Commercial Moon - Starship, Dragon, and Starliner
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- Опубликовано: 6 сен 2024
- SLS and Orion are operational, but they aren't going to fly very often. Are there options to send people to the moon that don't rely on them?
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I´d modify the option 5. No need to take the Lunar Starship back to LEO if we are flying regulary. Just keep it in NRHO and save propellant. The crew starship will bring 336 tons of propellant with them, that is enough to land the Lunar version on the Moon and get back as long as they don´t carry too much cargo and the lunar version has dry mass around 100 tons. Disadvantage in both full resuse cases is that transferring tons of cargo between starships wouldn´t be practical but for crew it is not an issue.
If you wanted to transfer bulky cargo easily you have to develop a large lock door for both vehicles, sure it's doable but I suspect big mass penalty.
why not launch F9/Dragon into LEO and do an EOR with HLS Starship, which then does LEO -> Luna -> LEO before redocking with Dragon for the trip home? Only argument I can see against this is Starship’s payload being reduced, but surely it has enough delta-V?
Are you saying having lunar starship go from LEO, to the lunar surface, and then back to LEO?
That's about 11,000 meters per second of LEO. Way way more than starship could do - if it had that much LEO it could do single stage from earth to orbit *easily*
@@chyza2012 Certainly true, but the logistics get increasingly more complicated and expensive.
@@EagerSpacewell it could dock with a dragon thats upgraded to have a service module or something waiting in high earth orbit and then go to the moon, undock with dragon and land, then get back into moon orbit and dock with dragon and then it can return to high earth orbit and then wait there for the next mission. It should have enough delta-v to go from heo to moon and back to heo. Development cost of dragon service module will still be orders of magnitude cheaper than sls
One note about the Dragon/Falcon Heavy option, the superdracos are single-use. So, you’d have to use four of them for LOI and four for TEI. You might be able to use two at a time, but it may be a bit less stable. Obviously Dragon’s heat shield would need upgrading also.
Very interesting thought experiment. I love content like this!
Thanks! Keep up the great work. 👍
Completely unrelated to the video itself, but fiddling with how to best use your dv is really fun in KSP, like because you basically have to double your dv to land on the Mun and then get back into orbit, it makes me want to make a fueling station on the surface so I only have to carry enough dv to land, then the lander gets refueled from empty and goes back to low Mun orbit!
I've not heard someone else advocate #3 before, but it's my favourite (short-term) proposal too. There's a ton of flexibility with a generic return payload approach and, despite one version carrying along a capsule in habitable space, comparatively minimal risk.
Apogee did a video proposing variants of #3 and #5B. He called them the 'HLS tow truck' and 'HLS ferry' respectively.
The tow truck section start around 14:50 in his video: ruclips.net/video/GqBlUhZYhZE/видео.html
@@lazarus2691 +1 for reminding me of that video, but I do like the approach given here more, personally.
Options 4 and 5a & 5b are of course my favorites. I'm so grateful for the figures provided. I'm too tired this evening to give them the careful response they deserve so have confined myself to Comments on the other options for now.
(It never ends but) 6: (Falcon Heavy's 3x bottom boosters) + (single-Raptor 2nd stage, which doesn't exist today) + (Centaur machine) + (any capsule) could get to any kind of lunar orbit. An interesting idea.
The ride along solution is even better than you think, because a capsule only need 4100 m/s deltaV from LEO to low lunar orbit, that means that starship can carry 27 tons Orion from LEO to lunar orbit and sacrifice only 10 tons from the mass of payload that would be delivered to moons surface.
I originally had a slide where I talked about the effect of not having to carry the capsule beyond NRHO, but I cut it because it was a subtle point and added too much complexity.
@@EagerSpace indeed this is a interesting tradeoff, if the starship HLS does not travel from the moon surface to NRHO the total deltaV for 100 tons dry mass of starship(from LEO to moon surface and back into low lunar orbit) is lower than 8km/s, that alone actually allows increasing the payload delivered to the moon surface (from 50 tonnes to 100), so even if it carries 20 or 30 tons capsule into low lunar orbit still can deliver 90 tons of payload to the moon surface.
