Many false lessons have been learned from the Shuttle program in general, and from the Challenger loss particularly. Chair Force Engineer explains:
NASA management’s most enduring lesson from Challenger is the flawed mantra of “Crew must be kept separate from cargo.” While such flawed logic is enough to trick Congress into funding the development of two very different launchers, it doesn’t always hold true. If a launcher can be made safe enough for a human crew, there’s no reason why it can’t be trusted with carrying a reasonable amount of cargo at the same time.
Yes, that’s one of the more illogical ones. He has more.
It’s not illogical. A crew launcher has to be more reliable than a cargo launcher, and reliability costs money. At the production scale being contemplated, there is no way it can be cheaper to launch the very heavy and voluminous cargo envisioned for a Mars mission on a man-rated dual-role vehicle. During Apollo they did it with a single launcher because (a) the cargo was the absolute bare-bones minimum required to get two astronauts to the moon and back and (b) they had a blank check and a within-this-decade mandate.
Also, as far as NASA and its CxP contractors may be from getting back to the moon, SpaceX and Scaled Composites are much, much farther.
A crew launcher has to be more reliable than a cargo launcher, and reliability costs money.
Nope. A cargo launcher has to deliver hardware that costs hundreds of millions of dollars. Unreliability costs money. And they will never build a rocket that can do al all-up Mars mission in a single launch. They’re going to have to learn how to do on-orbit assembly anyway. They might as well start now, and not waste the money developing a heavy lifter that won’t be heavy enough, and will be horrifically expensive to launch, given its low flight rate.
In some hypothetical future where orbital launch is inexpensive, potentially the cargo/crew differentiation could make sense. Today it doesn’t, as expensive launch dictates expensive cargo. If you’re launching cargo worth hundreds of millions of dollars you end up wanting the same reliability as if you were launching crew.
I’m not sure I agree that on orbit assembly is the way to go for the earliest manned Mars missions. However, it’s definitely a technology that must be a cornerstone of our long term development of space.
Unreliability costs money.
Not necessarily, for cargo. If a 99% reliable launcher costs twice what a 90% reliable launcher does (and this is by no means unrealistic), in the long run you will pay far more using the 99% reliable launcher. This assumes that the cost of a failure is entirely accounted for by the replacement value of the payload and not schedule slips, failure investigations, congressional hearings, etc.
The calculation doesn’t work for crew. It isn’t acceptable to calculate the replacement value of a crew on purely economic terms, even though there would be an endless supply of volunteers for even the riskiest of missions. Man-rating means more stringent requirements means higher costs. There is no economic return on investment.
That being the case, why wouldn’t it make sense to put crew on the 99% launcher and cargo on the 90% launcher?
If a 99% reliable launcher costs twice what a 90% reliable launcher does (and this is by no means unrealistic)
It is unrealistic.
This assumes that the cost of a failure is entirely accounted for by the replacement value of the payload and not schedule slips, failure investigations, congressional hearings, etc.
This is unrealistic as well.
Man-rating means more stringent requirements means higher costs.
I don’t think that phrase means what you think it means. I wish that we could ban it from our vocabulary. NASA hasn’t built a “man rated” vehicle since the sixties, and probably never will again (hint: it has very little to do with reliability).
As I said, unreliability is expensive.
reliability costs money.
Southwest Airlines has the highest reliability in the airline industry. They also have the lowest fares and the highest profits. Reliability does not cost them money. It saves them money. If their planes were unreliable, it would hurt the bottom line.
When you want to buy a car, do you look for the least reliable car you can find, thinking that it will be cheaper to operate?
At the production scale being contemplated, there is no way it can be cheaper to launch the very heavy and voluminous cargo envisioned for a Mars mission on a man-rated dual-role vehicle.
Why do you assume the production scale should be limited to one Mars mission? Rand didn’t say that, and neither did the article he referenced. Neither of them even mentioned Mars.
Every heavy, voluminous cargo on Earth is moved by crewed vehicles. Fedex does not separate crew and cargo onto different vehicles. Neither do railroads, shipping lines, or air freight companies. They have crews on all their vehicles, because experience shows crewed vehicles are more reliable and reliability saves the company money.
Admiral Gehrman did not even follow his own advice. When he commanded the Eisenhower carrier battle group, he did not insist that the group’s cargo ships be unmanned so that no one would get hurt if a ship blew up. Instead, he ensured that the ships were reliable so they would not blow up.
