totm nov 2023 SpaceX Discussion Thread

[tater]

10 minutes ago, Ultimate Steve said:

Starship wants to land both parts in the crane that stacks them. We've known that for years and it still seems crazy. Granted I have not heard their plans for payload integration, and I think with the KSC pad they might have a separate catch tower or something, it has been a while since I've seen that. So maybe the plans have been scaled back.

There is an environmental impact doc that was recently circulated that showed SS being moved horizontally, FWIW.

As for Stoke, they really seem to be driven to accomplish the goals they set out in the timeframe they announce—so they throw around dates with more care. I really think they have a shot at flying fairly soon based on recent interviews I have heard with Lapsa.

[Nuke]

with air travel the smaller planes turned out to be more viable than the jumbos. the only reason 747s are still flying is they were easily retrofitted for cargo. a380s are not really all that great because they were designed with a second passenger deck which is not something that was designed to be removed. they might still be useful but i have a feeling the operating cost per kg is not as good. they wont be handling bulky cargo though. you can also make room for a few guppies and dreamlifters, and an occasional an225 (if you can avoid shooting at it) but not many. i worry the heavier rockets might get relegated to this kind of niche market with the small and medium launchers being the primary method. ride share certainly is a useful approach though in that you can aggregate payloads with similar mission profiles. though we might have everything from small systems that can put up a cubesat (eg spinlaunch and airlaunch) to utter behemoths for the big stuff in the end. a few clear workhorses will do most of the work. i like having a large reusable booster or suborbital spaceplane with multiple 2nd+ stage options in both reusable and disposable flavors.

[magnemoe]

2 hours ago, mikegarrison said:

That's not true, really. Airplanes are fully reusable, but it's still only profitable to use one that is the right size for your payload.

Maybe in a world where Starship was the only reusable launch vehicle, that wouldn't matter. But we aren't going to be living in that world, and SpaceX is going to have competition from other fully reusable launchers. And in that case, being "right-sized" is going to matter. Ground-handling costs and capital ownership costs and fuel costs all scale with size.

If the payloads are there to support Starship, then it will be profitable. If they aren't, then it will lose out to smaller, less expensive, fully-reusable launchers.

Sometimes payload capacity generates its own demand. That's what happened with the 747 when it first came into service. But sometimes it doesn't. That's what happened to the A380.

This is because the aircraft marked is very mature and large, rocket marked is not. I kind of expect Stoke space rocket to be much cheaper than Starship for smaller payloads as rocket is much smaller and easier to handle. 
Starship would still be much cheaper if you could use the capacity. 
As or the A380 its problem was that the passenger flight model was shifting from an spoke an hub model to far more direct flights with smaller planes as they was now more efficient and could fly longer.

1 hour ago, tater said:

There is an environmental impact doc that was recently circulated that showed SS being moved horizontally, FWIW.

As for Stoke, they really seem to be driven to accomplish the goals they set out in the timeframe they announce—so they throw around dates with more care. I really think they have a shot at flying fairly soon based on recent interviews I have heard with Lapsa.

Two reasons to move SS horizontally, either send them with ship to KSC, or they land somewhere in the Pacific or US west coast and then returned to an launch site. 
Now why would this require an environmental impact study?  Its shipped dry after all. An structural study makes more sense here, damage to tiles is an major one even if in an cradle. 

[tater]

1 hour ago, magnemoe said:

Two reasons to move SS horizontally, either send them with ship to KSC, or they land somewhere in the Pacific or US west coast and then returned to an launch site. 
Now why would this require an environmental impact study?  Its shipped dry after all. An structural study makes more sense here, damage to tiles is an major one even if in an cradle. 

It could have to do with road transit to and from a port area, they might have to widen roads to make corners with something that long.

Or perhaps even dredge closer to starbase to have a take-out on/off of a barge (however they ship it)

[RCgothic]

Hardly anyone else even has a reusable S1. Only electron, to nowhere near the extent of F9 thus far. Reusable vs reusable battle is a long way off IMO. It's cool that Stoke, RL and BO are working on potentially competing approaches.

Maybe Stoke's approach might be more easily realisable than starship. But for certain payloads (e.g. propellant) if each approach is fully realised that won't be anywhere close to as rapidly relaunchable as a "land on the launch tower".

Additionally, having an enormous mass margin will certainly not hurt. If Starship achieves full and rapid reusability, but it only manages 25t payload to orbit and something like 300 tonnes are required for rapid reuse, that still undercuts Falcon, current market leader in cost efficiency per payload, by a factor of at least 5.

