Author Topic: SLS as propellant truck  (Read 38954 times)

Offline Warren Platts

Re: SLS as propellant truck
« Reply #20 on: 12/31/2011 06:46 PM »
It looks like the 70 tonne SLS will only launch twice, so will not be used to launch propellant. The 105 tonne version will be available from about 2022 and the 130 (138?) tonne version from about 2027, the first few flights of each are unlikely to be propellant launches.

That pace of evolution would be fine. First few years will be sortie, shake-down, scouting missions anyways, and then the pace of base/mine construction will take a few years.

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It seems far too early to be saying what will be cheapest for launching propellant from 2025 onwards.

If SpaceX succeed with the FH, its price for launching propellant will be about $3,500/kg, this is likely to be cheaper than can be achieved by SLS.

At low flight rates for SLS, yes; but highly debatable for higher launch rates. I think estimates for high flight rates for Direct were around $3,000/kg, and my own BOTE here suggests that costs for SLS in the vicinity of $3,000/kg are not unlikely.


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I consider it likely that at least one of SpaceX, Orbital, LM, Boeing, Blue Origin, etc. have achieved 1st stage reusability and perhaps 2nd stage reusability as well. If SpaceX achieve their stated gaols they will likely be on their second iteration of reusable systems by then.

If 1st stage reusability is achieved then propellant prices of below $3,000/kg should be possible from any of the launch providers. 2nd stage reusability would lower prices to under $2,000/kg. Some tanker designs use a stretched 2nd stage for the tanker, if these were reusable then I consider for prices below $1,000/kg to be reasonable.

As we saw with the Shuttle, reusability isn't a panacea. A first stage slamming into salt water at 60 mph is going to require some major refurbishment, once the fleet of ships required to get it fishes it out of the drink.

$1,000/kg sounds too optimistic. Even Skylon in mature service doesn't claim future prices to be that low.

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If reusability is not achieved then a small launcher would have to have lots of flights getting into the "A rocket a day keeps the high costs away" territory where costs can be reduced by streamlining the production and launch procedures.

What I am getting at is that easily conceivable improvements to current and near future launchers will allow them to undercut the SLS in propellant launch.

I'm not sure you're right because SLS has one thing going for it: the rocket equation. It is a fact that other things being equal, payload mass fraction increases with increasing payload capacity. (Notice how the price for Falcon 1 launches is currently $10,000K/kg, but goes down for Falcon 9.) Moreover, reusability has costs in terms of payload mass fraction.

However, even if it's the case that commercial can eventually undercut SLS for propellant launch, your argument applies even more to using SLS to launch the Orions/landers/cargos, which in that case, the launch costs for SLS, not counting payload costs are going to be 10 or more $K/kg. In other words, SLS is already undercut by commercial launch for the low flight rates of SLS that are currently being contemplated. Throw in payload costs, and there isn't going to be much action left for private: just ISS support.

The premise of the thread is that SLS will get built. Given that premise, the question is What is the most efficient use of SLS? You might not think using SLS as a propellant truck would be as efficient as going commercial for propellant launch, but it will sure as hell be more efficient than using SLS at low rates to launch low-tonnages of high-value payloads.

IMO YMMV

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Offline deltaV

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Re: SLS as propellant truck
« Reply #21 on: 12/31/2011 08:04 PM »
At low flight rates for SLS, yes; but highly debatable for higher launch rates. I think estimates for high flight rates for Direct were around $3,000/kg, and my own BOTE here suggests that costs for SLS in the vicinity of $3,000/kg are not unlikely.

SpaceX is quoting $80M - $125M for 53 mt to LEO. The higher cost works out to $2,358 per kg. Six SLS launches a year corresponds to about 15 Falcon Heavies per year, so SpaceX would also benefit from economies of scale. Correcting for a little SpaceX optimism $3,000/kg from Falcon Heavy sounds reasonable. Of course the tanker adds weight and cost, especially if the fuels being hauled differ from what the launch vehicle uses. I would therefore give SpaceX the advantage in hauling liquid oxygen and hydrocarbons and SLS the advantage in hauling liquid hydrogen.

