totm dec 2023 Artemis Discussion Thread

[jadebenn]

29 minutes ago, sevenperforce said:

Upon review, that looks like four AJ-10s on the ascent stage and 6-7 on the descent stage.

If you can refuel the ascent stage, great, but you need to master microgravity propellant transfer. And pressurant transfer, if you're using pressure-fed engines, which is challenging at best.

I maintain that using thrusty engines for the ascent stage is a waste because a quarter of your dV requirement is not thrust-dependent.

Not AJ-10s. The Boeing lander will be methalox according to their partnership with Intuitive Machines.

[jinnantonix]

8 hours ago, sevenperforce said:

 

My model has an integrated expendable stage at 27.5t wet mass, including AV and engine(s), DV and transit drop tanks, excluding the reusable crew taxi.   From the above table, there is no LV second stage craft that can boost a craft this heavy to TLI, let alone to NRHO.  The best option for TLI would appear to be a Falcon expendable second stage which can get the craft to about 75% of TLI.  The Falcon Heavy expendable can launch 54t payload to LEO, so this would launch the lunar lander and adding drop tanks to the craft at launch to provide extra fuel to the complete the boost to TLI and then to insert into NRHO.

So each Artemis mission would include a Falcon Heavy expendable launch for the lunar lander plus TLI/NRHO insertion drop tanks,  a launch of a zero payload Falcon Heavy with expendable second stage which docks with the lunar lander in LEO, plus SLS/Orion with a co-manifested LOP-G component.

 

Edited October 26, 2019 by jinnantonix

[tater]

This will be interesting to watch. If Boeing were to win the lander contract it would not demonstrate that SLS was cost effective, it would be proof that the process is crooked, frankly. SLS launch cost is total annual cost of SLS program, plus marginal cost of vehicles, divided by the number of vehicles. 2X SLS means a launch cost (not including the payloads) of ~2.25 B$ per launch.

If a distributed launch took 3 expendable FHs, that's 450 M$? That's 20% of the cost of a single SLS (optimistically priced, BTW). So unless the Boeing lander concept comes in at maybe 1.8 B$ cheaper than BO's bid, it's not even competitive. IMO somewhere around 1.5 B$ cheaper than BO would be the point where I'd think that NASA should even bother to read the details of their proposal (a few hundred million might be worth a simpler launch with 1 rocket (in this case the cost of 2 fully expended FHs, 300 M$)).

I tend to think this is Blue's to lose.

Edited October 26, 2019 by tater

[jadebenn]

Current plan is to have two winners, ala COTS and CCrew, which is why I think Boeing's got a pretty good shot. If it was just one, I'd bet on Blue Origin and the National Coalition's very strong combined bid.

[tater]

6 minutes ago, jadebenn said:

Current plan is to have two winners, ala COTS and CCrew, which is why I think Boeing's got a pretty good shot. If it was just one, I'd bet on Blue Origin and the National Coalition's very strong combined bid.

So if they only get 2 entries, the process is crooked.

SLS being even considered in a case where the lander is question is not literally billions cheaper is a farce, IMO.

SLS does a thing---launch Orion, and that's fine. It can possibly simplify a lander, though any use of SLS that ALSO still requires a commercial launch removes this as a consideration. Ie: 1 Orion launch, 1 SLS launch, land on the Moon. That is fine, and worth some money (possibly) for the simplification of 2 launches vs 4, for example (SLS +3 HLV commercial). If it's SLS+SLS+commercial? Then look at the cost, and it must fail (or the accounting is crooked, min cost for SLS even marginal is over a billion (core alone is 900M$).

 

[tater]

People can make pro-SLS arguments from a crew standpoint, which is legitimate (man rated vs not man rated). For cargo this does not apply. Cargo is cargo. If you send a parcel overnight via any of the multiple providers who do this, all with tracking, guarantees, etc, the government paying 10X more for one of them to do the same thing would be pretty much proof someone was on the take. For the lab you have to fly a US carrier for travel, and coach. Someone using the Sandia credit card to buy a first class sleeper compartment to a meeting across the world would be in deep, deep trouble. Fired, and on the news, likely, for cheating the taxpayer. That's what buying an SLS launch for cargo amounts to.

