totm dec 2023 Artemis Discussion Thread

[kerbiloid]

3 hours ago, tater said:

The 4 lettered areas are possible sites where the area is illuminated 80% of the time.

Spoiler

The choice is obvious.

Quote

In the 1970s British science fiction series Space: 1999, the location of Moonbase Alpha is Malapert Crater.

Also, Boeing owes the Eagles.

Spoiler

 

Edited November 6, 2019 by kerbiloid

[sevenperforce]

16 minutes ago, tater said:

They are part of ULA... what's the throw of Vulcan Heavy to TLI?

By my numbers, a naked Vulcan 6 upper stage can throw just shy of 15 tonnes to TLI or can deliver 11.5 tonnes to LOP-G. Roughly comparable to the performance of Falcon Heavy with only the central core expended. Vulcan 2 beats Atlas V 551 for LEO but not for BLEO because the Atlas-Centaur has lower dry mass. 

This is all when you launch payload into LEO and then do a second launch with the naked upper stage to perform TLI or other BLEO work. I didn't bother to calculate Vulcan's single-launch throw to TLI, but given that Vulcan 6 can deliver 13.3 tonnes to GTO (2.27 km/s) or 6.0 tonnes to GEO (4.04 km/s), I'm guesstimating its throw at 9-10 tonnes to TLI (3.2 km/s).

If your want your cryogenic upper stage to deliver something all the way to LOP-G, its capacity is actually better than capacity to GEO, because Oberth.

Edited November 6, 2019 by sevenperforce

[tater]

So roughly the same as DIVH to TLI looks like.

 

[tater]

To be clear, @Barzon, I'm not against making a case for SLS as a LV for the lander, but I think that the cost alone should make it a very, very difficult case to make assuming the costs are appropriately considered, and as I said, I do not trust that this will be fairly done. I just don't see any evidence of that in recent contracts for SLS. Technically, it's worth considering, but the money is where my confidence fails utterly.

That's even aside from scheduling issues with somehow flying 2X SLS launches within several weeks of each other.

I think that with even the most unfair and optimistic pricing for a second SLS flight to this end, we're talking about the equivalent cost to 8 fully expended FH flights (@150M$ each) (payload to GTO is 26.7t, and to TMI is 16.8t, so presumably Gateway is closer to the Mars number than GTO, but is probably on the order of 20t to TLI). So 160t to Gateway, vs 37t to Gateway (this lander).

Edited November 6, 2019 by tater

[sevenperforce]

13 minutes ago, tater said:

So roughly the same as DIVH to TLI looks like.

I give a naked DCSS launched on DIVH the capacity to send 12.6 tonnes to TLI or 9.8 tonnes to LOP-G, whereas the numbers are 14.8 and 11.5 for Centaur V on Vulcan 6. I did not do the math for Vulcan 6 Heavy because not enough is known about Centaur Heavy.

[tater]

EDIT: another thing just occurred to me seeing that 160t vs 37t (B1b throw to TLI). Assembly of spacecraft in space is a useful thing for NASA to do, and to practice. There is valuable experience to be learned by assembling the lander. Heck, 8 FH flights could assemble 2 landers made of 4 elements. The first could be tested as a robot.

1 minute ago, sevenperforce said:

I give a naked DCSS launched on DIVH the capacity to send 12.6 tonnes to TLI or 9.8 tonnes to LOP-G, whereas the numbers are 14.8 and 11.5 for Centaur V on Vulcan 6. I did not do the math for Vulcan 6 Heavy because not enough is known about Centaur Heavy.

Yeah, and the flight date on that is supposed to be towards 2024 anyway, right?

Wiki on Vulcan Heavy says 16.3 to GTO, FWIW.

[sevenperforce]

15 minutes ago, tater said:

EDIT: another thing just occurred to me seeing that 160t vs 37t (B1b throw to TLI). Assembly of spacecraft in space is a useful thing for NASA to do, and to practice. There is valuable experience to be learned by assembling the lander. Heck, 8 FH flights could assemble 2 landers made of 4 elements. The first could be tested as a robot.

It's ridiculously important and I don't know why we haven't spent all the money wasted on SLS developing autonomous spacecraft assembly, propellant transfer, and ZBO tankage.

