totm dec 2023 Artemis Discussion Thread

[magnemoe]

4 minutes ago, tater said:

LSS dv based on different dry mass assumptions with 1200t of props. ~6.1 km/s is required to go from LEO to the lunar surface, and 8.1 km/s from the LEO to the lunar surface and back to LLO. 8.85km/s from LEO to the surface and up to NRHO. A round trip from LEO to the lunar surface and back to LEO is 12.2 km/s (with no aerobraking).

50t, 11.9 km/s

60t, 11.2 km/s

70t, 10.7 km/s

80t, 10.28 km/s

100t, 9.5 km/s

Note that all these mission dv values allow a flight from LEO to the lunar surface and back to Gateway.

Every mm of 304L thickness we lose drops ~11.6t from the dry mass of Starship. Not sure how thin they can go. There are loads of possibilities for alternate Starship architectures, or using a Starship variant as a hab that is never meant to leave the surface, etc.

Assuming they could do 2.6mm steel vs the 3.6mm that I think they are using now, then the dry mass is ~40t. Fitting out (descent engines up high per LSS, a crew area, etc, might get the thing up towards 60t.

A 49t (dry) version of SS, assuming 250t to LEO expended (Musk has said it's now up to ~300t expended) can go to the lunar surface with no refilling. At 300t to LEO expended, we can send a 71t SS to the lunar surface with no refilling required. This could be used to preposition assets on the surface for habitation, then go for smaller landers to deliver crew, I suppose.

Is it some option that the LSS, is not like the standard image of Starship? Its not that you need that you need the 1000 m*3  crew module for an 4 man maximum landing for 14 days.  Yes you want an cargo bay, you want multiple air locks, and comfortable crew areas and some labs and stuff but 3 floors at 8 meter diameter is plenty for this as in overkill. And you don't want steel for the crew compartment because of secondary radiation and weight. 

No reason to take LSS back to LEO, it goes to the moon and stays. I could imagine an second LSS as an gateway space station, there it might be an theoretical rescue craft if landed LSS can not launch again because an fuel leak or other non fatal incident. 
SpaceX would want to get the LEO tankers to be reusable but you might not need to on an SLS budged   The lunar tanker, you might dispose of it if needed for mission. 

One idea, launch an dragon to LEO, have an disposable tanker pick it up and take it the the moon, you also want two docking ports in addition to the refueling port so you could have an pressurized cargo hold in the nose for resupplying LSS. 
Just throwing ideas at the wall. 

[magnemoe]

1 hour ago, tater said:

Yeah, S-IVB did a brief burn to circularize the parking orbit, then they checked out that everything was "go" before doing the TLI burn. The circular orbit gave them contingency to do additional work, cause they could always stay a extra orbits and adjust the start position of the burn slightly. The mass in LEO that mattered for Apollo was the total mass of the S-IVB, and everything attached to it. What that total mass was didn't matter as long as that stack had ~3.2 km/s of dv sitting there in LEO.

 

Yes also doing the flip and dock to lunar module. If this failed it would be an abort. It was a lot of docking tests in the early 60's. Both the US and USSR went for an disposable lunar lander and docking in lunar orbit.  
Today sending the lunar lander separate is the perfected option but we has 50 years of docking practice. Still we want crew on capsules who is moved around on ISS. How much extra mass would it be to make an cargo dragon work as an return only capsule? 
You would need to move seats, and you need an say 24 h life support.  
Note Soviet had an Soyuz abort option over North America, and they gave NASA instruction about the Soyuz capsule to rescue crew if knocked out. 

Edited October 24, 2023 by magnemoe

[RCgothic]

3 hours ago, magnemoe said:

Still we want crew on capsules who is moved around on ISS. How much extra mass would it be to make an cargo dragon work as an return only capsule? 
 

This is so the crew aren't short a lifeboat if the capsule can't redock, not because the capsule can't do the docking itself.

If it absolutely came to it, I reckon a cargo dragon could serve as a lifeboat if it had to with an immediate deorbit burn and the crew strapped down to the floor. Last resort.