This is all ignoring development costs of course.

Offline Patchouli

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Re: SLS as propellant truck
« Reply #22 on: 12/31/2011 08:26 PM »
Seems kinda backwards as propellant is the one thing that has no problems at all in breaking down into smaller payloads.

I figured the best way to go would be SLS launches all the bulky stuff like landers,habs,and EDS stages preloaded with a partial fuel load then cheaper EELV class vehicles like Falcon heavy bring up the rest of the propellant esp the oxygen.

SLS can launch at most maybe six time a year while any of the EELV class vehicles probably could do 15 flights a year if needed.
« Last Edit: 12/31/2011 08:31 PM by Patchouli »

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #23 on: 12/31/2011 08:49 PM »
The premise of the thread is that SLS will get built. Given that premise, the question is What is the most efficient use of SLS? You might not think using SLS as a propellant truck would be as efficient as going commercial for propellant launch, but it will sure as hell be more efficient than using SLS at low rates to launch low-tonnages of high-value payloads.

That's not a good argument if it does significant collateral damage, especially if that damage is to about the only thing that matters, namely cheap lift. It would be a disastrously bad policy. The point shouldn't be to make SLS look good, but to do the best possible given SLS.
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Offline Patchouli

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Re: SLS as propellant truck
« Reply #24 on: 12/31/2011 09:16 PM »
The premise of the thread is that SLS will get built. Given that premise, the question is What is the most efficient use of SLS? You might not think using SLS as a propellant truck would be as efficient as going commercial for propellant launch, but it will sure as hell be more efficient than using SLS at low rates to launch low-tonnages of high-value payloads.

That's not a good argument if it does significant collateral damage, especially if that damage is to about the only thing that matters, namely cheap lift. It would be a disastrously bad policy. The point shouldn't be to make SLS look good, but to do the best possible given SLS.

I think SLS's biggest advantage is fairing size this is good for things like depot tanks which work better as a few large tanks vs several small tanks,Station modules,Mars EDL systems etc.

With existing LV's you're limited to making everything long and narrow to fit the fairing.
« Last Edit: 12/31/2011 09:16 PM by Patchouli »

Offline Warren Platts

Re: SLS as propellant truck
« Reply #25 on: 12/31/2011 09:24 PM »
Seems kinda backwards as propellant is the one thing that has no problems at all in breaking down into smaller payloads.

The converse principle, however, is that propellant has no problems maxing out the maximum payload capacity of a given LV. This guarantees that the payload capacity will be used to the fullest extent possible. No overkill.
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #26 on: 12/31/2011 10:11 PM »
The premise of the thread is that SLS will get built. Given that premise, the question is What is the most efficient use of SLS? You might not think using SLS as a propellant truck would be as efficient as going commercial for propellant launch, but it will sure as hell be more efficient than using SLS at low rates to launch low-tonnages of high-value payloads.

That's not a good argument if it does significant collateral damage, especially if that damage is to about the only thing that matters, namely cheap lift. It would be a disastrously bad policy. The point shouldn't be to make SLS look good, but to do the best possible given SLS.

This would be disastrous for prospects of cheap lift.

If there is to be an SLS, it should be used to launch crew to L1/L2, as proposed in the recent Boeing plan.

I know the SLS-as-propellant-hauler idea is counterintuitive at first--but try it see it my way for a minute: on the Boeing plan, just about everything is stuffed into an SLS so as to minimize the number of launches. Thus, the requirement that practically everything goes up in an SLS constrains the architecture sharply, resulting in, for example, anemic landers with little downmass capability.

The result is low mission rate to the Moon (1 or 2 per year sorties with limited functionality--permanent base will be humble if it can be done at all--ISRU? Anything beyond a mere demo--forget about it.)