Quote

Yeah, and the flight date on that is supposed to be towards 2024 anyway, right?

Wiki on Vulcan Heavy says 16.3 to GTO, FWIW.

Vulcan 6 is a 6-solid-booster methalox core with the two-engine Centaur V stage. Vulcan Heavy is a Vulcan 6 with a "Centaur Heavy" stage in place of Centaur V. I made decent estimates of Centaur V's dry mass and performance.

If Centaur Heavy is ACES, and ACES is Centaur V with IVF and two more RL-10s added, then it's straightforward enough, I suppose.

Edited November 6, 2019 by sevenperforce

[tater]

ACES seems sorta sidelined. That is in terms of seeing it pitched for Gateway operations (ULA posted that LLO station concept with Vulcan, ACES, and Bigelow for a while, then it fell off the radar).

ULA has to be careful not to step on Boeing, clearly, and ACES is transformative it its own way, and is a LEO distributed launch thing, which can obviate SLS missions all by itself. Build lander in LEO. Refill ACES. Attach ACES to lander. Go wherever you like with it.

Edited November 6, 2019 by tater

[Ultimate Steve]

Not related to the current conversation, but if New Glenn flies on time it may be a good choice for Artemis. 45 tons to LEO, presumably in the reusable configuration. Expendable New Glenn, although they don't want to expend boosters, would probably be better than Falcon Heavy, and may even be able to launch Orion to TLI.

[Barzon]

47 minutes ago, sevenperforce said:

If Centaur Heavy is ACES, and ACES is Centaur V with IVF and two more RL-10s added,

From what I've heard/seen, Centaur Heavy has stretched tankage, in addition to the 4 RL-10s.

[sevenperforce]

26 minutes ago, tater said:

ULA has to be careful not to step on Boeing, clearly, and ACES is transformative it its own way, and is a LEO distributed launch thing, which can obviate SLS missions all by itself. Build lander in LEO. Refill ACES. Attach ACES to lander. Go wherever you like with it.

Indeed. I just don't know enough about "Centaur Heavy" to make a good estimation of BLEO performance.

14 minutes ago, Ultimate Steve said:

Not related to the current conversation, but if New Glenn flies on time it may be a good choice for Artemis. 45 tons to LEO, presumably in the reusable configuration. Expendable New Glenn, although they don't want to expend boosters, would probably be better than Falcon Heavy, and may even be able to launch Orion to TLI.

Very broadly, the 2016 version of the BFR was quoted at 550 tonnes expendable or 300 tonnes reusable. Reusability included upper stage landing prop reserves, so reusing the lower stage and dumping the upper stage would probably have given 360 tonnes or so reusable. So expending a methalox core could be estimated as a 50% boost to capacity. Falcon 9 is quoted at 8300 kg to GTO expendable or 5500 kg to GTO reusable, which is also about a 50% boost.

However, New Glenn reserves less propellant since it doesn't do a boostback burn or entry burn. Then again, sending 5500 kg to GTO would not involve a boostback burn either. If we give New Glenn a 40% payload boost for expending the first stage then it would probably be able to put 63 tonnes in LEO. Not quite Falcon Heavy, but close...and New Glenn's hydrolox upper stage would outperform Falcon Heavy's kerolox for TLI purposes. Orion's injected lunar mass is 26.5 tonnes, so if it was launched to LEO on an expendable New Glenn we would expect it to have around 37 tonnes of hydrolox residuals. If it can push over 435 s isp and we assume upper stage dry mass of 5 tonnes then it can absolutely do TLI.

10 minutes ago, Barzon said:

From what I've heard/seen, Centaur Heavy has stretched tankage, in addition to the 4 RL-10s.

That would be nice. Wikipedia says "ACES is now expected to have the same tanks as Centaur V, but with the possible addition of two more RL-10s and IVF" but it is uncited so who knows who put it there.

Ah, I see it now. From one of ULA's graphics, the difference between Centaur V and Centaur Heavy:

[jinnantonix]

7 hours ago, tater said:

No one is landing inside a crater that is permanently shadowed. That is not, and has never been part of Artemis. The idea is to land in the areas that have nearly constant sunlight that are next to the dark polar craters. The sunlight (coming from the side) is the point.

