Author Topic: SLS as propellant truck  (Read 49921 times)

Online MikeAtkinson

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Re: SLS as propellant truck
« Reply #40 on: 01/01/2012 03:18 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.

There is no money in the NASA budget this decade for Lunar Landers, EDS, a Lunar base, ISRU, SEL tugs, deep space habs, long duration life support, etc. Some of them might be started, but thats it. SLS will not be ready "When 2020 rolls around" for propellant launches.

The idea that development will stop and that all the budget can be devoted to missions is bordering on fantasy. The SLS replacement boosters will not be complete in 2020 and there won't be an upper stage. Even if it came to pass it would surrender USA leadership in space within a decade or two, look what is happening with Russia (which essentially stopped development after the collapse of Communism).

Offline Patchouli

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Re: SLS as propellant truck
« Reply #41 on: 01/01/2012 03:44 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.

There is no money in the NASA budget this decade for Lunar Landers, EDS, a Lunar base, ISRU, SEL tugs, deep space habs, long duration life support, etc. Some of them might be started, but thats it. SLS will not be ready "When 2020 rolls around" for propellant launches.

The idea that development will stop and that all the budget can be devoted to missions is bordering on fantasy. The SLS replacement boosters will not be complete in 2020 and there won't be an upper stage. Even if it came to pass it would surrender USA leadership in space within a decade or two, look what is happening with Russia (which essentially stopped development after the collapse of Communism).

I think they should just go operational with the 70 Mt SLS as even that is big enough to be a game changer.
Forget the replacement boosters etc and go with a simple upper stage the rest goes to habs,landers,and small RLVs.

Back in the 80s they were willing to designed a Mars mission around Shuttle-c.
« Last Edit: 01/01/2012 03:47 PM by Patchouli »

Offline Zed_Noir

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Re: SLS as propellant truck
« Reply #42 on: 01/01/2012 05:12 PM »

I think they should just go operational with the 70 Mt SLS as even that is big enough to be a game changer.
Forget the replacement boosters etc and go with a simple upper stage the rest goes to habs,landers,and small RLVs.


Why would you need the 70mT interim SLS lite. It would be more cost effective to use the Falcon Heavy. IIRC it's roughly about 4 FH flights with up mass of 212mT as compare to 1 SLS lite flight with up mass of 70mT for about $500M at the current estimated prices.

If the current SpaceX plan for 10 FH flights annually happens. Protentially that is roughly about 525mT up mass to LEO for about $1.25B. As compare to 140mT from 2 SLS lite flights for about $1B. The FH cost per launch should go down with the high launch rate. I have my doubts about the SLS lite price per flight will not escalate, unlike most of the recent major NASA programs.

So IMO the 70mT SLS lite is not that efficient as a propellant tankers.

Yes, I realize both the FH and SLS are still paper rockets. But SpaceX should have all the component parts of the FH available in 2012 for integration.

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #43 on: 01/01/2012 05:33 PM »
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.

Absolutely, I meant that giving commercial space the high value payloads and leaving SLS to launch propellant gives very little commercial synergy, while the reverse would be enormously useful. Building the high value spacecraft that provide the demand should be NASA's top priority. The trick would be to spend as much as necessary and as little as possible on the spacecraft, to leave as much money as possible for launch services.

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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.

I should have said cheap lift, not small RLVs. That said, large RLVs are likely to be beyond our reach for a long time, so in that sense they're not ideal either. I'd love to be wrong, but I'm worried we may not even get the small ones.

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Again, tho, this idea doesn't pass the five gallon gas can versus tanker truck test.

RLVs need 50-100 flights a year to be profitable. On a small exploration program that means tiny RLVs.

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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.

Depending on RLVs would be a disastrous mistake. I'm always trying to decouple things, so that's not what I'm proposing. If you have a depot (or preferably, a spacecraft that can accept propellant in orbit), then you can fill it up with pretty much any launch vehicle. Initially those would be EELVs, Falcon and Antares. It might take ten years for commercial RLVs to emerge, so it is crucial we start with something else. And if we buy propellant in orbit, and do so competitively, then NASA doesn't have to worry about the launch vehicles. As soon as RLVs come online, they can be used. Until that time we can use existing ELVs. The RLVs are safely off the critical path, just as you and Warren also advocate.

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Arrrgh.  But a lot of the missions will be exactly the building of infrastructure!

