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SpaceX (general discussion)

sferrin

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That's the neat thing with LOX, the O/F ratios in the 3 range. 1 hydrocarbon needs 3 LOX to burn. In the end the amount of fuel is small when the amount of oxidizer (LOX) is huge.
Of course kerosene / peroxide is even better: O/F ratio of 7 !
Not better for easy reusabillity or making fuel on Mars though.
 

sferrin

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Didn’t say it was a donation, and doesn’t change my point.
Of course it does. There isn't a company on the planet that doesn't depend on customers.
My point was that you appeared to be suggesting that Space X had got where it was now on just private money.
Surely you understand the difference between a publicly funded program (SLS) and a private company selling goods/services?
 

Moose

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As an example of that optimisation though, quite soon they plan on producing Starship hulls via a continuous reel of steel (which is normally cut into plates at their supplier's factory) and use a single continuous weld, giving them more strength and therefore allowing thinner steel to be used.
With respect, this is a little inaccurate. He said that the individual barrel-ring sections would be produced directly "off the spool" with each joined via a single continuous weld, not that the entire hull would be produced from one piece of steel.
 

Michel Van

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That's the neat thing with LOX, the O/F ratios in the 3 range. 1 hydrocarbon needs 3 LOX to burn. In the end the amount of fuel is small when the amount of oxidizer (LOX) is huge.
Of course kerosene / peroxide is even better: O/F ratio of 7 !
So much i love Peroxide (HTP) as oxidizer for Rocket engines.
it got some disadvantages
like lower ISP compare to LCH4 or LH2 with Lox
IN-SITU productions of HTP is far complicated and more energy consuming as needed for Sabatier Reaction for LCH4/LOX production
Next to that you have to drag Kerosin als Fuel all way along to Mars and back
here is LCH4/LOX only choice you have for Mars mission with IN-SITU
 

NUSNA_Moebius

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As an example of that optimisation though, quite soon they plan on producing Starship hulls via a continuous reel of steel (which is normally cut into plates at their supplier's factory) and use a single continuous weld, giving them more strength and therefore allowing thinner steel to be used.
With respect, this is a little inaccurate. He said that the individual barrel-ring sections would be produced directly "off the spool" with each joined via a single continuous weld, not that the entire hull would be produced from one piece of steel.
I wonder what kind of weld cross section, profile and procedure they're using. Full penetration welds on stainless require shielding gas on the backside as well as front. I can imagine all sorts methods to maintain a non-problematic gas environment to prevent sugaring.
 

TomcatViP

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As an austenitic stainless steel, Core 301/4310 has good weldability and is suitable for the full range of conventional welding methods (like MMA, MIG, MAG, TIG, SAW, LBW, or RSW), except gas welding. Core 301/4310 has about 50% higher thermal expansion and lower heat conductivity compared to carbon steels. This means that larger deformation and higher shrinkage stresses may result from welding.
So that's what we might witness with all the wrinkles and large grind area. The outside skin is not structural by the way. So full weld would be as unpractical as unnecessary.

 
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Flyaway

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Didn’t say it was a donation, and doesn’t change my point.
Of course it does. There isn't a company on the planet that doesn't depend on customers.
My point was that you appeared to be suggesting that Space X had got where it was now on just private money.
Surely you understand the difference between a publicly funded program (SLS) and a private company selling goods/services?
Yes. But then I regard your original post as unclear.
 

sferrin

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Didn’t say it was a donation, and doesn’t change my point.
Of course it does. There isn't a company on the planet that doesn't depend on customers.
My point was that you appeared to be suggesting that Space X had got where it was now on just private money.
Surely you understand the difference between a publicly funded program (SLS) and a private company selling goods/services?
Yes. But then I regard your original post as unclear.
Can't help you. If you didn't understand it the first time, repeating myself won't help you.
 