Edited October 26, 2019 by tater

[jadebenn]

13 minutes ago, tater said:

So if they only get 2 entries, the process is crooked.

I'm certain there will be more, though I have my doubts we'll see any stronger bids. SpaceX is seemingly going to bid Starship for this, which will be interesting to watch. Aerojet Rocketdyne and some other smaller companies, are likely to bid as well, but I have severe doubts they'll be able to propose something that'll top the big three.

Ironically, I think the National Coalition sort of "gave" the second bid to Boeing. If Blue Origin and Lockheed Martin had competed independently as was the original plan, I think it would've been much more unlikely for Boeing to win.

13 minutes ago, tater said:

SLS being even considered in a case where the lander is question is not literally billions cheaper is a farce, IMO.

SLS does a thing---launch Orion, and that's fine. It can possibly simplify a lander, though any use of SLS that ALSO still requires a commercial launch removes this as a consideration. Ie: 1 Orion launch, 1 SLS launch, land on the Moon. That is fine, and worth some money (possibly) for the simplification of 2 launches vs 4, for example (SLS +3 HLV commercial). If it's SLS+SLS+commercial? Then look at the cost, and it must fail (or the accounting is crooked, min cost for SLS even marginal is over a billion (core alone is 900M$).

I'd wait for the financial details of the proposals to be released before making these statements. Let's see what Boeing has in mind before completely condemning it.

Edited October 26, 2019 by jadebenn

[tater]

13 minutes ago, jadebenn said:

I'd wait for the financial details of the proposals to be released before making these statements. Let's see what Boeing has in mind before completely condemning it.

We know what SLS program costs are, and WE pay them (we don't pay the overhead for BO, for example). We know what the core stage costs, we just saw that when they bought a bunch.

So we know that each SLS costs us over 2B$. Any details that change this are accounting that hides the actual cost to the taxpayer, and it's completely unfair to a primary (BO in this case) that is not having their dev costs paid for by the taxpayer. Boeing got paid to develop the core. They are getting paid for EUS, too. Then they get to sink those costs and compete against private entries?

The taxpayer should not be on the hook to deliver cargo with SLS. If it is COTS like, fine, but require that all the bids be LV agnostic (say require it fit on more than one LV capable of at least 15t to TLI). Boeing might win the lander, and have to fly it in parts on NG and FH, for example. BO might win and have to fly it on FH and DIVH or Vulcan. Any bid that enters that is not LV agnostic gets no money for launch at all. They only get paid for the lander delivered to lunar orbit, not a penny for the launch.

 

Edited October 26, 2019 by tater

[tater]

Take Commercial Crew as another example.

Boeing is getting paid basically 2X what SpaceX is for the same capability. I think the commercial model is good, but there needs to be some standard for costing. Having 2 suppliers is ideal (or more), but it would be entirely reasonable to say that the contract pays each bidder X amount for dev (same for every bidder), and Y amount for each spacecraft that reaches Gateway. Have no payment for launch whatsoever, it comes out of the Y dollars---which is identical for every bidder.

So if Y is 2 billion dollars for a lander stack (seems reasonable for this overprice program, if excessive, since Orion is about a billion), then if Boeing wants an SLS launch, they pay for all the parts (to themselves), plus they pay NASA's share of SLS program overhead that supports the fabrication, testing and launch, and they pay their cost on building the stack, and they profit whatever is left over. If their competitors use 4X commercial launches for the same thing, they still come out way ahead in the profit department.

 

 

[mikegarrison]

5 hours ago, tater said:

We know what SLS program costs are, and WE pay them (we don't pay the overhead for BO, for example).

Someone pays for Blue Origin.

Yeah, it could be just everyone who buys their hemorrhoid medication on Amazon, but somebody is paying somewhere.

I'll also point out that when you divide the program cost by the number of launches, each launch cuts the per/launch cost down dramatically. So the more SLS launches there are, the less each one costs. (Although, of course, the total cost of all the launches combined continues to increase.)

It makes more sense, from a decision-making standpoint, to simply ignore sunk costs. Which launcher to use should be made on the basis of marginal costs to build one more, not overall program costs that have already been spent.

[tater]

33 minutes ago, mikegarrison said:

Someone pays for Blue Origin.

