ESA needs to save NASA’s Moon plans.

[kerbiloid]

4.
If the re-entry vehicle had bounced from the atmosphere to drop the speed from ~11 to ~8 km/s, will it perform the secondary re-entry with partially spent heatshield and random trajectory angle?

[tater]

1 minute ago, kerbiloid said:

1.
Is the (trans)lunar Starship supposed to be refueled in high-eccentricity elliptic orbit on its way to home?

The HLS CONOPS is a little unclear. It would at the very least meet up with Orion in some lunar orbit, not sure what the reuse model is. Send props to lunar orbit, or send LSS home to Earth orbit?

1 minute ago, kerbiloid said:

2.
Is the (trans)lunar Starship supposed to enter the atmosphere, aerobrake, and land, rather than be a long-living orbital tug?
Or Orion will be the only aerobraking thing?

Orion for the lunar one. LSS has no tiles, flaps, etc.

[SunlitZelkova]

5 minutes ago, tater said:

If we have the ability to put pretty substantial stages in LEO for relatively low cost soon, all this becomes moot.

Even if it is “expensive”, it will probably still be far better than SLS and be an actually functioning SHLV with a decent cadence.

[kerbiloid]

I mean, what if both Orion and Starship are equally inappropriate for wide usage, so the design competition makes no sense.

As from time to time the reentry process will probably go wrong, and any vehicle will be ballistically aerobraking with its bottom forward, and the crew will be withstanding 30+ g for half-hour, this will possibly result into same consequences as the Soviet tortoises had, when one of them got its eye popped out, and who knows what happened to their intellect (if it was).
We'll never know the further tortoises probable fate, as they were killed together with a dozen of others from the tortoise space team, quickly after the flight, to compare their inner world.

As this can't be prevented or weakened by the RV shape, maybe it just means that any direct return from the Moon is appropriate only in the epoch of expendable crew heroes, while any lunar exploration necessary needs a return to LEO, and then landing at 8 km/s initial speed?
And this needs so much delta-V that chemical rockets are just not an option at all?

[tater]

15 minutes ago, SunlitZelkova said:

Even if it is “expensive”, it will probably still be far better than SLS and be an actually functioning SHLV with a decent cadence.

LOL, something can be really expensive and still be cheap compared to SLS.

Edited June 13, 2022 by tater

[Beccab]

Just now, tater said:

LOL, something can be really expensive and still be cheap compared to SLS.

Yeah i mean, ML-2 alone will literally cost the same as the Burj Khalifa at least 

[sevenperforce]

1 hour ago, tater said:

Problem is that any increase in SM mass just borrows from the lander in the above calculations. Total TLI mass remains unchanged, it's just where the props are, in the SM, or in the lander or on a LOI stage for said lander—or drop tanks—then the lander doesn't need another set of engines.

Technically, putting LOI props on the command module is slightly more efficient, unless your descent module uses cryogenics, in which case the higher isp cancels out the poor architecture choices.

[tater]

1 hour ago, sevenperforce said:

Technically, putting LOI props on the command module is slightly more efficient, unless your descent module uses cryogenics, in which case the higher isp cancels out the poor architecture choices.

Obviously. The lowest mass lander for Artemis per NASA has a NRHO—>LLO transfer stage, so those props (and associated dry mass) don't have to go to the surface. Single stage landers take everything there and back again, etc.

But to zeroith order, basically the same.

 

(and regardless, more than SLS can do)

Edited June 13, 2022 by tater

[Jeb x Valentina]

On 6/10/2022 at 7:59 AM, Exoscientist said:

 The SLS was planned to have a large upper stage called the Exploration Upper Stage(EUS). This would take the SLS Block 1 to the SLS Block 2, needed for a single flight lunar architecture. However, the multi-billion dollar cost for development of a large upper stage from scratch means it’s unlikely to be funded.