@@EagerSpace on a second thought maybe I'm misunderstood what you said, I was speaking about the effects of not launching HLS after landing on the moon further away than low lunar orbit, because of the exponential nature of rocket equation and large dry mass of starship that allows to increase payload delivered to the moon surface dramatically,of course you need some extra fuel for capsule, but we are talking only about few tons more, but the gain in transport capacity is 40 tons.
I enjoyed this video.
My favorite is Option 5A. Until looking at the budget for 18 Starship flights is dang expansive. Even if lowest cost, $360 M is real money.
I’ve been investigating this for the past year and find it fascinating, but came to a conclusion that the best solution to achieve this is my COLS/AAEP formal specific proposal with high energy optimization of upcoming effectively modifiable heavy lift vehicles like starship and new glenn, maybe Vulcan Heavy. I’ve mainly focused on the launch side since it’s more important to complement SLS than Orion, but if we do spacecraft too then Starliner is the best. It’s better for re entry than dragon since it’s got a great ballistic coefficient like Orion. It was even proposed recently as an ultra high energy mars return vehicle instead of Orion. Physics is what matters here, not just simple heat shield thickness, and with a similar diameter to Orion it’s better than dragon for nice wide room for the crew to have. It’s probably best to just beef up its service module than design a whole new unit for dragon. Starship is best used with CV-L instead of refueling to use it for what it’s best at
I’ve made a video about my proposal on my channel and doing it for the Conrad challenge too so we’ll see how far it gets in the real world outside of this mere proposal
The goal isn’t to replace SLS/Orion capability either, merely to complement it in lesser capability but higher cadence to achieve sustainability with a block 1 oriented architecture
That sounds really interesting. Do you have a reference that explains it in more depth?
7: A reused "stock" Super Heavy, heaving an expended, welded-stainless, Raptor-powered, non-refueled (1- or 2-stage) machine on top of it, can deliver gobs of weight into LLO or NHRO in one trip. No kerosine no hydrogen no aluminum no nothing. It could also pick up any capsule in LEO and take it from there. Plenty of extra fuel to boil off and finish the job anyway.
One of my constraints was to do this as much as possible with existing vehicles.
While SpaceX did get a Raptor development contract for a Falcon upper stage variant, it never went beyond the engine stage once SpaceX proved that they could do long-duration flights with the existing stage.
Option 2: It's interesting that a fully fueled Centaur is nearly within the capability of F9, but that's in expendable mode. It can be launched on a FH with all 3 cores recovered, I think. (One at sea.)
Very gratifying to know the numbers, that Dragon has the delta-v to enter & leave NRHO. Scratches an itch, even though I think Option 5 is a lot more likely. The Falcons-for-SLS scenario has tantalized so many of us since the Bridenstine comment, and even before.
In case anyone is interested, Orion can work as a capsule option. NASA may want its long duration and it already has a lunar-return heat shield. Stupidly expensive but OKish for the near-term. Even SpaceX would need considerable time to upgrade Dragon that much. If launched uncrewed Vulcan can carry Orion, it's under 27t if the LAS is omitted. Of course FH can carry this. Once again, the crew launches on a Dragon.
A few thoughts:
1: Yes, you could use FH to launch centaur and attempt to recover all three cores. It's probably a little cheaper if everything goes right, though the economics are complex - a core that has flown 15 times has less future value than a new one.
If you did this architecture, the logical thing to do is to launch it on Vulcan. It has the payload to do so, and since they are using centaur already they have the infrastructure and experience to deal with hydrolox, while SpaceX has neither. And there's something poetic about using centaur to launch centaur.
2: Dragon could have enough delta-v to get into and out of NRHO, but you need to put props in the trunk, which will change a bunch of things.
3: I didn't talk about Orion as the capsule option because a) I wanted to go full commercial, b) their production system has a specific cadence, c) it's designed to work as part of SLS, and d) I'm very, very lazy.