On the other hand, if SLS can get 700 to 800 tonnes of propellant to LEO in a year, this is enough propellant using a ULA-style depot-based architecture to fund 5 heavy missions to the Moon per year that would in turn require an extra 300 to 400 tonnes of dry mass that would also have to be launched: here is where commercial could shine because the diversity of payloads is easily matched by a diversity of LV's.

So given the choice:

A: 2 missions per year where SLS practically launches everything

OR

B: 5 missions per year where SLS takes care of the propellant

which do you think will result in further opportunities for commercial? Plan B obviously.
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #27 on: 12/31/2011 10:13 PM »
But why should those be the only two choices?
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #28 on: 01/01/2012 03:04 AM »
The world is what it is. The current path forward is through SLS. That's the plan anyways. It's not written in stone--no metal is bent yet, but politically for now, it's the only thing on the table.

Given that, one might argue that the best strategy for the loyal opposition is to simply watch the train wreck happen in slow motion, and let events overtake SLS and it joins the laundry list of cancelled NASA projects.

E.g., the Boeing proposal: it's really inadequate for what should be a monumental achievement. I call it Apollo-on-junk-food, because it follows the old Apollo template, but it's really not even a more athletic version of Apollo. It's back to 1972. It will be unsustainable, and the results it generates won't seem to justify the huge budget it takes up.

Alternatively, one could urge for a radically different architecture: e.g., the ULA architecture. Let's just literally do ACES. SLS and ACES are not exclusive alternatives; by coincidence, they actually fit together hand and glove.

According to Zegler et al. (2009), their year 3 Summary of Operations (Table 5.) shows total mass to LEO of 1011 mT and total propellant to LEO of 728 mT.

This is what I mean when I say SLS and the ULA plan are a perfect fit for each other: 728 mT/year / 6 flts/year = 121 mT/flight. This is perfect: it leaves a little margin of about 9 tonnes for the tanks and motors required to make it to the depots.

Essentially, the SLS "3rd-stage" (for lack of a better term) will simply be a fat ACES-121 tanker.

What about commercial spaceflight? Well, there is still all the dry mass payloads and cargos that also need to be launched. Let's review what those might consist of: there will be 5 missions per year:

3 cargo landers (~27.0 mT ea.)
2 crewed landers (~13.5 mT ea.)
2 MPCV+ACES tugs (~14.0 mT ea.)

So those are 8 high-value payloads per year, plus whatever sundry items as might be made available (e.g., communications, Lunar GPS satellites), plus the entire ISS concession.

A good rule of thumb is that high-value payloads tend to cost $30K/kg by the time they get to orbit. The total list above weighs 136 mT. Thus 136 mT * $30K/kg = $4B. Meanwhile six SLS propellant launches = $3B. Set aside $2B for ISS.

$4B + $3B + $2B = $9B = NASA HSF budget.

See? It all fits perfectly. We can have our cake and eat it too, as long as we're not afraid of success.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: SLS as propellant truck
« Reply #29 on: 01/01/2012 08:03 AM »
If we can get the flight rate of SLS up to 6 or more flights per year, and keep it packed full, it can beat Falcon Heavy IMO.

It will only beat FH if SLS costs less than its projections and FH cost more. Don't be fooled by the FH price range of $80 -125M into thinking that the cost to beat is $125M for 45 tonnes = $2,770/kg [1]. The upper end cost includes fairing, multi-payload carrier and payload integration, none of which apply to propellant launch and assumes a flight rate of 4 per year. With a FH flight rate of 12/year (8 of them propellant) my guess is that propellant launches would be priced at about $90M for 50 tonnes (53 tonne payload - 3 tonne for the tanks, etc) = $1,800/kg

But the SLS won't be competing with FH. By 2025 or so when the 105 tonne SLS will be available for propellant launch, the FH will have been replaced. Either its replacement or SpaceX's competitors responses will be cheaper.

