Not sure why some people are surprised. Elon discussed expendable Starship many times over the years, even when it was still called BFR and some presentations had payload mass specs for an expendable option.Starship turning into a much cheaper mass manufactured stainless steel vehicle makes it even more reasonable than before. Also any ambitious deep pace mission (that doesn't use some additional kick stage, separate probe) will have to be expendable by definition and there was a tweet from Elon suggesting doing that years ago.
4. You could have an expendable version that is refuelable, very much like HLS. You omit tiles, flaperons, etc., and you build fairings the same dimensions as original nosecone. You refuel the thing and it becomes a gigantic Earth Departure Stage that never comes back. Perfect for sending a nuclear submarine which lands on the surface of an outer solar system moon, melts its way through a frozen ocean, and explores an undersea alien world.
Some of us saw this coming from a mile away: Launching Orion on SH with Disposable S2
for and expendable SS the cost is in labor for stacking (and the time tying up the high bay) and raptors. conceivably they'd only have to stack the tanks as the fairing would be a traditional clamshell that would be closed up after the payload is loaded. Expendable wouldn't need any header tanks, of course. So they could churn out expendable upper stages pretty quickly.They've got how many raptors? >150, right? surely some of those would be serviceable for one time use.There's also the consideration that the current thermal protection, or even their whole reusability scheme, might not work. It's a good idea to have a plan to make money from all the starship investment while they troubleshoot reusability.
There's no guarantee an expendable Starship would be all that much cheaper than a reusable: Still needs the engines which are the major cost driver. Atill needs to the tank structure to be assembled. Still needs avionics. Still needs the high power electrical subsystem for engine TVC. The flaps and tiles can be omitted, but are unlikely to make up a significant proportion of the cost of the vehicle.
Quote from: edzieba on 02/01/2023 03:07 pmThere's no guarantee an expendable Starship would be all that much cheaper than a reusable: Still needs the engines which are the major cost driver. Atill needs to the tank structure to be assembled. Still needs avionics. Still needs the high power electrical subsystem for engine TVC. The flaps and tiles can be omitted, but are unlikely to make up a significant proportion of the cost of the vehicle.If you think the engines are a major cost, and you also believe Elon's assertion that each of the 6 engines will ultimately cost $250,000, then the engine cost will be $1.5 million even if they use new engines instead of end-of-life engines.
Quote from: TomH on 02/01/2023 08:35 am4. You could have an expendable version that is refuelable, very much like HLS. You omit tiles, flaperons, etc., and you build fairings the same dimensions as original nosecone. You refuel the thing and it becomes a gigantic Earth Departure Stage that never comes back. Perfect for sending a nuclear submarine which lands on the surface of an outer solar system moon, melts its way through a frozen ocean, and explores an undersea alien world.This. Being able to have Uranus, Neptune (and Pluto?) orbiters that don’t spend decades in transit would be nice too.
Quote from: DanClemmensen on 02/01/2023 03:35 pmQuote from: edzieba on 02/01/2023 03:07 pmThere's no guarantee an expendable Starship would be all that much cheaper than a reusable: Still needs the engines which are the major cost driver. Atill needs to the tank structure to be assembled. Still needs avionics. Still needs the high power electrical subsystem for engine TVC. The flaps and tiles can be omitted, but are unlikely to make up a significant proportion of the cost of the vehicle.If you think the engines are a major cost, and you also believe Elon's assertion that each of the 6 engines will ultimately cost $250,000, then the engine cost will be $1.5 million even if they use new engines instead of end-of-life engines.I think that even a expandable upper stage will be extremely cheap by today's standards, the major advantage compared with a standard model will be the shape. To land a starship, it needs certain outer properties, which even with a large cargo door add limits. Wonder how big a pre-assembled replacement for ISS could be (and what it would cost), if you put it on top of the tank section. If there is a use case for space power, a 200 T module would be a great start. I at least could imagine some quite surprising science satelites. Wonder how big a radio telescope could become. And putting orion and the european service module on top of a Frankenspaceship, should work too.
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.
Quote from: TheRadicalModerate on 02/01/2023 10:54 pm*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?Probably with expendable Starship only. Musk does specify in the Tweet "expendable upper stage." ...
Quote from: whitelancer64 on 02/01/2023 11:01 pmQuote from: TheRadicalModerate on 02/01/2023 10:54 pm*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?Probably with expendable Starship only. Musk does specify in the Tweet "expendable upper stage." ...If only the upper stage is expended, then isn't there a 1:1 correspondence between the additional payload to orbit and the landing propellant, header tanks, heat shields, and body flaps which are not needed for an expendable mission?Where is the 100t found (to increase payload from 150t reusable to 250t expendable) if the dry Starship only weighs ... what? ~ 85 - 100t? How much landing propellant are we talking about?
Let’s say the heat shield issue can never be reliably solved for rapid, cheap upper stage reuse.In that case, Starship can still be a greatly improved evolution of F9. My interest is, how much cheaper can a partially reusable Starship be than a partially reusable F9, on a kg to LEO basis?That would largely depend on the cost of expending the upper stage. So I then ponder on how the upper stage can be easily redesigned to be as cheap as possible? Does it simply become an upsized F9 upper stage? In that case you can have a flared out, detachable and recoverable fairing (upsized from F9’s fairing), allowing for payloads significantly exceeding 9m in diameter.In my view, even if such a partially reusable configuration is the best Starship ever achieves, it can still probably get to around a $30M launch cost, for 150t to LEO.That’s ~$200/kg, which is ~7 times cheaper than F9’s ~$1500/kg cost to LEO.That in itself revolutionises the industry.
Quote from: M.E.T. on 02/02/2023 01:32 amLet’s say the heat shield issue can never be reliably solved for rapid, cheap upper stage reuse.In that case, Starship can still be a greatly improved evolution of F9. My interest is, how much cheaper can a partially reusable Starship be than a partially reusable F9, on a kg to LEO basis?That would largely depend on the cost of expending the upper stage. So I then ponder on how the upper stage can be easily redesigned to be as cheap as possible? Does it simply become an upsized F9 upper stage? In that case you can have a flared out, detachable and recoverable fairing (upsized from F9’s fairing), allowing for payloads significantly exceeding 9m in diameter.In my view, even if such a partially reusable configuration is the best Starship ever achieves, it can still probably get to around a $30M launch cost, for 150t to LEO.That’s ~$200/kg, which is ~7 times cheaper than F9’s ~$1500/kg cost to LEO.That in itself revolutionises the industry. If the development of a reusable and repeatable Starship fails or takes a long time, a simplified, single-use Starship could be used to quickly fill the Starlink-2 constellation of satellites.
What's the risk involved in splashing a Starship in the pacific? I realize Skylab/Mir were big and splashed but they were thin walled structures. SS is solid stainless and a lot of it so wondering how much would make it back to sea level.Quote from: Valerij on 02/02/2023 09:54 amIf the development of a reusable and repeatable Starship fails or takes a long time, a simplified, single-use Starship could be used to quickly fill the Starlink-2 constellation of satellites.
If the development of a reusable and repeatable Starship fails or takes a long time, a simplified, single-use Starship could be used to quickly fill the Starlink-2 constellation of satellites.