Oh, and it costs a ton.
Thank you very very much.
Could a F9 heavy dragon make it to lunar orbit? Maybe with some more insulation to keep the engines operational on the upper stage
There's another method.
Two Starships. An Interplanetary (IP) Starship that lands on the lunar surface with 100t of cargo and up to 20 passengers. And an uncrewed tanker Starship that accompanies the IP Starship.
Both Starships are refilled in LEO and fly together to low lunar orbit (LLO) at 100 km altitude.
The tanker transfers 100t of methalox to the IP Starship, which lands on the lunar surface, unloads cargo and passengers, loads departing passengers and cargo, and returns to LLO.
Another 100t of methalox is transferred to the IP Starship. Both Starships return to LEO using propulsive capture.
Full reusability. Only one type of spacecraft used--Starship.
My simplifying assumption was that payload to surface was the same as payload coming back.
If you are leaving stuff behind, then yes, there may be other options, though it's going to be sensitive to how much payload you bring, how much you leave behind, and what your dry weight is.
I might revisit that in another video - adding that in to this one was going to be too confusing.
I like this method. No need for heat shields or landing header tanks, no need for fins. Lots of weight saving.
You could even get away with fewer engines on the upper stage if you’re willing to launch the starships only partially filled since you’re going to refuel in orbit anyway.
Inherently safer than trying to airbrake (as long as the engines are sufficiently reliable).
This is really clever. I was thinking along similar lines but didn't notice how much delta V is saved just by refuelling *after* the return from the surface
Delta-V from NRHO-surface-NRHO will be larger than LLO-surface-LLO (Apollo lander). NRHO is a higher orbit than LLO so I think it will require about 1000 m/s more than Apollo. This matches the lower Delta-V needed to capture at the moon and to break orbit at the moon. (No free lunch)
I've used 900 m/S as the distance between LLO and NRHO in other videos - if you look at my artemis architecture video, for example.
At last! Hard numbers on full Starship reuse, Option 5. Yay! So much to cover here. First:
I agree, Option 3 is what can be used soonest, and it's the most acceptable to NASA. It can be made even easier with a much lighter carry-on Dragon - there's no need carry along the full-size taxi-to-LEO-one. The Starship for the journey (JSS) can launch uncrewed with a very stripped-down Dragon (Reentry Dragon) carried in the cargo bay.* Crew gets to LEO on a conventional Dragon. The only time the crew boards the Reentry Dragon is when Starship is approaching Earth on the return, thus it has minimal ECLSS and consumables, etc. The trunk is much reduced, with just enough radiator to cool the capsule for a couple of hours. Battery power should suffice, no solar needed. No SuperDracos, and only a minimal propellant mass is needed for the Dracos. A tiny fraction of the mass saved can be used for a beefed up heat shield, if needed. Starship could even propulsively decelerate a small amount before release to make the capsule reentry process easier to engineer. So, the crew enters the Reentry Dragon and proceeds to splashdown. The JSS returns and is caught autonomously.
*This also eliminates the complexity of stowing a Dragon while in LEO, along with the mass of the mechanism needed, if a nose-ride configuration won't work. The Reentry Dragon can be stowed more simply and stably on Earth, with a simple release mechanism for the return.
It's a tradeoff between engineering cost (time/effort/distraction) and performance.
My off-the-cuff reaction is that I would invest those resources into something that has more leverage rather than build a one-off version of dragon. But my assumption is that crew will fly on starship a lot sooner than many people think, so any architecture with dragon would not be long term.
You can save around a ton of dragon mass by simply venting off the abort propellant once you get into orbit if you really care about mass, and maybe a bit more by putting fewer expendables in it. But my guess is that it isn't worth it.
@@EagerSpace Carrying a standard Dragon with its full propellant load to the Moon does have the advantage of offering redundancy for the return. In the unlikely event the Journey Starship can't leave NRHO then the Dragon can return independently. Your figures show a Starship will have the delta-v to carry this to the Moon, so I'll agree and give up on my Dragon-lite idea.