I meant transport infrastructure, does that make a difference in your opinion? Nevertheless I still wouldn't want to spend too much on surface infrastructure either until after we have cheap lift.

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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.

100% agreement. We do need a spacecraft for missions though. I propose it is the simplest one possible, a transfer stage capable of accepting propellant in orbit, based on the Orion SM + avionics with a science spacecraft provided by the SMD on top. We should be able to do this within three years. In time this could evolve into a full lander, or a propulsion module for a Nautilus-like spacecraft.

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The prospecting missions don't need a depot.  Probably the installation of the comsat constellation doesn't need it either.

Agreed, nor does a lunar base. A depot is infrastructure and should be left to the market, depending on levels of traffic. We should forget about depots and focus on mission spacecraft like exploration ships, landers and their orbital precursors.

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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.

I'm arguing none of them do and also arguing that's an important observation.

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All those distant destinations would consume too much budget and should be "moratoriumized" for the foreseeable future.

I don't think NEO missions would be more expensive than lunar surface missions. In fact the fact that you don't need surface hardware makes things easier and the orbital spacecraft would have more synergy with future commercial space stations. I think it is more a matter of preferences, some might care more about planetary bodies (maybe even specific ones, say the moon, Mars or Ceres), others care more about orbital destinations or about commercial space. None of these are unreasonable in my opinion, and I believe we should be talking about these preferences more often, to see if we can reach an honourable compromise. But they aren't equally difficult or expensive, and that's important too as you pointed out. Personally, I find the orbital missions attractive because I believe they would allow you to spend more on launches while still maintaining a viable exploration program.

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Absolutely right, but a new RLV is a rather large hurdle.

Maybe I didn't express myself clearly. The idea was to create a large market for launch services, and then see if the market develops a privately financed commercial RLV or not. And in parallel with an exploration program. In fact, this plan wouldn't work without an exploration program, because it's that program that provides the demand for launch services.
« Last Edit: 01/01/2012 06:04 PM by mmeijeri »
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Online MikeAtkinson

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Re: SLS as propellant truck
« Reply #44 on: 01/01/2012 05:44 PM »

I think they should just go operational with the 70 Mt SLS as even that is big enough to be a game changer.
Forget the replacement boosters etc and go with a simple upper stage the rest goes to habs,landers,and small RLVs.


Even better, just don't develop SLS in the first place and use the billions saved to design and build the in-space elements.

[I should point out I'm not totally against SLS, its just that in the current budget environment it takes too big a slice of the budget for launch. Start with the NASA HSF budget of $9B, subtract $2B for ISS, $1B for technology development, $2B for in-space element development (leaves $4B), then use the rule of thumb that launch should be ~30% of total mission costs. So we are looking for launch costs of about $1.3B, far too small to give a decent launch rate for SLS. SLS only really makes sense with HSF budgets of greater than $15B, and I just don't see that happening]

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #45 on: 01/01/2012 05:45 PM »
"S" is the operative letter. Having all kinds of missions in mind is equivalent to having no mission in mind.

A well-defined sequence of missions in fact, much like the Flexible Path. Warren, I can't help but feel you're not being constructive here, mainly because you appear to be unwilling to listen. I think that's highly unfortunate, as I believe we are on the same side. I would like it if we could work together. I'm open to suggestions on what needs to happen to make that possible.

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Hah!  Keep dreamin' dude!

No so far removed from what you believe is possible with SLS. And Musk believes he can hit $1,000/kg with FH, even without reuse. But yes, this is the crucial point, if you don't believe this is possible, then I can understand why you wouldn't want to focus on cheap lift. Similarly, you can imagine how crucial I think this is, precisely because I believe it is possible. But even if you don't think it's possible, it still makes sense to try and get as closely to this point as possible.

And note that I'm not advocating spending all of NASA's budget on propellant launches to get to RLVs as soon as possible (as you were falsely suggesting), but to get maximum synergy between an exploration program (incorporating a lunar ISRU facility I hasten to add) and development of cheap lift.

Focussing everything on RLVs would delay exploration and accelerate cheap lift, but what I'm advocating would not delay exploration by one bit and still accelerate cheap lift as much as possible within the constraint of having a viable exploration program. That's not as fast as without that constraint, but still an important acceleration.

So it appears to me that it there should be no downside to proceeding as I advocated, even from your perspective. If cheap lift does not materialise, then we'll probably end up with FH and EELV Phase 1 or even Phase 2. No delays, no extra costs.