Edited October 24, 2023 by RCgothic

[tater]

54 minutes ago, magnemoe said:

No reason to take LSS back to LEO

With a stretch to Starship (supposedly already planned), and a smaller crew volume, you could use a "ferry" SS to take crew from LEO to lunar orbit propulsively. With a version that could aerobrake at least some of the needed 3.65 km/s to come back to LEO it becomes possible for a Artemis architecture that has commercial crew delivering astronauts to Starship, then Starship ferries them to Gateway, also retanking LSS (which needs ~280t of props to do a RT from Gateway to the surface and back).

Make an 80t tanker that has a small crew area in the nose. Small in this case means ~600 m³, lol. It holds 1520t of props (~3 rings of the cargo area are props, instead).

It can fly from LEO to Gateway, with ~420t of residual props. It transfers 280t to the LSS at Gateway, allowing another RT to the surface for LSS. It reserves 140t for its own flight back to LEO after the lunar crew returns—less if it can aerobrake.

Evolved version of this...

We want the 1000m³ crew volume, because the crews are now used to luxury . Can we do this with less mass? Let's assume some sort of methalox landing engine smaller than Raptor, and maybe lower I_sp (less insanely optimized)—call it 330s?

We'll use ~11t of 2.6mm steel for the nose section (crew). It needs some mass for fitting out, obviously. Every ring of tank is ~113t of props (saw this someplace as the average). It needs 5.5 km/s of dv to do a RT from Gateway.

With just 2 rings of props (we'll mass it as 3 cause they are domed) we have 14.3t of steel. Dunno what mass for the lower I_sp landing engines, 4 at 1 ton each? That's 18.3t. To be able to do the RT that leaves us with 27.6 tons of additional mass to play with for fitting out. So each flight now uses 214t of props to land the same hab size. Same concept could be used for a taxi version that is much lighter. Stage off the nose cone curve bit as a fairing, and underneath are canted engines, and the props are on top. Crew area is the bottom. You could land the thing with a single ring volume of props, and still have a 9m dia, 2 story lander (4.5t steel, plus engines and fitting out for a total mass of 23t dry). To be clear, it can land, and fly back to Gateway on that one 110t tank of props.

Edited October 24, 2023 by tater

[tater]

 

 

[Vl3d]

10 hours ago, tater said:

 

Good luck to Blue Origin! Hope the lobby team gets them to orbit and to the moon.

[darthgently]

 

 

[Exoscientist]

Starship lunar lander missions to require nearly 20 launches, NASA says
Jeff Foust
November 17, 2023
BERLIN — As SpaceX prepares for its next Starship test flight, a NASA official said that the use of that vehicle for Artemis lunar landings will require “in the high teens” of launches, a much higher number than what the company’s leadership has previously claimed.

In a presentation at a meeting of the NASA Advisory Council’s human exploration and operations committee Nov. 17, Lakiesha Hawkins, assistant deputy associate administrator in NASA’s Moon to Mars Program Office, said the company will have to perform Starship launches from both its current pad in Texas and one it is constructing at the Kennedy Space Center in order send a lander to the moon for Artemis 3.
https://spacenews.com/starship-lunar-lander-missions-to-require-nearly-20-launches-nasa-says/

 The “nearly 20” may mean it will require a launch for the Starship HLS, a launch for the propellant depot, the launch of the SLS itself, and 8 to 16 refueling launches.

 If it is 16 launches of the Starship, then at 150 tons payload for the reusable version that’s 2,400 tons payload launched to orbit. As a point of comparison the International Space Station masses 455 tons.

 But a better understanding of the enormity of the current Artemis plan, comes from using the parameter IMLEO, initial mass to LEO.  IMLEO includes also the dry mass of the stage reaching orbit. The Starship masses about 100 tons dry. Then the IMLEO per launch would be 250 tons. So 16 Starship launches would mean 4,000 tons being sent to orbit for a single lunar lander mission. In comparison the Apollo missions required ca. 130 tons, IMLEO.

 Why IMLEO is so relevant is because of the argument the Starship HLS would be superior in being capable of ca. 100 tons to the lunar surface. But the point is the current plan is to use Starship HLS just for carrying two crew to the surface, the other two crew carried to space on the Orion would stay on the Gateway. That’s no more than the Apollo plan of carrying two crew to the lunar surface.