antigravite

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Didn’t say it was a donation, and doesn’t change my point.
Of course it does. There isn't a company on the planet that doesn't depend on customers.
My point was that you appeared to be suggesting that Space X had got where it was now on just private money.
Surely you understand the difference between a publicly funded program (SLS) and a private company selling goods/services?
Yes. But then I regard your original post as unclear.
Can't help you. If you didn't understand it the first time, repeating myself won't help you.
Gentlemen,
how about closing this nice and polite kidding exchange in this open thread, and fixing a vocabulary, grammatical and syntactic solution in DMs? It’s not funny any more here and now. Thx
A
 

RanulfC

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As I noted before Elon has an agenda that pretty much requires this approach but that in no way makes it the BEST or even the smartest way to do things. If it works as planned and blows open space I will have no heartburn or complaints. If it doesn't there's going to be another 'space-crash' and I've been through enough of those already to want to see another one.
Spot on. Musk is trying to marry "Saturn V HLV" with "full-reusability" and the end result - a brute force approach - is so huge, so massive, it can only be justified by a grand scale onslaught on Mars. Although it could be very interesting for the Moon, too, admittedly.
But that's only the human exploration part of space.
Pretty much, and again while I understand his rush and his ambition, (and as noted its not my money in the first place :) ) I only question some of his assumptions, not his actual ideas or history. He's made vertical, powered return landing of a booster rocket rather 'ho-hum' and only of real interest when it doesn't work. Exactly like every other transporation system out there.

One thing Scott Manley pointed out in his review of the presentation is that it's not likely that Starship will be used to service the Moon for very long if it is used to land there. The math shows the raptors are going to throw some regolith pretty far, (possiblity of some of the debris almost making orbital velocity) with all that implies for 'sandblasting' any nearby structures :)

Commercial space might think it is a little oversized.

I mean, the 747 is an outstanding aircraft, but for Ryanair or Easyjet low-cost short-haul airlines it would be completely overkill. Which mean: there is room for smaller RLVs just like there is is room for much smaller airliners bar 747 or A380 (fortunately enough).

Musk somewhat acknowledged this recently when he admitted that Falcon 9 and Heavy might not be replaced by Starship-Super-heavy.
That's actually good to hear because it was looking and sounding to likely that there was a high expectation that the entire market would switch to Starship once it became available which wasn't likely to be the case. But keep in mind that air-travel isn't an analog of space travel and won't likely be for quite a while yet. I'm just hoping the actual rather than percieved/hoped-for market can support multiple launchers.

Also for space tourism / passenger transportation (suborbital, orbital, cislunar, whatever) Starship is really huge. Finding enough people to fill all these seats won't be an easy task.
I don't see Starship being used for suborbital tourism per-se. If SpaceX can find a way to make suborbital point-to-point travel work that would likely cover the available market pretty quickly unless the price point goes WAY down. On the other hand orbital and Cis-Lunar tourism I can see Starship doing since it's big enough to cover many of the 'requirements' for the high end and middle price point passenger services. But I'm not sure SpaceX could provide the 'services' needed and they would have to partner with someone in the businesss to provide the service staff and customer support capability. (More specifically if they don't have a 'destination' in orbit to go to the passengers will want at least a two day to one week 'stay' on-orbit with various activities and experiances provided. Starship once all-up can provide that capability due to it's size and design but it will also have to carry a passenger service crew and facilities to support them as well.
(Including the 'clean up crew' because SAS is going to be a thing :) https://en.wikipedia.org/wiki/Space_adaptation_syndrome)

The good news here is that's going to require setting up a space maintenanance and service certiifcation system which will open new career paths to space :)

Whatever, if that works, Musk will have accomplished full-reusability the Bono / Truax way (king size) rather that "The Rocket Company DHC-1" style. Starting with an enormous vehicle with a huge payload.
Again I'm not going to complain if I'm totally wrong and this blows space wide open. :)

Randy
 

sferrin

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Re: a SpaceX lander. I'm think it would be relatively easy for them to adapt some of their existing hardware. Question is, how big can you realistically go without causing too much erosion at landing? And maybe they only need a temporary solution for that anyway. Once a hardened landing pad is operational that problem goes away.
 

