ESA needs to save NASA’s Moon plans.

[Exoscientist]

21 hours ago, tater said:

There's a zero percent chance of this happening.

I would say it is more interesting to consider cislunar architectures using existing, soon to exist, and plausible vehicles already under development. Not cobbled together KSP style, but each vehicle contributing something by itself.

Existing:

SLS Block 1

Falcon 9

Falcon Heavy

Delta IV Heavy

Soon to exist:

Starship

Vulcan

New Glenn

Plausible under development:

SLS Block 1b

Neutron

Terran R (? this is more far-fetched they have yet to do anything at all)

 Why not? NASA wants an extended upper stage, except the one proposed by Boeing would be too expensive, adding another $1 billion per launch to the cost. This stage in contrast is already developed so would be much cheaper. Note this also eliminates the need to develop a new carbon-fiber advanced SRB for the Block 2 and that attendant cost. Furthermore it would save on the ~$1 billion launch cost for the SpaceX proposal while at the same time making it a single launch per mission architecture.

 The intention is to make spaceflight to the Moon routine. This is much more likely to happen under a single launch architecture. Also, SLS launches can be less expensive under a reusable approach.

 As for your proposals for lunar missions I like the idea of several approaches to accomplish it. Note that for example SuperHeavy/Starship could also do it in a single launch architecture with the addition of a third stage.

   Robert Clark

Edited August 6, 2022 by Exoscientist

[SunlitZelkova]

33 minutes ago, Exoscientist said:

The intention is to make spaceflight to the Moon routine. This is much more likely to happen under a single launch architecture.

Single launch profile does not necessarily mean routine.

It should be noted that Crew Dragon/Soyuz flights technically fly to an “orbital base” (ISS), but these don’t happen in one flight, it takes multiple resupply flights, involving numerous launches, for each mission to be possible. And yet access to the “orbital base” is routine, despite a multiple launch architecture. Trying to launch all the supplies in one go would be a nightmare.

What matters is cost, for the most part. Once tests are in done and infrastructure is in place, in theory any rocket can launch quickly once the order is placed. But if it costs too much, it will take forever.

In theory SLS could probably launch at the same rate as the Saturn V, but it is so expensive there will never be more than one available at a certain time. Before that, there is infrastructure missing/not up to standard for manufacturing more in the first place, but again, because of cost, despite using Shuttle components it will never fly as often as the Shuttle* or Saturn V.

SpaceX is in the process of displaying they can launch quickly and Starship is cheap enough, and thus there are no problems with their multiple launch architecture.

*Obviously, but in theory I don’t see why it couldn’t have a fairly rapid launch rate. If they could manufacture ETs and refurbish SRBs at a rate to launch as often as they did, couldn’t components be built to allow a Saturn V like launch rate (at best, around three a year)?

[tater]

4 hours ago, Exoscientist said:

 Why not? NASA wants an extended upper stage, except the one proposed by Boing would be too expensive, adding another $1 billion per launch to the cost.

They already have a contract. EUS is going to put money in Boeing's pocket regardless of it ever getting built. This contract for a stage with parts built in however many States (as close to 50 as possible!) will not be canceled to give the money to France/wherever.

Adding cost is the point. The only mission SLS was ever designed to actually accomplish was spending money.

 

4 hours ago, Exoscientist said:

This stage in contrast is already developed so would be much cheaper. Note this also eliminates the need to develop a new carbon-fiber advanced SRB for the Block 2 and that attendant cost. Further more it would save on the ~$1 billion launch cost for the SpaceX proposal while at the same time making it a single launch per mission architecture.

No it would not. Not any of the above. It would be SLS, so still too expensive, the SRBs as-is are around $970M a pair. The RS-25s are supposed to become "cheap" after a few flights—down to $99M... each. The core stage must be some hundreds of millions by itself, so without any upper stage at all every SLS launch (and they can't do better than ~1/yr without MORE money) costs >$2.5B. Then whatever the fantasy Ariane stage costs, plus a new MLP (another billion and several years). Then you have to dev a lander that fits in the stack, and you need that in time to make the new MLP since it impacts height/access for MLP.