 

The 4 lettered areas are possible sites where the area is illuminated 80% of the time.

 

 

Those are the locations of permanent sunlight, sure.  And useful sites for advance observation missions for deployment of scanning equipment, but .... There is no ore there, nor is there any expected to be in any of the surrounding plateaus.  

The Artemis program is about gathering science regarding resources that are presumed at the bottom of Shackleton Crater.  So how are the crew getting to the bottom of that crater?  The Crater is deep, several km from rim to floor, with very steep sides.  The crew has two weeks on the surface, doing what?  Abseiling?  Robotic drones have too much mass for multiple missions, and will not be able to carry much payload.  If we are using rovers and drones, why send humans at all?

So let's say they are going to land and do the analysis remotely,  then let's say they actually determine that there is suitable ore at the bottom of the Crater.  Mining equipment needs to be landed on the crater floor.  Crew will need to deploy and maintain that equipment.  Right?  Someone at NASA knows this.  And the technology to do this is not sophisticated.  Advance CLPS probes position LIDAR equipment on the rim, and also find and mark the best landing sites with laser guidance equipment and LED strobes.  Darkness is not a barrier. 

Quote

Artemis will not land people in the dark. That's not a thing, and never has been a thing.

It wasn't a thing for Apollo.  We have developed some technology since then.  I can't see Artemis succeeding in it's fundamental mission objective if there are are no human landings on the Crater floor.

[jadebenn]

5 minutes ago, jinnantonix said:

So how are the crew getting to the bottom of that crater?  The Crater is deep, several km from rim to floor, with very steep sides.  The crew has two weeks on the surface, doing what?  Abseiling?

The latest Artemis graphic has an unpressurized rover deployed on the first surface mission, ala the later Apollo missions. They could use that.

[jinnantonix]

4 hours ago, sevenperforce said:

Assuming the stack is dropped in proper LEO, it needs 3.63 km/s to get all the way to LOP-G. My calculations give a naked FHeUS 44.8 tonnes of residuals in LEO, but FHe is quoted as being able to deliver up to 63.8 tonnes of payload to LEO, so my number may be low.

I can get a 44 tonnes payload to LEO, with plenty of propellant remaining.  Perhaps 64 tonnes is possible.

Quote

Even with my numbers, however, a naked FHeUS can take 18.9 tonnes all the way to LOP-G. If a naked FHeUS has closer to 55 tonnes of residuals, on the other hand, it would be able to deliver about 25 tonnes to LOP-G.

25 tonnes to LOP-G  is about right for the KSP model I am using.  Unfortunately the 2 tank pair lander has a mass of 32 tonnes.

 

7 minutes ago, jadebenn said:

The latest Artemis graphic has an unpressurized rover deployed on the first surface mission, ala the later Apollo missions. They could use that.

Did I mention steep sides?

A rover would be useful if the intention is to travel to multiple locations on the rim to deploy scanning equipment.

Edited November 6, 2019 by jinnantonix

[tater]

2 hours ago, jinnantonix said:

Those are the locations of permanent sunlight, sure.  And useful sites for advance observation missions for deployment of scanning equipment, but .... There is no ore there, nor is there any expected to be in any of the surrounding plateaus.  

The Artemis program is about gathering science regarding resources that are presumed at the bottom of Shackleton Crater.  So how are the crew getting to the bottom of that crater?  The Crater is deep, several km from rim to floor, with very steep sides.  The crew has two weeks on the surface, doing what?  Abseiling?  Robotic drones have too much mass for multiple missions, and will not be able to carry much payload.  If we are using rovers and drones, why send humans at all?

So let's say they are going to land and do the analysis remotely,  then let's say they actually determine that there is suitable ore at the bottom of the Crater.  Mining equipment needs to be landed on the crater floor.  Crew will need to deploy and maintain that equipment.  Right?  Someone at NASA knows this.  And the technology to do this is not sophisticated.  Advance CLPS probes position LIDAR equipment on the rim, and also find and mark the best landing sites with laser guidance equipment and LED strobes.  Darkness is not a barrier. 