Archibald

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One thing Scott Manley pointed out in his review of the presentation is that it's not likely that Starship will be used to service the Moon for very long if it is used to land there. The math shows the raptors are going to throw some regolith pretty far, (possiblity of some of the debris almost making orbital velocity) with all that implies for 'sandblasting' any nearby structures
Wow. Never, ever thought about this. You said orbital lunar velocity ? as in, what, 2.5 km/s ? no need for mass driver then o_O
Which makes me wonder, might still be a problem on Mars. Stronger gravity plus atmosphere, ok, but still...

As for a lunar base, the more I learn about Oceanus Procellarum / Marius Hills, the more I like it. It has large underground lava tubes with a big skylight / opening; some interesting KREEP ore concentrations; and also some of Kagyua underground reflectors that might be underground water (if not false signal, admittedly).
Smooth the interior of the cave, crush the rocks removed into LUNOX, then inflate BA-330s or BA-2100s Bigelow modules. Chain them like sausages. Rinse, repeat. Could make one hell of a lunar base, even more since calculation shows that lunar weak gravity would allow 3-miles wide caves. o_O
And being underground, it would not care about Starship sending regolith flying all over the place.
 
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Archibald

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Re: a SpaceX lander. I'm think it would be relatively easy for them to adapt some of their existing hardware. Question is, how big can you realistically go without causing too much erosion at landing? And maybe they only need a temporary solution for that anyway. Once a hardened landing pad is operational that problem goes away.
There is also ULA bold and clever "horizontal lander" concept. Make the descent from LLO to 2 miles over the lunar surface, on the huge engine; then flips to horizontal and land smoothly on banks of smaller thrusters.
 

sferrin

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Re: a SpaceX lander. I'm think it would be relatively easy for them to adapt some of their existing hardware. Question is, how big can you realistically go without causing too much erosion at landing? And maybe they only need a temporary solution for that anyway. Once a hardened landing pad is operational that problem goes away.
There is also ULA bold and clever "horizontal lander" concept. Make the descent from LLO to 2 miles over the lunar surface, on the huge engine; then flips to horizontal and land smoothly on banks of smaller thrusters.
space-1999-tv-sci-fi-silk-poster-eagle-transporter-model.jpg
 

RanulfC

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RanulfC said:
The question though is do we really NEED a Saturn V class rocket and payload capability or do we need regular and inexpensive access to orbit. The two while not mutually exclusive are also not automatically the same for a reason.
I think this is absolutely a point worth making. I also think it might be a tad short-sighted.

I am not Musk's biggest booster (bad pun had to be made), but if he delivers, you might see a paradigm shift of sorts: to this point, satellite design has been heavily dictated by weight because of the exorbitant costs. If you can bring costs down substantially, it might not matter that a future refined Falcon grants a lower $/lb rate: there may be a shift at some price point toward heavier satellites which trade weight gain for capability/longevity/survivability. And that might make heavy or super-heavy lift essential.

Actually satellite mass has apperently been going down for the last few decades rather than continuing to grow as was originally assumed would happen. Higher reliability parts, the ability to reconfigure the system on the 'fly' to bypass malfunctions and damage and other inovations have made modern satellites more capable at the same or lesser mass than pervious satellites.

There are a lot of things one might want in a spacecraft/satellite that are simply abandoned right now because of weight and the extremely high $/lb rates. Commercial space programs exist, so clearly the market can bear the current costs. If prices come down substantially, maybe adding more fuel for longer missions, physical shielding against collisions with space debris, perhaps shaping and even thick RAM for certain customers becomes much more attractive. You may start to see design compromises take advantage of the lower $/lb to achieve greater capability and cost to the extent we can drive down price -- and that will require higher payload to orbit capabilities than designs that are strictly weight-driven.
The satellite design and production trades have been making a point for the last few years that satellites are going to get lighter simply because the long-life parts and ability to reconfigure around failures and damage are more common. But it's also one of the reasons that despite SpaceX's price-point satellite companies are not flocking to flood them with launch orders in that the satellites and thier launch costs were 'paid' several years ago and saving several million on the cost of launch really isn't a priority. Satellite design and production isn't a steady business and it comes in waves with peaks and valleys and we just passed the latest "peak" a few years ago and orders are in decline since it had been assumed (and planned) that the newest satellites would have a 10 to 20 year service life. It's actually access more than cost-per-pound, (though that's an issue too of course) since satellite designs have to be "fixed" about 5 years prior to launch and the buyers want the most updated hardware available that has a high "mean-time-between-failure" for the parts. So the makers are currently working with the satellite customers to project what the "next" generation of satellites will need for hardware and capability.

