Launching fuel with a disposable Starship make no sense. Refueling will be the cheapest option even for LH2 (though why LH2 I have no idea, a double-refueled Starship in a GTO has 15km/sec of Vinf with 150t of cargo)Throwaway Starship takes the base reusable price of $50k/ton and raises it to $400k/ton. Why would anyone want to pay 8x?The only thing I can think of is a structure that can't be easily divided into two launches and then assembled in orbit. Orbital assembly will still be a pretty expensive proposition unless it can be fully automated. We haven't done that on Earth yet.Even then the structure would have be very dense, there's only so much room in the payload bay.
Starship was always touted as a ship for exploring the whole Solar System, so yeah, sure, there has been lots of ideas about expendable ships aired. Unmanned missions to planets and moons without an athmosphere would of course not have heatshields or fins and would not be coming back to Earth either.That's the genius of Starship, as compared to the Shuttle: all the reëntry stuff can be discarded, unlike the Shuttle wings and heatshield.
Quote from: InterestedEngineer on 02/01/2023 05:54 amLaunching fuel with a disposable Starship make no sense. Refueling will be the cheapest option even for LH2 (though why LH2 I have no idea, a double-refueled Starship in a GTO has 15km/sec of Vinf with 150t of cargo)Throwaway Starship takes the base reusable price of $50k/ton and raises it to $400k/ton. Why would anyone want to pay 8x?The only thing I can think of is a structure that can't be easily divided into two launches and then assembled in orbit. Orbital assembly will still be a pretty expensive proposition unless it can be fully automated. We haven't done that on Earth yet.Even then the structure would have be very dense, there's only so much room in the payload bay.I can't think of a reason to launch 250t in one piece just to LEO, but there are lots of reasons you might want to launch 250t for some kind of non-Mars interplanetary mission that needs lots of storable prop on arrival. You'd just have to refuel it in its staging orbit before departure.If you're doing an expendable StarKicker, then what you'd ordinarily consider to be the enclosure for the payload bay becomes a more traditional fairing, which can be jettisoned once q is low enough. That likely gives you a substantial increase in payload. If they manage to get the Raptor thrust increased so that it'll handle ~200t reusably, then 250t isn't an unreasonable number.Note also that, with the fairing gone, you can now assemble even bigger packages by docking them together on the nose. I can't really think of a mission for this other than the extrasolar missions we discussed here, but there's a lot of flexibility to move huge payloads around in one go if you're willing to expend the Starship.
But it has nothing to do with lifting 250t to LEO.
Now, back to - what could require a 250t one-time LEO launch?
Orion is wildly off topic, and can go be discussed in it's own thread to avoid derailing this one.
Quote from: edzieba on 02/01/2023 03:07 pmOrion is wildly off topic, and can go be discussed in it's own thread to avoid derailing this one.Wrong! It is not off topic in the least. You are being political rather than focusing on theoretical technical specifications and possible applications.
Agreed and I loved that thread on extra-solar missions, but the launch capability to LEO of 250t is what is being touted on Spacex's website, and nobody can think of any use for that.
*snip*¹Did we get an answer for whether 250t to LEO is with only an expendable Starship, or does it require expending the SuperHeavy as well?
Quote from: InterestedEngineer on 02/01/2023 04:20 pmBut it has nothing to do with lifting 250t to LEO.The 250t figure was only one of several possible metrics mentioned in the op and the linked information. You seem to be grasping at any minutiae you can find simply to be contentious.Quote from: InterestedEngineer on 02/01/2023 09:04 pmNow, back to - what could require a 250t one-time LEO launch?That is NOT the thread topic! Why are you obsessed with making it so?
Quote from: InterestedEngineer on 02/01/2023 09:06 pmAgreed and I loved that thread on extra-solar missions, but the launch capability to LEO of 250t is what is being touted on Spacex's website, and nobody can think of any use for that.I think you're misreading this, or at least not taking the logical next step. If you have 250t to LEO, then you can refuel and have 250t to anywhere in the solar system. The trick, though, is to get the 250t into orbit in one piece.¹Why would you want to? Two broad classes of payloads:1) Genuine LEO payloads. A 250t payload that fits in 900m³ has a density of 280kg/m³, which is way, way too high for any human spaceflight application. But I can think of a few applications for such a payload:a) Any number of ASAT or counter-ASAT systems, which need massive amounts of delta-v to win.b) I notice that ex-DoD people are writing op-eds about the Chinese looking at FOBS, and how the US should respond. You can pack a whole bunch of Rods From God into a 250t payload. Or, even better, 50t of Rods From God and enough prop to do the inclination and RAAN changes needed to have a prompt strike capability within 90 minutes.c) And of course there are Star Wars-like payloads: orbital anti-ballistic lasers or other beam weapons, kinetic-kill ABMs, who knows? But if you tell Space Force, "250t, price no object," they'l think of ways to use it.d) As for civilian payloads: 280kg/m³ density is way, way more dense than any human habitation can be (air in livable amounts of volume is not dense), but you could put all the heavy equipment for a really big space station / hotel in one payload and have it reach those kinds of densities--especially if you're trading mass for ease of engineering.2) Any number of interplanetary probes, but especially icy moon landers. You can't have a Starship anywhere near an icy moon, for planetary protection reasons. But, after refueling, an expendable Starship can put a 250t payload into JTO that'll get on-station quickly and do a buttload of science for a very long time. You might even be able to do a sample return with 250t to play with.An obvious question for an interplanetary probe is, "Since you have to refuel to get to JTO anyway, why can't you assemble the pieces-parts in LEO?" There are a couple of answers to that:a) Planetary protection regulations make us certify the whole probe is clean before we put it on the rocket, and we can't certify that more than one piece will remain clean when we put them together. (A weak engineering excuse, but bureaucracies don't care that much about engineering.)b) EOR assembly comes with risk, and we don't want to take any risks we don't have to with Flagship programs. (250t is almost certainly a Flagship program.) We want to integrate the whole thing on the ground and have done with it.c) We need a lot of arrival and post-arrival prop, and we can't use methalox, because:i) We can't load cryogenics on the pad and guarantee cleanliness.ii) We're super-conservative and don't want to count on multi-year cryogenic storage.d) You're not getting the Starship back on an outer planets mission no matter what, so why do you care if we push the payload mass limits?____________¹Did we get an answer for whether 250t to LEO is with only an expendable Starship, or does it require expending the SuperHeavy as well?
Because some of us read the actual Twitter thread - 250t to Earth Orbit was the thread. Don't believe me, believe pic from the Twitter thread the OP linked to
It's just a big number for hype, and most LVs do this. Payload numbers for a 200 km circular Earth orbit are very common, even though such an orbit is essentially useless except as an initial parking orbit. It's extremely rare to ever launch a payload that even comes close to an LV's maximum theoretical LEO performance. Maximum performance numbers to higher orbits, GEO, and interplanetary, are much more important.