don't have to recover the booster, load it up and transfer it back to the recovery & restoration bay, you save time and money. Not to mention if you can land the booster directly on the tower, clean it, fuel it up, and send it right back... imagine 4 Starships launching per day!

Any technical specifics available yet on the reason the catch was aborted? Eg. Which parameters were out of range.

SpaceX hasn't yet released anything AFAIK. My wild speculation: not wanting to risk anything with both Trump and Musk being present at the launch site?!

But normally they do risk any other people? No, not at all. People are miles from where the robot could potentially go even after it is remotely aborted/blown up.

It's not just the area where the first stage might touch down, it's how far large pieces of debris might be thrown in a worst case RUD.

Plus, the Secret Service may be feeling far less tolerant of "eh, it's less than a 1 in BigNum chance of anyone getting hurt" odds than your average Tom, Dick, or Harry.

Sounds a bit farfetched, not like they wouldn't hear it later?

Trump, and Musk, and Cruz (US Senator), and Saltzman (USSF General), and a fair number of other VIP's.

Whatever was or wasn't going wrong in the booster during its landing approach, I'd for-sure bet that the "acceptable" parameters for a chopstick landing were tightened down quite a ways from the prior launch. (Or such a landing had simply been ruled out, by Security fiat.)

> Following a nominal ascent and stage separation, the booster successfully transitioned to its boostback burn to begin the return to launch site. During this phase, automated health checks of critical hardware on the launch and catch tower triggered an abort of the catch attempt. The booster then executed a pre-planned divert maneuver, performing a landing burn and soft splashdown in the Gulf of Mexico.

from here https://www.spacex.com/launches/mission/?missionId=starship-...

Fascinating, the more distractions Musk has, the more impressive SpaceX does. Just imagine what he could do if he were the CEO of a hundred companies!

Is there a publicly documented (or guesstimated) timeline for Starship? What comes next?

Yes. Flight around the moon with passengers scheduled for 2023 [1][2]. No point looking to the public statements of a person who is legally recognized [3] as making such fanciful claims that no reasonable person could possibly believe them.

[1] https://www.cnbc.com/2021/03/02/yusaku-maezawa-opens-up-publ...

[2] https://en.wikipedia.org/wiki/DearMoon_project

[3] https://www.theverge.com/2024/10/1/24259588/tesla-lawsuit-au...

I have been promised a fast iterative development cycle. All I'm seeing are very very small incremental gains with each launch.

It looks like it will take as long as any space project. It will be delayed and take almost a decade from start to completion.

All actual future launch dates and profiles are all TBD. This program is still in its experimental phase. Also all guesstimates are technical only and optimistic - the FAA and/or any kind of serious anomaly can slow things down by months.

What has been guesstimated by the observers and/or stated by Gwynne/Elon:

- next flight some time in jan/feb

- next flight will be a V1 booster with a V2 ship (still Raptor 2s)

- next flight profile will be similar to this one, if they land the ship in the ocean precisely again, the they will try to catch the next one afer that (note this is not currently possible as no existing ship has catch hardware installed)

- stated flight test cadence they would like to reach in 2025 is 25, observers think 10-12 are more likely, in both cases they need to move pretty fast

- both the star factory and the second launch pad should come online fully within the first half of 2025, launch cadence should improve a lot after that

- for Artemis 3 they need to demonstrate fuel transfer in 2025, otherwise the timeline of that program will for sure have to be extended (probably even beyond the already expected delay to 2027)

- elon wants to send a few starships to mars in the 2026 window, and that may actually happen if everything goes smooth as butter until then, but the 2028 window with humans on board is just a wish, very much "elon time", most observers do not think starship will be human rated for such long flights before 2030s

Mars in two years if that goes well - Humans 2 years later, so humans on Mars before end of decade seems like a bet.

They are not that far behind the aspirational goals Elon laid out at IAC in 2016.

Then it was called ITS not the starship and steel was not yet thought about. https://youtu.be/WVacRKN1tAo?si=s0MBP8ejQt3zv-sF&t=3309

As you can see from the chart Mars flights from late 2022. But there was a pandemic amongst other things that came along etc.

Seems they are about 4 years late on a thing 4 years out so you have to double everything?

Is this due to the higher incidence angle ? Seemed like the main 'difficulty' factor that was upped in the mission description

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.

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.

Iirc on the way up they announced the tower was go for catch. Divert order was given on the way back down. Really curious to find out what the reason was because it seemed like a picture perfect splash down. No random fires, no (visible) component explosions. Maybe a range issue like a boat or something?

Yep, may not be related, I'm just going off the speculation + a picture from one of everydayastronaut's cameras showing a rather bent looking antenna structure on the top of the tower.

Many people have lost money on Polymarket. The chance of the sticks catching the Starship was around 75% and of course immediately dropped to 0% after the announcement.

Why can't the tower/chopsticks be as portable as the booster?

Then you have to have something to catch the tower.