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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....

I suggested no such thing. Again, we appear not to be communicating effectively. I'm willing to accept my share of responsibility for that and I'm open to suggestions on how to change that. Work with me here.
« Last Edit: 01/01/2012 05:47 PM by mmeijeri »
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Online MikeAtkinson

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Re: SLS as propellant truck
« Reply #46 on: 01/01/2012 05:52 PM »
And Musk believes he can hit $1,000/kg with FH, even without reuse.

I think you mean $1,000/lb.

1st stage reuse (core+boosters) would be needed to reach $1,000/kg

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #47 on: 01/01/2012 05:54 PM »
I think you mean $1,000/lb.

1st stage reuse (core+boosters) would be needed to reach $1,000/kg

You're right, thanks for catching that.
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Offline Bill White

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Re: SLS as propellant truck
« Reply #48 on: 01/01/2012 06:47 PM »
IMHO,

No one will reach $1000/lb if NASA (and the US taxpayers) are expected to provide the majority of the funding or to act as the #1 anchor tenant.

Therefore, increasing demand for IMLEO beyond what NASA itself will ever need is a mission critical element for lowering costs.

IMHO.
EML architectures should be seen as ratchet opportunities

Offline mmeijeri

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Re: SLS as propellant truck
« Reply #49 on: 01/01/2012 06:53 PM »
No one will reach $1000/lb if NASA (and the US taxpayers) are expected to provide the majority of the funding or to act as the #1 anchor tenant.

Why not? NASA's money is as good as anyone else's and propellant is about the easiest payload possible.
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Offline Bill White

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Re: SLS as propellant truck
« Reply #50 on: 01/01/2012 07:04 PM »
No one will reach $1000/lb if NASA (and the US taxpayers) are expected to provide the majority of the funding or to act as the #1 anchor tenant.

Why not? NASA's money is as good as anyone else's and propellant is about the easiest payload possible.

NASA does not have enough money and Congress has its own agenda that diverges from the cheap lift agenda.

= = =

Edit:

I agree with Warren's basic premise - - Insofar as Congress wants to build SLS, let's use SLS to loft fuel that can be used to fill a depot pipeline stretching from LEO to the EML points and the lunar surface and beyond cislunar space.

Whether SLS should be used only for that purpose is a nuance I am not prepared to address, at the moment.
« Last Edit: 01/01/2012 08:34 PM by Bill White »
EML architectures should be seen as ratchet opportunities

Offline Warren Platts

Re: SLS as propellant truck
« Reply #51 on: 01/01/2012 08:36 PM »
Even better, just don't develop SLS in the first place and use the billions saved to design and build the in-space elements.

[I should point out I'm not totally against SLS, its just that in the current budget environment it takes too big a slice of the budget for launch. Start with the NASA HSF budget of $9B, subtract $2B for ISS, $1B for technology development, $2B for in-space element development (leaves $4B), then use the rule of thumb that launch should be ~30% of total mission costs. So we are looking for launch costs of about $1.3B, far too small to give a decent launch rate for SLS. SLS only really makes sense with HSF budgets of greater than $15B, and I just don't see that happening]

(OK folks, let's not turn this into an SLS bashing thread please. There are plenty of others out there...)

Re: ongoing engineering costs: you're right I forgot about those. Zegler, however, had $1B/year for "sustaining engineering" (see his fig. 17 sand diagram).

Shouldn't be a showstopper: if SLS operations were a streamlined, 1-trick pony where they only did 1 thing over and over--launch propellant once every other month--they might be able to achieve a modest savings over the $3B/year I had projected. Similarly, ULA makes a big point of how the ACES system, by using commonality of parts, can reduce manufacturing costs, so the $30K/kg for high-value payloads could probably be reduced at the margins somewhat. Thirdly, hand over ISS operations to IP's and commercial to the maximum extent possible, and it might be able to reduce the $2B/year for ISS a little. Thus:

$1.5B for ISS
$2.5B for SLS propellant operations
$3.5B for ACES-based space and Lunar systems
$1.5B for ongoing tech development
-----------------------------------------------------
$9B total HSF budget

Piece of cake!

(yeah right....)
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Offline Warren Platts

Re: SLS as propellant truck
« Reply #52 on: 01/02/2012 02:20 AM »
Edit:

I agree with Warren's basic premise - - Insofar as Congress wants to build SLS, let's use SLS to loft fuel that can be used to fill a depot pipeline stretching from LEO to the EML points and the lunar surface and beyond cislunar space.