People seem to forget, that they have 2 expandable upper stages on the books.The storage depot and the moon lander are exactly this.And I don't get, why people here don't see the advantages for building an ISS replacement (it is due soon).The ISS has 420t took years and ~40? launches to get operational status and did cost around 100.000.000.000 $.Using an expendable Starship, you could be able to archive the same with just 2 launches, possibly ready for usage from day 1.
Quote from: volker2020 on 02/02/2023 12:18 pmPeople seem to forget, that they have 2 expandable upper stages on the books.The storage depot and the moon lander are exactly this.And I don't get, why people here don't see the advantages for building an ISS replacement (it is due soon).The ISS has 420t took years and ~40? launches to get operational status and did cost around 100.000.000.000 $.Using an expendable Starship, you could be able to archive the same with just 2 launches, possibly ready for usage from day 1.I think we need to distinguish an "expendable second stage" from a "Custom non-EDL SS". Depot and HLS are custom SSs and are no more expendable than is ISS or a Mars rover. They launch into space and then perform an ongoing function. An "expendable second stage" delivers its payload to orbit and then has no further use. The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster. A custom SS delivered by an expendable booster will be heavier than that by quite a bit, so the comparison to the 420 tonne ISS needs some interpretation. Qualitatively, quite a bit of the ISS mass is in the walls and other elements of the pressurized structure, and this function will be done by the walls and structure of the SS, not by its "payload". ISS currently has a lack of storage space. A custom SS design can include a method to convert the tanks into storage space. schemes for converting tanks into anything more sophisticated have been considered and rejected in the past, but storage space should be feasible.The most cost-effective way to replace ISS is likely to be one or more custom SS using reusable boosters.
Quote from: DanClemmensen on 02/02/2023 02:28 pmQuote from: volker2020 on 02/02/2023 12:18 pmPeople seem to forget, that they have 2 expandable upper stages on the books.The storage depot and the moon lander are exactly this.And I don't get, why people here don't see the advantages for building an ISS replacement (it is due soon).The ISS has 420t took years and ~40? launches to get operational status and did cost around 100.000.000.000 $.Using an expendable Starship, you could be able to archive the same with just 2 launches, possibly ready for usage from day 1.I think we need to distinguish an "expendable second stage" from a "Custom non-EDL SS". Depot and HLS are custom SSs and are no more expendable than is ISS or a Mars rover. They launch into space and then perform an ongoing function. An "expendable second stage" delivers its payload to orbit and then has no further use. The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster. A custom SS delivered by an expendable booster will be heavier than that by quite a bit, so the comparison to the 420 tonne ISS needs some interpretation. Qualitatively, quite a bit of the ISS mass is in the walls and other elements of the pressurized structure, and this function will be done by the walls and structure of the SS, not by its "payload". ISS currently has a lack of storage space. A custom SS design can include a method to convert the tanks into storage space. schemes for converting tanks into anything more sophisticated have been considered and rejected in the past, but storage space should be feasible.The most cost-effective way to replace ISS is likely to be one or more custom SS using reusable boosters.Not only more cost effective, there's no way to fit an ISS into Starship's payload bay.
The "traditional" alternative would be to send ISS modules that will fit into the SS cargo bay and assemble them in space. Nominal SS cargo payload volume is listed at 9 meter diameter by 18 meter "height", but I suspect the actual payload must be a bit smaller: call it 8 meters in diameter. One module would be at least 5 times the volume of an existing ISS module.
I think we need to distinguish an "expendable second stage" from a "Custom non-EDL SS". Depot and HLS are custom SSs and are no more expendable than is ISS or a Mars rover. They launch into space and then perform an ongoing function. An "expendable second stage" delivers its payload to orbit and then has no further use. The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster.
Quote from: DanClemmensen on 02/02/2023 02:28 pmI think we need to distinguish an "expendable second stage" from a "Custom non-EDL SS". Depot and HLS are custom SSs and are no more expendable than is ISS or a Mars rover. They launch into space and then perform an ongoing function. An "expendable second stage" delivers its payload to orbit and then has no further use. The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster.Agree with your point, but I believe that the 250 tonne number is for an expendable Starship on a reusable booster.
Quote from: DanClemmensen on 02/02/2023 04:13 pmThe "traditional" alternative would be to send ISS modules that will fit into the SS cargo bay and assemble them in space. Nominal SS cargo payload volume is listed at 9 meter diameter by 18 meter "height", but I suspect the actual payload must be a bit smaller: call it 8 meters in diameter. One module would be at least 5 times the volume of an existing ISS module.Just to post an example, there is Gravatics' concept "StarMax" space station module. https://twitter.com/brickmack/status/1602425257423429632
Quote from: sevenperforce on 02/02/2023 05:02 pmQuote from: DanClemmensen on 02/02/2023 02:28 pmI think we need to distinguish an "expendable second stage" from a "Custom non-EDL SS". Depot and HLS are custom SSs and are no more expendable than is ISS or a Mars rover. They launch into space and then perform an ongoing function. An "expendable second stage" delivers its payload to orbit and then has no further use. The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster.Agree with your point, but I believe that the 250 tonne number is for an expendable Starship on a reusable booster.Why do you think this? You may very well be correct, but I assumed that SpaceX was publishing the largest credible number they can as an apples-to-apples comparison to fully-expended SLS and Saturn V. It's not as if there are any actual unitary 250 tonne payloads that fit into an SS payload bay.
Quote from: whitelancer64 on 02/02/2023 04:23 pmQuote from: DanClemmensen on 02/02/2023 04:13 pmThe "traditional" alternative would be to send ISS modules that will fit into the SS cargo bay and assemble them in space. Nominal SS cargo payload volume is listed at 9 meter diameter by 18 meter "height", but I suspect the actual payload must be a bit smaller: call it 8 meters in diameter. One module would be at least 5 times the volume of an existing ISS module.Just to post an example, there is Gravatics' concept "StarMax" space station module. *snip tweet*You would not need the header tank in this case, would you?
Quote from: DanClemmensen on 02/02/2023 04:13 pmThe "traditional" alternative would be to send ISS modules that will fit into the SS cargo bay and assemble them in space. Nominal SS cargo payload volume is listed at 9 meter diameter by 18 meter "height", but I suspect the actual payload must be a bit smaller: call it 8 meters in diameter. One module would be at least 5 times the volume of an existing ISS module.Just to post an example, there is Gravatics' concept "StarMax" space station module. *snip tweet*
The 250 tonne number is fairly silly due to payload density unless the payload volume can be increased. If someone wants a huge payload on an expendable SS (or custom) SS, how large could the fairing (or SS body above the tanks) be? They don't need to worry about EDL. They are however constrained by the launch system and by the fabrication technique (e.g., high bay height, if used) So how wide, and how long? There is also a problem with CoM during stacking. I guess you could in theory make this part of the SS wide instead of circular if necessary.
Quote from: DanClemmensen on 02/02/2023 05:50 pmThe 250 tonne number is fairly silly due to payload density unless the payload volume can be increased. If someone wants a huge payload on an expendable SS (or custom) SS, how large could the fairing (or SS body above the tanks) be? They don't need to worry about EDL. They are however constrained by the launch system and by the fabrication technique (e.g., high bay height, if used) So how wide, and how long? There is also a problem with CoM during stacking. I guess you could in theory make this part of the SS wide instead of circular if necessary.An empty nose cone that can split in half and be jettisoned would be the most direct and straightforward way to do it. Also, hammerhead fairings are very common. But in theory, you can make a fairing just about any shape you need it to be to accommodate a payload of any awkward shape. A fun example is the asymmetric fairing which was actually developed to the point of wind tunnel testing for use on Atlas V Heavy.