[1] I'm ignoring the cost of tanks, etc to hold and transfer the propellant. Assuming that the cost will scale with propellant mass, it can be ignored when comparing FH and SLS. But, even if FH tanks added 50% to costs and SLS tanks added nothing to its costs, FH would still be cheaper!

The trend in SpaceX prices is up, not down. I'll believe $2000/kg, when I see them do it. Meanwhile, the cost of the Shuttle program is a reasonable surrogate for what SLS launch costs will be, and that's in the low $3,000's. That's pretty frackin' good, and it's relatively low risk.

But even if it's the case that FH is somehow cheaper than SLS, and can maintain a high enough flight rate to get 728 mT to LEO (728 / 40 = 18 flights/year)--and it's not obvious that the preponderance of evidence supports that--even then you would want to max out 6 flights of SLS on pure propellant, because that is the most efficient use of SLS. Given that SLS will be built for good or ill, the best thing to do is use it in the most efficient manner.

ULA and SpaceX can then slug it out for who gets to launch the most of the dry mass, high-value payloads that still need to get launched.  The 728 tonnes of propellant to LEO that the SLS could deliver would guarantee that there will be plenty of business for everyone.
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Offline MikeAtkinson

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Re: SLS as propellant truck
« Reply #30 on: 01/01/2012 09:36 AM »
The trend in SpaceX prices is up, not down.

There is no clear trend in SpaceX prices, using the published prices depending on whether you take maximum payload or typical (80%), payload to GTO (maximum or 3000kg), gross cost or cost/kg, year of launch and which inflation deflator, SpaceX prices have either gone down slightly, or gone up quite a bit. Using the 16 tonne payload for the Merlin 1D version that was published on their web site for a couple of hours then SpaceX F9 prices would have fallen no matter how they were measured.

There is no trend in FH prices as they have not yet been updated.

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #31 on: 01/01/2012 10:07 AM »
The world is what it is. The current path forward is through SLS. That's the plan anyways. It's not written in stone--no metal is bent yet, but politically for now, it's the only thing on the table.

Even assuming SLS, the options are not just the two you mentioned. I've sketched in a fair amount of detail a variant of the Boeing plan that would maximise the rNPV of commercial propellant launches, even in the presence of an SLS.

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Given that, one might argue that the best strategy for the loyal opposition is to simply watch the train wreck happen in slow motion, and let events overtake SLS and it joins the laundry list of cancelled NASA projects.

A loyal opposition can do much more than just sitting back. They can fight something they believe is totally wrong with all their might. Look at the Republicans and Obamacare.

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So those are 8 high-value payloads per year, plus whatever sundry items as might be made available (e.g., communications, Lunar GPS satellites), plus the entire ISS concession.

High value payloads are precisely what we don't need. The road to cheap lift will likely go through tiny RLVs at first, and those are really only good enough for propellant, bulk materials and consumables. Later, larger versions could also carry humans. I think it will be a long time before there will be a need for EELV class RLVs or bigger. But that's fine, cheap small lift, the ability to launch propellant and people cheaply is all we need to open up space. Existing ELVs are good enough for reusable spacecraft and habs, since those can be amortised over many years / missions / clients and are much more expensive than their launch costs anyway.

This is the great potential synergy between commercial development of space and exploration:

On the one hand, RLVs need high flight rates, which requires affordable payloads. Only small RLVs will be able to achieve these high flight rates, even with NASA as an anchor customer. But small RLVs can really only carry propellant and the like. Conveniently, propellant (even hypergolic propelllant) is essentially free compared to current launch prices and easily replaced in case of failure. Not so with expensive aerospace hardware, let alone people. Propellant is about the only affordable payload for the needed amounts of payload to generate a high flight rate even for tiny RLVs. NASA on the other hand just happens to need vast amounts of propellant in orbit if it wants to do exploration.