If we want man’s future in space to be limited to a very small number of missions, like past programs, then we might be able to get by ignoring reliability and putting cargo on exploding totem poles. If we want to see non-trivial human activities in space, then we need to operate like transportation companies, not the trivially manned space programs of the past.
You are playing games with words beacuse you cannot admit you are wrong.
Please refer to NASA NPR8705.2A, “Human Rating Requirements for Space Systems”, currently in force with a big red “COMPLIANCE IS MANDATORY” at the top. Are you telling me these requirements are illusory, ignored, obtainable at no cost, or what?
As far as the costs of that extra “9” in reliability, I guess we’ll have to agree to disagree on that, since nobody has ever really calculated it. My opinion is based on many years’ experience in the mission assurance business for military space launch.
Are you telling me these requirements are illusory, ignored, obtainable at no cost, or what?
No one said that requirements have no cost, or that NASA’s human-rating requirements are good requirements, or that they are the only/best way to achieve reliability. You keep making bad assumptions.
Do you think that blowing up vehicles, cargo, ground equipment, etc. has no cost?
As far as the costs of that extra “9” in reliability, I guess we’ll have to agree to disagree on that, since nobody has ever really calculated it.
Of course people have calculated it.
Vehicles with good reliability and good management operate at about three times fuel costs. Current launch vehicles operate at hundreds of times fuel cost. The difference is the cost of unreliability (including the complete loss of vehicle even on a “successful” flight).
If what you’re saying is true, then unreliable vehicles should be able to operate at less than three times fuel costs, not more.
To put it in colloquial terms, “If you’re so smart, why aren’t you cheap?”
Edward:
Southwest can offer high reliability at a competitive price because it is better managed and has lower costs (outside of the savings in repairs or damage claims), neither of which are relevant to this particular discussion.
The car you drove today contains parts that are not as reliable as they could be, because the manufacturer made a tradeoff between the cost of a failure and the initial cost of building in quality.
Launch vehicle reliability is purely mechanical. The Shuttle crew does not “fly” the Shuttle into orbit – they just sit there and take g’s. The presence of a crew on a ship has nothing to do with mechanical reliability – they are required because a ship has to react to unforeseeable circumstances, and because its many systems require human intervention. The same applies to FedEx trucks, trains, and whatnot.
Yes, reliability pays — but only up to a certain point. Look at my first post. In 100 launches, my 90% reliable vehicle delivers 90 payloads to orbit. It takes 91 launches of my 99% reliable vehicle to do the same thing. To break even, the 99% reliable LV has to cost no more than 100/91=1.1 times the cost of the 90% LV. I would submit respectfully that it costs far, far more than 10% of the cost of a vehicle to boost reliability from 90% to 99%. We are talking actual launch vehicles built with currently available technology here, not delivery trucks or magical spaceships built of carbon nanotubes by genius philanthropists.
Are you telling me these requirements are illusory, ignored, obtainable at no cost, or what?
The first two. Do you believe that the Shuttle meets these requirements? It does not.
They are basically an arbitrary set of rules that NASA can use to exclude competition, that it waives for itself when necessary, which is always. To the degree that man rating exists, it has little to do with reliability, and much more to do with failure onset detection, and ability to fly a trajectory that won’t kill the astronauts in an abort.
Is there such a thing as a “man-rated” airliner? The answer is “no.” “Man rating” is an obsolete concept, left over from the sixties.
Launch vehicle reliability is purely mechanical. The Shuttle crew does not “fly” the Shuttle into orbit – they just sit there and take g’s.
Yes, I know the “unmanned space” party line. The facts do not support your beliefs.
In 100 launches, my 90% reliable vehicle delivers 90 payloads to orbit. It takes 91 launches of my 99% reliable vehicle to do the same thing. I would submit respectfully that it costs far, far more than 10% of the cost of a vehicle to boost reliability from 90% to 99%.
There’s one problem with that argument: your numbers are wrong. The actual figure is nowhere close to 10%.
Convair and the US Air Force conducted two independent studies of vehicles with similar size and performance. One of the vehicles in each study was a rocketplane with 99% reliability (the X-15). The other vehicles were guided missiles with comparable performance and much lower reliability.
If you are correct, the X-15 should have cost 10% more to develop than a guided missile with much less reliability. It didn’t. It cost 40% less to develop.