The satellite industry was highly interested in the DoD/DARPA plans to experiment with robotic on-orbit servicing as a concept but in truth allowing such capability would require a major redesign of the industry satellies and operations which is where you have issues with new capability coming along. The main satellite market is pretty inflexible on cost and access because of the time factor mentioned above and the cycle for new satellite launch which came with it. That's part of the reason LEO constellations have come back into vouge

LEO satellites have a shorter life-span and therefor need to be replaced more often so not only does cost-to-orbit play a bigger factor but reliable access is also a major need since the provider needs to keep replacing end of life satellites in a timely manner. Now the kicker is that iwth regular, low cost access to LEO the deployment and operation of things like on-orbit servicing of satellites become vastly cheaper and easier. On top of that at some point in the near future from there the entire 'satellite market' as it has been known is viable for a major change in operational and design philosophy which would change the underlying paradigm so much that the whole industr would change virtually over night. Needless to say this hasn't gone unnoticed or uncommented on in that industry. The consensus is currently to wait and see how things shake out but until the change is inevitable the 'standard' satellite design, construction and launch paradigm will likely remain.

Does it really matter that I can get a microsat to orbit with a Pegasus launch for substantially lower-$/lb if Pegasus doesn't loft enough payload to carry the design/capabilities that I'm willing to pay for?
Pegasus isn't exactly cheap you know, right? You're also looking at the issue backwards. You design to a launch payload mass and then put in what systems you can till you hit that limit while trying to mount both redundancy and hardware/software forward and backward compatability as possible and using the 'latest' technology (which is why it's usually about 5 years behind the latest) and systems. And keep in mind the payload mass you are aiming at is never to LEO but to GTO since most satellites go into GEO not LEO.

Now the recent upswing in LEO "Nano/Micro/Small-satellites" is because technology both for satellies and on the ground has advanced enough that such satellites are practical and useful. Similarly for LEO constellations the fact that you will be replacing a satellite every couple of years, (and in theory at a lower price than putting a large satellite into GEO) means you will have a couple of years technollgy advantage over an older GEO satellite. As the LEO satellite population grows however the issues with 'traffic' and accidents grows as well and though LEO and MEO orbits are petty much unrestricted this is going to change. (And industry has been talking about this issue since the mid-90s)

Meanwhile GEO is already highly restricted for commercial use due to the number of orbital 'slots' available for the (growing) number of users of GEO satellites. And somewhat worse it's getting to the point where various nations are attempting to "take-over" the regulator and finanicial aspects of that market:

So while it looks every more likely that the satellite launch market may change significantly, what is worrying the satellite service providers is what will be the longer term changes in the design, building and operations of "satellites" themselves?

Randy
 

RanulfC

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Re: a SpaceX lander. I'm think it would be relatively easy for them to adapt some of their existing hardware. Question is, how big can you realistically go without causing too much erosion at landing? And maybe they only need a temporary solution for that anyway. Once a hardened landing pad is operational that problem goes away.
Well the main thing is as long as your engines are on the bottom of your lander they are going to throw up debris. (Less with a hardened pad but there will still be some, and they you have to worry about exhaust reflection onto the bottom of the vehicle) One way to mitigate this of course is to move your landing engines upwards such as in the Hercules lander, (https://www.secretprojects.co.uk/threads/nasa-hercules-landing-vehicle.32337/#post-362255) and some other VTVL lander concepts. You lose some efficiency of course but it may be worth it since you can also put your cargo/passenger bay lower down and therefore have easier off/on-loading of both.