Small RLVs are the ideal way for NASA to reduce its launch costs without investing more, indeed while investing less! Propellant is the ideal initial payload for small RLVs. It would be a marriage made in heaven.

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See? It all fits perfectly. We can have our cake and eat it too, as long as we're not afraid of success.

Could you kindly stop disparaging alternatives to your own preferred course of action as being afraid of succes? I find it offensive.
« Last Edit: 01/01/2012 10:16 AM by mmeijeri »
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #32 on: 01/01/2012 11:36 AM »
The world is what it is. The current path forward is through SLS. That's the plan anyways. It's not written in stone--no metal is bent yet, but politically for now, it's the only thing on the table.

Even assuming SLS, the options are not just the two you mentioned. I've sketched in a fair amount of detail a variant of the Boeing plan that would maximise the rNPV of commercial propellant launches, even in the presence of an SLS.

But you don't have a concrete mission beyond so-called cheap lift. That's your problem. On the one hand, you never define cheap lift. I get the feeling you won't be satisfied till launch costs get down to $1/kg. Taken to the logical extreme, we should should start a massive, Keynesian stimulus spending effort on launching nothing but sandbags into space until they get it right.

Cheap lift might be best for the rest of the world, but for right now, from a selfish, American perspective, launching maximal numbers of sandbags into orbit in order to achieve cheap lift is not the best use of NASA's budget.

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So those are [at least] 8 high-value payloads per year, plus whatever sundry items as might be made available (e.g., communications, Lunar GPS satellites), plus the entire ISS concession.

High value payloads are precisely what we don't need. The road to cheap lift will likely go through tiny RLVs at first

You do not know this. It's equally likely that big, dumb, expendable super-HLV's can deliver large amounts of propellant even cheaper.

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and those are really only good enough for propellant, bulk materials and consumables. Later, larger versions could also carry humans.

And you don't know this to be true either. It's at least equally likely that the first reusable spacecraft will be something along the lines of X-38 that will carry a couple of people at a time to orbit. But I wouldn't recommend using X-38 for hauling boatloads of propellant to orbit.

Quote from: Martijn
This is the great potential synergy between commercial development of space and exploration:

On the one hand, RLVs need high flight rates, which requires affordable payloads. Only small RLVs will be able to achieve these high flight rates, even with NASA as an anchor customer. But small RLVs can really only carry propellant and the like. Conveniently, propellant (even hypergolic propelllant) is essentially free compared to current launch prices and easily replaced in case of failure. Not so with expensive aerospace hardware, let alone people. Propellant is about the only affordable payload for the needed amounts of payload to generate a high flight rate even for tiny RLVs. NASA on the other hand just happens to need vast amounts of propellant in orbit if it wants to do exploration.

Small RLVs are the ideal way for NASA to reduce its launch costs without investing more, indeed while investing less! Propellant is the ideal initial payload for small RLVs. It would be a marriage made in heaven.

Only one problem: RLV's are nowhere going to be near ready enough when we need them, which is this decade. The US of frackin' A is going back to the Moon before the 50th anniversary happens, RLV's be damned. Sorry.
 
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See? It all fits perfectly. We can have our cake and eat it too, as long as we're not afraid of success.

Could you kindly stop disparaging alternatives to your own preferred course of action as being afraid of succes? I find it offensive.

Well, you shouldn't, Martijn, because it wasn't directed at you personally. There are psychological factors out there. The main human drivers are fear and greed. The greed shows up in the jockying for bigger shares of the pork pot pie. Then there is the fear. See, on the one hand, there is a lot of dreaming going on about spreading humanity throughout the galaxy and fantasies about what it would be like to homestead on Mars. But when it comes to actually doing something truly ambitious, there is a noticeable trepidation. The trepidation cannot stem from fear of failure, because the current impasse is a failure. Therefore, the trepidation must stem from fear of success. The meme that America is in decline has become so ingrained, that people just can't imagine doing something actually great. The thought of it makes them uncomfortable. They're not "happy" if they're not in a situation that they are used to, which in this case is chronic stagnation. That's what I mean by fear of success. It's a fear of stepping into a new situation that you're not used to.
« Last Edit: 01/01/2012 11:51 AM by Warren Platts »
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Offline mmeijeri

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Re: SLS as propellant truck
« Reply #33 on: 01/01/2012 12:39 PM »
But you don't have a concrete mission beyond so-called cheap lift. That's your problem.