 Note then the SLS is far too expensive for cargo flights at $2 billion per flight, with each flight to the lunar surface by the current plan also needing the Starship HLS as the lander. But in actuality even for cargo flights, no crew, the cost per flight will likely be in the range of $5 billion range because you have also the cost of the Starship HLS and the amortized cost of the lunar Gateway.

Far better would be to use commercial launchers for the cargo flights. For instance the Falcon heavy at a 63 ton payload to LEO could deliver ca. 15 tons one way to the lunar surface using cryogenic in-space stage(s). The Falcon Heavy’s upper stage only weighs 4 tons. To get 100 tons to the lunar surface with the Falcon Heavy would require 7 launches, as 7*15 = 105 tons, for 7*67 = 469 tons IMLEO. This is compared to the 4,000 tons IMLEO by the SLS+Starship HLS approach. 

 BUT since we are considering commercial launchers for the cargo delivery, supposed we used just the Starship for cargo delivery, no SLS? The huge IMLEO in the current plan is because of the numerous refuelings. But based on the ca. 150 tons to LEO of the Starship and making analogy to the Falcon Heavy case, a quarter of this mass could be carried to the lunar surface using cryogenic in-space stages. So only three flights of the Starship would be required to deliver 100 tons to the lunar surface. Note this is not using refueling. Rather each Starship launch, using additional in-space stages, would be launching the cargo to the lunar surface, with a smaller in-space stage doing the landing not the Starship HLS.

  Robert Clark

[tater]

42 minutes ago, Exoscientist said:

 But a better understanding of the enormity of the current Artemis plan, comes from using the parameter IMLEO, initial mass to LEO.  IMLEO includes also the dry mass of the stage reaching orbit. The Starship masses about 100 tons dry. Then the IMLEO per launch would be 250 tons. So 16 Starship launches would mean 4,000 tons being sent to orbit for a single lunar lander mission. In comparison the Apollo missions required ca. 130 tons, IMLEO.

So what? Mass is irrelevant, and it's fixed price.

42 minutes ago, Exoscientist said:

 Why IMLEO is so relevant is because of the argument the Starship HLS would be superior in being capable of ca. 100 tons to the lunar surface. But the point is the current plan is to use Starship HLS just for carrying two crew to the surface, the other two crew carried to space on the Orion would stay on the Gateway. That’s no more than the Apollo plan of carrying two crew to the lunar surface.

Again, so what? It still costs less.

42 minutes ago, Exoscientist said:

Far better would be to use commercial launchers for the cargo flights. For instance the Falcon heavy at a 63 ton payload to LEO could deliver ca. 15 tons one way to the lunar surface using cryogenic in-space stage(s). The Falcon Heavy’s upper stage only weighs 4 tons. To get 100 tons to the lunar surface with the Falcon Heavy would require 7 launches, as 7*15 = 105 tons, for 7*67 = 469 tons IMLEO. This is compared to the 4,000 tons IMLEO by the SLS+Starship HLS approach. 

Why the obsession with mass to LEO? Mass is irrelevant.

Someone could buy a few Cessna 172s, and fly a few (X amount)  people—1 per plane—across the US, then throw the planes away. With fuel, the total mass is maybe 2+ tons per plane+pilot. You could also buy enough seats (X amount) on a 777 to fly them the same trip. It would cost grossly less than throwing X 172s away. Say 2 guys. So we've spent a single digit number of tons, and ~$800,000 in planes (not counting gas). For the airline seats? What, a grand? Mass is ~200t.

Same result, but the 777 uses 200t of mass—50X more mass than the Cessnas! The Cessnas use maybe 50X less mass, but cost 800X more. Which do you choose?

When looking at this stuff, the only thing that matters is cost. Really.

Edited November 19, 2023 by tater

[darthgently]

Destin asking questions others fear to ask

 

[tater]

1 hour ago, darthgently said:

Destin asking questions others fear to ask

Wow. Well done.

That said, there are a few issues with "simplify," since the baseline is not simple (existing Orion, launched by SLS), causing literally everything else to be less simple.

If the entire system had been designed from the start with a mission, they would not be having this issue. Hence the usual complaint (at least from me), that SLS is "a rocket to nowhere."