I looked back at Apogee's video on this, it was in a recent reddit thread. Not as good as yours, some of his ideas aren't fully baked, and I was never comfortable relying on his figures, but he does mention that the IDSS docking collar is rated to take the load it would undergo at TLI if Dragon is mounted on the nose of Starship. Says this is built in because of possible use cases considered when Orion was designed. Also, the IDSS can withstand transmitting the force of Starliner firing to boost the ISS. That's nowhere near the force of Starship firing but it does squash the IDSS between Starliner and the inertial mass of the ISS. That means something, right?
I agree that it's likely Starship will be launching and landing crews by the time it's used for the translunar journey. Politics and NASA changing direction as nimbly as a supertanker means that's unlikely until after Artemis 4 flies, with will be NET 2028 by Eric Berger's latest estimate. Dear Moon 2 or Polaris 5 may have landed by then.
How would the admittedly-guesswork costs and mission profiles change if we:
1. Sent purely robotic missions (no human-rated vehicles needed).
2. Left all vehicles on the moon to serve as construction material (no return missions).
Lunar starship is currently the only vehicle that can land on the moon, so you need one of those, or at least the shell of one of those. Get it into orbit, refuel it with enough fuel to land it on the moon, and you're done.
A quick estimate says you need 5800 meters per second of delta v. You can do that with 50 tons of payload and 5 tanker flights, or you can do a full 100 tons of payload and 6 tanker flights. If lunar starship can get 150 tons to earth orbit, it can deliver it to the lunar surface with full tanks (8 tanker flights is my assumption).
That's assuming the thrusters / engines are powerful enough to land that much payload on the moon.
So my model would say $200 million to build the starship and get it in orbit plus $100 million to do 5 tanker flights, or $300 million.
For comparison, the Cargo Dragon CRS flights to ISS are about $230 million.
Of course, you can push the costs wherever you want by changing the numbers.
@@chyza2012 I think we should change strategies.
Your Starliner and Crew Dragon numbers don't seem to include the extra dry mass of a larger service module needed to achieve a higher delta V, only extra propellant mass.
Considering both capsules are comparable to the Orion CM mass and dimensions (8-9 tons), a new SM would likely need to be somewhat smaller and lighter than Orion's ESM, which weighs around 15 tons.
I find it hard to believe that either modified versions of these spacecraft to be less than 20 tons in total mass, potentially more than that considering the need for a beefier heat shield, radiation protection, extra life support, propellant margins etc.
Orion has all those things, it would only make sense for any complementary spacecraft to be able to do the same.
Considering Falcon Heavy's TLI capability when fully expended is 15-16 tons, from data by NASA LSP (not 20 like you cite in your assessment) you'd need an SLS Block 1 to carry either modied spacecraft to TLI.
Only other option would the the FH+ICPS combination that was considered for Artemis 1 back in 2019 but was found to lack the needed rocket performance to send Orion to TLI without the ESM needing to burn some of it's own propellant.
Centaur III couldn't get the needed much mass to TLI in the dual launch scenario either, but maybe Centaur V could.
Regarding option 3, I've heard that the delta V margins on Lunar Starship are rather thin at the end of the mission.
Would carrying over 20 tons of effectively extra dry mass for the trip to the Moon have a significant impact on those margins? Perhaps, but I can't say for certain.
Option 4 would require Starship launces in the dozens, and the feasibility of the standard Lunar Starship CONOPS is already questionable based on the number of tankers needed just for that, and this would need close to 30 total launches for the full reuse scenario.
Not gonna be cheap, even if you can somehow pull off that logistical nightmare.
At the end of the day it boils down to, whether paying for the development and operations of a new spacecraft configuration/lunar architecture would be cheaper than utilizing the existing SLS and Orion production lines, which NASA is already paying for regardless of cadence, and just adding an additional vehicle in the annual manifest.
All the facilites and workforce needed to build SLS and Orion are now in place, and are sized to be able to build a lot more than 1 vehicle/year after Artemis 2.
