You’ll be as shocked as I was to learn that NASA’s evaluation of DIRECT may not have been completely impartial:
“NASA’s October 2007 analysis of DIRECT, on the surface, appears to be a carefully executed analysis of the DIRECT architecture and its central launch vehicle, Jupiter,” notes the rebuttal document.
“However, a closer examination of the document reveals significant flaws in the evaluation of DIRECT that sets up a scenario where DIRECT would inevitably look inferior when compared to Ares.
“The errors are so numerous that the only conclusion possible is that this document was not a true analysis, but rather an attempt to discredit the DIRECT architecture.”
I’ve never been a proponent of that architecture, and haven’t even looked at it in any detail or given it much thought, other than that it’s almost certainly better than NASA’s current plans. But that’s a pretty low bar. I think that if we’re going to be investing billions in new launch systems, we should get some that actually, you know, reduce launch costs, and particularly marginal costs. But I know, that’s just crazy talk.
Rand, lets do the math, divide the +25 year ‘proven’ $/kg to orbit of the Space Shuttle by a factor of five. Why five you ask? Because that is the payload improvement per launch of the Jupiter over the Space Shuttle assuming no net change in the fixed or variable cost. Given that the Jupiter also removes one of the highest fixed and variable costs associated with the STS (ie the Orbiter) the Jupiter has more than a good shot at being among the lowest if not the lowest cost to orbit bar none.
This is even before one incorporates the serious cost overruns in current unmanned spacecraft development programs like JWST and MSL running many times their respective launch costs. A fair portion of these cost overruns are directly attributable to trying to do more than the past missions while being constrained by the launch system capabilities of the past.
Even manned exploration has experienced this same issue. What were the cost, time and capabilities of Skylab, put up in one shot using the Saturn V vs. using the method of 20 ton chunks employed to construct the ISS?
“I hope we’re smart enough that we never again try to place such a large system in orbit by doing it in twenty-ton chunks.” – Mike Griffin
BTW, ULA, Boeing, Lockheed/Martin, USA, SpaceX etc. are all ‘commercial‘ companies. Simple changing who the primary consumer of launch services (ie the Federal Government) writes the checks to doesn’t equal commercialization. True commercialization will only happen once private consumers of launch services are the dominate customer. Until that point in time the political strings associated with all money derived through political methods will continue to color all decisions.
The Direct architecture is probably the best thing we can hope for from NASA. Hopefully, it would keep NASA busy while private spaceflight quietly takes off.
You don’t have the payloads.
Given that the Jupiter also removes one of the highest fixed and variable costs associated with the STS (ie the Orbiter)
Huh?
The Orbiter has high fixed costs, but it is a low variable cost. The highest variable costs in the STS are the ET and SRBs. The Shuttle has a marginal cost per flight of only a hundred fifty million or so. The reason that per-flight costs are so high is because the flight rate is so low. You may have lower fixed costs for Jupiter, but your marginal costs will never be low.
What were the cost, time and capabilities of Skylab, put up in one shot using the Saturn V vs. using the method of 20 ton chunks employed to construct the ISS?
Kind of a pointless question. You can’t draw grand general conclusions from single examples. ISS construction was hindered by Shuttle costs and flight rates. There is nothing intrinsically expensive about in-space assembly — it’s largely a function of launch costs.
“I hope we’re smart enough that we never again try to place such a large system in orbit by doing it in twenty-ton chunks.” – Mike Griffin
If we haven’t learned anything else from the past five years, I would hope that we’re smart enough that we never again pay much attention to what Mike Griffin says. You of all people should be at least that smart.
I guess I am stating the obvious, but the whole reasoning behind the Stick was OK, we had one fatal accident where stuff came off the SRBs (i.e. leaking gasses) and wrecked the ET, and we had our second fatal accident where stuff came off the ET (dislodged foam) and wrecked the crewed spacecraft.
OK, let’s stick the ET on top of a lone SRB and give it one liquid fueled engine, and lets stick (to excuse the pun) the crewed spacecraft on top of that. Voila! Safe, crew-rated launch vehicle.
Of course that design ignored things such as whereas the SRBs are heavy, they are segmented and hence none too stiff and weren’t really designed to be used in anything but a strap-on parallel staging arrangement, and the go-to LFE, the SSME, was never designed to be “air started”, that is used in anything other than a parallel staging arrangement either, where then one design compromise led to many another and the rest of the story and so forth.
Look, I thought NASA has solved the problem of the SRB O-rings, so the parallel staging of a pair of SRBs should not be a problem, and I am sure they haven’t solved the problem of stuff coming off the ET, but if the crewed spacecraft is perched on top, that should not be a problem because foam hitting the SRBs isn’t going to do anything.
From there on out the 2-SRB Direct vehicle isn’t too much different from the original Shuttle C (OK, RS 68’s at the bottom instead of podded and (recoverable?) SSMEs at the side, payload and crew modules up on top instead of in a shrouded canister on the side). And wasn’t Shuttle C something NASA was going to do if they had the money?