Quote from: M.E.T. on 02/02/2023 01:32 amLet’s say the heat shield issue can never be reliably solved for rapid, cheap upper stage reuse.In that case, Starship can still be a greatly improved evolution of F9. My interest is, how much cheaper can a partially reusable Starship be than a partially reusable F9, on a kg to LEO basis?That would largely depend on the cost of expending the upper stage. So I then ponder on how the upper stage can be easily redesigned to be as cheap as possible? Does it simply become an upsized F9 upper stage? In that case you can have a flared out, detachable and recoverable fairing (upsized from F9’s fairing), allowing for payloads significantly exceeding 9m in diameter.In my view, even if such a partially reusable configuration is the best Starship ever achieves, it can still probably get to around a $30M launch cost, for 150t to LEO.That’s ~$200/kg, which is ~7 times cheaper than F9’s ~$1500/kg cost to LEO.That in itself revolutionises the industry.Have been thinking along the same lines. The partially reusable version can sustain NASA's HLS, Starlink, and many other nice things, even up to a NASA-led humans to Mars mission. This would actually be a huge success, and ten years before China aims to field a comparable system.
Quote from: kdhilliard on 02/02/2023 02:33 amQuote from: whitelancer64 on 02/01/2023 11:01 pmQuote from: TheRadicalModerate on 02/01/2023 10:54 pm*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?Probably with expendable Starship only. Musk does specify in the Tweet "expendable upper stage." ...If only the upper stage is expended, then isn't there a 1:1 correspondence between the additional payload to orbit and the landing propellant, header tanks, heat shields, and body flaps which are not needed for an expendable mission?Where is the 100t found (to increase payload from 150t reusable to 250t expendable) if the dry Starship only weighs ... what? ~ 85 - 100t? How much landing propellant are we talking about?It's very close to 1:1, but you've left off a biggie: You can jettison the whole nose fairing pretty early in the ascent. I suspect that's good for close to 50t-70t extra payload right there. I've been assuming that all the elonerons, TPS, header tanks, and residuals are good for at least 25t, so now we're getting pretty close.This of course assumes that the vanilla-flavored Starship can actually get 150t to LEO, which isn't a done deal yet. And I'd also guess that the baseline for the 250t claim assumes the existence of "Raptor Full-Thrust", as well, which reputedly takes the vanilla mass to LEO to almost 200t.
The "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster.
Quote from: DanClemmensen on 02/02/2023 02:28 pmThe "250 tonne expendable" refers to a payload delivered by an expendable SS atop an expendable booster. I, like all of us, cannot confirm my words with a calculation due to the lack of accurate initial data. But I got the impression that 250 tonns in orbit is a expendable Starship on a reusable booster. I'll try to explain why I have such an opinion. Yes, I agree, a expendable Starship should not have thermal protection tiles, aerodynamic planes, part of the fuel plant, intended for return, but this is a lot less than a hundred tonns in total. As I understand it, a reusable Starship must have about 40 tonns of fuel in its tanks to return to Earth. Unlike it, the expendable Starship can use these forty tonns of fuel to enter orbit, and therefore may have an additional supply of fuel in excess of these forty. In my opinion, due to an increase in the available fuel supply and a decrease in the mass of the Starship itself, its maximum carrying capacity is growing to 250 tonns. That is, the starting mass of a expendable Starship may be more due to for more fuel and more payload.
Quote from: InterestedEngineer on 01/21/2023 06:47 pmQuote from: DanClemmensen on 01/21/2023 06:29 pmQuote from: InterestedEngineer on 01/21/2023 06:24 pmQuote from: eriblo on 01/21/2023 04:11 pmExpendable payload has been estimated as ~2x reusable which gives HLS + 2 tankers with quite a bit of margin for boiloff and residuals.There's no way it takes an extra 100t of propellant to reuse a Starship.1.2x I'd believe, but not 2xIt's not just the propellant. If SS is designed to be expendable it does not have TPS or Elonerons.Do the math, you still don't get 2xHave you done the math? flightclub.io has a Starship profile (120 t payload, 119 t + 250 t dry mass, 1200 t + 2970 t of propellant) that gets to a ~200 km orbit with 12 t of residuals/landing propellant.Expending the booster gets ~50 t of residuals. Loading the booster fully with 3400 t gets ~87 t of residuals.If we say that TPS + flaps + actuators + smaller batteries + payload bay is a conservative 23 t that would mean a stripped down tanker would deliver 230 t of propellant even before extending it and launching it heavy.
Quote from: DanClemmensen on 01/21/2023 06:29 pmQuote from: InterestedEngineer on 01/21/2023 06:24 pmQuote from: eriblo on 01/21/2023 04:11 pmExpendable payload has been estimated as ~2x reusable which gives HLS + 2 tankers with quite a bit of margin for boiloff and residuals.There's no way it takes an extra 100t of propellant to reuse a Starship.1.2x I'd believe, but not 2xIt's not just the propellant. If SS is designed to be expendable it does not have TPS or Elonerons.Do the math, you still don't get 2x
Quote from: InterestedEngineer on 01/21/2023 06:24 pmQuote from: eriblo on 01/21/2023 04:11 pmExpendable payload has been estimated as ~2x reusable which gives HLS + 2 tankers with quite a bit of margin for boiloff and residuals.There's no way it takes an extra 100t of propellant to reuse a Starship.1.2x I'd believe, but not 2xIt's not just the propellant. If SS is designed to be expendable it does not have TPS or Elonerons.
Quote from: eriblo on 01/21/2023 04:11 pmExpendable payload has been estimated as ~2x reusable which gives HLS + 2 tankers with quite a bit of margin for boiloff and residuals.There's no way it takes an extra 100t of propellant to reuse a Starship.1.2x I'd believe, but not 2x
Expendable payload has been estimated as ~2x reusable which gives HLS + 2 tankers with quite a bit of margin for boiloff and residuals.
FWIW, here's a Silverbird calculation with:SuperHeavy, with somewhat improved thrust (255.1tf):dry=200t, prop=3400t, Thrust=33 x 2500kN = 82,500kN, launch Isp=333sExpendable Starship with 50t jettisonable fairing, 9 engines, and avg 265.3tf thrust:dry=95t, prop=1200t, Thrust=9 x 2600kN avg = 23,400kN, avg vac Isp=370sLaunched from Canaveral into 200km x 200km x 28.5º.Midpoint is 213t payload to LEO. 95% CI is 164.2t - 271.5tThis is de facto a fully expendable (both SH and SS) calculation, with (assumed) nominal residuals. It is of course possible that Silverbird's set of approximations doesn't work very well with something this big, but it implies that 250t might be... aspirational?