 NASA is proposing a solution using the Starship making separate flights. But this plan takes 6 flights total or likely more of the Superheavy/Starship for the Starship to fly to the Moon to act as a lander. One look at this plan makes it apparent it’s unworkable:

 Actually, it’s likely to be more complex than portrayed in the figure, needing 8 to 16 refueling flights. This is what SpaceX submitted to NASA in proposing the plan, requiring 6 months to complete the Starship refueling:

SpaceX CEO Elon Musk details orbital refueling plans for Starship Moon lander. By Eric Ralph Posted on August 12, 2021
First, SpaceX will launch a custom variant of Starship that was redacted in the GAO decision document but confirmed by NASA to be a propellant storage (or depot) ship last year. Second, after the depot Starship is in a stable orbit, SpaceX’s NASA HLS proposal reportedly states that the company would begin a series of 14 tanker launches spread over almost six months – each of which would dock with the depot and gradually fill its tanks.
…
In response to GAO revealing that SpaceX proposed as many as 16 launches – including 14 refuelings – spaced ~12 days apart for every Starship Moon lander mission, Musk says that a need for “16 flights is extremely unlikely.” Instead, assuming each Starship tanker is able to deliver a full 150 tons of payload (propellant) into orbit after a few years of design maturation, Musk believes that it’s unlikely to take more than eight tanker launches to refuel the depot ship – or a total of ten launches including the depot and lander.
https://www.teslarati.com/spacex-elon-musk-starship-orbital-refueling-details/

 

Everyone, remember the Apollo missions where we could get to the Moon in a single flight? In fact, this would be doable with the SLS given a large upper stage. Then the suggestion is for the ESA to provide a Ariane 5 or 6 as the upper stage for the SLS. It would save on costs to NASA by ESA paying for the modifications needed for the Ariane core.  

 As it is now ESA is involved in a small role in the Artemis lunar program by providing the service module to the Orion capsule. But it would now be playing a major  role by providing the key upper stage for the SLS.  

 The argument might be made that the height of the Ariane 5/6 is beyond the limitations set forth by NASA for the EUS. However, if you look at the ca. 30 m height of Ariane 5 core compared to the 14 m height of the interim cryogenic upper stage now on the SLS, this would put the total vehicle height only a couple of meters beyond the height that had already been planned for the SLS Block 2 anyway:

 

 

 See discussion here:  

Budget Moon Flights: Ariane 5 as SLS upper stage, page 2.   

https://exoscientist.blogspot.com/2013/09/budget-moon-flights-ariane-5-as-sls.html

 Coming up: ESA also could provide a low cost lander for the Artemis program.

   Robert Clark

in fact, NASA has already a better solution: the getaway space station, which would look somewhat like this:

(credits to NASA for the image)

The Orion spacecraft would dock into it, the crew would get on a lander docked on the station, and then get back to the station

[SunlitZelkova]

Just now, Jeb x Valentina said:

the getaway space station

Typo of the century.

[Jeb x Valentina]

15 minutes ago, SunlitZelkova said:

Typo of the century.

LMAO (gateway, HAPPY?)

[tater]

47 minutes ago, Jeb x Valentina said:

in fact, NASA has already a better solution: the getaway space station, which would look somewhat like this:

It's not a better solution, it's no solution to the problem this thread is about, getting astronauts to the surface at less cost using one SLS launch.

The total dv requirements are only slightly higher using Gateway, but it doesn't really buy you anything. Because the NRHO orbit only passes over the landing site every ~6.5 days, the lander concepts have to be able to stay at least that long (more consumables). The min lander sizes for the Gateway mission architecture are posted up thread, 36 to 50 tonnes. So in this case it doesn't actually help since SLS can't send Orion, plus a 36t lander to Gateway.

[RCgothic]

The Gateway station is the single most pointless part of the Artemis architecture.

[kerbiloid]

The gateway allows to split the lander and the cruiser to use a rocket twice lighter.

[Exoscientist]

On 6/13/2022 at 2:42 AM, tater said:

A Centaur based lander is a good thing, but there is no way to comanifest one with Orion with the available volume. BTW, if you were to pick a 5.4m hydrolox stage to act as stage 2, why use Ariane 5/6, just use Vulcan's upper stage—which is a 5.4m Centaur.

Anyway, you're still not going to have a stack that is an additional 14m, then stick a Centaur lander on top (sideways, presumably as the XEUS concept was), then Orion. Then you need the whole stack to TLI, and the lander has to do the LOI burn for itself, plus Orion.