I should have also mentioned that Scott's other main point was that since Starship is pretty much designed around using an atmoshpere to help with the propellant fraction using it to go to the Moon is always going to be missing one of its greater strengths. So going with something all propulsive from Lunar Orbit to the Surface may be a better idea. (Using Starship to go to Lunar orbit and back would allow the use of aerobraking so its pretty much JUST the last part of the journey where something speciifclly designed to do the job would be a better option)

One thing Scott Manley pointed out in his review of the presentation is that it's not likely that Starship will be used to service the Moon for very long if it is used to land there. The math shows the raptors are going to throw some regolith pretty far, (possiblity of some of the debris almost making orbital velocity) with all that implies for 'sandblasting' any nearby structures
Wow. Never, ever thought about this. You said orbital lunar velocity ? as in, what, 2.5 km/s ? no need for mass driver then o_O
I'd only become aware of the issue a few years ago, oddly enough from the Atomic Rockets site which has since updated the section with pictures from damage done to Surveyor 3:
(Which mind you was technically 'below' the rim of a crater so should have been protected)
And it was discussed quite a bit on the New Mars forums.

Which makes me wonder, might still be a problem on Mars. Stronger gravity plus atmosphere, ok, but still...
That helps but you still end up with needing 'berms' (https://www.researchgate.net/figure/Contoured-Berms-can-Deflect-Lander-Exhaust-Plume-and-Debris_fig4_330145093) around the landing pads and you still have to worry about 'bounce-back' debris on the lander and exhaust recirculation. Oddly enough the two (2) static firings of solid missile boosters I've attended they actually installed a trench with chalk in it so it can color the exhaust plume and make it more impressive. Which it is :)

As for a lunar base, the more I learn about Oceanus Procellarum / Marius Hills, the more I like it. It has large underground lava tubes with a big skylight / opening; some interesting KREEP ore concentrations; and also some of Kagyua underground reflectors that might be underground water (if not false signal, admittedly).
Smooth the interior of the cave, crush the rocks removed into LUNOX, then inflate BA-330s or BA-2100s Bigelow modules. Chain them like sausages. Rinse, repeat. Could make one hell of a lunar base, even more since calculation shows that lunar weak gravity would allow 3-miles wide caves. o_O
And being underground, it would not care about Starship sending regolith flying all over the place.
Marius is one of my want to see more of places on the Moon as well but keep in mind that just because YOU are underground doesn't meant you don't need to deal with the problem of flung debris. I can't find the diagrams/article it was originally from but there is a Moon denier site where they use the fact that Surveyor 3 was damaged when it's "not possible" as evidence and then show diagrams on how the debris could have done so anyway. There's also some speculation that some of the 'damage' that the Apollo 11 astronauts saw on the bottom and sides of the descent stage may have come from deflected debris from the surface.
There is also ULA bold and clever "horizontal lander" concept. Make the descent from LLO to 2 miles over the lunar surface, on the huge engine; then flips to horizontal and land smoothly on banks of smaller thrusters.
Yep though you still have a surface interaction plume the smaller thrusters are always going to be somewhat better.

Again I won't argue that solution :)

Then there is the SHADO option, or how much do you trust your 'automatics/pilot' anyway? :)
 

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RanulfC

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Dragon029

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I mean, the 747 is an outstanding aircraft, but for Ryanair or Easyjet low-cost short-haul airlines it would be completely overkill. Which mean: there is room for smaller RLVs just like there is is room for much smaller airliners bar 747 or A380 (fortunately enough).

Musk somewhat acknowledged this recently when he admitted that Falcon 9 and Heavy might not be replaced by Starship-Super-heavy.
Do you have a link to an article, etc where he says Falcon 9 / Heavy might not be replaced by Starship? If he did say that, I imagine that would just be in the event that Starship turns out to be significantly more expensive to operate than expected.

As it is today, Falcon 9 is like a 737 (vs Starship being an A380), but a 737 that has to jettison an entire engine nacelle before landing. They were and might still be looking at cost effective methods of returning F9 second stages, but unless that happens there is a decent chance that Starship could turn out to be cheaper to launch (with a number of reuses of course) than Falcon 9, let alone Falcon Heavy.