It would also take many years. It would take less time to simply scrap Orion, and make an Apollo CSM/LEM stack clone with the goal of squeaking in with less mass than SLS can throw to TLI as-in. That's not happening, either.

 

4 hours ago, Exoscientist said:

 The intention is to make spaceflight to the Moon routine. This is much more likely to happen under a single launch architecture. Also, SLS launches can be less expensive under a reusable approach.

LOL, SLS can never have routine flight assuming "routine" is more than once or maybe twice a year. SLS can never be cheap, it can never utilize reuse of the booster. If they did "SMART" reuse for SLS (not possible without massive performance hits if actually possible at all) they'd find a way to make that process cost as much as the engines I'm sure. They'd also then charge to redo the RS-25 to make it reusable again (the large dev $$$ they just spent was to make the RS-25 expendable, after all).

Note: I like anything that looks like ACES, or XEUS (horizontal landing upper stage), but to get an SLS-derived stage like that to space requires throwing away ~$2.5B on SRBs/Core stage, so it's instantly too expensive.

 

4 hours ago, Exoscientist said:

 As for your proposals for lunar missions I like the idea of several approaches to accomplish it. Note that for example SuperHeavy/Starship could do it in a single launch architecture with the addition of a third stage.

If Starship works with refilling in orbit, it obviates everything.

Any sensible cislunar architecture with Starship functioning uses Starship, and until someone is crazy enough to ride on top of it, probably crew vehicles that transfer crew in LEO.

Sortie landings like Apollo were not supposed to be the goal, so single stack launches are not important, and routine flights that result in hours of EVA on the surface are not the same as a few work-weeks of EVA from a comfortable facility (and Starship by itself is that facility, it's as big as a house inside)

Musk just said on a podcast yesterday that the marginal launch cost of Starship/Super Heavy right now is $50M to $100M. Less than the cost of a single RS-25. 4-5 SS/SH expendable flights for the cost of a single SRB for SLS.

Any architecture that includes SLS at all is too expensive, and never results in "routine" anything.

Edited August 6, 2022 by tater

[tater]

Assume for argument that SS/SH never becomes fully reusable. Booster recovery is a given, though they might have to put legs on it F9 style, reducing payload by some 10s of tons.

We'd have truly a "big Falcon rocket." Upper stage can be lighter—no reuse on Earth, no or less TPS (might keep some for aerobraking, just not enough for full reentry), possibly fewer engines (all vacuum since no landing), etc. We get 150-200t to LEO in this mode not including the vehicle, maybe more—certainly more with booster expended, SS payload already includes RTLS landing of SH after all.

Split the difference, 175t to LEO for $50M-$100M right now. If Raptors get cheaper, that drops it further. Call the cost the full $100M. About 75% of the cost has to be the booster, since it has ~79% of the engines, and most of the mass. So each Falcon 9-style SS/SH launch only expends ~$25M, the booster lands.

Our "old fashioned" SS/SH architecture looks like it can deliver cargo to LEO for $166/kg, possibly as low as $125/kg. That's 30X cheaper than the cheapest cost now—expending a Starship every launch.

Starship/Super Heavy will certainly work done like a giant F9, the upper stage reuse (Earth EDL) is the hard part. It makes everything else absurd just in that config.

So we have a capability larger than SLS—any variant you care to imagine, with any upper stage, even if it magically became a thing right now with zero cost or time impact—for $25M. A single SLS flight, likely close to $4B each flight, no matter how you do the math, would buy 160 of these half expended SS/SH flights.

LOL.

I would imagine if NASA paid for a white paper on using an Ariane core for SLS stage 2 the white paper would cost enough to buy several of these SS/SH launches.

Edited August 6, 2022 by tater

[tater]

Let's play with this. Dump SLS. SpaceX cost would allow 160 SS/SH flights, but they mark it up. Say they charge $100M per flight—an incredible bargain for NASA, and they (SpaceX) net $75M per flight. That means we only have 40 of these flights to play with per year to replace the single SLS.

That's 6,000 tons in LEO. Think we can build a cislunar mission with that? More than one mission—10 600t missions?