If Stoke needs 50t dry mass to LEO for rapid reusability but total mass to orbit ends up being 40t, they'll be stuck.

Also the "but it'll be oversized!" case is somewhat rebutted by pointing at the transporter missions that are currently eating smallsat launchers' lunch.

If there's a payload capacity of 200t and a customer only needs to send up 2t, it'll be sent up with 50-100 other payloads and the "Cesna" won't compete against the "A320" outside of extremely niche applications.

Edited August 17 by RCgothic

[darthgently]

2 hours ago, RCgothic said:

and the "Cesna" won't compete against the "A320" outside of extremely niche applications.

Agreed.  Starship is playing a longer game.  There may have been a very short time span when massive ocean going container ships were risky from a market perspective, for example.  But that perception didn't last long if it ever was a reality. 

The first mass product that benefits greatly from microgravity manufacture seals the deal.

How many people out of 8 billion daily could benefit from microgravity-grown organs from their own stem cells?  Everyone eventually.  Big market.  That's just one example

We focus on payload tonnage to orbit, but payload tonnage from orbit needs to also be considered and 2nd stage reusability and return payload capacity will rule here.  The out the door price of that return payload per ton will be a big factor.

I don't have to know Starship's and Stoke's exact payload tonnage from orbit to know that Starship would be the relative "container ship".

On a side note, distribution of goods returned from space could become a minor market chunk all on its own.  Brownsville TX is not a bad location all things considered (access to both oceans, air, and space). 

[Exoscientist]

On 8/16/2024 at 1:15 PM, Exoscientist said:

IF it really turns out to be that price, still a big IF, then it would be a better price than the Falcon 9 new of $67 million while being twice the payload of the F9 at 45 tons to LEO.

 

 I do think it is possible for a mid-size launcher to be comparable to the Falcon 9 in price following the commercial space approach of private financing. That would put the New Glenn though in the range of $120 million, having twice the payload capacity of the F9.

 

 IF it really does turn out to be ca. $68 million, then that would be a major development In having a rocket half the price per kilo than the Falcon 9. We’ll likely know for sure later this year when New Glenn makes its first launch.

 

 IF it does, then this might give price incentive for SpaceX  to cut the price of the Falcon 9 in half. Note Elon once said the production cost to SpaceX of the Falcon 9 is only $15 million. So they could still make a profit though not as profitable as before.

 I found out that the $68 million price for 45 tons is for the partially reused New Glenn where the booster is landed downrange. So the comparison actually should be made to the price per kilo of the partially reusable F9 when it lands the booster downrange. So at $40 million for 17 tons payload for partially reusable F9 that’s $2,350 per kilo. And at $68 million, if true, for 45 tons for New Glenn, that’s $1,500 per kilo. So if SpaceX did want to reduce the price to match New Glenn reused price per kilo, it would reduce the reused F9 from $40 million to $25 million, still a significant reduction.

  Robert Clark

[magnemoe]

6 hours ago, tater said:

It could have to do with road transit to and from a port area, they might have to widen roads to make corners with something that long.

Or perhaps even dredge closer to starbase to have a take-out on/off of a barge (however they ship it)

They are shipping in tower segments already, its an ship breaker north of the build site who I assume is used for bringing them inn. You might need to move some power lines and cut down some trees but nothing serious. 
But you are probably correct, might also update that harbor a bit who would be the big one. 

[CBase]

Anyone knows why FAA Approval of Flight 5 is taking so long ? Is landing boosters not covered in general admissions of the launch site ?

[darthgently]

2 hours ago, CBase said:

Anyone knows why FAA Approval of Flight 5 is taking so long ? Is landing boosters not covered in general admissions of the launch site ?

I'm pretty much completely guessing it may possibly be intended to dispell any rumors that they are being easy on SpaceX given the activist clamor.  That or it is just bureaucratic overhead glacially dealing with the mercury typo

Edited August 18 by darthgently

[Ultimate Steve]

A discussion elsewhere gave me an idea. Well most of it wasn't my idea. But part of it is.

This pertains to Martian Colonization, which is a ways away at best. Though it could work for a large non-colonial base too.