Elon Musk is upbeat about Starship 1 flight tests, he said that they would begin in one to two week’s.

https://www.bbc.co.uk/news/science-environment-49870154
The article might have been in error and been edited since your post, but they expect to begin flight tests in one to two months rather than weeks.

Well the main thing is as long as your engines are on the bottom of your lander they are going to throw up debris. (Less with a hardened pad but there will still be some, and they you have to worry about exhaust reflection onto the bottom of the vehicle) One way to mitigate this of course is to move your landing engines upwards such as in the Hercules lander, (https://www.secretprojects.co.uk/threads/nasa-hercules-landing-vehicle.32337/#post-362255) and some other VTVL lander concepts. You lose some efficiency of course but it may be worth it since you can also put your cargo/passenger bay lower down and therefore have easier off/on-loading of both.
Perhaps they could do something with those methalox RCS thrusters that they want to replace the Starship's cold gas thrusters with on Mk5+. They're already going to be doing a suicide burn with Raptor to land on the Moon (3x Raptors for symmetry at minimum throttle still have a T:W of 1.05 with Starship 100% fueled and with 150t of payload), so maybe they could kill their speed with the Raptors, then cut them and descend under the power of something kind of arrangement of methalox UltraDraco engines; perhaps mounted along the raceway between the fins, angled diagonally downward or something.
 

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Key mentions regarding Starship:

1. The header tanks currently in the Mk1 prototype will be replaced with a properly integrated double-bulkhead set of tanks in the nose.
2. Starship currently has 4x Tesla 100kWh battery packs in the nose, with Tesla Model 3 motors pressurising hydraulic accumulators, which then power hydraulic actuators that actuate the flaps.
3. For Starship Mk3 and onward he wants to move to fully electromechanical actuators.
 
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Orionblamblam

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Re: a SpaceX lander. I'm think it would be relatively easy for them to adapt some of their existing hardware. Question is, how big can you realistically go without causing too much erosion at landing?
Obvious solution: landing "tractor" engines at the nose. These would necessarily have some losses since you'd have to angle them off to the side to keep from tearing up the sides of the vehicle, but it shouldn't be too bad.

And if the weight hit of added engines in the nose is problematic, you could mount the engines to a ring... and leave them in lunar orbit. Starship comes from Earth, enters lunar orbit, docks with the engines, lands, lifts off, leaves engines in lunar orbit.
 
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RanulfC

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Do you have a link to an article, etc where he says Falcon 9 / Heavy might not be replaced by Starship? If he did say that, I imagine that would just be in the event that Starship turns out to be significantly more expensive to operate than expected.
I'd like to see the context too since he was pretty adament that Falcon would go away and pretty much because it would be 'competition' with Starship in the end. The thing is it's a damn good and solid launcher as it is and it fits the market quite well even beyond what the market needs at the moment.

As it is today, Falcon 9 is like a 737 (vs Starship being an A380), but a 737 that has to jettison an entire engine nacelle before landing. They were and might still be looking at cost effective methods of returning F9 second stages, but unless that happens there is a decent chance that Starship could turn out to be cheaper to launch (with a number of reuses of course) than Falcon 9, let alone Falcon Heavy.
Spacecraft are not airplanes and airplanes are not spacecraft :) Most specifically they don't have airplane like operations. IF you want to go that route then we'd compare it to the Short-Mayo (https://en.wikipedia.org/wiki/Short_Mayo_Composite) system where the Mercury "upper-stage" is automatially controlled and is destroyed once it 'drops off' its cargo. Of course that utterly fails to make a very good analogy but if you insist on using aircraft understand that more akin to early aircraft trying to cross great bodies of water. With nobody at the 'destination' nor any infrastructure or support. As I keep saying trying to compare space travel to any Earth transporation system is clumsy at best and the various compromises you have to make to accuratly cover the sitution are pretty redicoulus.