Whether SLS should be used only for that purpose is a nuance I am not prepared to address, at the moment.

Hi Bill, I'm not a purist: there are probably a few super-high volume payloads that could really take advantage of the big SLS fairing size.

E.g., we'll need two depots, one at LEO and one at your Gateway.

Also, why not use it to send up a BA-1000--with twice the interior volume of ISS!--for your Gateway living quarters and be done with it in a single launch.

But for launching items like landers, crewed capsules and things like that where the dry mass rarely exceeds 30 tonnes, it's really overkill. Sure, you can add some propellant to the mix to increase the payload mass, but then you're back to the worst of both worlds that the Boeing proposal represents....
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Offline sdsds

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Re: SLS as propellant truck
« Reply #53 on: 01/02/2012 04:14 AM »
we'll need two depots, one at LEO and one at your Gateway.

This is where your thinking differs from that of many others, who see a need in LEO for (at most) the rendezvous of components in a two-launch mission, and the associated LEO loiter capability.  I understand some of the reasons you dislike transporting CH4/O2 to the EML gateway, but that is the type of propellant trucking the customer seems to want SLS to provide.  (The customer for SLS is represented by the U.S. Congress; Congress says it wants NASA to use SLS to launch missions beyond LEO.)

Sure, the current plan is for a hellaciously-low flight-rate of an expensive-lift vehicle.  I'm asking:  "What would make the customer want to fund this SLS-to-LEO concept?"
-- sdsds --

Offline Warren Platts

Re: SLS as propellant truck
« Reply #54 on: 01/02/2012 05:26 AM »
we'll need two depots, one at LEO and one at your Gateway.

1. This is where your thinking differs from that of many others, who see a need in LEO for (at most) the rendezvous of components in a two-launch mission, and the associated LEO loiter capability. 

2. I understand some of the reasons you dislike transporting CH4/O2 to the EML gateway, but that is the type of propellant trucking the customer seems to want SLS to provide.  (The customer for SLS is represented by the U.S. Congress;

3. Congress says it wants NASA to use SLS to launch missions beyond LEO.)

4. Sure, the current plan is for a hellaciously-low flight-rate of an expensive-lift vehicle.  I'm asking:  "What would make the customer want to fund this SLS-to-LEO concept?"

1. Zegler said we need two depots. I'll take his word for it.

2. Huh? The Senate stipulated a lot of things. That we must use anemic, low Isp Lunar landers wasn't one of them....

3. Two out of the six ACES-121's would proceed directly to the L2 depot.

4. Efficiency?
« Last Edit: 01/02/2012 06:30 AM by Warren Platts »
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Online Robotbeat

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Re: SLS as propellant truck
« Reply #55 on: 01/02/2012 05:43 AM »
...girly-man, fart-burning Lunar landers...
Are you 11 years old?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Warren Platts

Re: SLS as propellant truck
« Reply #56 on: 01/02/2012 07:28 AM »
You want SLS to be launching fuel for the depot???  Fuel is not High Value-and should be a job for commerical.  Please provide the analysis where fuel is cheaper on SLS rather than on Falcon or a FH???

Here ya go:

http://forum.nasaspaceflight.com/index.php?topic=27591.msg845619#msg845619

A.M. Swallow is right: for every other transportation endeavor: trucks, trains, barges, cargo ships, tankers, airplanes, the biggest vehicles move the most cargo for less money.
Then why was the space shuttle fueled with only semi-truck-trailer tanks of fuel at a time (i.e. about the payload of an EELV Heavy)? Why didn't they build enormous customized trucks to do it all at once? It could be because simplistic arguments like that don't pass for muster in real life.

Oh Brother... Get out of your Ivory Tower, dude, and go on a road trip! Then you'll see that trucks are sized the way they are because of things like road widths and bridge heights.

When you're done with that, find a big strip mine and see if they'll give you a tour: then check out the size of their trucks. You will then see for yourself that they are not little EELV sized trucks, they are monster-trucks, SLS-sized or better.

Talk about simplistic arguments! Indeed!

This is a test Robotbeat: can you for once admit you are wrong about something?