You can drive the tower

At some point you might as well just stick rockets on the Earth and move that around.

it's towers all the way down!

I forget that sf novel with mobile cities on crawlers.

Mortal Engines?

It was Mortal Engines by Philip Reeve. Was an ok book. (Better than the film)

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.

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.

why is elon musk never in these comments answering questions? to my knowledge hes never left a comment publicly on HN but has on reddit

Maybe a venture capitalist micro forum isn’t as important as you think it is?

not so micro really

Does it even have an Elon Musk though?

It's not too crazy of a question since Elon Musk has given public interviews in association with YCombinator [1] [2] (and was a founder in partly YC-associated OpenAI [3]), and the fact he seems to spend his limited time these days posting on X, streaming video games, memeing and presumably lurking on Reddit.

[1] https://www.youtube.com/watch?v=tnBQmEqBCY0

[2] https://www.youtube.com/watch?v=SqEo107j-uw

[3] https://www.techemails.com/p/elon-musk-and-openai

Honestly do not understand why rockets are a big deal. What are we going to do with them? If anything we have too many satellites in the sky as is.

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.

They recovered the underwater remains of IFT4’s booster, or at least the business end. As I understand it, IFT4 landed in a relatively shallow area unlike IFT3, which was also in smaller pieces.

https://spaceexplored.com/2024/09/23/spacex-recovers-flight-...

I dunno, I’d be hauling them out and laying them on the beach next to boca chica like dead whales. We’ve gotta start our first spaceship graveyard somewhere.

> think they want to recover it for investigation purposes

These are V1s. Not worth the effort.

FTS wouldn’t have done much anyway. It basically cuts a slit down the length of the rocket and aerodynamics does the rest. FTS at splashdown would just cut it open, it would still be sitting there floating around albeit opened up like a butterflied pork chop.

Soft landings on the ocean never activated FTS. Same for Falcon. Better to sink big pieces than to spread a million little pieces in the ocean.

Hypothetically speaking (asking for a friend), can you intercept the Starship with standard AA missiles as it re-enters?

Nah, Starship is going 6 times faster than standard missile as it re-enters, and ~100km up.

However, it can certainly be hit soon after that phase of flight. That's part of the reason that I never understood the point to point military pitch. There are so many reasons why Starship can't land anywhere near a hot zone.

Eh, still exposed less to AA due to the flight path/time in flight than a typical airplane would be. Any AA would need to be near point of landing (or very long range/expensive, like a theatre level SAM).

Not as crazy an idea as it sounds.

Biggest issue is unlike nap of the earth flying, good luck hiding you were coming in or where you landed. So better get out and moving ASAP once you land.

Yeah, exactly on the ballistic trajectory which lights up every ICBM early warning system in the hemisphere.

The other thing is how many options for diverting does a Starship have? How many mechazilla’s ya got? Can Starship change the LZ mid flight? Can it abort? Are there booster stages ready at each location for quick turn around?

And.. what exact cargo needs to be moved in 1hr, announced to the world, that would not serve the mission better by being moved more quietly in a C-130, or C-17, in 12 hours? I can’t think of one. There are spec ops teams pre positioned around the globe, and they like to keep things quiet. So what is this special cargo?

All good points.

But also, FedEx Worldwide This Afternoon(tm).

For civilian, I can imagine some use cases, kinda. Just not for military.

But such concerns are just as valid for military transport aircraft, yet they exist.

Sometimes, the benefit of getting the cargo to the destination outweighs the risk of being shot down.

Heh, you should check out the reentry velocities of MIRVs - they come in at Mach 7 plus, and intercept is a well solved problem.

Standard missiles, no. (Note there's a type of AA missile called the Standard SM-1/2/3/6.) However, specialized missiles (like the American THAAD and, uh, Standard SM-3) probably could

It could definitely be intercepted by anti-ballistic-missile systems such as the Israeli Arrow system, and modern large calibre systems like the Russian S-400.

Could they have crashed it because of security/safety concerns for President-elect Trump, who was there as a surprise guest, watching the launch with Elon?

Per NYTimes: “It was pretty epic on Attempt 1,” Kate Tice, a senior quality engineering manager at SpaceX, said of the last test flight’s tower catch on the company’s livestream. “But the safety of the teams and the public and the pad itself are paramount.”

Not sure what would have changed compared to the first launch, other than Trump’s presence - and they haven’t described any anomalies.

A launch is one thing: lots of explosive potential, but the kinetic energy is quickly dispersed.

The KE of a botched landing of what’s essentially a ballistic missile would be a whole lot more concentrated…

Or maybe they just didn’t have time to file a modified flight plan for it to enter even-more-specially-restricted controlled airspace.

As far as I’ve seen when airspace is restricted, it’s restricted, there are no “levels of restriction”. If a spaceship is launching, no one can fly - if the president-elect is there, no one can fly. Also, I believe star base is over two miles away, so I doubt this was a concern.

Reply on news.ycombinator.com