SpaceX has stated they have given up on making the Falcon 9 upper stage reusable for the current time, (and then announed Falcon 9 was being 'replaced' by Starthip so take it for what it's worth given they may be walking that back too) because to do so would eat up to much payload mass. And there's a good reason for this once you realize their main 'market' and 'destination' is GTO which is even harder to get back from than LEO. Worse the performance of the Falcon 9 upper stage is severly limited due to the propellants used. As long as they stick to kerolox it just won't have the performance to carry a payload AND be recoverable from GTO/GEO.

There's also the issue with payload volume over mass since the easyist way to accomodate various size payloads is to have a fairing and having a forward fairing and all the attachment points and hardware makes reentry and such a LOT more difficult. (Not impossible and there's a really good in depth discussion over at NASA Space Flight forums on concepts on how to do it and possible 'upgrades' to the uppre stage to help allow that. I suggest anyone interested go check it out)

Now if you only had to have the upper stage go to LEO and back that makes recovery a LOT easier, but as noted the 'market' Falcon 9 mostly serves is GTO/GEO so there aren't a lot of options open to reusablity under those circumstances. Now if someone put up a Solar Electric Propulsion Space Tug or somethig that could take the satellite from LEO to GTO/GEO then SpaceX can probably design an economicially recoverable upper stage. Then the only thing that might get expended on a regular basis is the fairing, (which they've demonstrated partial recovery on IIRC) and the "trunk" of the Dragon 1/2. ("Cute" idea I've seen is using a 'gutted' Dragon 1 with the docking port replaced with an extensible nozzle or plug-cluster engine as a recoverable Service Module which reenters and is picked up with the Crew Dragon)

The thing is if you can up the performance enough of the Falcon 9 upper stage you can in fact use a similar reentry and landing procedure to Starship. (I suspect they may have to go parachute unless they can get a really good engine/propellant mix, which isn't bad)

Perhaps they could do something with those methalox RCS thrusters that they want to replace the Starship's cold gas thrusters with on Mk5+. They're already going to be doing a suicide burn with Raptor to land on the Moon (3x Raptors for symmetry at minimum throttle still have a T:W of 1.05 with Starship 100% fueled and with 150t of payload), so maybe they could kill their speed with the Raptors, then cut them and descend under the power of something kind of arrangement of methalox UltraDraco engines; perhaps mounted along the raceway between the fins, angled diagonally downward or something.
The problem is the payload and landing mass. Hercules can get away with landing on the upper thrusters even with the cosign losses since it caps out around 20MT to 30MT. 100Mt to 15Mt is going to require more power than the RCS could provide. The Ultra-Draco's would require to worked into the system along with their propellant, (might be able to use methalox) but that would mean one or more of them is probably on the windward side during atmopshereic interface which could lead to heating issues. (Or not I mean come on Stainless Steel actually makes a huge amount of sense to people who've been looking at this stuff for decades, you just tend to forget because nobody is listening :) )

Obvious solution: landing "tractor" engines at the nose. These would necessary have some losses since you'd have to angle them off to the side to keep from tearing up the sides of the vehicle, but it shouldn't be too bad.
Hercules arriving :)

Of course for something the size of Starship that becomes somewhat problematical, challengine to accomplish given the overall mission requirements of the ship design but possible I'd think.

And if the weight hit of added engines in the nose is problematic, you could mount the engines to a ring... and leave them in lunar orbit. Starship comes from Earth, enters lunar orbit, docks with the engines, lands, lifts off, leaves engines in lunar orbit.
At which point you'd need to ask if you really want to try and use Starship for everything? It might be just better to add a cargo section to the 'ring' and ferry the payload down to the surface and back rather than bring Starship down and up again.

Randy
 

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Orionblamblam

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At which point you'd need to ask if you really want to try and use Starship for everything? It might be just better to add a cargo section to the 'ring' and ferry the payload down to the surface and back rather than bring Starship down and up again.
I'd say have the ring include *just* the engines and attachments, never mind propellant and tankage. That would remain in the Starship. The engines would be to Starship what a tug is to a ship... or a jetliner.