No, that's not my problem. I do have concrete missions in mind, in fact that is one of the main points I keep stressing, we need to focus on spacecraft and missions, not on infrastructure. I've spent quite a lot of time proposing all kinds of missions, seeking synergy with both commercial manned spaceflight and unmanned science missions. Maybe you weren't present or maybe you weren't listening, but I've stressed exactly this point.

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On the one hand, you never define cheap lift. I get the feeling you won't be satisfied till launch costs get down to $1/kg.

Not true either, by cheap lift I mean $100/kg - $1,000/kg. This is the standard commercial space meaning of the term and its bewildering array of synonyms.

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Taken to the logical extreme, we should should start a massive, Keynesian stimulus spending effort on launching nothing but sandbags into space until they get it right.

No, that's a strawman. You've made this argument before and I have pointed out that's not what I am proposing. If anything what I'm advocating would be more like monetarism than Keynesianism. I am in favour of starting with missions as soon as possible. In other words, start doing exploration as soon as possible and start consuming competitively launched propellant (not sandbags) in orbit as soon as possible.

You could begin with unmanned science missions or robotic precursor missions to the moon, probably in support of lunar ISRU facilities. Then you could move to manned missions to moon Lagrange points, Earth Lagrange points, NEOs, the moon, Phobos & Deimos, then Ceres and Mars.

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Cheap lift might be best for the rest of the world, but for right now, from a selfish, American perspective, launching maximal numbers of sandbags into orbit in order to achieve cheap lift is not the best use of NASA's budget.

Can we agree to drop the sandbags as I've never proposed them? Can we also agree to stop misrepresenting my position in the face of repeated clarifications? You have repeatedly made accusations of the form "you propose X, but that would lead to Y, which would be undesirable, therefore we need to do Z instead" when my real argument was "we shouldn't do X, because that would lead to Y, which would be undesirable, therefore we should do z instead", with z a deliberately less ambitious version of your Z, one which could be accomplished much sooner. In other words you were accusing me of advocating almost the opposite of what I was really advocating.

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You do not know this. It's equally likely that big, dumb, expendable super-HLV's can deliver large amounts of propellant even cheaper.

I said likely, not certain. But the argument is agnostic on HLV vs RLV and on the use of depots vs just refuelable spacecraft. Competitive procurement would select for cost / kg not reusability per se. If an HLV turned out to be economically superior, it would win out. And in fact I think we would quickly see smallish HLVs like EELV Phase 1 and FH emerge regardless of what happens with RLVs. Especially since ACES would make an excellent EDS.

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And you don't know this to be true either. It's at least equally likely that the first reusable spacecraft will be something along the lines of X-38 that will carry a couple of people at a time to orbit. But I wouldn't recommend using X-38 for hauling boatloads of propellant to orbit.

I said that tiny RLVs (~1mT) would only be useful for propellant and the like, not RLVs in general. We will not have opened up space until we have cheap lift for both people and propellant.

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Only one problem: RLV's are nowhere going to be near ready enough when we need them, which is this decade. The US of frackin' A is going back to the Moon before the 50th anniversary happens, RLV's be damned. Sorry.

No need to be sorry, as again that's not what I'm proposing. Your problem is that you appear to be so sure you are right that you don't listen to people and consequently misunderstand what it is they are proposing.

My point is to establish a market for competitively launched propellant as soon as possible and with as few hurdles to entry as possible. Specifically I would want to maximise rNPV and to make sure that even a 1mT vehicle could contribute.