Quote from: TheRadicalModerate on 02/03/2023 07:19 pmFWIW, here's a Silverbird calculation with:SuperHeavy, with somewhat improved thrust (255.1tf):dry=200t, prop=3400t, Thrust=33 x 2500kN = 82,500kN, launch Isp=333sExpendable Starship with 50t jettisonable fairing, 9 engines, and avg 265.3tf thrust:dry=95t, prop=1200t, Thrust=9 x 2600kN avg = 23,400kN, avg vac Isp=370sLaunched from Canaveral into 200km x 200km x 28.5º.Midpoint is 213t payload to LEO. 95% CI is 164.2t - 271.5tThis is de facto a fully expendable (both SH and SS) calculation, with (assumed) nominal residuals. It is of course possible that Silverbird's set of approximations doesn't work very well with something this big, but it implies that 250t might be... aspirational?50t seems like very heavy for a faring, but dropping it in half only helps about 10t.when I set the fairing to 10t and the dry mass of SS to 70t I get 250t.(I also set Isp for first stage to 345. It's only 333 the first few kilometers, vacuum Isp is 355).Second stage is 365, which is what you get with all vacuum engines 100% and the regular at 50% thrust.
Quote from: InterestedEngineer on 02/03/2023 07:31 pmQuote from: TheRadicalModerate on 02/03/2023 07:19 pmFWIW, here's a Silverbird calculation with:SuperHeavy, with somewhat improved thrust (255.1tf):dry=200t, prop=3400t, Thrust=33 x 2500kN = 82,500kN, launch Isp=333sExpendable Starship with 50t jettisonable fairing, 9 engines, and avg 265.3tf thrust:dry=95t, prop=1200t, Thrust=9 x 2600kN avg = 23,400kN, avg vac Isp=370sLaunched from Canaveral into 200km x 200km x 28.5º.Midpoint is 213t payload to LEO. 95% CI is 164.2t - 271.5tThis is de facto a fully expendable (both SH and SS) calculation, with (assumed) nominal residuals. It is of course possible that Silverbird's set of approximations doesn't work very well with something this big, but it implies that 250t might be... aspirational?50t seems like very heavy for a faring, but dropping it in half only helps about 10t.when I set the fairing to 10t and the dry mass of SS to 70t I get 250t.(I also set Isp for first stage to 345. It's only 333 the first few kilometers, vacuum Isp is 355).Second stage is 365, which is what you get with all vacuum engines 100% and the regular at 50% thrust.I was assuming that the dry mass included the fairing, which was then subtracted after the jettison time. The fairing would be the entire nose of the vehicle. There will be no header tanks, but the nose is really designed to maximize payload bay volume, rather than minimizing dynamic pressure loads. I guess they could make a radically different fairing and slap it onto the propulsion section, but that seems like quite a bit more work.I was also assuming that you plugged in SL Isp for the first stage, but it appears that's wrong and it should be vac Isp. That takes the midpoint up to 235.8t.
Would there be any noticeable gain / loss in deleting the sea level engines and just runningthe RVAC’s ??
One payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔
If you want an expendable or non returnable starship could you lighten it by building it out nof aluminum?
Quote from: MickQ on 02/03/2023 10:38 pmOne payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔It appears That Subaru is the largest monolithic mirror on Earth. The mirror is 8.2 m diameter with a mass of 22.8 tonnes. Should easily fit in a standard reusable SS. But why? A bigger segmented mirror is probably a better choice. https://subarutelescope.org/en/about/
Quote from: DanClemmensen on 02/03/2023 11:58 pmQuote from: MickQ on 02/03/2023 10:38 pmOne payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔It appears That Subaru is the largest monolithic mirror on Earth. The mirror is 8.2 m diameter with a mass of 22.8 tonnes. Should easily fit in a standard reusable SS. But why? A bigger segmented mirror is probably a better choice. https://subarutelescope.org/en/about/Not really. IIRC the internal diameter of the Starship is about 8 meters. Something like the Subaru monolithic mirror needs to be mounted in a telescope structure that is likely to have a bigger diameter than the 9 meter external diameter of the Starship .
Quote from: Zed_Noir on 02/04/2023 03:55 amQuote from: DanClemmensen on 02/03/2023 11:58 pmQuote from: MickQ on 02/03/2023 10:38 pmOne payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔It appears That Subaru is the largest monolithic mirror on Earth. The mirror is 8.2 m diameter with a mass of 22.8 tonnes. Should easily fit in a standard reusable SS. But why? A bigger segmented mirror is probably a better choice. https://subarutelescope.org/en/about/Not really. IIRC the internal diameter of the Starship is about 8 meters. Something like the Subaru monolithic mirror needs to be mounted in a telescope structure that is likely to have a bigger diameter than the 9 meter external diameter of the Starship .That's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.
Quote from: su27k on 02/04/2023 04:11 amQuote from: Zed_Noir on 02/04/2023 03:55 amQuote from: DanClemmensen on 02/03/2023 11:58 pmQuote from: MickQ on 02/03/2023 10:38 pmOne payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔It appears That Subaru is the largest monolithic mirror on Earth. The mirror is 8.2 m diameter with a mass of 22.8 tonnes. Should easily fit in a standard reusable SS. But why? A bigger segmented mirror is probably a better choice. https://subarutelescope.org/en/about/Not really. IIRC the internal diameter of the Starship is about 8 meters. Something like the Subaru monolithic mirror needs to be mounted in a telescope structure that is likely to have a bigger diameter than the 9 meter external diameter of the Starship .That's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.Have doubts that the Starship structure is stable enough for use as a telescope structure without a lot of modifications. Might just be cheaper to not use the Starship as a telescope and build a new space telescope instead.
Quote from: Zed_Noir on 02/04/2023 05:09 amQuote from: su27k on 02/04/2023 04:11 amQuote from: Zed_Noir on 02/04/2023 03:55 amQuote from: DanClemmensen on 02/03/2023 11:58 pmQuote from: MickQ on 02/03/2023 10:38 pmOne payload that comes to mind is a bigger and much more capable optical space telescope.Imagine a 7+ metre monolithic mirror 🤔It appears That Subaru is the largest monolithic mirror on Earth. The mirror is 8.2 m diameter with a mass of 22.8 tonnes. Should easily fit in a standard reusable SS. But why? A bigger segmented mirror is probably a better choice. https://subarutelescope.org/en/about/Not really. IIRC the internal diameter of the Starship is about 8 meters. Something like the Subaru monolithic mirror needs to be mounted in a telescope structure that is likely to have a bigger diameter than the 9 meter external diameter of the Starship .That's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.Have doubts that the Starship structure is stable enough for use as a telescope structure without a lot of modifications. Might just be cheaper to not use the Starship as a telescope and build a new space telescope instead.This thread is about "expendable SS" and includes custom non-EDL SS. The designer of a huge telescope has two options: do the engineering to design a standalone free flyer, or do the engineering to use the SS as part of the structure. You have stability problems to solve either way. Not being a telescope engineer, I have no idea which is the better solution.
Quote from: Zed_Noir on 02/04/2023 05:09 amQuote from: su27k on 02/04/2023 04:11 amThat's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.Have doubts that the Starship structure is stable enough for use as a telescope structure without a lot of modifications. Might just be cheaper to not use the Starship as a telescope and build a new space telescope instead.This thread is about "expendable SS" and includes custom non-EDL SS. The designer of a huge telescope has two options: do the engineering to design a standalone free flyer, or do the engineering to use the SS as part of the structure. You have stability problems to solve either way. Not being a telescope engineer, I have no idea which is the better solution.