Boeing and NASA are now expecting to be able to build 2+ SLS vehicles per year by using facilities at KSC to produce more SLS engine sections and freeing up space at Michoud for the production of more core stages and EUS.
Keeping them at a low production cadence only serves to make each vehicle a lot more expensive than it needs to be due to high fixed costs and a low cadence.
You end up with billions of dollars of annual fixed costs and only one vehicle to account for all of it, you *_need_* a higher cadence to bring down individual vehicle costs.
Makes a lot more sense to just order an additonal set of hardware to be produced (which would also drive down individual costs for SLS and Orion by a lot) rather than develop and operate a whole new spacecraft/architecture alongside the existing programs.
Lots to talk about, and thanks for writing all that. My generic comment is that there's a lot of slop in many of the numbers that I use.
WRT Dragon/Starliner modifications, the Orion ESM is heavy for what it is, probably because of its ATV heritage. I went with propellent masses because those were calculatable and dry mass is challenging.
WRT Falcon Heavy TLI it is asserted that the mass given by NASA LSP is not up do date - see here for discussion: space.stackexchange.com/questions/26155/what-is-falcon-heavys-payload-capacity-to-trans-lunar-injection
WRT option 3, I do expect that lunar starship margins will be low at the end of the mission - from LEO to the lunar surface and back to NRHO requires a ton of delta v, and without knowing the payload to the lunar surface and how much they will leave behind, it's hard to make much headway.
WRT option 4, yes, it will require starship launches by the dozens. There is important work to get orbital refueling working but frankly I think second-stage reentry is a far harder problem to crack. And option 4 is built around the assumption that refueling works well - if it doesn't, it's obviously not an option. My only other note here is that betting that SpaceX will not accomplish something has not been a winning strategy, and NASA appears to be fine with the architecture as it pertains to HLS.
WRT SLS and Orion flying more often, I would like to do a video on that. AFAICT, NASA hasn't talked about SLS per-flight costs for the past 5 years or so and therefore I'm lacking data on which to hang an analysis. I do know that core booster engine costs go *way* up once you get to to Artemis V, EUS is going to cost more than ICPS, and NASA needs to fit gateway hardware and flights into their budget, along with the second lander option if that ends up happening.
Will the lunar starship have additional insulation beyond white paint? or it will add too much mass?
How about a Space Umbrella that expands out from the bow of the ship? Not much mass ( it can be very thin), like sunshield from Webb telescope
We don't know; there are very few details on lunar starship.
A sunshade is possible but remember that the vehicle is going to have a significant amount of solar cells on it to produce electricity and you don't want to shade those. I guess the solar cells can be considered insulation.
The other issue is that the lunar surface is fairly reflective which means during the day you are getting a fair bit of heat gain from all around you.
My *guess* is no sunshade. But it's only a guess at this point.
I did some calculations in my propellant depot video to look at starship in orbit, and there you can do pretty well with paint and some air gaps. Lunar surface is more complicated to analyze and I never got around to it.
Another question regardless both artemis and propellant depot!
How to pump fuel from one starship to another?
When you trying to start rocket engine in space you just use ullage thrusters or something like that to push ship a little to collect fuel at the bottom and then your engine do all the work. But using ullage thrusters for 2 giant starships for long fuel transfer and do it 8-16 times is seems very wastefull, or not? Or is it passible to spin both ships and make some kind of space ballet to separate fuel centrifugally)
The moon is commercial.
Can Falcon Super Heavy work here? Isn't there talk of adding two more side boosters?
It's clear SLS is not an option
I tried to limit myself to available vehicles.
I've seen proposals about more boosters for Falcon Heavy, but I haven't seen any signs that SpaceX is at all interested. The biggest reason they finished Falcon Heavy is so that they can bid on the NSSL launches for the government, but the investment they made in it wasn't a great financial move.
Maybe if they weren't working on a new rocket they might explore that.
@@EagerSpace good points. Inevitably SpaceX wants to be 100% Starship.
Great analysis. I wonder if the math changes with more rings being added. S24 is not the final flight configuration length.