One flight is Lunar SS with some residual props. 6 expended tankers to refill it (possibly fewer, we could save mass on stretched, expendable tankers I think). We now have 33 flights left this year to play with.

A version of the Lunar SS could be made that is in fact just a crew ferry. With 4 refilling flights, it can take crew to LLO and back propulsively. If slightly stretched, and fully filled, it would be able to transfer enough propellant to LSS for another surface sortie (LSS from LLO to the lunar surface and back is <200t of props), AND bring the crew propulsively back to LEO (saves fillings if it can aerobrake at all). So 1 crew ferry this first year, and every flight is 8-9 tankers (7 the first time because of residuals). So 8, and we have 25 flights left. that means we can fly to the Moon every 4 months or so.

Assuming the LSS and crew ferry don't need to be replaced every year, we can then send bespoke upper stages to land as habitats, etc.

Edited August 6, 2022 by tater

[Exoscientist]

 

 An upper stage for the SLS could be made by combining two Centaur V’s. This might allow a single launch Artemis lunar landing architecture, no SpaceX Starship launches required:

Possibilities for a single launch architecture of the Artemis missions. http://exoscientist.blogspot.com/2022/10/possibilities-for-single-launch.html

  However, I used the Silverbirdastronautics.com payload estimator that has rather large error bars. I’d like to see a Kerbal Real Solar System mod to get a better estimate. 

   Robert Clark

[SunlitZelkova]

3 hours ago, Exoscientist said:

 

 An upper stage for the SLS could be made by combining two Centaur V’s. This might allow a single launch Artemis lunar landing architecture, no SpaceX Starship launches required:

Possibilities for a single launch architecture of the Artemis missions. http://exoscientist.blogspot.com/2022/10/possibilities-for-single-launch.html

  However, I used the Silverbirdastronautics.com payload estimator that has rather large error bars. I’d like to see a Kerbal Real Solar System mod to get a better estimate. 

   Robert Clark

I’m curious, what is your rationale for single launch architecture over multi-launch?

There’s nothing inherently wrong with multi-launch missions. The only reason it was rejected in the 60s was because of the unreliable technology of the time and Apollo being based around a timeline- landing before 1969- rather than efficiency.

If we are going to do a single launch architecture, I think it would make more sense to put Orion and a lander on top of Super Heavy with modified upper stages derived from Starship.

The lander would likely be pretty bare bones though, so really the architecture we have now isn’t too bad. The only thing I would change is having crew launched on Dragon and board Starship HLS in LEO rather than rendezvousing in lunar orbit.

This presents some issues with redundancy (I don’t think Starship has anything that could serve as the “Aquarius” to the “Odyssey” in the event of an anomaly) but these could be solved.

[tater]

4 hours ago, Exoscientist said:

 

 An upper stage for the SLS could be made by combining two Centaur V’s. This might allow a single launch Artemis lunar landing architecture, no SpaceX Starship launches required:

Possibilities for a single launch architecture of the Artemis missions. http://exoscientist.blogspot.com/2022/10/possibilities-for-single-launch.html

  However, I used the Silverbirdastronautics.com payload estimator that has rather large error bars. I’d like to see a Kerbal Real Solar System mod to get a better estimate. 

   Robert Clark

How is ~55t to TLI a single launch mission? It seems to just close with a small lander—but the requirement for every mission after the first landing is a longer duration stay. Not ideal for what ends up looking like a slightly larger Apollo LEM.

There's also the issue of cadence, ignoring any likely delays from doing literally anything outside of what they have already planned. They will not even launch once per year.

Once Starship is flying—the HLS system of record—SLS is entirely obviated, as multiple launches at vastly reduced cost can do the same mission. Forget Starship as the crew vehicle from Earth.

Dragon as the Earth to LEO vehicle, then a Starship crew/tanker variant in LEO as the taxi to LLO and back. For the cost of a single SLS, they could probably fly once a month, lol, or at least every 2 months.

 

[sevenperforce]

52 minutes ago, tater said:

How is ~55t to TLI a single launch mission? It seems to just close with a small lander—but the requirement for every mission after the first landing is a longer duration stay. Not ideal for what ends up looking like a slightly larger Apollo LEM.