So we have a bad, required starting point (Orion), and added to that is an entirely different mission from Apollo (here's a link to the PDF he mentioned). Apollo was brief duration stays. Artemis is meant to be longer stays, both to be less rushed, and ALSO because Orion/Gateway won't be back for at least 6.5 days, so that's kind of the minimum stay. If the mission was changed to mimic the simplicity of Apollo within the Orion requirements, then you still need something like the LM, but fit for at least 6.5 days habitation.

So take a specific observation he makes about hypergolics. He's right of course, but then you need a lot of hypergolics. The lander must be bigger for the required mission duration.

A lander that is 20t dry needs to be ~90t wet to do the RT from NRHO using methalox. Using hypergols? It needs to be 118t wet.

What about a 10t lander (~2X the Apollo LM)? 45t with methalox,  59t with hypergolics.

So that gives us some sense of what the simple solution could look like. A ~60t (wet) lander done with hypergolic props. Except you need a way to send a 60t lander to Gateway/NRHO.

Interestingly, Starship, assuming a 75t variant (which is actually pretty beefy, could be lower), could send the 60t lander to NRHO (I'm having it fly all the way to Gateway here, else lander needs more dv) with 225t of residual props. That's 285t of payload, including lander. In short, and expended SS could send a 10t dry hypergolic lander to Gateway. Note I assumed a single stage lander.

[sevenperforce]

14 hours ago, tater said:

Starship, assuming a 75t variant (which is actually pretty beefy, could be lower), could send the 60t lander to NRHO (I'm having it fly all the way to Gateway here, else lander needs more dv) with 225t of residual props. That's 285t of payload, including lander. In short, and expended SS could send a 10t dry hypergolic lander to Gateway. Note I assumed a single stage lander.

Elon had previously said that Raptor V3 would bump a "better optimized" Starship V1's expendable payload up to 300 tonnes LEO. I'm assuming he's accounting for a vehicle that is specifically being launched without heat shielding and so forth. A while back he had suggested 40 tonnes dry for a minimal-mass expendable BLEO Starship without SL Raptors, so if we keep all six Raptors then we're looking at something like 45 tonnes dry. We also know that the main tanks on Starship V1 carry 1170 tonnes of propellant. Plugging these values into the rocket equation (with an average ~371.75 seconds I_sp, assuming an even split between SL and Vac Raptors for the first two-thirds of the burn and only one SL Raptor accompanying the Vacs for the last third of the burn) gives us 5,396 m/s of Δv from staging off an expendable Superheavy to get to LEO.

But Starship V2 has an expected tank stretch and bump up to nine engines. The main tanks of Starship are about 23 meters in (vertical) length, so we could expect a notional 7-meter tank stretch to add around 350 tonnes of propellant. Crudely subtracting off 9.6 tonnes for engines from the 45-tonne Starship V1 got us tankage and plumbing mass of ~35 tonnes, so let's bump this up to 42 tonnes to account for the stretch, then add in nine engines to get to around 57 tonnes dry. Staging velocity will be just slightly lower here due to the increased mass for Superheavy to lift, so let's subtract 100 m/s from staging velocity (increasing the corresponding Δv requirement to 5,496 km/s). We bump up the average specific impulse to 374.9 seconds, though (assuming all nine engines firing for the first third of the burn and only one SL raptor accompanying the Vacs for the last two-thirds of the burn). Load that up with payload, and you find that the expendable Starship V2 can presumably put 383 tonnes into LEO.

If it can put 376 tonnes into LEO, then it can send ~101 tonnes to TLI monolithic. But we can do better.

Let us imagine a "Starship Saturn" with two expendable upper stages that together have the same total expected propellant capacity of Starship V2. All nine engines on the second stage and two Raptor Vacuums on the third stage:

 

Doing it this way allows us to stay within known variables for the stack (since we are only increasing propellant and tank weight by what is already expected for Starship V2), so this shouldn't require any significant changes to Superheavy. It gets taller, of course, but only by the height of the new second interstage.

With these constraints, figuring out where to "divide" Starship V2 into two separate stages becomes a simple optimization problem. Maximum payload is reached by placing 461.5 tonnes of propellant onto the third stage, which allows us to send just over 132 tonnes to TLI, and the third stage has a staging T/W ratio of 0.98:1, which is fine since it will be mostly firing in orbit. It will stage just shy of LEO and burn for 101 seconds to circularize, and you'll only need a 126-second burn for TLI.