Quote from: su27k on 02/04/2023 04:11 amThat's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.Have doubts that the Starship structure is stable enough for use as a telescope structure without a lot of modifications. Might just be cheaper to not use the Starship as a telescope and build a new space telescope instead.
That's why it may be a job for expendable Starship: Use the ship structure itself as telescope structure and leave the ship in space (since it _is_ the telescope). Pretty sure Elon mentioned something like this before.
This thread is about "expendable SS" and includes custom non-EDL SS. The designer of a huge telescope has two options: do the engineering to design a standalone free flyer, or do the engineering to use the SS as part of the structure. You have stability problems to solve either way. Not being a telescope engineer, I have no idea which is the better solution.
Trying to build a giant precision optical instrument kitbashed from parts of an unrelated spaceship is about as difficult as trying to build a large ground telescope from bits of the semi trailers that transported it to site. The structural requirements for an optical assembly are pretty radically different from those of Starship (thermal bridging, thermal stability CoTE, flex when repointing, internal emissivity, etc. etc.), and trying to incorporate Starship into the telescope assembly is just adding more headaches unnecessarily.
Quote from: edzieba on 02/05/2023 08:44 pmTrying to build a giant precision optical instrument kitbashed from parts of an unrelated spaceship is about as difficult as trying to build a large ground telescope from bits of the semi trailers that transported it to site. The structural requirements for an optical assembly are pretty radically different from those of Starship (thermal bridging, thermal stability CoTE, flex when repointing, internal emissivity, etc. etc.), and trying to incorporate Starship into the telescope assembly is just adding more headaches unnecessarily.I take your point, but what about building a large ground telescope by mounting it inside the semi trailer, using the semi trailer as the structural frame, so that once you get to your destination you can simply jettison the top of the trailer box and start observing?
I think the "Starship as a satellite bus" idea is pretty bad overall. In virtually every case you're better off using Starship for its designed purpose - to launch the satellite. You're not saving any time or money in the long run by building your instruments into the LV.
But if you have a heavy industrial application, building it straight into a Starship, either with or without a fairing, will be a lot easier than having to design, build, and deploy a free-flying bus for a heavy application. I suspect that there are also a fair number of scientific packages that are easier to put together in a rack-mounted format, rather than a bus-mounted one.
But if you have a heavy industrial application, building it straight into a Starship, either with or without a fairing, will be a lot easier than having to design, build, and deploy a free-flying bus for a heavy application. I suspect that there are also a fair number of scientific packages that are easier to put together in a rack-mounted format, rather than a bus-mounted one. Having a Starship, either expendable or not, with the power and thermal systems to support rack-mounted stuff sounds like a pretty good idea to me.
One of my favorite industrial apps is a self-contained methalox plant for Mars. Just land it, deploy power and heat rejection, and use the existing LCH4 and LOX tanks, with suitable cryo-cooling, as storage.
You can build versions that work with water delivered to them, but you can also work a bunch of the bugs out simply by carrying some LH2 feedstock. Of course, this requires getting some planetary protection relief, but it seems that everybody agrees that's a requirement. Getting from the current guidelines to relaxed guidelines will likely take a few years, but my guess is that's about how long we have before SpaceX tries anything with Mars in the first place.
Quote from: TheRadicalModerate on 02/06/2023 06:58 pm You can build versions that work with water delivered to them, but you can also work a bunch of the bugs out simply by carrying some LH2 feedstock. Of course, this requires getting some planetary protection relief, but it seems that everybody agrees that's a requirement. Getting from the current guidelines to relaxed guidelines will likely take a few years, but my guess is that's about how long we have before SpaceX tries anything with Mars in the first place. But here I disagree. Since we're going to have a pretty powerful energy source one way or another, it's much better to bring in rovers with a rig and ice and/or water extraction equipment. Better to spend the time to find water/ice and to develop methods for extracting it. We can continue this discussion in a more appropriate thread.
Starstack 2 Orion Special: "Princess Flies Coach"Starstack isn't a "design". It's a menu. Like Mexican food. Same few ingredients, many dishes.Here we open the fridge and pull out the perfect concoction to send Orion safely off to TLI.
Consider this mission plan: *Launch a "standard" EDL cargo Starship and have it consume all of its fuel during launch to put itself and a max payload to the least energetically expensive LEO. *Refuel in this orbit, deliver the payload to its desired orbit, and then EDL.Does this allow delivery of a larger payload than the simple reusable single-launch case? It should be cheaper than an expendable.
Quote from: DanClemmensen on 02/08/2023 04:49 amConsider this mission plan: *Launch a "standard" EDL cargo Starship and have it consume all of its fuel during launch to put itself and a max payload to the least energetically expensive LEO. *Refuel in this orbit, deliver the payload to its desired orbit, and then EDL.Does this allow delivery of a larger payload than the simple reusable single-launch case? It should be cheaper than an expendable.It's probably a bit larger payload, but I'm pretty sure that the 250t to LEO is with an expendable SuperHeavy as well. Also, by removing the TPS, header tanks, elonerons, and jettisoning the fairing, all that mass goes into the payload number.The issue isn't getting the payload from LEO to its final target orbit. It's getting it to LEO in the first place.Finally, if lift tankers don't actually have the refueling hardware on them, then you need a depot at the inclination and RAAN of the target orbit. That's a major expense.
I think a depot is needed in all refuelling cases. Direct tanker-to-target does not make sense to me. If depot is needed, it's production and launch cost is a one-time expense. It would be placed in the minimum-energy stable LEO for a particular launch site and would serve all launches from that site that need it. I envision the payload launch going to a barely-stable altitude and the depot descending to this altitude for the refuelling, and ascending back to a reasonable altitude after refuelling, while the payload carrier goes on its merry way. One depot would support hundreds of missions over its lifetime, and tanker flights are shared when the payload missions don't need exact multiples of a tanker.
This idea is on this thread because if this scheme works it raises the lower bound for the mass that requires an expendable launch, and that in turn changes the economics.
Quote from: DanClemmensen on 02/08/2023 04:41 pmI think a depot is needed in all refuelling cases. Direct tanker-to-target does not make sense to me. If depot is needed, it's production and launch cost is a one-time expense. It would be placed in the minimum-energy stable LEO for a particular launch site and would serve all launches from that site that need it. I envision the payload launch going to a barely-stable altitude and the depot descending to this altitude for the refuelling, and ascending back to a reasonable altitude after refuelling, while the payload carrier goes on its merry way. One depot would support hundreds of missions over its lifetime, and tanker flights are shared when the payload missions don't need exact multiples of a tanker.Only if all of those missions have the same inclination and RAAN. And they won't, especially for the vanilla-flavored reusable missions.QuoteThis idea is on this thread because if this scheme works it raises the lower bound for the mass that requires an expendable launch, and that in turn changes the economics.Let's assume we need 250m/s for EDL, with zero down-mass. At sea-level Isp=333s and 120t dry mass, that's 9.6t of prop. Let's ignore sump and boiloff losses and assume that payload to LEO is nominally 150t. To get to LEO, that mass ratio needs to be the same as the mass ratio for the system with the 9.6t of prop put back in. If we represent the improved payload mass as x, then they have to have the same mass ratios:(120+1200+150)/(120+9.6+150) = (120+1200+x)/(120+x)x = 161.9tA 7.9% payload improvement. Nothing to sneeze at.That said, unless your already-quite-exotic payload happens to need to go to an inclination that's popular enough to already have a depot (and that's likely only at a fairly low inclination that's good for TLI), you're incurring the cost of a depot launch, which you probably have to amortize all by your lonesome. In effect, the depot becomes an expendable component.Instead, if you expend your launch Starship, you can strip off all the EDL crap, which can then be turned into payload. I've been arm-waving the EDL crap at 25t, so instead you get 186.9t of payload, a 24.6% improvement over the presumptive 150t for the fully-reusable system with no refueling.Bottom line: What you're saying makes sense if you can amortize the cost of the depot. If not, it's much better to go with an expendable Starship stage.