So what is the problem changing direction to something that will work and reuses more of the Shuttle hardware apart from a level of face-saving on the level of Near Eastern cultures as documented Homer’s Greek epics?
Rand, my point exactly, the STS cost is primarily driven by fixed cost divided by the launch rate the incremental cost per launch is not the dominate portion. By the time it begins to dominate the cost structure in a Jupiter world we couldn’t afford to buy all the spacecraft we could deliver in a year anyway. Fortunately most of the mass we need in LEO is cheap to produce propellant. The key is make the spacecraft once in space reusable ideally with ISRU. The Earth to LEO portion will continue to be dominated by the limits of living physics and engine isp.
The ability to reprocess Orbiters is major contributor of the fixed cost of STS. By increasing the payload delivered per launch by a factor of 5 we will get at least a factor of five reduction in the cost per kg to orbit even if the fixed cost stayed the same. Quite frankly until someone produces something along the lines of Bussard rocket engine the cost of spaceflight is not going change significantly regardless of what organizational sticker is on the side of the vehicle. As in history of aircraft the engine defines the vehicle not the other way around.
Concerning Skylab vs. ISS. What do you guess the cost of ISS delivered in only four Jupiter launches would have cost? Granted all things considered EELV could have done the job at lower cost than STS but Jupiter is not the STS.
Concerning Mike Griffin, do you agree with this quote?
“Many, if not most, unmanned payloads are of very high value, both for the importance of their mission, as well as in simple economic terms. The relevant question may be posed quite simplistically: What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission? The answer is, of course, “none”. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention.”
In my book the truth is the truth regardless of the messenger. That is my primary frustration with Senior NASA Management. When I think they are right I fully acknowledge that fact. I just wish they would reciprocate once in a while when forced to choose between their ego and what is best for the Space program.
Hopefully Norm will feel the same way and find that DIRECT is the best solution for all concerned which by definition includes those writing the checks.
And the DIRECT guys dramatically understated the performance of the Shuttle C. What’s new about showing your system as all wonderful and the rest as kaka?
“Quite frankly until someone produces something along the lines of Bussard rocket engine the cost of spaceflight is not going change significantly regardless of what organizational sticker is on the side of the vehicle.”
Why do you say that?
There’s a necessary expenditure of energy that pure physics requires us to expend just for lifting. That piece is true. But actual fuel costs seem pretty far down the totem pole of current launch costs.
The Earth to LEO portion will continue to be dominated by the limits of living physics and engine isp.
The ability to reprocess Orbiters is major contributor of the fixed cost of STS. By increasing the payload delivered per launch by a factor of 5 we will get at least a factor of five reduction in the cost per kg to orbit even if the fixed cost stayed the same. Quite frankly until someone produces something along the lines of Bussard rocket engine the cost of spaceflight is not going change significantly regardless of what organizational sticker is on the side of the vehicle. As in history of aircraft the engine defines the vehicle not the other way around.
Sorry, but it is not physics that prevents low launch cost. It is market.
What do you guess the cost of ISS delivered in only four Jupiter launches would have cost?
It would surely have cost less. But it’s an irrelevant question, because delivering it in dozens of even smaller pieces could have cost even less, with low-cost space transport.
Are you somehow under the impression that I am defending the Shuttle? If not, then what is your point in continuing to bash it? As I said, you’re engaging in the fallacy of hasty generalization.
Concerning Mike Griffin, do you agree with this quote?
I agree absolutely with that quote. Unfortunately, Mike Griffin doesn’t seem to, since one of his recent “concerns” with EELVs is that they aren’t “human rated.”
Again, quoting Mike Griffin doesn’t aid your argument, at least not around here.
Rand, do you have a preferred architecture that you personally think is good or best? I know that you think creating and maintaining orbital fuel depots is one good step. You’ve convinced me that the (or at least one) central issue is operational costs and flight rates. I also think you don’t believe in any “one size fits all” solution, i.e. that there will ultimately be a market for different launch approaches with different cargo capabilities. But given all that, are there any particular approaches that groups in the industry are taking that you think hold the most promise? It think your criticism of Ares is valid, and I notice that you state you aren’t a proponent of the DIRECT architecture. I think I’ve read some criticism you’ve made of the “Burt Ratan knows everything” school of thought. Is there anything out there in the works that you think might really reduce the cost to orbit? SpaceX falcon? Armadillo? Something else? Or do you simply have more of a “let a bunch of companies try a bunch of things and see what sticks to the wall” market-type thinking?
It would be nice to hear “these people are doing something that may work” about some group or other.
“Rand, do you have a preferred architecture that you personally think is good or best? ”
I don’t know about rand but EELV, an updated Apollo CSM, and
a propelant depot at ISS and maybe shuttle-C to put up a
transfer cycler and a lander.
start paying for propellant by the pound, buy that at ISS, and
let NASA handle the cycler, the lander, ground Infrastructure and
hire out to DoD for the Propellant Depot. Let industry deliver
LOX to ISS.
add in some aerobraking and other parochialities and build a base
with some ongoing science instruments, such as a Decent Radio Telescope and a Transit Optical scope.