It wasn't a thing for Apollo.  We have developed some technology since then.  I can't see Artemis succeeding in it's fundamental mission objective if there are are no human landings on the Crater floor.

Artemis is NOT landing humans at the bottom of a dark crater. Not a thing, seriously. The entire point of the region in question is sunlight with proximity to permanent darkness. Sunlight for the humans/base, darkness for the water.

Boeing knows this, clearly, look at their lander festooned with solar panels.

Land next to crater. Enter crater (likely with rover), sample area for water. They can also use rovers that they can control in real time.

Artemis is flags and footprints for the foreseeable future. A real base with mining equipment and ISRU? Maybe if Starship can (actually fly, be reused, refill, make it to the Moon, then...) land, I'll believe that when I see it.

Edited November 7, 2019 by tater

[jinnantonix]

2 hours ago, tater said:

Land next to crater. Enter crater (likely with rover), sample area for water. 

Very challenging.  Shackleton Crater is 4000m vertical depth, with ~45 degree inclines at its side.  Climbing out using batteries and all terrain traction with a payload of crew and ore samples?    Maybe Electric Jesus can do it with a modified Tesla?

On the other hand, the good news it is possible to propulsively land equipment and humans on the floor of the Crater using available technology.  Declaring that this is "not a thing" does not constitute an argument, since there is absolutely nothing stopping from it "being a thing" if we decide to do it.

Quote

Artemis is flags and footprints for the foreseeable future.

I think NASA may have other ideas - not constrained by the idea that it's plans for scientific study cannot be done, because it is "not a thing".

Quote

A real base with mining equipment and ISRU? Maybe if Starship can (actually fly, be reused, refill, make it to the Moon, then...) land, I'll believe that when I see it.

So Starship can land in Shackleton Crater?  But otherwise it is not a thing?

A nuclear powered mining unit (Lunar Asset) appears to be what they plan to land on Artemis 8.  It will need to make that landing in the Crater, or there is no point to Artemis.   

ISRU is another matter, since it will need solar power.  My calculations show two options

1. A sustainable process could be established with the ISRU in NRHO, and the raw ore (water ice, methane, ammonia?) ferried from the surface using nuclear tugs, heated to liquid and pumped through filters into the orbiting solar powered ISRU for fuel manufacture.  If at NRHO, providing human support via Orion is established without a need for a lunar lander.  Nuclear tugs refuel by docking with the ISRU and utilising ESPRIT for fuel transfer.

2. Build solar powered ISRU on the crater rim, and deliver ore via rovers.  Human habitation required on the lunar surface, with associated lunar landers for ferrying humans and equipment to/from NRHO.  Nuclear tugs land and rendezvous on the surface for refueling.

 

Edited November 7, 2019 by jinnantonix

[tater]

48 minutes ago, jinnantonix said:

On the other hand, the good news it is possible to propulsively land equipment and humans on the floor of the Crater using available technology.  Declaring that this is "not a thing" does not constitute an argument, since there is absolutely nothing stopping from it "being a thing" if we decide to do it.

Show me any NASA document that shows Artemis landing on the floor of Shackleton.

Literally everything I have read shows them landing in the near always lit areas, that's the point of the spots they are looking at.

There are little craters in the region that are also in shadow.

50 minutes ago, jinnantonix said:

Maybe Electric Jesus can do it with a modified Tesla?

This is idiotic and off topic. Every crater in the region is not steep sided and deep, the Moon is covered with craters. The issue is simple geometry. A crater with similar shape, but a few meters across---exactly the same as one many km across from a shade standpoint.

Edited November 7, 2019 by tater

[jinnantonix]

28 minutes ago, tater said:

Show me any NASA document that shows Artemis landing on the floor of Shackleton.

Literally everything I have read shows them landing in the near always lit areas, that's the point of the spots they are looking at.

There are little craters in the region that are also in shadow.

 

So what is the content of these little craters?  https://www.nasa.gov/mission_pages/LRO/news/crater-ice.html .  Do you have documents confirming little craters is the plan?  