 

RanulfC

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I'd say have the ring include *just* the engines and attachments, never mind propellant and tankage. That would remain in the Starship. The engines would be to Starship what a tug is to a ship... or a jetliner.
Sure, which requires new feed lines and attachment point on Starship to support using a single system it uses only during one route, though you could argue it for Mars landing as well. Which still avoids the actual question which is does taking Starship down to the Lunar surface and back to orbit make enough sense to justify not using a seperate more effiecent vehicle to do it with?

Maybe early on and for a short time but that will change quickly once the local transport infrastructure is built up and alternative become available.

Randy
 

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Falcon 9 will probably hang around as long as SHS has not achieved full technical/operational maturity. After that, the launch cost of SHS will make it more profitable than Falcon 9 regardless of payload. It could carry a microsat and still make more profit than a Falcon 9 doing the same. Indeed, it could compete for that microsat against Rocket Lab and Virgin Orbit. The remainder of the 100 ton payload could be made up of tourists.

Space is a destination in and of itself as “cruises to nowhere” are here on Earth. However, the destinations will create themselves in the form of tourist space stations and micro G industrial facilities. I can imagine how many Bigelow 2100 modules could be sent up once SHS is available. Long shelved ideas like solar polar satellites would likely come under fresh re-examination. At the target launch price under $10 million, even medium sized companies could pursue R&D projects in space.

As for debris recoil on the moon, I would imagine the eventual solution would be the same as on Earth: landing on a prepared pad although in this case made of lunar regolith. The NextSTEP2 Human Landing System now in planning would be enough to allow construction of such a pad. As with Commercial Crew, NextSTEP2 is an industry provided solution where NASA does not own the vehicle.
 

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Orionblamblam

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Sure, which requires new feed lines and attachment point on Starship to support using a single system it uses only during one route,
If the solution is to mount landing rockets up front, you're goi ngneed those lines and something like those attachment points anyway.

Which still avoids the actual question which is does taking Starship down to the Lunar surface and back to orbit make enough sense to justify not using a seperate more effiecent vehicle to do it with?
Ain't nobody got time for that. Starship is going to consume all of SpaceX/Musk's attention... until the *next* ship comes along.


Maybe early on and for a short time ...
Exactly so. And in SpaceX time, a "short time" is not long enough to build up the lunar surface infrastructure for a base, but it may well be long enough to land a *lot* of ships. Dozens of Starships could potentally land before the Starfleet Corps of Engineers could build the pad. Especially since "how do you build a landing pad on the Moon" is an unanswered non-trivial question.
 

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And if the weight hit of added engines in the nose is problematic, you could mount the engines to a ring... and leave them in lunar orbit. Starship comes from Earth, enters lunar orbit, docks with the engines, lands, lifts off, leaves engines in lunar orbit.
Got a very similar idea to land my suborbital refueling rocketplane on the Moon, Starship style (= tail-sitter). A kind of landing gear shaped like a four-legs milk-stool, to be docked to the rear fuselage once in lunar orbit. Picked up by a robotic arm during a refueling at a cislunar propellant depot.

A naive question incidentally. Let's suppose I have a 100 mt rocket lander with 60 mt of thrust. On Earth it could not lifoff but on the Moon, does 1/6 gravity helps ? Never realized this. The LM weighed 15 mt but did the descent engine had 15 tons thrust + or less ? or just 1/5 or 1/4, enough in the lunar gravity ?
 

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You'll need to decelerate first before attempting to land smoothly. The small ratio b/w landing weight and thrust is a question only during the terminal phase of a lunar landing. With a throtable engine, the answer lies simply in the throttle settings.
I very much doubt that Starship will reach the lunar surface with her engine blasting full thrust.
 

Richard N

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Just imagine the same interview with the head of ULA. It could only be far less inspiring and cool; A non happening.
 

sferrin

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Just imagine the same interview with the head of ULA. It could only be far less inspiring and cool; A non happening.
And scripted, edited, have to go through an approval process, etc. etc.
 
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