Right now It's Bezos selling a billion in stock every year.

33 minutes ago, mikegarrison said:

Yeah, it could be just everyone who buys their hemorrhoid medication on Amazon, but somebody is paying somewhere.

True, but people elect to buy what they buy on Amazon. They don't give Senator Shelby their annual Amazon expense budget, and let him shop for them.

33 minutes ago, mikegarrison said:

I'll also point out that when you divide the program cost by the number of launches, each launch cuts the per/launch cost down dramatically. So the more SLS launches there are, the less each one costs. (Although, of course, the total cost of all the launches combined continues to increase.)

It makes more sense, from a decision-making standpoint, to simply ignore sunk costs. Which launcher to use should be made on the basis of marginal costs to build one more, not overall program costs that have already been spent.

No, this makes sense. But I think that some % of the annual, operational program costs---I was not talking about dev costs---be folded into the launch cost.

That said, the retail price of a launch with ULA, SpaceX, or BO does (or will) reflect what they need to charge in order to potentially pay off dev costs. The business can elect to ignore those costs going forwards, or try to pass them off over time, that's their choice. Doesn't change the fat that retail costs are what they are. SpaceX can charge literally anything just below ULA and they are very competitive. They might be saving millions with reuse, or whatever (none of us know), but to the extent that they don't lower prices, it doesn't matter to us, but they pay off dev costs. If a DIVH costs ULA only slightly more than at Atlas V, then they pocket a lot of money. If Boeing charges NASA 900M$ for an SLS core, but it only costs them 50M$, they pocket a lot of money. Without actual competition, we don't really know. If SS was a thing as an expendable upper stage (cheaper, and lighter, no reuse, no SL raptors at all), it totally competes with SLS. In fact, it is far, far better (probably gets more like 200t to LEO).

[jinnantonix]

Total mission cost including launch costs.  I can't see an architecture that includes a SLS Cargo launch will win - it is just too expensive.  In my opinion, any lunar landing mission architecture that includes more than 2 x HLV commercial and 1 x SLS is going to fail, it simply won't get long-term funding approval.

[tater]

22 minutes ago, jinnantonix said:

Total mission cost including launch costs.  I can't see an architecture that includes a SLS Cargo launch will win - it is just too expensive.  In my opinion, any lunar landing mission architecture that includes more than 2 x HLV commercial and 1 x SLS is going to fail, it simply won't get long-term funding approval.

Any landing is probably going to require 3 commercial HLV launches. Ascent, Descent, and transfer stage. The problem is Gateway.

[jinnantonix]

8 minutes ago, tater said:

Any landing is probably going to require 3 commercial HLV launches. Ascent, Descent, and transfer stage. The problem is Gateway.

 If the Blue Origin assumption about ascent vehicle wet mass = 6.5t is practical, then my calculations show that a simpler design can complete the missions with just the 3 launches, and still add a LOP-G component with each mission.  

Edited October 27, 2019 by jinnantonix

[tater]

Just now, jinnantonix said:

 If the Blue Origin assumption about ascent vehicle wet mass = 65.t is practical, then my calculations show that a simpler design can complete the missions with just the 3 launches, and still add a LOP-G component with each mission.  

They need a transit vehicle at Gateway,plus the blue moon lander. Not sure what the specs are  on the stretch version descent stage.

[jinnantonix]

Just now, tater said:

They need a transit vehicle at Gateway,plus the blue moon lander. Not sure what the specs are  on the stretch version descent stage.

I am not suggesting Blue Moon lander will win, I doubt they will.  If the 6.5t assumption is correct i think there are better, simpler designs that could work.

[jinnantonix]

On 10/26/2019 at 1:31 AM, sevenperforce said:

The primary reason to go with a pressure-fed engine in the first place is safety first so that you never need engine-out capability. If you are going for multiple engines for engine-out, then you should go with pump-fed engines and balloon tanks, which saves way more dry mass and cranks up specific impulse.

After a bit of testing it would seem that your notion of using a single AJ10 OMS is ideal from a cost and simplicity  perspective, it certainly has sufficient thrust and down throttle capability.  Although it takes 30 minutes of continuous full thrust from LLO to lunar surface, which is ponderous.  I take your point about the reliability of the pressure-fed engines, and  will keep the the 3 engine safety concept in the back pocket, maybe someone in NASA or Congress would want to argue for it.   