Also seems to be a lot of discussion about the content of Shackleton.  Why so?  if the intention is to ignore the crater floor.  https://www.youtube.com/watch?v=lVivBNlg9z8

It is possible that NASA's plan for the first mission on Artemis 3 is to go to the rim to set up scanning instruments to map the crater floor for landing sites.  In which case, utilising solar panels on the first lunar lander makes sense.  It also fits with the assumption that the first craft may be expendable, but subsequent craft will have a re-usability component and would be designed with RTG so able to land on the crater floor for a 2 week mission there.

[kerbiloid]

Spoiler

6 hours ago, jinnantonix said:

So how are the crew getting to the bottom of that crater?  The Crater is deep, several km from rim to floor, with very steep sides.

Just there should be two crews. On on the peak of the eternal day to get solar baths and wash solar panels, another one in the pit of the eternal night to mine lunar ice for their drinks.
They can use codenames:

Spoiler

Eloi

Morlocks

 

 

[tater]

I'm all for space nuclear power (used to help out with the space nuclear power conference here many years ago), but That's just not a thing right now (RTGs are fine for small requirements, but mining/ISRU will need kilopower, etc). BO lander is all about long duration power cells, and others all have solar. Every plan I have seen is about landing on the crater rims.

Every dot in the above image never sees sunlight.

https://www.lpi.usra.edu/lunar/lunar-south-pole-atlas/maps/SPole_80S_LOLA-PSR_v20190515.pdf

There are many smaller craters not as daunting as Shackleton.

Edited November 7, 2019 by tater

[jinnantonix]

29 minutes ago, tater said:

mining/ISRU will need kilopower, etc)

Then how will mining be done in a place where there is no sunlight?  Is NASA really embarking on a project that cannot be done?  IMHO a small modular reactor could easily power a mining and milling operation.  And NASA appears to be pursuing it.   https://www.forbes.com/sites/jamesconca/2018/02/01/martian-and-lunar-colonies-to-be-powered-by-nuclear-energy/#1e9086684140

41 minutes ago, tater said:

There are many smaller craters not as daunting as Shackleton.

True, but there is nothing mentioned by NASA except Shackleton, and landing sites are all in proximity to Shackleton

[jinnantonix]

11 hours ago, tater said:

EDIT: another thing just occurred to me seeing that 160t vs 37t (B1b throw to TLI). Assembly of spacecraft in space is a useful thing for NASA to do, and to practice. There is valuable experience to be learned by assembling the lander. Heck, 8 FH flights could assemble 2 landers made of 4 elements. The first could be tested as a robot.

If the Boeing lander is 37 tonnes, surely it makes sense to use the technique @sevenperforce and I have been suggesting for our drop tank lander concept. i.e. Launch the Boeing lander to LEO on a FHe and then launch a second FHe with no payload, dock lander and FHe upper stage, and boost to TLI (or near to TLI).  The lander should have sufficient propellant to rendezvous at LOP-G ~450 dV, and complete the mission.  

 

[tater]

7 hours ago, jinnantonix said:

True, but there is nothing mentioned by NASA except Shackleton, and landing sites are all in proximity to Shackleton

The very circular crater in center of the image I posted above is Shackleton. Literally every crater in that image with the green dots is in the vicinity of Shackleton. The larger PDF I linked shows many more in the extended area.

Nothing I have seen suggests landing inside a permanently dark crater, you keep acting as if that is certain to be the site, and that the landers will have RTGs (which are fairly weak, anyway), even when so far zero lander proposals have RTGs. I'm certain the won't be doing this straight off the bat for a number of reasons, and you're sure the other direction... for no real reason I can see. The huge primary reason is risk because the landing site would not be visualized (none of the CLPS lander locations published so far have been even polar, much less inside such a crater). There are loads of other issues as well, from power, to EVA efficiency (walking around in pitch black will be slow, and less effective). The fact that the primary goal of Artemis is honestly PR (if the goal was science, ISRU research, etc, they'd use robots) is another reason they won't land in the dark. They want good images. They want the HD moonwalk video to be worth the many, many billions it will have cost. A white space suit illuminated by artificial light, with some gray on the ground, and... nothingness. Yeah, that's not gonna cut it.

 

7 hours ago, jinnantonix said:

Then how will mining be done in a place where there is no sunlight?  Is NASA really embarking on a project that cannot be done? 