No, the whole idea is that all such launches go the the same orbit and then refuel, so they all use the same depot. The refuelling provides enough delta-v to do a plane change, so you can hit a fairly large range of RAAN from a particular depot. I suppose you might need several depots (three?) in strategically-placed orbits so the payload-bearing SS can change planes and refuel several times. All of this assumes that tanker operations are really, really cheap.And all of this, including any expendable SS, leaves open the question: how many unitary payloads greater than 150 tonne are there?
*snip*And all of this, including any expendable SS, leaves open the question: how many unitary payloads greater than 150 tonne are there?
Quote from: DanClemmensen on 02/08/2023 07:53 pm*snip*And all of this, including any expendable SS, leaves open the question: how many unitary payloads greater than 150 tonne are there?Expendable starship does not necessarily assume a 150+ ton payload. With an expendable Starship-derived upper stage you could maximum yeet a 10 ton probe on an outer planets mission, so it won't take 10 years to fly by the outer planets. For reference, Cassini (at launch, with Huygens probe) was 5 metric tons, the New Horizons probe to Pluto was less than 500 kg.
Q1) Does this seem feasible?
To flip this old thread on its head... I'm pondering Starship backloading as a way of recovering otherwise expendable upper stages from other launch vehicles.You space-tug an empty Falcon 2nd stage or Centaur etc. to the future orbit of a Starship commercial payload launch, integrate into the payload bay in orbit, then extract it after landing. (the concept is this is low cost as the the Starship needs to land anyway and there isn't much demand for down-mass)Falcon 2nd stage is 13.8m high, Centaur V is 12.7m, Starship payload bay is 17m tall - so they would fit vertically.Falcon 2nd stage is 3.7m diameter, Centaur III is 3.05m diameter. payload bay interior approx 8m (± ??)Depending on the exact details of the payload bay you could fit 2 or 3. (or in theory 1 Falcon and 3 Centaurs - or 1 Centaur V)I'm assuming the upper stages being recovered would be from GTO missions, so not directly competing with Starship and not from wildly different inclinations. The space tug side could be its own whole discussion, but this is about the Starship part.Since the upper stages are empty, the mass is well within the down-mass Starship can land.Q1) Does this seem feasible? (other than the space tug part)Q2) What technical challenges? e.g. robotic loading & securing, pressurizing them before they get crushed...Q3) How much potential value? is the marginal upper stage replacement cost much?Q4) Would 3rd parties even pay a competitor for this service? Or would it be in-house only?Q5) Or could you kill 2 birds with 1 stone and just re-fuel an old upper stage in orbit and re-use it as a kick stage? (I doubt it)
To flip this old thread on its head... I'm pondering Starship backloading as a way of recovering otherwise expendable upper stages from other launch vehicles. Q1) Does this seem feasible? (other than the space tug part)
On Sept. 7, the GAO released (another) report stating that SLS costs are unsustainable. Of course, they've always said that.If hot staging proves to be successful, and increases standard SS payload by 10 tons, I wonder how much it would increase payload for a stripped down expendable SS US. ...
If hot staging proves to be successful, and increases standard SS payload by 10 tons, I wonder how much it would increase payload for a stripped down expendable SS US. If you add in downrange drone ship landing for SH, you increase payload even further. (I acknowledge landing legs issue.)
<snip>Any Orion-on-SS will require some customization of the launch tower to add a crew access arm. I assume the plan will be to stack the Orion atop the SS in the Megabay and then stack this mess atop the SH on the OLM using the chopsticks: this may be "interesting".
Quote from: DanClemmensen on 09/17/2023 02:24 pm<snip>Any Orion-on-SS will require some customization of the launch tower to add a crew access arm. I assume the plan will be to stack the Orion atop the SS in the Megabay and then stack this mess atop the SH on the OLM using the chopsticks: this may be "interesting".Think it is cheaper and easier to build a mobile service gantry with crew access than to modified the launch and integration tower.
It isn't a customized SS that is needed. Just an austere SS with a few extra ring segments with lifting attachments above the propellant tanks and an adopter ring segment to the Orion stack. Don't think the chopsticks should have too much difficulties with the SS & Orion integrated stack.
Quote from: TomH on 09/17/2023 04:55 amIf hot staging proves to be successful, and increases standard SS payload by 10 tons, I wonder how much it would increase payload for a stripped down expendable SS US. If you add in downrange drone ship landing for SH, you increase payload even further. (I acknowledge landing legs issue.)If you just want to replace SLS while retaining Orion and the rest of the Artemis architecture, then why bother with re-usability at all? Just fly an expendable SH and a custom expendable SS with an Orion stuck on top as you pictured. Since Orion only flies once a year, recovery has low ROI. SLS costs at least $2 B. An expendable SH will be a whole lot cheaper and even the custom SS should be fairly cheap: a wild guess would be the SH is less than $100 M and the custom SS is less than $100 M. SS cost is mostly the amortized development cost.Any Orion-on-SS will require some customization of the launch tower to add a crew access arm. I assume the plan will be to stack the Orion atop the SS in the Megabay and then stack this mess atop the SH on the OLM using the chopsticks: this may be "interesting".
Quote from: DanClemmensen on 09/17/2023 02:24 pmQuote from: TomH on 09/17/2023 04:55 amIf hot staging proves to be successful, and increases standard SS payload by 10 tons, I wonder how much it would increase payload for a stripped down expendable SS US. If you add in downrange drone ship landing for SH, you increase payload even further. (I acknowledge landing legs issue.)If you just want to replace SLS while retaining Orion and the rest of the Artemis architecture, then why bother with re-usability at all? Just fly an expendable SH and a custom expendable SS with an Orion stuck on top as you pictured. Since Orion only flies once a year, recovery has low ROI. SLS costs at least $2 B. An expendable SH will be a whole lot cheaper and even the custom SS should be fairly cheap: a wild guess would be the SH is less than $100 M and the custom SS is less than $100 M. SS cost is mostly the amortized development cost.Any Orion-on-SS will require some customization of the launch tower to add a crew access arm. I assume the plan will be to stack the Orion atop the SS in the Megabay and then stack this mess atop the SH on the OLM using the chopsticks: this may be "interesting".The Starship being designed to carry up to 100 people on long-duration, interplanetary flights begs one simple question: is a special access arm would be required for a large number of people to safely board the Starship stage?
If NASA were to slightly delay Artemis 4 and 5, then a SH/SS version could be developed to not just carry the Orion but also use strap-on solid-fuel rocket boosters to allow it to fly past max-q velocity in a much shorter period of time than a basic SH/SS.