Also reconsidering the losses associated with landing near empty descent vehicle fuel tanks on the surface.  ... hang on, why have multiple vehicles anyway?  Why not simply have a crew taxi (with thrusters), and just add drop tanks which are ejected at key moments when the debris is on a suborbital trajectory?  There are five transits 1. LEO-NRHO 2. NRHO-LLO 3. LLO-Surface, 4. Surface-LLO 5. LLO-NRHO.   By chance it seems the first three transits all require about the same amount of propellant (~11.5t including tanks), which means a common design for each drop tank sequence, assumed to be radial mount.  The final two drops are inline tanks.Is there anything difficult about drop tanks IRL (e.g. safety, reliability concerns) that I should be considering here?

According to this simple model, each mission looks like this:

• Launch lunar lander on Falcon Heavy to LEO (approx 42-45 t wet mass).  Crew taxi (2.7t) included on first launch.
• Launch SLS/Orion, with co-manifested with LOP-G component and logistics
• Launch Falcon Heavy second stage (no payload), dock with lunar lander in LEO
• SLS/Orion and FH secondary/LL transit to LOP-G.  The latter completes TLI and NRHO rendezvous after ejecting FH secondary stage. 
• Orion docks inline, crew use Canadarm to dock lunar lander.
• Two crew board lunar lander, undock and retrofire and drop LEO-NRHO transit tanks.
• Lunar lander circularises at 100km alt, polar orbit, begins descent to south pole, and ejects NRHO-LLO tanks
• Prior to touchdown LLO-Surface tanks are ejected.
• After two weeks on surface, launch, ejecting lander legs.  Prior to circularising in LLO, eject Surface-LLO tank and engine.
• Crew taxi returns to LOP-G using thrusters, eject final thruster propellant drop tank at LOP-G
• Orion returns 4 crew to Earth.

Below testing eject of the lander legs and payload storage containers at lunar lift off.

 

@jadebenn writes:

Quote

Aerojet Rocketdyne and some other smaller companies, are likely to bid as well, but I have severe doubts they'll be able to propose something that'll top the big three.

Why not?  The model being developed here is simply based on wrapping detachable fuel tanks around a single AJ10 engine and a scaled down an Orion pressure vessel, it would not look out of place on a Aerojet Rocketdyne drawing board.  Sure NASA would need to weigh in on detailing the lunar lander design and build, but that's a validation of Orion, so NASA admins and engineers are gonna love that.  This proves there are simpler (arguably more practical) designs that are more affordable compared to the big three concepts.

 

Edited October 27, 2019 by jinnantonix

[tater]

1 hour ago, jinnantonix said:

I am not suggesting Blue Moon lander will win, I doubt they will.  If the 6.5t assumption is correct i think there are better, simpler designs that could work.

The 6.5t landed on the surface is using the BO Descent stage. That's a Be-7 engine design. I_sp is 453d. Nothing based on methalox (the rumored engine for the Boeing design) is gonna top that in terms of mass efficiency, and any SLS-based architecture has 37t to play with, all-in for the entire stack.

 

 

[jinnantonix]

3 minutes ago, tater said:

The 6.5t landed on the surface is using the BO Descent stage. That's a Be-7 engine design. I_sp is 453d. Nothing based on methalox (the rumored engine for the Boeing design) is gonna top that in terms of mass efficiency, and any SLS-based architecture has 37t to play with, all-in for the entire stack.

The model being developed here is assuming a single hypergolic fueled AJ10-190 OMS engine at I_sp =319 that is used multiple times for all aspects of the 3 week mission, and this re-use provides a lot of mass efficiency, which makes up for lack of I_sp efficiency.

Blue Origin BE-7 is designed for multiple firing, and may offer superior I_sp efficiency, but the Be-7 carries with it limitations over cryo fuel storage requirements and hydrogen boil off - I think is not feasible as single use across a full 3 week mission.  I think BO intends to use the BE-7 only for lunar transit and descent, and is assuming the ascent stage has a separate hypergolic fueled engine.  AJ10 perhaps? and if so, why have a separate descent stage engine at all?

