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Artemis Discussion Thread

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3 minutes ago, sevenperforce said:

Hypergolics are nice because you can pack them into any old nook or cranny because you don't have to worry about boiloff...yet you can't, because if you're pressure-feeding, you need a spherical tank to minimize weight.

If you are volume limited, impulse density of hypergols is 11% higher than kerolox, 34% higher than methalox, and 181% higher than hydrolox.

I think the 2 tanks have the volume required, though they might have to have one component on one side, the other on the other side (assuming rough 1:1 mix ratios).

They show spherical tanks, so they are saving mass.

Dynetics-HUMAN-LANDER.jpg

Image looks slightly compressed side to side to me, but my guess (looking at crew and ladder for scale) that the tanks are indeed 2.4-2.5m in diameter.

The crew compartment is a simple tube, and you can see that the solid framework around that compartment that is part of the tank-support is robust, and could transmit force laterally well (mount it sideways for launch under a standard fairing).

I hope this one gets to move to the next step. based on nothing but what we know so far, I'd down-select to this and BO/LockMart without a second thought.

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28 minutes ago, tater said:

Image looks slightly compressed side to side to me, but my guess (looking at crew and ladder for scale) that the tanks are indeed 2.4-2.5m in diameter.

The crew compartment is a simple tube, and you can see that the solid framework around that compartment that is part of the tank-support is robust, and could transmit force laterally well (mount it sideways for launch under a standard fairing).

I hope this one gets to move to the next step. based on nothing but what we know so far, I'd down-select to this and BO/LockMart without a second thought.

I really like having a short ladder to the surface and what appears to be an airlock. Tons of internal volume for sure.

There's only so much that can be relied upon in a render like this, but I do note small tanks tucked between the large ones and the capsule body, which are too small to be oxidizer tanks. Thus they are more likely pressurant tanks, which suggests pressure-feeding and hypergolics. The engines look very bare-bones so this suggests the same thing -- no turbopumps. With eight inline engines you can use differential throttling for all your pitch and yaw needs and use RCS for roll control.

Something like this could, if the capsule was removed, drop a LOT of cargo on the lunar surface direct from TLI. It could even loft on a smaller launch vehicle and provide part of the TLI burn itself.

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FH TLI throw is in the low 20s (tonnes), so this lander could be sent with FH (and they are making a longer fairing for the USAF along with vertical payload integration, apparently).

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15 hours ago, sevenperforce said:

Something like this could, if the capsule was removed, drop a LOT of cargo on the lunar surface direct from TLI. 

Not if it is a single stage craft.  The Lockheed Martin Mars-Precursor Lunar Lander single stage craft was a dud with respect to payload delivery.  It could land humans, not much else.  Even with capsule removed, it is very inefficient compared to a staged craft.

The LH 2 stage concept , way way better.  Utilising the the Orion pressure vessel and building the ascent vehicle from service module components (8x R-4D + AJ10-190)?  Good idea I think.

If the Dynetics design is 2 stage.  i.e. includes a transit vehicle/ drop tank inline under the main body that is ejected prior to the AV landing,  there is much greater payload potential, as well as much better potential for capsule/habitat re-usability.  I like the idea of dropping the TV just prior to landing, advantages are the short ladder and re-usable leg mechanisms.

Edited by jinnantonix

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I like the idea of a minimalist human lander, frankly (as I have said up thread). Use the CLPS program to pre-place whatever gear the crew needs, in whatever way is most efficient---including quarters once they get past a sortie mission stage of operations.

Edited by tater

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9 hours ago, jinnantonix said:
On 1/14/2020 at 2:12 PM, sevenperforce said:

Something like this could, if the capsule was removed, drop a LOT of cargo on the lunar surface direct from TLI. 

Not if it is a single stage craft.  The Lockheed Martin Mars-Precursor Lunar Lander single stage craft was a dud with respect to payload delivery. 

The LockMart single-stage LL was not designed to drop off cargo. A stage with engines mounted on each side can drop objects more easily.

9 hours ago, jinnantonix said:

If the Dynetics design is 2 stage.  i.e. includes a transit vehicle/ drop tank inline under the main body that is ejected prior to the AV landing,  there is much greater payload potential, as well as much better potential for capsule/habitat re-usability.

I am totally here for a crasher-stage lander. Throw the big dV requirements at a balloon tank; make the throttleable, complicated bit the triple-redundant, super-safe part.

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I hate the idea of a crasher for aesthetic reasons, frankly. I know how useful it is as a concept, mind you, but it bugs me, particularly if the goal is a sustainable human presence on the lunar surface (I don't like the Chinese doing it in China, either ;)  ).

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Dunno where to put it, but this is cool:

 

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17 hours ago, tater said:

I hate the idea of a crasher for aesthetic reasons, frankly. I know how useful it is as a concept, mind you, but it bugs me, particularly if the goal is a sustainable human presence on the lunar surface (I don't like the Chinese doing it in China, either ;)  ).

There are just a lot of possible architectures. I wonder how much of a weight penalty it is to use larger, stronger landing legs to accommodate the descent stage.

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I understand why a crasher stage looks ugly, but what the difference between a crashed drop tank or two, and a descent stage sitting neatly on the surface?  How much are we willing to compromise efficiency with aesthetics?


I sense the idea of the Dynetics design is that the AV is re-usable, including legs.  If that is the case, then it's either a big inefficient single stage craft, or drop tanks/crasher stage.   

Edited by jinnantonix

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Or, what about a "crasher" stage that can take the lander down to the last few hundred m/s, before separating  and heading for a separate landing site. The idea is to maximize the possible salvage potential, ideally repurposing the entire structure and (hopefully) eventually having the capability to refill them.