You'll notice that the propellant mass on this third stage is only a bit more than the total amount of propellant that gets added from the tank stretch, so it may be much easier (for this purpose) to just keep the original Starship V1 tank tooling but strengthen and plumb the bottom for nine Raptors instead of six. Won't reduce your TLI delivery by much.

Another possibility, depending on what your lunar stack design is like, is to use the terminal stage as the braking stage to get into cislunar orbit. Things get a little trickier here because we assume some boiloff will occur in transit. Let's assume a four-day coast and 0.1% boiloff per day, measured against total original propellant mass on the third stage.  Now the total required Δv is much higher, which changes up how you balance the stages: here the optimal propellant load on the third stage is 368 tonnes, and the sorties stack that is delivered all the way to low lunar orbit is a whopping 95.5 tonnes. If you want to squeeze out just a little more from the whole affair, you can even drop down to a single vacuum Raptor, although that will double the length of your burns which could cause either Oberth or cosine losses depending on the trajectory optimization you use.

If you can deliver 95.5 tonnes all the way to low lunar orbit in a single launch, then you can deliver Orion AND a 69-tonne lander. That's enough mass budget for pretty much any approach you want to use.

 

 

[SunlitZelkova]

8 hours ago, sevenperforce said:

If you can deliver 95.5 tonnes all the way to low lunar orbit in a single launch, then you can deliver Orion AND a 69-tonne lander. That's enough mass budget for pretty much any approach you want to use.

Lol it's funny comparing this proposal with the single launch SLS you designed in the SLS or Artemis thread during the discussion brought about by Exoscientist's concerns over how many launches the current architecture requires.

I'm amazed at how you and others can whip out these great graphics so quickly. I always wondered what a Starship launched Orion architecture might look like but didn't realize it could carry such a large lander. I always envisioned it as a sort of "Commercial Heavy Crew Program".

Part of me really likes such a concept because I think Orion looks cool and think it's a decent way to allow some degree of pork while otherwise trying to use better priced stuff as much as possible, but at the end of the day all of this is really obviated by an EOR architecture with Crew Dragon taking crew to meet Starship HLS in LEO. It would comprise stuff that is already funded basically, and travelling in Starship HLS is probably safer than the dinky Orion if an Apollo 13 style accident occurs during the coast to or from the Moon.

[Exoscientist]

On 12/3/2023 at 9:40 PM, tater said:

Apollo was brief duration stays. Artemis is meant to be longer stays, both to be less rushed, and ALSO because Orion/Gateway won't be back for at least 6.5 days, so that's kind of the minimum stay. If the mission was changed to mimic the simplicity of Apollo within the Orion requirements, then you still need something like the LM, but fit for at least 6.5 days habitation.

So take a specific observation he makes about hypergolics. He's right of course, but then you need a lot of hypergolics. The lander must be bigger for the required mission duration.

A lander that is 20t dry needs to be ~90t wet to do the RT from NRHO using methalox. Using hypergols? It needs to be 118t wet.

What about a 10t lander (~2X the Apollo LM)? 45t with methalox,  59t with hypergolics.

So that gives us some sense of what the simple solution could look like. A ~60t (wet) lander done with hypergolic props. Except you need a way to send a 60t lander to Gateway/NRHO.

 

 Keep in mind Destin also doesn't like the NRHO Gateway, in addition to not liking the multiple refueling launches for the Starship HLS. He prefers an architecture that does go to low lunar orbit.  

But the present SLS can’t send the Orion to LLO and be able to return Orion back to Earth again. That is why the NRHO Gateway was proposed in the first place. But a low cost modification would give the SLS the capability to send Orion to LLO and back again, and also allow a single launch architecture for the Artemis lunar lander missions:

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage.
http://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.html

  Robert Clark

[sevenperforce]

10 hours ago, SunlitZelkova said:

I'm amazed at how you and others can whip out these great graphics so quickly. I always wondered what a Starship launched Orion architecture might look like but didn't realize it could carry such a large lander. I always envisioned it as a sort of "Commercial Heavy Crew Program".