[tater]

7 minutes ago, jinnantonix said:

The model being developed here is assuming a single hypergolic fueled AJ10-190 OMS engine at I_sp =319 that is used multiple times for all aspects of the 3 week mission, and this re-use provides a lot of mass efficiency, which makes up for lack of I_sp efficiency.

Blue Origin BE-7 is designed for multiple firing, and may offer superior I_sp efficiency, but the Be-7 carries with it limitations over cryo fuel storage requirements and hydrogen boil off - I think is not feasible as single use across a full 3 week mission.  I think BO intends to use the BE-7 only for lunar transit and descent, and is assuming the ascent stage has a separate hypergolic fueled engine.  AJ10 perhaps? and if so, why have a separate descent stage engine at all?

They are not making the ascent stage, I am talking about the Descent stage only. LM is making their ascent stage.

Regardless, I think it would be criminal to give Boeing more money after their abject mismanagement of SLS core up to this point (according to NASA OIG, not me).

[jinnantonix]

1 minute ago, tater said:

They are not making the ascent stage, I am talking about the Descent stage only. LM is making their ascent stage.

I know, and I think this is clearly resulting in inefficiencies - design by committee  .  Blue Origin have a good lander, very suitable for delivering heavy static payloads to the lunar surface (e.g. rovers, ISRU equipment etc), but it is not ideally suited to the Artemis crewed lunar landing mission.  A single contractor could design the whole lander better.  LM had a go, but were overly focused on 100% re-usability.   I am hoping one of the smaller players sees the opportunity to design a re-usable lander with multiple staged, expendable components.

Quote

Regardless, I think it would be criminal to give Boeing more money after their abject mismanagement of SLS core up to this point (according to NASA OIG, not me).

The Boeing design is too expensive and inefficient, 2 x SLS launches per mission is not going to happen.  Even if NASA likes it, I reckon Congress will kill it, and the whole Artemis program with it.

[tater]

13 minutes ago, jinnantonix said:

I know, and I think this is clearly resulting in inefficiencies - design by committee  .  Blue Origin have a good lander, very suitable for delivering heavy static payloads to the lunar surface (e.g. rovers, ISRU equipment etc), but it is not ideally suited to the Artemis crewed lunar landing mission.  A single contractor could design the whole lander better.  LM had a go, but were overly focused on 100% re-usability.   I am hoping one of the smaller players sees the opportunity to design a re-usable lander with multiple staged, expendable components.

I think the Ascent stage needs hypergolics, so I have no problem with the BO team concept, honestly, given the constraints.

Reuse? Yeah, not really a thing, honestly. IMHO reuse only makes sense if the vehicle bringing the propellants from their source is reused 100%, and operationally (no refurb, etc). So ISRU on the Moon? Sure, reusable craft makes sense. Reused on the Moon with props from Earth? Not unless the spacecraft delivering the props is reused from where it gets tanked up with the props it delivers (Earth, in this case).

So for Earth-source props, reuse requires Starship, or Skylon, or something that does the same job and is not thrown away.

If they get ISRU going... then whatever can land and get refilled with props.

[mikegarrison]

[jinnantonix]

 

2 hours ago, tater said:

Reuse?

I think re-use can make sense for components.  For example the lunar lander habitat, avionics, airlock, these can all be effectively re-used many times to save on constructing and launching again and again.  To some degree engines can be re-used within the constraints of reliability.  But for fuel and tanks, nope, I agree with you that fixed construction space ships that are refueled in space make no sense.  Even more so as BO and SpaceX develop large-scale low-cost methane-fueled launch vehicles that allow larger and cheaper payloads to LEO.
 

Quote

ISRU on the Moon? 

The whole idea of Artemis is to determine whether ISRU is even feasible.  Until it is proven, any architecture we use should assume best economics which is mainly expendable.  If ISRU is feasible this would open up options like operating re-usable nuclear tugs for deep space missions, but that's a decade or two down the track at least.

Edited October 27, 2019 by jinnantonix

[ThatGuyWithALongUsername]

21 hours ago, jinnantonix said:

a bit of testing

*coughs* https://m.xkcd.com/1244/