Henry Ford's genius didn't just include the assembly line. Suppliers thought he was nuts for specifying where to put the bolt holes in the shipping crates, but he took apart the crates and used them for floorboards in his Model T's*. The same sort of planning for re-use and re-purposing needs to be applied as much as possible to everything headed  towards any infra-structure building project BLEO. Even if it is just recycling the materials, since building materials will be in short supply aside from dirt and bricks. It's not like there are trees to cut down....

A large, Skylab-class transfer/descent stage designed to be landed separately, moved, tipped over, buried, and converted into habs, labs, airlocks, storage, or hydroponic units. Waste not, want not.

*- I wanted to find a link to back this up, but I found this instead. Still, reusing as much as possible  is the sensible thing to do when the nearest hardware store is a quarter-million miles away..

Spoiler
Quote

One of my favorite “legends” doesn’t pertain to Classics but to the Ford Model T. At least once a year, I hear a car collector tell someone how Henry Ford directed his suppliers to build packing crates in such a way that the boards could be reused as floorboards in the Model T.

When I ran this story past my old friend, Bob Casey, transportation curator at The Henry Ford–and author of a book on the Model T’s centennial–he was well aware of it, but said there was no documented proof that this ever happened.

 

 

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Spoiler

A pool of tar.
On landing - melt, after usage - let freeze.
The parts will just sink and stick there.

 

Edited by kerbiloid

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On 1/16/2020 at 12:41 AM, tater said:

Dunno where to put it, but this is cool:

 

wth i was literally reading about this yesterday....

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13 hours ago, StrandedonEarth said:

Or, what about a "crasher" stage that can take the lander down to the last few hundred m/s, before separating  and heading for a separate landing site. The idea is to maximize the possible salvage potential, ideally repurposing the entire structure and (hopefully) eventually having the capability to refill them.

This will require additional avionics, a very complex remote control services (via the LOP-G?), more mass to orbit for lander legs and fuel - all for "possible salvage potential"?  I think the plan for reuse needs to be very well established to make this a viable strategy. 

To resolve the problem of ejecta, attach stretchy, light weight, heat resistant fabric/mesh between the lander legs.  On leg deployment, the material forms a skirt from above the pads, to a few meters below.  Each craft has it's own skirt. 

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The House's draft NASA Authorization for this year is a hot mess. It's almost as if they want to say to anyone trying to defend SLS, "Yeah, try it NOW!"

Lunar landings? Sure, in 2028. ISRU work? No. A base? No. All this in anticipation of a Mars Orbital mission in 2033. This last bit... I notice they don't also double the NASA budget, so yeah, that's not a thing.

https://science.house.gov/imo/media/doc/NASA_AUTH_01_xml.pdf

 

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29 minutes ago, tater said:

The House's draft NASA Authorization for this year is a hot mess. It's almost as if they want to say to anyone trying to defend SLS, "Yeah, try it NOW!"

Lunar landings? Sure, in 2028. ISRU work? No. A base? No. All this in anticipation of a Mars Orbital mission in 2033. This last bit... I notice they don't also double the NASA budget, so yeah, that's not a thing.

https://science.house.gov/imo/media/doc/NASA_AUTH_01_xml.pdf

 

It's gonna be quite funny seeing their reaction to China getting their moon base set up, while NASA are forced to change priorities every two years.

This is why I see the new space race as being between China and SpaceX, not because I think that SpaceX are inherently better than NASA, but because they have a clear, unchanging goal in mind (Yes, I know that SpaceX aren't aiming at the Moon, I'm talking more broadly about getting humans actually living in space.)

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NASA would happily set a goal and stick with it. The problem is Congress.

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This bill is a gift to Boeing on the lander front. Which makes no sense given their recent history. It says that any human lander system has to be completely owned by NASA. That pretty much writes off BO, and any other bid that wants to own their lander, right? Kills Commercial Crew lander unless I read it wrong.

Also says the lander should be integrated.

If the 2 versions merge with anything like the House bill as part of it, I'm gonna start rooting for a RUD, frankly.

Edited by tater

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Hopefully when the 2 bills are reconciled the Senate keeps the private sector in. The idea that NASA should own all the things is maddening, and exactly the opposite of what they should be doing.

Edited by tater

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3 hours ago, tater said:

It's almost as if they want to say to anyone trying to defend SLS, "Yeah, try it NOW!"

Oh, there are defenders in this forum, so just you wait :)

I mean, I understand when people defend this pork rocket as a job to lobby for Boeing, but for free? 
 

And I’m not saying it because I’m a SpaceX fan, I like the BO blue lander, IVF-enabled depots and other ULA proposals, etc.

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4 hours ago, MinimumSky5 said:

the new space race

Its slogan: "Make the opponent build the moonbase first and go bankrupt on its support."

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They'll be here, no doubt. It's just such an abject failure of understanding for the House to do this. There are issues with Artemis, but it has support outside the US (which Mars simply doesn't). The new focus on commercial partners is also a breath of fresh air. The 2 vehicles that should win are not from Boeing on their merits---and that is with knowing nearly nothing about the SN entry. Boeing doesn't want to put skin in the game (which makes sense, because they spend all their money on stock buybacks to jack the price, so they have little to invest on meaningless junk like "engineering.")

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If Boeing for any reason decides to pull out of Artemis at some point, or messes up the lander so badly it can’t be used, the whole program will end. There won’t be backups like in Commercial Crew or “buy seats from Roscosmos”-option.

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Just now, sh1pman said:

If Boeing for any reason decides to pull out of Artemis at some point, or messes up the lander so badly it can’t be used, the whole program will end. There won’t be backups like in Commercial Crew or “buy seats from Roscosmos”-option.

Unless crew starship actually works. It probably will, just not in time to be useful during Artemis.

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