What about Starship being Mars/Solar System rated and 100 People per Starship flight? Where is all off that nowdays? You're telling me that One Single Starship (being refuled as much as needed) can't go and land on the moon and come back to Earth? Can Starship with wings, heatshield land on the moon? It can be even refuled in NRO if needed I guess...And btw, how are they going to keep starship's fuel at cryo temps while sitting on the moon for few days? Won't it evaporate?
Mars Starship hasn't been talked about much recently - I expect we'll learn more when SpaceX has finished their orbital flight testing.
A "normal" starship with wings and heatshield can land on the moon if it was refueled on orbit, assuming that there are no issues using the raptors to land on the lunar surface.
Can it take off back to orbit? The answer to that depends on how heavy you think starship is going to be - some people think its 90 tons or even lighter, others think its 150 tons. And payload matters, including how much you leave behind. Choose different numbers and you get different answers.
Propellant boil off is all about heat gain. The only heat gain in space or on the moon is due to radiation, and that's why lunar starship is painted white. They will certainly boil off some of the propellant, but it takes a *lot* of heat to change a little bit of propellant to gas, so it's unlikely to be an issue for short stays. There are some more advanced techniques NASA has designed for dealing with keeping hydrogen liquid for long missions - which is much much harder because it's so much colder - that they could use but I think it's unlikely they will need them.
@@EagerSpace Thanks for the answers. 😊
Also, is there an email address we can use to contact you directly?
There's a link to the eager space twitter account in the description. Hit me up there.
Option 3 seems backwards. Use the Crew Dragon as the lander and return the crew to Earth in the starship which then needs tiles and flaps. You can optionally discard the dragon lander after the moon landing as in Apollo. This configuration is similar to dear Moon and is an obvious next step after dear Moon succeeds.
Getting from lunar orbit down to the surface and back up to NRHO takes over 4600 meters per second of delta v. I had to do a lot of hand-waving to get dragon up to 1000 meters per second in some of these options. If you want 4600 meters per second for, a quick calculation suggests that you need to take the 12,000 kg dragon and add 42,000 kg of extra fuel to it.
@@EagerSpacehow much delta v to get from lunar surface to leo? Can you do a video on starship only without lunar starship
Do you think Tanker variant of Starship needs to be something unique? I mean it is supposed to have docking equipment and some unknown liquid propellant transfer equipment, and solar baterries and then it is supposed to be reusable. Its is supposed to be very expensive ship i think and they will be very intrested in saving it, it won't be just another barrel, the tankers would be so valuable they would probably have specific names, not just Tanker N2131, but something more unique, like Endevour or something and they are going to check that Endevour tanker for a long time before sending up again on the refueling mission. So this Tanker needs its own R&D before it is constructed and its own testing window on the ground, and in space.
But the same can be said about Orbital fuel depot, with the exception that its not going to be reusable, but just one launch thing with extended life on orbit. But i don't see any prototypes even, so how are they going to make it by 2025 or 2026?
You can do tanker stuff with just a generic starship, plus any required refueling hardware.
The first optimization is to take rings out of the payload section at the top and use them in the tank section to make the tanks bigger. I haven't done the calculations to estimate how many you would move but there are 6 rings in the payload part, so you would add some to the tanks, and perhaps remove some to reduce weight.
I think there's additional engineering there - you need to increase the length of the downcomer in the top tank, but it's probably not too bad. I don't think you need additional testing of the basic vehicle design.
@@EagerSpace hm...no. In fact i doubt there is such thing as generic starship at all. For refueling purposes you need to have specific tanks with DIFFERENT types of fuel. TWO DIFFERENT FUEL TYPES, DIFFERENT CENTER OF MASS, pumps, specific thrusters for docking, specific solar panels. Comprende? What is this even supposed to mean generic starship? Its payload bay already going to be specialised for Starlink dispensors on one version. Generic starship supposedly doesn't have a crew bay at all, so by Generic starship you mean low earth Cargo Starship? Feels like you not putting any more thought into it than Musk.