Quote from: TomH on 09/17/2023 04:55 amIf hot staging proves to be successful, and increases standard SS payload by 10 tons, I wonder how much it would increase payload for a stripped down expendable SS US. If you add in downrange drone ship landing for SH, you increase payload even further. (I acknowledge landing legs issue.)Any Orion-on-SS will require some customization of the launch tower to add a crew access arm. I assume the plan will be to stack the Orion atop the SS in the Megabay and then stack this mess atop the SH on the OLM using the chopsticks: this may be "interesting".
How much would it cost for SpaceX to add a crew access arm to the launch tower for the Starship?
Quote from: Vahe231991 on 09/18/2023 03:54 amHow much would it cost for SpaceX to add a crew access arm to the launch tower for the Starship?Elon recently tweeted that the full stack will likely grow by 10%-20% in height. This will require tower modifications. IDK for sure, but I believe this tower is much more easily modified than SLS tower. I think it was designed with simplicity of future modifications in mind.
If they can support 150+ tonnes at 4(?) g axially (FH payload & fuel at MECO), but can't support their own empty mass of 4 tonnes at 2 g laterally even with the aid of "highly specialized structures"... that would be quite a result for a horizontally-integrated LV
It will be interesting to see how SpaceX intend to land both vehicles to make the system fully reusable as stated. The Super Heavy goes higher and faster than the Falcon 9 first stage but they haven't tested such a landing. As far as the second stage is concerned assuming it will have the capability to do a controlled landing from LEO escape velocity is a different story. Currently, a ballistic re-entry is the only possibility.
You might need to expend the starship for higher delta-v, instead you could just fill the spacecraft inside with a big fuel tank and let that do some of the work.
Here's a fun one I don't recall seeing before, but may well have overlooked:Could SH SSTO with a simple nose cone for low-altitude aerodynamics?If so, with orbital refueling you could stack a payload after the fact and REALLY expend a booster.
The only operational payload I expect from starship in the next 2 years is starlink. Part of the reason is that nobody knows what the final dimensions of the payload bay are or how a payload will be deployed. Chomper starships, if still in the pipeline, feel like they won't be tested this year. Companies and governments will start designing for NG assuming that if it'll fit in NG it'll fit in starship when it's done.the big starlink sats have been held up by starship development, so a disposable upperstage, no wings, just tanks and raptors with a fairing (stainless, even) could have filled that gap and attracted attention from the industry (someone is going to want a simple disposable upper stage sooner or later to put up something massive). They could have been improving their ground operations and working on booster reuse all while launching payloads and the occasional starship for testing. While they want to ramp up this year to 25, the mishap investigation(s) are going to eat into their time, so these failures hurt.Hindsignt and all, but i feel there was a better way.
Decided to dredge up this thread as a better place to continue this discussion.Quote from: RoboGoofers on 01/17/2025 05:35 pmThe only operational payload I expect from starship in the next 2 years is starlink. Part of the reason is that nobody knows what the final dimensions of the payload bay are or how a payload will be deployed. Chomper starships, if still in the pipeline, feel like they won't be tested this year. Companies and governments will start designing for NG assuming that if it'll fit in NG it'll fit in starship when it's done.the big starlink sats have been held up by starship development, so a disposable upperstage, no wings, just tanks and raptors with a fairing (stainless, even) could have filled that gap and attracted attention from the industry (someone is going to want a simple disposable upper stage sooner or later to put up something massive). They could have been improving their ground operations and working on booster reuse all while launching payloads and the occasional starship for testing. While they want to ramp up this year to 25, the mishap investigation(s) are going to eat into their time, so these failures hurt.Hindsignt and all, but i feel there was a better way.Is there a true customer need for an expendable upper stage for very large payloads? Where the Starship structure won't allow a payload to be deployed? Something like a single launch space station, or huge station modules for a fuel depot or starship service dock. A big space tug or space debris catcher or asteroid miner?Would it be cost effective if it enabled truly massive infrastructure?
Quote from: Norm38 on 01/20/2025 03:08 pmDecided to dredge up this thread as a better place to continue this discussion.Quote from: RoboGoofers on 01/17/2025 05:35 pmThe only operational payload I expect from starship in the next 2 years is starlink. Part of the reason is that nobody knows what the final dimensions of the payload bay are or how a payload will be deployed. Chomper starships, if still in the pipeline, feel like they won't be tested this year. Companies and governments will start designing for NG assuming that if it'll fit in NG it'll fit in starship when it's done.the big starlink sats have been held up by starship development, so a disposable upperstage, no wings, just tanks and raptors with a fairing (stainless, even) could have filled that gap and attracted attention from the industry (someone is going to want a simple disposable upper stage sooner or later to put up something massive). They could have been improving their ground operations and working on booster reuse all while launching payloads and the occasional starship for testing. While they want to ramp up this year to 25, the mishap investigation(s) are going to eat into their time, so these failures hurt.Hindsignt and all, but i feel there was a better way.Is there a true customer need for an expendable upper stage for very large payloads? Where the Starship structure won't allow a payload to be deployed? Something like a single launch space station, or huge station modules for a fuel depot or starship service dock. A big space tug or space debris catcher or asteroid miner?Would it be cost effective if it enabled truly massive infrastructure?There's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.
I guess one use for an expendable upper stage would be a deep space probe. Picture something huge, 8m antenna, nuclear power ion drive. The upper stage could even remain attached in LEO, be refueled by tankers and be a massive departure stage. No need to haul along the empty tanks and engines.Might be the cheapest option to go fast to the outer planets. What could NASA do with that?
Sure. And maybe with robotic assembly and welding, it would make sense to have a shipyard and the pez dispenser ejects IKEA flat packs of material to be built into all kinds of things.But there are very complex things that are not easily dividable. A large nuclear reactor core, inflatable habitats that need to be manufactured on earth and can't be smaller than 8-9 meter diameter. Maybe the chomper will work out and be able to deploy something that large. But I wouldn't be surprised if an expendable is built every once in a while because there's no other way to get something large into orbit.
Quote from: Norm38 on 01/20/2025 05:25 pmSure. And maybe with robotic assembly and welding, it would make sense to have a shipyard and the pez dispenser ejects IKEA flat packs of material to be built into all kinds of things.But there are very complex things that are not easily dividable. A large nuclear reactor core, inflatable habitats that need to be manufactured on earth and can't be smaller than 8-9 meter diameter. Maybe the chomper will work out and be able to deploy something that large. But I wouldn't be surprised if an expendable is built every once in a while because there's no other way to get something large into orbit.Yep. I think each expendable will be a custom build. Depending on the application, the aerodynamic nose or fairing needed for launch may be part of the payload that gets used as part of the structure of the spacecraft. I do not think we will see one of these any time soon, since each of them will take a long time to design and build and the engineers don't even know the capabilities of the launcher yet.
I expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.
Quote from: steveleach on 01/20/2025 03:20 pmThere's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.I expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.
There's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.
Quote from: Twark_Main on 01/25/2025 01:30 amI expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.Yet another reason to want that "orbital drydock." Especially if we can get NASA to pay for it!
Quote from: Twark_Main on 01/25/2025 01:30 amQuote from: steveleach on 01/20/2025 03:20 pmThere's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.I expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.Yes, clearly small things that can transported in a single reusable vehicle will be cheaper.But when you go larger than that you have to choose between...
I don't expect risky and training-intensive EVAs to be a thing for very long, once Starship brings launch costs down to where SpaceX want them to be. Starship's refuelling model, when implemented at scale, will make rendezvous and docking fast and trivial.