This whole idea stems from the idea that Mars ISRU is the bottleneck on mission size, which is a fairly common sentiment. It follows that you want to minimize your total ISRU requirements. If they actually can pump cargo ships out like Liberty ships, the fuel cost to send them home will be so high (my highly optimistic numbers say 422 tons) that it would be better to just keep them on Mars. Thus, this analysis will only focus on crew ships.

Taking your entire roomy space station to land on Mars is good for the first few missions as you'll need a ton of life support and such, but once you have a base set up, it is a waste to bring all of that down to Mars and back up. Thus, the idea: Send a number of "transfer" ships to Mars. They aerocapture into a low orbit. The transfer ships rendezvous with and transfer their crew to a "shuttle" ship which is waiting in Mars orbit. This "Shuttle" is laid out like an airliner, lots of seats, designed for short term habitation. The shuttle lands on Mars. The crew exit for the base. The shuttle is refueled, and then at the next transfer window, launches the crew (those that wish to return at least) to the transfer ships. It then waits for the next round of incoming transfer ships as the transfer ships all return to Earth, where it will be reused.

This means that all of the fuel for transfer ship Earth return has to come from LEO refueling, and requires significantly more LEO refueling. As an aside, the assumption is that all of the transfer ships return to Earth, either because all of the crew are, or because the expensive crew rated ship is to be reused. 

I made a spreadsheet to compare various approaches with a lot of tweakable values: https://docs.google.com/spreadsheets/d/1HUDZwD90kcUYPOvI87MgN6ZaRnhkfMiZGpwheewFxDA/edit?usp=sharing

All of the mass values are suspect, but this is less about the raw numbers and more about the ratios between approaches so it shouldn't be too terribly bad.

In short, if you can fit 8x as many people into a shuttle ship than you can fit into a transfer ship, you can reduce the ISRU burden by a factor of 18 at the cost of increasing LEO refueling burden by a factor of ~2.3-2.5 for the numbers I chose, compared to the baseline "ship lands on Mars, is refueled on Mars, and returns to Earth" approach.

This would however require zero boiloff tech on the main tank, the capability for ships to loiter in LMO without maintenance, the development of an additional Starship variant, and probably a few other things I'm forgetting, so it isn't free. But I think that's an amazing tradeoff! Scaling up LEO refueling by 2.5x and doing all these things seems a lot easier to me than scaling up Mars ISRU by 18x!

Depending on a few factors it might be advantageous to also do this the other way around, aerocapturing the transfer ships into Earth orbit and using an Earth shuttle ship to send the crew up to reduce the need for launches. However I don't think this will be done as you will probably need an overhaul (and cargo loading) of each transfer ship between missions that is almost certainly easier to do on Earth. Also, leaving that loitering in Earth orbit for 2 years between missions cannot be good for the heat shield from a debris perspective if you're staying high enough to avoid orbital decay. And it isn't even that big of an advantage because the reduction in launches would be low, as for every launch you save you still have to do several refueling flights either way.

Also, related: Another reality check of how much easier it is to send a Starship to Mars than it is to send one to the Moon. Many analyses go as far as refueling in stages using an elliptical orbit for a zero payload Lunar Starship to close because the tank simply isn't big enough depending on which numbers you take to be true.

For Mars? Take your dry mass (plus payload) and multiply it by 2.5 or so. That's more or less how much you need for a (one way) trip to mars.

[tater]

1 hour ago, Ultimate Steve said:

In short, if you can fit 8x as many people into a shuttle ship than you can fit into a transfer ship, you can reduce the ISRU burden by a factor of 18 at the cost of increasing LEO refueling burden by a factor of ~2.3-2.5 for the numbers I chose, compared to the baseline "ship lands on Mars, is refueled on Mars, and returns to Earth" approach.

Is this the refilling burden for just the LMO transfer ship vs a normal SS with (as per your argument) X people?

If that is the case it makes me think instead of return ships doing direct entry, why not have the transfer ship burdened with more than 2.5X refilling flights, and give it the dv to aerocapture to LEO with enough of a burn it can do it in 1 pass, then circularize?

[Ultimate Steve]

21 minutes ago, tater said:

Is this the refilling burden for just the LMO transfer ship vs a normal SS with (as per your argument) X people?

If that is the case it makes me think instead of return ships doing direct entry, why not have the transfer ship burdened with more than 2.5X refilling flights, and give it the dv to aerocapture to LEO with enough of a burn it can do it in 1 pass, then circularize?

Yes. Need about 2.5x as much prop starting in LEO to go LEO -> mars transfer -> mars aero brake and circularizarion into LMO -> earth transfer -> earth landing burn than it takes to go LEO ->mars flyby -> mars landing burn.