I never said it could not be done, I said it will not be done by these early Artemis landings, assuming they happen. NASA even says there is a difference between their rush job landing (the first one) and subsequent landings. They'll be serious about flying kilopower etc when we see them saying that one is funded. Literally no lander proposal we've seen to this point has nuclear, as such, it's not a thing yet.

Talking about anything past the first landing is kinda silly unless we see something real. Right now we're not even seeing proposals for surface infrastructure.

Edited November 7, 2019 by tater

[sevenperforce]

16 hours ago, jinnantonix said:

I can get a 44 tonnes payload to LEO, with plenty of propellant remaining.  Perhaps 64 tonnes is possible.

It's a tricky proposition. As @tater always points out, an expendable Falcon Heavy cannot actually inject a 64-tonne monolith into LEO; its PAF alone wouldn't be able to handle it, and the upper stage has structural limits below that. What Falcon Heavy can do is put 64 tonnes of usable mass into LEO, as a sum of the actual payload and the propellant residuals, intended for a BLEO restart. The question for distributed launch is the amount of residuals for any upper stage when launched without payload, but no rocket companies quote "naked" residuals. However, since virtually all rockets quote GTO payload, that's the apples-to-apples comparison I chose.

Using the quoted GTO payload (26.7 tonnes at 2.27 km/s) and reverse-calculating gave me 44.8 tonnes of LEO residuals when launched without payload. However, SpaceX also quotes Falcon Heavy's payload to Mars (16.8 tonnes at 3.6 km/s) and payload to Pluto (3.5 tonnes at 8.2 km/s). Getting 26.7 tonnes from LEO to GTO would require 29.5 tonnes of propellant residuals, which makes enough sense. Getting 16.8 tonnes from LEO to Mars Transfer Injection would require 39.8 tonnes of residuals. Still tracking. However, getting 3.5 tonnes from LEO to a direct Pluto transfer, at the same 348 s specific impulse as everything else, would require a whopping 80.4 tonnes of residuals!! This suggests that when flying Falcon Heavy fully-expendable with a 3.5 tonne payload, core staging occurs just 1,031 m/s shy of LEO.

If you imagine launching FHe with a max-GTO payload but dropping it at staging, then you end up with 44.8 tonnes of residuals at LEO, which is what I used for the tables I've built. If you imagine launching FHe with a max-MTI payload but dropping it at staging, then you end up with 48.9 tonnes of residuals at LEO, which is slightly better. However...and here's the ridiculous part...if you launched a 3.5 tonne Pluto payload on an expendable Falcon Heavy and dropped it at staging, you would hit LEO with 81.3 tonnes of residuals.

If my math is right...holy crap. That's enough to throw up to 47.8 tonnes of distributed-launch payload to TLI. It's enough to deliver 38.3 tonnes of distributed-launch payload direct to LOP-G. It's enough to deliver a 26.9 tonne two-stage lunar lander to LOP-G, load it up with astronauts, and then drop it off in LLO.

16 hours ago, jinnantonix said:

25 tonnes to LOP-G  is about right for the KSP model I am using.  Unfortunately the 2 tank pair lander has a mass of 32 tonnes.

See above...evidently not a problem. And of course you can make it even better by sending the reusable ascent cabin/module to LOP-G ahead of time.

 

[Ultimate Steve]

6 minutes ago, sevenperforce said:

If my math is right...holy crap. That's enough to throw up to 47.8 tonnes of distributed-launch payload to TLI. It's enough to deliver 38.3 tonnes of distributed-launch payload direct to LOP-G. It's enough to deliver a 26.9 tonne two-stage lunar lander to LOP-G, load it up with astronauts, and then drop it off in LLO.

Except after you leave leo you can't really use the upper stage any more due to boiling and freezing of the propellants. A few hours after, yes, but not the multiple days that are likely for transit to gateway.

But this is still big. As long as the distributed launch payload can dock itself, which an Artemis lander would almost definitely be able to do, the only real modification you need to do to fhus is adding a docking port under the fairing, and modify the adapter/docking port to be able to deal with the high g forces at burnout. The fhus has rcs so it can hold orientation while it is docked to.

Europa clipper, however, would need to be given a docking port or some form of attachment system, and the necessary rcs and instruments to dock. Or you could modify the fhus for that.