Moon missions would in no way depend on the availability of RLVs, and deliberately so, for precisely the reason you've mentioned, among others, and which I have tirelessly mentioned too. EELVs are available today, Falcon will be soon and Antares after that. Five to ten years after the beginning of a propellant launch program we might have the first commercially viable RLVs, which makes it urgent to start as soon as possible. Not because moon missions depend on them (they deliberately don't), but because commercial development of space does depend on them and because moon missions can still make seamless use of them to reduce costs enormously.

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That's what I mean by fear of success. It's a fear of stepping into a new situation that you're not used to.

Fine, but that still doesn't mean that any alternative to your preferred course of action is based on fear of success. In particular mine isn't.
« Last Edit: 01/01/2012 12:47 PM by mmeijeri »
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Offline JohnFornaro

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Re: SLS as propellant truck
« Reply #34 on: 01/01/2012 01:57 PM »
High value payloads are precisely what we don't need.

I think you exaggerate here.  Dumb prop makes little sense if there aren't hi value dry landers and such to make use of it.

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Small RLVs are the ideal way for NASA to reduce its launch costs without investing more, indeed while investing less! Propellant is the ideal initial payload for small RLVs. It would be a marriage made in heaven.

This is the first time I recall you discussing small RLV's.  Pardon my previous ignorance.  I don't think that they are ideal, but I do think that they will be enablers of cheap lift, since they wouldn't be disposable.

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On the one hand, RLVs need high flight rates, which requires affordable payloads.

Again, tho, this idea doesn't pass the five gallon gas can versus tanker truck test.  But worse, first you need RLV's in order to implement that plan.  The problem here is that yes, we have no RLV's.  My feeling on the crucial nature of speed of deployment being more important than some other efficiencies would argue that RLV's deserve a parallel development track, as would SEP.

I do have concrete missions in mind, in fact that is one of the main points I keep stressing, we need to focus on spacecraft and missions, not on infrastructure.

Arrrgh.  But a lot of the missions will be exactly the building of infrastructure!  Not all of them for sure, and maybe not even a number of the early ones either.  We simply can't wait for a new vehicle to be developed before starting the enterprise.  The prospecting missions don't need a depot.  Probably the installation of the comsat constellation doesn't need it either.  And maybe, should they manage to build SLS; build some rovers; build a dry hab, or a dry power plant; then some of the early lunar landings might not need a depot either.

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You could begin with unmanned science missions or robotic precursor missions to the moon, probably in support of lunar ISRU facilities. (Yes) Then you could move to manned missions to moon Lagrange points, (Yes) Earth Lagrange points, (?) NEOs, (No) the Moon, (Yes) Phobos & Deimos, (No) then Ceres (No) and Mars (No).

Well, yes and no, so to speak.  All those distant destinations would consume too much budget and should be "moratoriumized" for the foreseeable future.  As to the Earth Lagrange points, the only need here is the possible capability of being able to work on JWST, should it not be cancelled for non-performance.  What is needed is BTDT experience in cis-lunar.  Again, a parallel RLV development track, informed by the successes nearby should take place.

And in any case, I totally agree that extrapolating to logical and illogical extremes without cause does nothing but decrease the s/n ratio.

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My point is to establish a market for competitively launched propellant as soon as possible and with as few hurdles to entry as possible.

Absolutely right, but a new RLV is a rather large hurdle.  And also right in asking which kind of stone will SLS be.

So I'm struggling a bit with the idea of an RLV.
Sometimes I just flat out don't get it.

Offline MikeAtkinson

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Re: SLS as propellant truck
« Reply #35 on: 01/01/2012 02:30 PM »
A good rule of thumb is that high-value payloads tend to cost $30K/kg by the time they get to orbit. The total list above weighs 136 mT. Thus 136 mT * $30K/kg = $4B. Meanwhile six SLS propellant launches = $3B. Set aside $2B for ISS.