I'm having a little trouble parsing the second half of your comment. Are you talking about the transfer ship on the return to Earth phase aerocapturing and circularizing into LEO instead of going straight to a direct entry and landing burn as I had proposed?

Assuming it is either then refueled to land or refueled to go to Mars again (in my comment I speculated that a refit may need to happen on the ground) this might actually require slightly less refueling burden as the post aerocapture circularization might be less Delta V than the Earth landing burn. If this is in addition to the landing burn, it would increase the burden by a little, but we are getting somewhat close to exceeding the fuel capacity of at least the V2 ship (V3 is a thing but it looks so goofy I think my brain blocked me from using it haha) and that's with the fairly optimistic delta v numbers I used.

 

[tater]

Yeah, avoiding direct entry, then using a similar “shuttle” SS to bring the crew home. Then the transfer vehicle only needs TPS scaled to aerobraking vs full reentry.

[magnemoe]

3 hours ago, Ultimate Steve said:

A discussion elsewhere gave me an idea. Well most of it wasn't my idea. But part of it is.

This pertains to Martian Colonization, which is a ways away at best. Though it could work for a large non-colonial base too.

This whole idea stems from the idea that Mars ISRU is the bottleneck on mission size, which is a fairly common sentiment. It follows that you want to minimize your total ISRU requirements. If they actually can pump cargo ships out like Liberty ships, the fuel cost to send them home will be so high (my highly optimistic numbers say 422 tons) that it would be better to just keep them on Mars. Thus, this analysis will only focus on crew ships.

Taking your entire roomy space station to land on Mars is good for the first few missions as you'll need a ton of life support and such, but once you have a base set up, it is a waste to bring all of that down to Mars and back up. Thus, the idea: Send a number of "transfer" ships to Mars. They aerocapture into a low orbit. The transfer ships rendezvous with and transfer their crew to a "shuttle" ship which is waiting in Mars orbit. This "Shuttle" is laid out like an airliner, lots of seats, designed for short term habitation. The shuttle lands on Mars. The crew exit for the base. The shuttle is refueled, and then at the next transfer window, launches the crew (those that wish to return at least) to the transfer ships. It then waits for the next round of incoming transfer ships as the transfer ships all return to Earth, where it will be reused.

This means that all of the fuel for transfer ship Earth return has to come from LEO refueling, and requires significantly more LEO refueling. As an aside, the assumption is that all of the transfer ships return to Earth, either because all of the crew are, or because the expensive crew rated ship is to be reused. 

I made a spreadsheet to compare various approaches with a lot of tweakable values: https://docs.google.com/spreadsheets/d/1HUDZwD90kcUYPOvI87MgN6ZaRnhkfMiZGpwheewFxDA/edit?usp=sharing

All of the mass values are suspect, but this is less about the raw numbers and more about the ratios between approaches so it shouldn't be too terribly bad.

In short, if you can fit 8x as many people into a shuttle ship than you can fit into a transfer ship, you can reduce the ISRU burden by a factor of 18 at the cost of increasing LEO refueling burden by a factor of ~2.3-2.5 for the numbers I chose, compared to the baseline "ship lands on Mars, is refueled on Mars, and returns to Earth" approach.

This would however require zero boiloff tech on the main tank, the capability for ships to loiter in LMO without maintenance, the development of an additional Starship variant, and probably a few other things I'm forgetting, so it isn't free. But I think that's an amazing tradeoff! Scaling up LEO refueling by 2.5x and doing all these things seems a lot easier to me than scaling up Mars ISRU by 18x!

Depending on a few factors it might be advantageous to also do this the other way around, aerocapturing the transfer ships into Earth orbit and using an Earth shuttle ship to send the crew up to reduce the need for launches. However I don't think this will be done as you will probably need an overhaul (and cargo loading) of each transfer ship between missions that is almost certainly easier to do on Earth. Also, leaving that loitering in Earth orbit for 2 years between missions cannot be good for the heat shield from a debris perspective if you're staying high enough to avoid orbital decay. And it isn't even that big of an advantage because the reduction in launches would be low, as for every launch you save you still have to do several refueling flights either way.

Also, related: Another reality check of how much easier it is to send a Starship to Mars than it is to send one to the Moon. Many analyses go as far as refueling in stages using an elliptical orbit for a zero payload Lunar Starship to close because the tank simply isn't big enough depending on which numbers you take to be true.