It doesn't even close, either, because it contemplates magically adding 10 tonnes of propellants to the ESM without any dry mass growth.

[tater]

4 hours ago, sevenperforce said:

It doesn't even close, either, because it contemplates magically adding 10 tonnes of propellants to the ESM without any dry mass growth.

I'll admit I just skimmed it. I had started to do the math, but had a few things that needed to be done.

Still, the Apollo LEM was ~16t, so keeping the dry mass of added tankage within those 3 tons seems possible. But then you've sent a huge CM to LLO, and a lander that can hold 2 guys in discomfort for some double digit number of hours. Not the "sustainable" notion of Artemis.

[sevenperforce]

On 10/25/2022 at 11:43 PM, tater said:

I'll admit I just skimmed it. I had started to do the math, but had a few things that needed to be done.

Still, the Apollo LEM was ~16t, so keeping the dry mass of added tankage within those 3 tons seems possible. But then you've sent a huge CM to LLO, and a lander that can hold 2 guys in discomfort for some double digit number of hours. Not the "sustainable" notion of Artemis.

Another critical issue is that ICPS, currently, is 13.7 meters high, while Centaur V is 12.3 meters high. The Exploration Upper Stage is planned to be 16.6 meters high.

Trying to stack two Centaur Vs on top of each other would raise the height of the stack by 8 meters higher than SLS Block 1B. Adding National Team's lander (without the transfer stage, since we're staging in LLO) would add 12 meters to this. Block 1B Crew stands 111 meters high, so we add 20 meters to that plus the 7-meter-high crawler-transporter, and that brings the entire stack to 138 meters. But you've also doubled the propellant load on the ESM, so it's going to be about twice as long, adding another 4.8 meters and bringing the top of the vehicle to nearly 142 meters, about 3 meters taller than the VAB doors. And that's not even accounting for adapters or spacing between anything.

EDIT: Also, merely doubling the propellant load on the ESM wouldn't come anywhere close to what's necessary to brake the National Team's lander into LLO so we're DOA there too.

Edited October 27, 2022 by sevenperforce
See above

[tater]

47 minutes ago, sevenperforce said:

Another critical issue is that ICPS, currently, is 13.7 meters high, while Centaur V is 12.3 meters high. The Exploration Upper Stage is planned to be 16.6 meters high.

Trying to stack two Centaur Vs on top of each other would raise the height of the stack by 8 meters higher than SLS Block 1B. Adding National Team's lander (without the transfer stage, since we're staging in LLO) would add 12 meters to this. Block 1B Crew stands 111 meters high, so we add 20 meters to that plus the 7-meter-high crawler-transporter, and that brings the entire stack to 138 meters. But you've also doubled the propellant load on the ESM, so it's going to be about twice as long, adding another 4.8 meters and bringing the top of the vehicle to nearly 142 meters, about 3 meters taller than the VAB doors. And that's not even accounting for adapters or spacing between anything.

Any use of Centaur as-is seems silly as well, since it likely means a third mobile launch tower be built. Better of course would have been for EUS to have been Centaur from the start (ACES, ideally) at the full tank diameter. The dry mass would likely be higher than under-fairing Centaurs, but they would have the common bulkhead at least as an offset.

Edited October 27, 2022 by tater

[RCgothic]

The bottom line is that the only rocket that could send the enormously overweight Orion/ESM plus a lander with more than a few hours of endurance through TLI in a single launch is an expendable Superheavy.

But there's also absolutely zero reason to strive for a single launch. Any system using distributed launch is much more capable, and the main flaw with SLS/Orion is that it's not distributed enough.

[Exoscientist]

 The whole root of the problem is that Boeing proposed this over expensive upper stage that NASA balked at paying for. But there really was no need for it to be that expensive:

Why does the Boeing Exploration Upper Stage(EUS) cost so much?
https://exoscientist.blogspot.com/2022/11/why-does-boeing-exploration-upper.html

  Robert Clark

[tater]

25 minutes ago, Exoscientist said:

 The whole root of the problem is that Boeing proposed this over expensive upper stage that NASA balked at paying for. But there really was no need for it to be that expensive:

I'd say at least part of the issue is Orion. It's way too massive.