Any change to 8.4m tanks means EUS, effectively, so that's off the table for this discussion.

I'm not seeing any possible way to make SLS work as a single stack Moon vehicle (surface mission) unless Orion is dumped. Then the dev cycle includes a lander, and a CSM so that the whole thing works in whatever limited TLI throw it has.

@Exoscientist, IMO, the most important thing that your blog posts lack is specifics on the actual payload, and subsequent throw to TLI. You say 130-150t to LEO. OK, go with that (though the upper stage is then doing substantially more work than ICPS is just to get to parking orbit—which I will completely ignore). Your concept uses an engine with an I_sp of 432-440s. We can look at 130t in LEO to 150t in LEO, largely residuals. Ariane core is 12-14 t, but we need interstage for lander, etc, call it 15t being generous. Orion is ~27t (not counting the LES). So our LEO stack is 130-150t minus 42t for dry mass plus the CSM. That's 88t-108t to play with for the lander, plus residuals in S2 for the TLI burn.

These are masses assuming operation from NRHO. So the min comanifested lander to NRHO is 41t, upper limit 50t.

So now of 88-108t, we have our stage 2 prop reserves as 38t to 47t props for the 130t to LEO estimate, and 58t to 67t for the 150t to LEO estimate.

Try the min mass 2 stage lander. The TLI stack has a dry mass now of 42+41=83t. 47t of props, and we'll use the best case I_sp, 440. Our Ariane in LEO has ~1900m/s dv. Nope, not getting to TLI. For that stack (note I was being really generous saying 65-70t to TLI), the 150t to LEO won't do it either (~2500 m/s). For the Orion plus minimum lander stack to work, we need 83t to TLI, which means ~175t to LEO, any less than that, and a single stack SLS to the lunar surface—assuming Orion—is impossible.

So this idea is a nonstarter for the 2 stage.

The 3 stage lander has a lower minimum mass. Using all the lowest masses, the 130t to LEO does not close (screwed up sleepy last night) at ~2300 m/s (need 3200) even with RL-10. 150t to LEO doesn't work, either, even with a less massive 3 stage lander.

So we need to get the mass to LEO at or very close to 160 tonnes to LEO for any SLS mod to work.

If Orion could be dumped, then all we need is ~50t to TLI (and stock SLS is still garbage, but some variant might work). Then we need a new CSM and a small Apollo style lander.

 

 

 Those lander concepts in the image are all 40 to 50 tons fueled. Note the Apollo lander was only 15 tons fueled. Perhaps the large size for these Artemis(Constellation?) landers was coming from assuming it would also provide the propulsion for insertion into orbit, a la the Altair lander?

 Also, the plan using Ariane 5 as upper stage would not go to NRHO, but to low lunar orbit. I think the NRHO idea from NASA came from the limited capabilities of the SLS. This then led to the proposal of the Gateway for the astronauts to loiter at. With the more powerful upper stage you don’t need the NRHO intermediate stop or the Gateway. 

 Let’s say we use an Apollo size lander at ca. 15 tons. Note that even in the SpaceX Starship as lander plan, 2 of the astronauts would remain on orbit in Orion while only 2 would go down to the lunar surface, as with the Apollo lander.  So from 60 tons to TLI, with a ca. 27 ton Orion+service module, with a 15 ton lander, you would have 18 tons available for extra propellant to get the stack to low lunar orbit and for the Orion to be returned to Earth.

  Robert Clark 

 

[Beccab]

2 minutes ago, Exoscientist said:

Let’s say we use an Apollo size lander at ca. 15 tons. Note that even in the SpaceX Starship as lander plan, 2 of the astronauts would remain on orbit in Orion while only 2 would go down to the lunar surface, as with the Apollo lander.  So from 60 tons to TLI, with a ca. 27 ton Orion+service module, with a 15 ton lander, you would have 18 tons available for extra propellant to get the stack to low lunar orbit and for the Orion to be returned to Earth.