We know there are companies developing robotic orbital assembly technologies, but they aren't currently financially viable because current launch costs...
Quote from: steveleach on 01/25/2025 09:16 amQuote from: Twark_Main on 01/25/2025 01:30 amQuote from: steveleach on 01/20/2025 03:20 pmThere's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.I expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.Yes, clearly small things that can transported in a single reusable vehicle will be cheaper.But when you go larger than that you have to choose between... Let me stop you right there.If. If you go larger than that. There's no inevitable progression where things have to necessarily get bigger, such that this is somehow an unavoidable problem that must be solved.If bigger things are dramatically more expensive, then the far more obvious answer is that you just won't make things bigger. "Doctor, it hurts when I do this!" Quote from: steveleach on 01/25/2025 09:16 amI don't expect risky and training-intensive EVAs to be a thing for very long, once Starship brings launch costs down to where SpaceX want them to be. Starship's refuelling model, when implemented at scale, will make rendezvous and docking fast and trivial.We've had rendezvous and docking long before the ISS, and yet we still used many many "risky and training-intensive EVAs" for that. So clearly this analysis is missing something.Quote from: steveleach on 01/25/2025 09:16 amWe know there are companies developing robotic orbital assembly technologies, but they aren't currently financially viable because current launch costs...That's just one hypothesis to explain why they aren't financially viable.Looking at the actual technology, a more likely hypothesis is that they haven't actually solved the right problem. Most of the "robotic assembly" I see is just creating empty shells, but the vast majority of the cost isn't in the shell, it's in outfitting the interior equipment.
...There's no inevitable progression where things have to necessarily get bigger, such that this is somehow an unavoidable problem that must be solved.
If bigger things are dramatically more expensive, then the far more obvious answer is that you just won't make things bigger.
Most of the "robotic assembly" I see is just creating empty shells, but the vast majority of the cost isn't in the shell, it's in outfitting the interior equipment.
Quote from: Twark_Main on 01/27/2025 07:35 pmQuote from: steveleach on 01/25/2025 09:16 amQuote from: Twark_Main on 01/25/2025 01:30 amQuote from: steveleach on 01/20/2025 03:20 pmThere's a small gap between "small enough to fit in the cargo bay" and "large enough to require orbital assembly" that might benefit from it in the short term. But if Starship meets its launch cost goals I suspect most customers will quickly move on to the larger structures constructed in orbit.I expect it will be the opposite, actually. Anything you can fit in Starship will be cheap, but anything requiring risky and training-intensive EVAs for assembly (or some sort of custom R&D assembly robot) will be a lot more expensive.Yes, clearly small things that can transported in a single reusable vehicle will be cheaper.But when you go larger than that you have to choose between... Let me stop you right there.If. If you go larger than that. There's no inevitable progression where things have to necessarily get bigger, such that this is somehow an unavoidable problem that must be solved.If bigger things are dramatically more expensive, then the far more obvious answer is that you just won't make things bigger. "Doctor, it hurts when I do this!" Quote from: steveleach on 01/25/2025 09:16 amI don't expect risky and training-intensive EVAs to be a thing for very long, once Starship brings launch costs down to where SpaceX want them to be. Starship's refuelling model, when implemented at scale, will make rendezvous and docking fast and trivial.We've had rendezvous and docking long before the ISS, and yet we still used many many "risky and training-intensive EVAs" for that. So clearly this analysis is missing something.Quote from: steveleach on 01/25/2025 09:16 amWe know there are companies developing robotic orbital assembly technologies, but they aren't currently financially viable because current launch costs...That's just one hypothesis to explain why they aren't financially viable.Looking at the actual technology, a more likely hypothesis is that they haven't actually solved the right problem. Most of the "robotic assembly" I see is just creating empty shells, but the vast majority of the cost isn't in the shell, it's in outfitting the interior equipment.I know you like a good argument, but I think you're maybe trying a little too hard here.
Quote from: Twark_Main on 01/27/2025 07:35 pm...There's no inevitable progression where things have to necessarily get bigger, such that this is somehow an unavoidable problem that must be solved.Inevitable? Maybe not, but human history shows that humans do like to make things bigger, whether that is transportation systems, buildings, machines, etc. And the reason for that is economic in a lot of cases, in that making whatever it is bigger results in being able to do more of something.
Quote from: Twark_Main on 01/27/2025 07:35 pmIf bigger things are dramatically more expensive, then the far more obvious answer is that you just won't make things bigger.This is really a question for the people and companies that want to solve problems in space by building something here on Earth and launching it into space. THEY will be the ones to decide how big or small something should be.
Me personally, though the cost of a Starship Cargo launch will be economical even if you don't fill up the payload bay, I think everyone will be trying to maximize each launch opportunity, since time is money too.
Quote from: Twark_Main on 01/27/2025 07:35 pmMost of the "robotic assembly" I see is just creating empty shells, but the vast majority of the cost isn't in the shell, it's in outfitting the interior equipment.The ISS was the last major assembly project in LEO, and it used humans to do all of the detailed assembly work, though sometimes with the help of robotic arms. Even the Chinese are still using humans for their much smaller space station.But humans cost a LOT to get to and keep in space, so for commercial activity in space that requires some degree of assembly I think the hardware designers will focus on how to use remote and robotic assembly techniques to assemble large (and small) components in space.
Since it seems SpaceX has the Superheavy booster down pat. However, why can't they just build a stripped down Starship upper stage, expendable for now, to launch Starlink satellites? Then work on the Reusable Starship. They could probably do both at the same time. It would at least see how much refurbishment the booster will take before relaunching. If they can do 200-250 tons expendable, that could get a lot of Starlinks up on one launch. Sure, it would probably be in line with what it is costing using F9 expending the upper stage, but Starlink would work faster and get more customers. Also, with an expendable upper stage, they could do an entire moon launch with lander and Orion ala Apollo with Saturn V in one launch. Starship is to me, going to be the hard part, making it work reusable.
Expendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.
If going to worlds with no atmosphere (Mercury, moons of gas or ice giants, unless you’re willing to aerocapture in the GG itself - very risky potentially, we’ve never done that), the fairing is dead weight
No TPS (~25t)No Elonerons (~10t including actuators & stuff?)
Quote from: TomH on 01/30/2025 05:00 amExpendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.Why would you jettison a fairing? You waste up to 10km/sec of aerocapture potential
The radiation environment of Europa is so extreme that it probably wouldn't have the same con-ops as an Enceladus lander-drill mission.For eg, you might not want to leave most of your hardware on the surface, but instead leave just a passive comms relay, while everything else is melted into the ice.
While Enceladus has significant atmosphere
Paul451 just sent me a PM with a very germane fact:
Quote from: InterestedEngineer on 01/30/2025 06:00 amQuote from: TomH on 01/30/2025 05:00 amExpendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.Why would you jettison a fairing? You waste up to 10km/sec of aerocapture potentialYou eliminate all atmospheric paraphernalia on the US: tiles, elonerons, and jettison the fairing. The lander itself has its own much smaller TPS and landing system. This is advantageous in mass trades. Rather than managing the mass of an entire Starship entering the atmosphere of Enceladus, you have something similar to (but larger than) a Curiosity/Perseverance EDL architecture.