:popcorn:
« Last Edit: 01/02/2012 07:31 AM by Warren Platts »
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Offline spectre9

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Re: SLS as propellant truck
« Reply #57 on: 01/02/2012 09:48 AM »
SLS will not be a fuel tanker because NASA doesn't want it to be one.

http://www.nasa.gov/pdf/138033main_griffin_aas1.pdf

Read that please. I like Griffin, he seems to make sense.



Offline Warren Platts

Re: SLS as propellant truck
« Reply #58 on: 01/02/2012 11:39 AM »
SLS will not be a fuel tanker because NASA doesn't want it to be one.

http://www.nasa.gov/pdf/138033main_griffin_aas1.pdf

Read that please. I like Griffin, he seems to make sense.

WOW!! Excellent catch Spectre9! Of course I vehemently disagree with the good Doctor, but this will make an excellent springboard for discussion.

Here is the relevant part of the paper for this thread; it's a bit long, but this will save people from having to sift through the paper:

Quote from: Griffin
Astute observers will note that the Shuttle-derived heavy lift vehicle (SDHLV) that we have proposed is not, as a rocket,being optimally utilized for its lunar mission. This is because some of the fuel in the so-called“Earth departure stage” is used to lift the lunar payload into Earth orbit, but additional fuel must yet be retained for the translunar ignition burn of over 3 km/s. From a purely architectural point of view, the SDHLV is an expensive vehicle, most aptly utilized for lifting only expensive cargo, such as the man-rated systems it carries. But in our architecture, some of its lift capacity must be utilized to carry fuel into low Earth orbit. This is unsatisfying, because when on the ground, fuel is about the cheapest material employed in any aspect of the space business. Its value in orbit (at least several thousand dollars per pound) is almost completely a function of its location rather than intrinsic to its nature. In contrast, the value of, say, the Lunar Surface Access Module (LSAM) brought up on the heavy-lifter will be well over $100 K per pound, most of which represents its intrinsic cost. The additional value it acquires when transported to its new position in LEO remains a small part of the total value.

Logically, then, we should seek to use the SDHLV only for the highest-value cargo, and specifically we should desire to place fuel in orbit by the cheapest means possible, in whatever manner this can be accomplished, whether of high reliability or not. However, in deciding to embark on a lunar mission, we cannot afford the consequential damage of not having fuel available when needed. Recognizing that fact, our mission architecture hauls its own Earth departure fuel up from the ground for each trip. But if there were a fuel depot available on orbit,one capable of being replenished at any time, the Earth departure stage could after refueling carry significantly more payload to the Moon, maximizing the utility of the inherently expensive SDHLV for carrying high-value cargo.

But NASA’s architecture does not feature a fuel depot. Even if it could be afforded within the budget constraints which we will likely face – and it cannot – it is philosophically the wrong thing for the government to be doing. It is not “necessary”; it is not on the critical path of things we “must do” to return astronauts to the Moon. It is a highly valuable enhancement, but the mission is not hostage to its availability. It is exactly the type of enterprise which should be left to industry and to the marketplace.

So let us look forward ten or more years, to a time when we are closer to resuming human exploration of the Moon. The value of such a commercially operated fuel depot in low Earth orbit at that time is easy to estimate. Such a depot would support at least two planned missions to the Moon each year. The architecture which we have advanced places about 150 metric tons in LEO, 25 MT on the Crew Launch Vehicle and 125 MT on the heavy-lifter. Of the total, about half will be propellant in the form of liquid oxygen and hydrogen, required for the translunar injection to the Moon. If the Earth departure stage could be refueled on-orbit, the crew and all high-value hardware could be launched using a single SDHLV, and all of this could be sent to the Moon.

There are several ways in which the value of this extra capability might be calculated, but at a conservatively low government price of $10,000/kg for payload in LEO, 250 MT of fuel for two missions per year is worth $2.5 B, at government rates. If a commercial provider can supply fuel at a lower cost, both the government and the contractor will benefit. This is a non-trivial market, and it will only grow as we continue to fly. The value of fuel for a single Mars mission may be several billion dollars by itself. Once industry becomes fully convinced that the United States, in company with its international partners, is headed out into the solar system for good, I believe that the economics of such a business will attract multiple competitors, to the benefit of both stockholders and taxpayers.