This also means you can get to the surface as much cargo as the LM, which is equal to an extremely limited and compact rover and a couple surface experiments. If your lunar rocket can only launch once a year and can only get a negligible amount of cargo to the surface you've effectively done worse than Apollo; add to that the fact that the costs are roughly comparable to the Apollo program, and you'll hardly get further than the point Apollo got.

An Ariane upper stage won't save Artemis, nor SLS. The ideal way for the program to develop would be to gradually abandon the latter, switching to Starship plus if needed a less unsustainable commercial LEO capsule to launch the crew (Starliner, Dragon or Dream Chaser all work in this context). Hell, if needed you can even use the ISS or one of its successors as a staging ground, both to check out the lander and simplify operations

[tater]

23 minutes ago, Exoscientist said:

 Those lander concepts in the image are all 40 to 50 tons fueled. Note the Apollo lander was only 15 tons fueled. Perhaps the large size for these Artemis(Constellation?) landers was coming from assuming it would also provide the propulsion for insertion into orbit, a la the Altair lander?

Yes, exactly—but Orion is the Constellation CSM, and it cannot do the LOI burn to a low orbit even alone, and still have dv to return to Earth. It requires a huge lander as a result.

23 minutes ago, Exoscientist said:

 Let’s say we use an Apollo size lander at ca. 15 tons. Note that even in the SpaceX Starship as lander plan, 2 of the astronauts would remain on orbit in Orion while only 2 would go down to the lunar surface, as with the Apollo lander.  So from 60 tons to TLI, with a ca. 27 ton Orion+service module, with a 15 ton lander, you would have 18 tons available for extra propellant to get the stack to low lunar orbit and for the Orion to be returned to Earth.

Just did the math. Orion+15t lander. That added propellant gives us ~1500 m/s (assumed 8% tank mass) with the best possible RL-10. So it could work since it needs ~1000, although while Orion can get home, it does not have a lot of margin (not sure how much is needed for contingency ops (lander aborts, etc).  If we assume hypergolics, then it is still enough for LOI at 1045m/s. Looks like it closes.

What we get in that case, though, is an Apollo sort of landing. Short duration.

To do the desired missions would require a second launch, and a habitat/rover pre-deployed I think.

In short, SLS should have been designed from the start (as I have said in the SLS/Orion thread many times) with something like 60-70 tons to TLI as the minimum requirement.

This would allow single stack missions to the surface. Then you use a sort of "Moon direct" architecture, where the hab is sent ahead.

10 minutes ago, Beccab said:

An Ariane upper stage won't save Artemis, nor SLS. The ideal way for the program to develop would be to gradually abandon the latter, switching to Starship plus if needed a less unsustainable commercial LEO capsule to launch the crew (Starliner, Dragon or Dream Chaser all work in this context). Hell, if needed you can even use the ISS or one of its successors as a staging ground, both to check out the lander and simplify operations

I agree. That said, in a sensible world, the math above would have been done to establish the minimum requirements of the SLS/Orion system that were acceptable for the vehicle to be useful. Since the lunar surface is the ONLY interesting crew mission in cislunar space, reaching the surface is the min requirement.

 

 

Edited June 15, 2022 by tater

[Stosh]

On 6/14/2022 at 12:37 AM, RCgothic said:

The Gateway station is the single most pointless part of the Artemis architecture.

So not a big fan of gatherering data on a human rated facility exposed outside of Eath's magnetic field for the long term? 

[tater]

It's all because Orion is too big. What's the point of a capsule for 4 astronauts, then only 2 land?

The whole point was to get more people to the surface (after the initial landing mission). They are also supposed to be one the surface longer. The Apollo missions were incredibly jam-packed, and there were many times when the crew wanted to do stuff they simply did not have time to do. More crew, and longer duration means they can explore in a less stressed way. and they can actually respond to conditions on the ground in real time—the whole point of humans vs robots.

The Lunar Starship is shockingly good for this mission profile. Loads of cargo. Tons of crew room. leave the incredibly dirty suits downstairs on the airlock deck, chill, heck, take a shower upstairs, and sleep in a bed. Use an actual toilet. Plan the next day.

1 minute ago, Stosh said:

So not a big fan of gatherering data on a human rated facility exposed outside of Eath's magnetic field for the long term? 