Part of me really likes such a concept because I think Orion looks cool and think it's a decent way to allow some degree of pork while otherwise trying to use better priced stuff as much as possible, but at the end of the day all of this is really obviated by an EOR architecture with Crew Dragon taking crew to meet Starship HLS in LEO.

Obviated to some degree, yes, but if we are going to contemplate any expendability to Starship+Superheavy then we should just go with an all-up expendable architecture like the Saturn V.

[darthgently]

I always come back to leveraging the payload of lunar Starship.  A lunar starship, outfitted properly, is  a spacious base.  Double digits are a small town, research campus, and/or industrial complex.  And every lunar starship planted on the lunar surface is that much less DV required to launch it off the lunar surface.  Robots and technicians could convert the tanks into useful space with ground level airlocks etc

Edited December 5, 2023 by darthgently

[RCgothic]

2 hours ago, Exoscientist said:

 

 Keep in mind Destin also doesn't like the NRHO Gateway, in addition to not liking the multiple refueling launches for the Starship HLS. He prefers an architecture that does go to low lunar orbit.  

But the present SLS can’t send the Orion to LLO and be able to return Orion back to Earth again. That is why the NRHO Gateway was proposed in the first place. But a low cost modification would give the SLS the capability to send Orion to LLO and back again, and also allow a single launch architecture for the Artemis lunar lander missions:

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage.
http://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.html

  Robert Clark

None of us like Gateway, but there isn't any cheap modification to SLS, and certainly not anything that would be as cheap or capable as simply moving Orion/ESM on top of a Starship Super Heavy stack.

NASA should stop making bad puddings just because they've spent a long time preparing bad ingredients.

Edited December 5, 2023 by RCgothic

[tater]

59 minutes ago, Exoscientist said:

But the present SLS can’t send the Orion to LLO and be able to return Orion back to Earth again. That is why the NRHO Gateway was proposed in the first place. But a low cost modification would give the SLS the capability to send Orion to LLO and back again, and also allow a single launch architecture for the Artemis lunar lander missions:

No, it wouldn't.

A single launch SLS architecture, even if possible results in a sortie lander like Apollo. Surface stay for 2 measured in hours.

To be an Artemis mission it needs to have the possibility for FUTURE missions (after the first landing) to be more astronauts, and for 1-2 weeks minimum. So your claim requires redefining Artemis goals entirely to flags and footprints, never better.

Edited December 5, 2023 by tater

[darthgently]

I just had an image of Lunar Starbase pop in my head.  Highbays, megabays, tank farm and all.  Smaller stage 0 and boosters of course

 

Re: NRHO:

The NRHO makes sense only from LOS to earth.  Redundant relay sats make a lot more sense as they could be leveraged by all kinds of rovers, bases, landers, and stuff in lunar orbit

Edited December 5, 2023 by darthgently

[Ultimate Steve]

Gateway has grown on me. It's engineering benefits are questionable, but I've gradually learned the lesson that in this era, cost and engineering aren't what you need to optimize for. The best most cost effective program is going nowhere if you don't have political support, and even if it does its not going to go on for very long.

For better or worse, support is the thing to optimize for these days. Artemis is very very good at this. It's gotten legacy contractors, new contractors, democrats, republicans, Canada, Japan, ESA, and many others all behind a Lunar program and Gateway is a wonderful part of that, both as sunk cost infrastructure to point to and a relatively easy place for contractor or international participation. A pit stop in NRHO is a small price to pay if it means that a semi sustainable Lunar program actually happens instead of being cancelled. 

[tater]

1 hour ago, Exoscientist said:

 Keep in mind Destin also doesn't like the NRHO Gateway, in addition to not liking the multiple refueling launches for the Starship HLS. He prefers an architecture that does go to low lunar orbit.  

 I liked his video, but I think he starts out by fundamentally misunderstanding the mission goal.

The mission goal for Artemis is a sustainable, and sustained human presence on the Moon, and specifically in a polar site where water is possibly available. It is not, "replicate Apollo." The mission goals were profoundly different.

Any mission architecture that does not deliver that is wrong from the start. I could see using a frozen LLO for access, but the need for a habitat for at least 2 weeks is part of the equation and over time, I would assume something that can survive night (however many days that is at the chosen landing site given vehicle height, etc).

