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.
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.
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.
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.
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.
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.
Quote from: Warren Platts on 12/31/2011 06:46 pmThe 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.
Seems kinda backwards as propellant is the one thing that has no problems at all in breaking down into smaller payloads.
Quote from: Warren Platts on 12/31/2011 06:46 pmThe 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.
Quote from: Warren Platts on 01/01/2012 03:41 amIf 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/kgBut 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!
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.
The trend in SpaceX prices is up, not down.
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.
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.
See? It all fits perfectly. We can have our cake and eat it too, as long as we're not afraid of success.
Quote from: Warren Platts on 01/01/2012 03:04 amThe 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.
QuoteSo 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
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.
and those are really only good enough for propellant, bulk materials and consumables. Later, larger versions could also carry humans.
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.
QuoteSee? 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.
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.
You do not know this. It's equally likely that big, dumb, expendable super-HLV's can deliver large amounts of propellant even cheaper.
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.
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.
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.
High value payloads are precisely what we don't need.
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.
On the one hand, RLVs need high flight rates, which requires affordable payloads.
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.
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).
My point is to establish a market for competitively launched propellant as soon as possible and with as few hurdles to entry as possible.
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.
Quote from: Warren Platts on 01/01/2012 03:04 amA 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.
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.
I do have concrete missionS in mind.
QuoteOn 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.
QuoteThe 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.
The US of frackin' A is going back to the Moon before the 50th anniversary happens, RLV's be damned! Sorry.