@@дроу The point of the tankers is to refuel starship, so all you need is bigger versions of your existing tanks to hold the fuel.
Plus what you need to move the fuel across.
@@EagerSpace What you are saying is something completelly different from the generic starship, because if the fuel tanks are bigger, it means the space where payload bay is - its completelly sealed for any cargo and the ship is specialized only on one and only things. What about fuel that it will cary - will it cary oxygen, methane and hypergolic fuel for thrusters, and Lunar lander Starship refueling? This is 3 or 4 types of different plumbing systems on one ship.
And don't forget that its heavy in orbit, so it needs some very special RCS system to move it around, to stop its rotation, to stop its wobbling for docking. That RCS system must be something new. The whole docking of tanker with the depot will be something veery very careful, because both are expensive and LARGE, so the risk of collision would be very nasty. Plus tanker itself must be very vulnerable, imagine it rupturing like Soyuz ship recently and leaking all of its fuel, or worse if depot is hit, or fuels mix ...
@@дроу Yes, the tanker would be specialized to be a tanker.
It will carry LOX and liquid methane, exactly what starship uses. The last plans I saw said they are using cold gas thrusters with ullage gas (ie oxygen or methane), so no hypergolics.
I agree that SpaceX has yet to demonstrate on-orbit refueling, but they have tons of experience docking with Dragon. The fact that starship is much bigger doesn't really change the difficulty of that.
People cannot be serious about sending Starship to land on the moon, that thing takes 6 more starship launches to fully refuel, and then you end up only sending possibly 2 astronauts to the moon?
That is the current NASA Artemis architecture. They *do not* get to the lunar surface without that working.
So clearly NASA is serious about doing that.
The two astronaut thing is the requirement from the HLS contract that SpaceX won - NASA went with two astronauts because it drastically reduced the payload to the lunar surface and back.
SpaceX bid starship which could definitely carry more astronauts, but the contract is based on the HLS requirements, so it's 2 astronauts until/unless SpaceX and NASA negotiate to change it.
I think it's unlikely to be more than 2 for Artemis 3 and Artemis 4. Beyond that, lunar starship could likely do more, so who knows.
And yes, it's only two astronauts, but it's also a huge amount of cargo, and that would drastically increase what NASA could do on the surface. So there will be negotiation there above what HLS required.
@@EagerSpace just seems incredibly wasteful to me, isn't a fully stacked Starship only marginally smaller than the Saturn V, but now we're using like 10 launches to do what Apollo did with one launch. The starship vehicle is way too heavy to send to the moon, so much of its mass is dead weight and not useful but have to be send to the moon, landed, and again lifted back to lunar orbit.
@@chengong388 say it with me. FULLY REUSABLE.
@@chengong388 Apollo put a two crew members plus a rover and a small amount of scientific instruments on the lunar surface.
Lunar starship is expected to have a payload to the surface of around 50 tons, though some of that will be consumed by the astronaut quarters inside.
Starship has a high mass fraction because it's so big. That will enable it to get from the earth to lunar orbit, land, and return to lunar orbit.
Apollo has a low mass fraction; the LEM could make it to the surface and back to orbit, but it had to leave the descent stage on the surface.
@@chengong388 The more I study Artemis the more impressive Apollo seems. Certainly multiple launches to refill Starship plus a separate SLS launch for Orion seems less efficient and a step backwards (at least on the face of it). I think they would have been better off starting with Apollo/Saturn V and refining it. Better materials, computers, solar panels, and try to reuse parts of it. I can imagine Saturn V first stage landing on a drone ship for instance. Overall Artemis seems inferior in most ways to Apollo.
But I can imagine SpaceX transporting people to the moon without help from SLS and that makes more sense. Start with dearMoon (which is far more significant than people realise). If that works it proves SpaceX can put people round the moon with a fully reusable vehicle and can land them propulsively on earth (no parachutes!). Once that huge milestone is passed I can imagine SpaceX developing of a moon lander as well possibly using a method shown in the video.