So if the mission is some sort of pared down "simple" lander, then the mission must also include placing a habitat on the surface ahead of time. if the hab needs consumable resupply, then that needs to be figured out as well. Any reusable lander will need to be refilled at NRHO (or LLO, whatever). 10s of tons of hypergols delivered to lunar orbit means multiple expended launch vehicles for each lunar sortie.

In addition to the examples above in the thread on how SS/SH can get things done in a single flight if pared down, if SS is capable of refilling at all—regardless of how many flights it takes—it completely obviates SLS/Orion.

Edited December 5, 2023 by tater

[RCgothic]

I don't see why the Artemis partner nations couldn't be just as bought in to a lunar surface base.

[Exoscientist]

22 hours ago, sevenperforce said:

If you can deliver 95.5 tonnes all the way to low lunar orbit in a single launch, then you can deliver Orion AND a 69-tonne lander. That's enough mass budget for pretty much any approach you want to use.

That has been the argument Robert Zubrin has been making: the SuperHeavy/Starship should be given a third stage both for lunar and Mars missions, a mini-Starship. That would make single launch SS/ST/Mini missions to both the Moon and Mars possible. No SLS and no refueling flights required. Zubrin makes the point trenchantly with his line, “The Starship is a reusable Saturn V. It is not a LEM.”

 See his discussion of Mars Direct 2.0 using the Starship with a small 3rd stage to do single launch missions to the Moon and Mars here:

 In point of fact you don’t even have to produce new this third stage. Either the Falcon 9 first stage or second stage could be used for the purpose.

 Zubrin tells of having discussions with Elon about why the SS/ST should be given a third stage. Elon responds, “Tell me why I need it.” Well sure, you can do these missions by having multiple refuelings, but you can do it more efficiently in just one flight by having that small third stage.

  Robert Clark

[darthgently]

2 minutes ago, Exoscientist said:

That has been the argument Robert Zubrin has been making: the SuperHeavy/Starship should be given a third stage both for lunar and Mars missions, a mini-Starship. That would make single launch SS/ST/Mini missions to both the Moon and Mars possible. No SLS and no refueling flights required. Zubrin makes the point trenchantly with his line, “The Starship is a reusable Saturn V. It is not a LEM.”

 See his discussion of Mars Direct 2.0 using the Starship with a small 3rd stage to do single launch missions to the Moon and Mars here:

 In point of fact you don’t even have to produce new this third stage. Either the Falcon 9 first stage or second stage could be used for the purpose.

 Zubrin tells of having discussions with Elon about why the SS/ST should be given a third stage. Elon responds, “Tell me why I need it.” Well sure, you can do these missions by having multiple refuelings, but you can do it more efficiently in just one flight by having that small third stage.

  Robert Clark

I imagine Musk figures he is working on the equivalent of a 53' tractor/trailer and hears Zubrin going on about the equivalent of putting a pickup truck in the trailer so the driver can go further when the semi tractor runs out of fuel. 

And Musk is like, but what about the rest of the cargo in the 53'?  He is simply not thinking about a few occupants or tiny payloads.  Maybe he should though for Artemis-related and early Mars Starships as it would allow less expensive trials of landing sites, isru tests, and such.  A "failing faster" for destination concepts maybe?

 

[SunlitZelkova]

3 hours ago, darthgently said:

I just had an image of Lunar Starbase pop in my head.  Highbays, megabays, tank farm and all.  Smaller stage 0 and boosters of course

 

Re: NRHO:

The NRHO makes sense only from LOS to earth.  Redundant relay sats make a lot more sense as they could be leveraged by all kinds of rovers, bases, landers, and stuff in lunar orbit

It would be very interesting to have someone more versed in the maths to investigate what benefits (or costs!) a lunar SS/SH launch site would offer.

The vehicle is already so capable already I can’t see any necessary improvements though.

1 hour ago, RCgothic said:

I don't see why the Artemis partner nations couldn't be just as bought in to a lunar surface base.

Well, I don’t know about ESA, but JAXA’s budgets have risen over the past couple years. If they are already building the lunar rover with Toyota, they would probably be interested building a lunar base module too.