Best of all, such an approach enables us to leverage the value of the government system without putting commercial fuel deliveries in the critical path. If the depot is there and is full, we can use it. But with the architecture we have advanced, we can conduct missions to the Moon without it. The government does not need to have oversight, or even insight, into the quality and reliability of the fuel delivery service. If fuel is not delivered, the loss belongs to the operator, not to the government. If fuel is delivered and maintained in storage, the contractors are paid, whether or not the government flies its intended missions. If long-term delivery contracts are negotiated, and the provider learns to effect deliveries more efficiently, the gain is his, not the government’s. Since fuel is completely fungible, it can be left to the provider to determine the optimum origin, size and method of a delivering it. And finally, though I would rather not do it, it is even possible that we could develop such a market in stages, with the first fuel tank provided by the government, and then turned over to a commercial provider to store and maintain fuel for future missions, and to expand the tank farm as warranted by the market.
(my emphasis throughout)
« Last Edit: 01/02/2012 11:41 AM 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

Offline JohnFornaro

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Re: SLS as propellant truck
« Reply #59 on: 01/02/2012 02:19 PM »
Depending on RLVs would be a disastrous mistake. I'm always trying to decouple things, so that's not what I'm proposing. If you have a depot (or preferably, a spacecraft that can accept propellant in orbit), then you can fill it up with pretty much any launch vehicle. Initially those would be EELVs, Falcon and Antares. It might take ten years for commercial RLVs to emerge, so it is crucial we start with something else. And if we buy propellant in orbit, and do so competitively, then NASA doesn't have to worry about the launch vehicles. As soon as RLVs come online, they can be used. Until that time we can use existing ELVs...

Well, I'm a mite confused about what it is that you're saying that I'm not agreeing with, then.  Briefly put, I think we need a depot, but you don't? 

As has been said, a rocket a day keeps the high costs away, so clearly, the launch rate should increase, God and budget willing.  Leaving God out of the equation for the moment, the government budget doesn't seem willing... to build a depot that is.  Or even a reasonably sized tanker truck.  So it may come to be that a depot up there at EML-1 will have to be built with private funds.  But.  Local billionaire Allen, just to pick one at random, has decided to put his money into launching disposable Falcon class rockets sideways, rather than taking Mr. Rutan's idea and extrapolating it into a genuine RLV capable of going to and from EML-1, building a depot, which is what everyone is beginning to agree upon as the desirable approach to BEO.  And he can't back off the idea now; he's spent a couple hundred dollars on a website already.  He'll continue to waste time and effort in order to appease his ego.

Point is, private depot funding hasn't caught the imagination of fiscally capable investors yet.  And unfortunately, our government is apparently not interested in much accomplishment on the LV front either, which could certainly enable much.  So all of that is a quandary outside of your and my speculations and recommendations on how best to proceed.  Alas.

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I meant transport infrastructure, does that make a difference in your opinion? Nevertheless I still wouldn't want to spend too much on surface infrastructure either until after we have cheap lift.

We've got the surface infrastructure at the Cape, at Wallops, etc.  If that's what you mean.  That would naturally grow should the number of launches so require.  But we're not going to get cheap lift until we start launching a lot more, and build on the experiences of manufacturing and launch ops.  Not to mention launching stuff.  So, not sure quite what you mean.

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We do need a spacecraft for missions though. I propose it is the simplest one possible, a transfer stage capable of accepting propellant in orbit, based on the Orion SM + avionics with a science spacecraft provided by the SMD on top. We should be able to do this within three years. In time this could evolve into a full lander, or a propulsion module for a Nautilus-like spacecraft.

Along the lines of my thinking as well.

Quote from: JF
The prospecting missions don't need a depot.  Probably the installation of the comsat constellation doesn't need it either.

Quote from: Martijn
Agreed, nor does a lunar base. A depot is infrastructure and should be left to the market, depending on levels of traffic. We should forget about depots and focus on mission spacecraft like exploration ships, landers and their orbital precursors.

No. [Waves hand.] You must remember the depots. [Waves hand again.]  These depots are for sale, if you're interested.

Parallel development for a sustainable future would definitely call for a depot architecture.  In a way, the landing at Normandy provides a good example.  For it to have been successful meant that all of the equipment of the invasion had to be constructed in parallel.  Settling the Moon, even with a small several dozen person outpost is an exercise of similar complexity, and in my and other minds, as urgent a need.  But instead of planning the invasion properly, our government is focusing on building the biggest, baddest battleship it can imagine; forgetting totally that we need landers (landers), troops (astros), airplanes (probes), observation blimps (comsat constellation), tankers (depots), yada yada.  The government has already set the stage for program failure.
Sometimes I just flat out don't get it.

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