We could just continuously x-ray them at home, instead.

 

[Exoscientist]

19 minutes ago, tater said:

Yes, exactly—but Orion is the Constellation CSM, and it cannot do the LOI burn to a low orbit even alone, and still have dv to return to Earth. It requires a huge lander as a result.

Just did the math. Orion+15t lander. That added propellant gives us ~1500 m/s (assumed 8% tank mass) with the best possible RL-10. So it could work since it needs ~1000, although while Orion can get home, it does not have a lot of margin (not sure how much is needed for contingency ops (lander aborts, etc).  If we assume hypergolics, then it is still enough for LOI at 1025m/s. Looks like it closes.

What we get in that case, though, is an Apollo sort of landing. Short duration.

To do the desired missions would require a second launch, and a habitat/rover pre-deployed I think.

 Thanks for running the numbers! I get if we take the delta-v to enter and exit lunar orbit as 800 m/s, it is variable depending on altitude, and the Isp for the hypergolics as 3200 m/s, the crewed lunar lander can be about 50% larger to about 22 tons.

 Also, note you should separate the cargo and crew flights. I get about 25 tons  payload one way to lunar surface using hypergolics with no Orion or service module included.

  Robert Clark

Edited June 15, 2022 by Exoscientist
Clarity

[Stosh]

3 minutes ago, tater said:

6 minutes ago, Stosh said:

So not a big fan of gatherering data on a human rated facility exposed outside of Eath's magnetic field for the long term? 

We could just continuously x-ray them at home, instead.

so not a fan of having a pile of sensors (Dosimeters etc.) in three differently designed pressure vessels, well two likely built by the same manufacturer, might provide for some useful new data without trying to infringe on comic book territory.

[Exoscientist]

On 6/12/2022 at 11:54 AM, tater said:

Can it do LOI for the lander, plus the ~27t Orion CSM?

 Yes. Note with the larger 170 ton propellant load upper stage, we can get ca. 60 tons to TLI. This allows more propellant to be used for the Orion service module to get the entire stack to low lunar orbit. Then a ca. 15 ton lander a la Apollo only needs to go from low lunar orbit to the lunar surface and back again.

  Robert Clark

[tater]

5 minutes ago, Stosh said:

so not a fan of having a pile of sensors (Dosimeters etc.) in three differently designed pressure vessels, well two likely built by the same manufacturer, might provide for some useful new data without trying to infringe on comic book territory.

That doesn't require sending people. You could put dosimeters under materials representing different pressure vessel configurations and check using those as well, for a lot less money. Sending astronauts for 2 weeks once a year will not provide much useful information, and exposes them to isotropic GCRs (plus solar, etc). Short of pretty hefty shielding (prop tanks? Poly polypropylene? Whatever it is you want a lot of H around people), nothing is going to matter anyway vs GCRs.

[Stosh]

Just now, tater said:

That doesn't require sending people. You could put dosimeters under materials representing different pressure vessel configurations and check using those as well, for a lot less money. Sending astronauts for 2 weeks once a year will not provide much useful information, and exposes them to isotropic GCRs (plus solar, etc). Short of pretty hefty shielding (prop tanks? Poly polypropylene? Whatever it is you want a lot of H around people), nothing is going to matter anyway vs GCRs.

I understood that the plan was always both human and sensors.

At some point in time you have to send people to practice new skills and install new equipment, otherwise what exactly is the point of 2 week duration Lunar sorties?

[Exoscientist]

On 6/13/2022 at 4:45 PM, sevenperforce said:

Technically, putting LOI props on the command module is slightly more efficient, unless your descent module uses cryogenics, in which case the higher isp cancels out the poor architecture choices.

You could like the SpaceX Dragon put the launch escape hypergolic thrusters on the capsule, eliminating the launch escape tower. You would have like the Dragon an escape system that worked all the way to orbit. 

You would then put more propellant on it so the same thrusters could be used for lunar orbit insertion, eliminating the service modules propulsion systems. Note though some of the dry mass of the service module would have to be retained since it contains some consumables and the power systems.

   Robert Clark