For Mars? Take your dry mass (plus payload) and multiply it by 2.5 or so. That's more or less how much you need for a (one way) trip to mars.

Don't disagree on you but then you need to develop the Mars lander and have enough of them to get the crews in orbit down even if you had one crash and one out of action until you get new parts from earth. 
You could also refuel the ship in orbit at Mars in an pitch. 

I don't see this as practical at the initial landings as developing this craft would be expensive for an single purpose craft. But landing something designed for long interplanetary missions is not an good idea. 

I would also change moonship for reducing weight if it would have an 2-4 man crew. Probably use an fairing and an smaller habitation section made more light weight. Might use an fairing to let you put more stuff on top. You could still make it very luxurious. 
 

[Ultimate Steve]

23 minutes ago, magnemoe said:

Don't disagree on you but then you need to develop the Mars lander and have enough of them to get the crews in orbit down even if you had one crash and one out of action until you get new parts from earth. 
You could also refuel the ship in orbit at Mars in an pitch. 

I don't see this as practical at the initial landings as developing this craft would be expensive for an single purpose craft. But landing something designed for long interplanetary missions is not an good idea. 

I would also change moonship for reducing weight if it would have an 2-4 man crew. Probably use an fairing and an smaller habitation section made more light weight. Might use an fairing to let you put more stuff on top. You could still make it very luxurious. 
 

Yeah this wouldn't have as many advantages for the initial landings. But to be clear I'm not suggesting a completely different vehicle. I'm suggesting a Starship with a different interior configuration. That's still not nothing, it would need different life support and such. But it should be on the easier end of problems you'd have to solve for Mars.

[tater]

3 hours ago, Ultimate Steve said:

Yeah this wouldn't have as many advantages for the initial landings. But to be clear I'm not suggesting a completely different vehicle. I'm suggesting a Starship with a different interior configuration. That's still not nothing, it would need different life support and such. But it should be on the easier end of problems you'd have to solve for Mars.

With the pressurized volume of an A380, you could put several hundred seats in a SS for short hops.

[darthgently]

5 hours ago, tater said:

Yeah, avoiding direct entry, then using a similar “shuttle” SS to bring the crew home. Then the transfer vehicle only needs TPS scaled to aerobraking vs full reentry.

Though full re-entry capability as an emergency option would be nice, that is a lot of TPS overhead.  Something to weigh

[tater]

From NSF vid showing ring counts for the current V1 vs the V2 version (the V2 ship in question already being stacked). 1 ring added, payload section reduced by 2 rings (not counting any ring section with even part of a dome in it). Useful for spitballing variant capabilities.

[darthgently]

KASA (Korean, not Kerbin) to launch GEO sat on SpaceX rocket

https://spacenews.com/south-korea-spacex-geo-kompsat-3-launch/

Do we have a KASA thread yet?

2 minutes ago, tater said:

From NSF vid showing ring counts for the current V1 vs the V2 version (the V2 ship in question already being stacked). 1 ring added, payload section reduced by 2 rings (not counting any ring section with even part of a dome in it). Useful for spitballing variant capabilities.

Is the above-tank "payload" apparent volume accurate?  Seems like it would be larger

[tater]

4 minutes ago, darthgently said:

Is the above-tank "payload" apparent volume accurate?  Seems like it would be larger

The bulk of payload mass is generally residual props, so tanks make more sense.

[darthgently]

6 minutes ago, tater said:

The bulk of payload mass is generally residual props, so tanks make more sense.

I'm now considering that max payload mass given the typical density of payloads may have taught them that the original was too voluminous for the max.  Maybe in  V2 the volume is better matched to the max payload given typical payloads densities?

Edited August 19 by darthgently

[tater]

10 minutes ago, darthgently said:

I'm now considering that max payload mass given the typical density of payloads may have taught them that the original was too voluminous for the max.  Maybe in  V2 the volume is better matched to the max payload given typical payloads densities?

The only current "real" payload in any numbers for LEO is Starlink V2 sats.

The other payload is props for refilling HLS.

That's all it's gonna fly, so non-tank volume is not super critical.

Also:

 

[Brotoro]

Why increase LOX tank by one ring and Methane tank by two rings?

[darthgently]

Imitation is the sincerest form of flattery?  Cosmoleap in China plans innovative catch tower for rocket recovery

https://en.cosmoleap.cn/products_detail/5.html