$4B + $3B + $2B = $9B = NASA HSF budget.

30-50% of the NASA HSF budget will be in developing new stuff. The above is great if you just want NASA to do the same things over and over again.

Cut it back to allow for $3B in new development a year and 3 SLS propellant flights would be all that was affordable.

Offline MikeAtkinson

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Re: SLS as propellant truck
« Reply #36 on: 01/01/2012 02:45 PM »
Only one problem: RLV's are nowhere going to be near ready enough when we need them, which is this decade. The US of frackin' A is going back to the Moon before the 50th anniversary happens, RLV's be damned. Sorry.

One thing we know for certain, SLS is not going to be ready this decade, there might be a couple of development flights, but the 105 tonne version won't be ready for propellant launches until about 2025. At current budgets there is unlikely to have been enough money left over from SLS + Orion development to have a EDS and Lunar Lander ready until 2028 or so.

We know of two reusable 1st stages in development (SpaceX and Blue Origin). I would guess that 1st stage reusability would take about 5 years development effort, so there are still a couple of years for other organisations to start reusable 1st stage development and still be complete this decade. I consider it likely that someone will succeed.

Edit: change to correct author of comment I was replying to.
« Last Edit: 01/01/2012 02:46 PM by MikeAtkinson »

Offline Warren Platts

Re: SLS as propellant truck
« Reply #37 on: 01/01/2012 02:58 PM »
A good rule of thumb is that high-value payloads tend to cost $30K/kg by the time they get to orbit. The total list above weighs 136 mT. Thus 136 mT * $30K/kg = $4B. Meanwhile six SLS propellant launches = $3B. Set aside $2B for ISS.

$4B + $3B + $2B = $9B = NASA HSF budget.

30-50% of the NASA HSF budget will be in developing new stuff. The above is great if you just want NASA to do the same things over and over again.

Cut it back to allow for $3B in new development a year and 3 SLS propellant flights would be all that was affordable.

No, the development costs are mostly going to happen during this decade (which is still early in the decade--it's only 2012: happy New Year...). When 2020 rolls around, it will be time to get busy and do the same thing over and over again: building real, physical infrastructure.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Patchouli

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Re: SLS as propellant truck
« Reply #38 on: 01/01/2012 03:06 PM »


High value payloads are precisely what we don't need. The road to cheap lift will likely go through tiny RLVs at first, and those are really only good enough for propellant, bulk materials and consumables. Later, larger versions could also carry humans. I think it will be a long time before there will be a need for EELV class RLVs or bigger. But that's fine, cheap small lift, the ability to launch propellant and people cheaply is all we need to open up space. Existing ELVs are good enough for reusable spacecraft and habs, since those can be amortised over many years / missions / clients and are much more expensive than their launch costs anyway.



A small RLV of lets say in the Delta II class or smaller is something that can be cheap enough to be developed as a side project or be the pet project of a single digit billionaire or even a multi millionaire.

The DCX program for example did not cost much at all.

Dragon and F9 where done on the cost of a single shuttle mission.

Offline Warren Platts

Re: SLS as propellant truck
« Reply #39 on: 01/01/2012 03:16 PM »
I do have concrete missionS in mind.

"S" is the operative letter. Having all kinds of missions in mind is equivalent to having no mission in mind.

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On the one hand, you never define cheap lift. I get the feeling you won't be satisfied till launch costs get down to $1/kg.

Not true, by cheap lift I mean $100/kg - $1,000/kg.

Hah!  Keep dreamin' dude!

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The US of frackin' A is going back to the Moon before the 50th anniversary happens, RLV's be damned! Sorry.

I am in favour of starting with missions as soon as possible. In other words, start doing exploration as soon as possible. My point is to establish a market for competitively launched propellant as soon as possible.

lol! Martijn, do you realize you are the only person on this entire forum that has accused me of proposing that NASA move too slow....
« Last Edit: 01/01/2012 07:21 PM by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

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