The reason why it cost less is quite simple. In the words of the late Dr. Maxwell Hunter, the people who argue that unreliable vehicles are cheaper to develop forget that to develop a rocket, you need to fly a rocket. A vehicle that is designed to be reliable and reusable will be cheaper in every phase of its lifecycle, including development.
SpaceShip One is another example. During its flight test program, Scaled flew the carrier aircraft 66 times and the upper stage 17 times. If the vehicles had been only 90% reliable, Scaled would have lost 6 or 7 carrier aircraft and 1 or 2 upper stages. Instead of building only two test vehicles, they would have had to build 8-10 vehicles, greatly increasing the cost of the development program.
Another fact is that a vehicle that returns to the launch site after a partial failure gives engineers more useful information than a “flaming datum.” Debriefing a pilot and examining a piece of intact hardware is a lot easier than collecting debris and conducting a mishap investigation.
We are talking actual launch vehicles built with currently available technology here, not delivery trucks or magical spaceships built of carbon nanotubes by genius philanthropists.
You are misinformed. Reusable launch vehicles do not require carbon nanotubes. The X-15 was built using conventional aerospace materials available in the 1960’s. Similar materials would have been used to build DynaSoar, Reusable Atlas, etc. No one has ever seriously proposed building a launch vehicle out of carbon nanotubes.
Ed,
What is this reusable Atlas of which you speak?
First off, reusable and manned are two completely different concepts. Let’s stick to the main argument.
There is no way — no way — that you can go from one-nine reliability to two-nine reliability at only a 10% increase in unit LV cost, for a comparable set of requirements. X-15 and a guided missile are apples and oranges.
Look at historical reliability numbers for unmanned launch vehicles. You will see that they sit right around 90%. (Never mind what the programs “require”.) Further reliability improvements are technologically feasible, but more costly than dropping a bird in the pond every few years. There’s not a lot of deviation from that number from program to program or country to country. It has held constant for several decades now.
I think you guys are looking far, far into an imagined future where spaceflight can attract investment capital on the scale of the automotive or computer industries. It cannot do so now, for what are probably sound economic reasons. When there are as many launch vehicles as there are airliners or FedEx vans, sure, manned is probably the way to go, and NASA will become irrelevant, just like you’ve always dreamed. But this did not happen in the 60s, 70s, 80s, or 90s, and as the fundamental economics have not really changed, it almost certainly won’t happen in the 00s or the 10s. The road to space is still going to pass through Washington DC.
Rand: as I am sure you know, one requirement for manned vehicles is a 1.40 design factor, versus 1.25 for unmanned vehicles. I have never seen NASA flat out waive this. Have you, and if so, when?
What is this reusable Atlas of which you speak?
The Reusable Atlas was a vehicle proposed by Convair and Rocketdyne in the 1960’s. The first stage was based on the Atlas propulsion system with new tanks, hot structure based on the X-15, swept wings with General Electric turbojets for flyback and landing, and cockpit and ejection seat from the X-15 program. The second stage was an M2-shaped lifting body with ablative TPS, cryogenic LOX and LH2, RL-10 engines, guidance computer from the Centaur upper stage, and another X-15 style cockpit.
Convair and Rocketdyne pitched it to the Air Force and wanted to pitch it to AT&T. Unfortunately, the government didn’t want the Air Force doing manned space and then Kennedy nationalized the communication satellite industry, which was the end of it.
First off, reusable and manned are two completely different concepts.
No, they are not. Piloted vehicles* are orders of magnitude more reliable (hence, more reusable) than unpiloted vehicles.
This has been demonstrated by decades of experience with vehicles ranging from aircraft and UAVs to missiles and rocketplanes. Literally hundreds of programs.
You’ve made the standard anti-human spaceflight arguments but you’ve presented no facts to support your arguments.
(*Whether those pilots are men or women is irrelevant.)
There is no way — no way — that you can go from one-nine reliability to two-nine reliability at only a 10% increase in unit LV cost, for a comparable set of requirements. X-15 and a guided missile are apples and oranges.
“10% increase” is a number you pulled out of your six o’clock.
Once again, Convair discovered that the reusable vehicle was 40% cheaper to develop, not 10%.
The Air Force made similar findings. The requirements for the vehicles were similar, despite your belief to the contrary.
Look at historical reliability numbers for unmanned launch vehicles. You will see that they sit right around 90%
Even for unmanned launch vehicles, your numbers are off. Only the worst ELVs are as bad as that.
Which is irrelevant because no one was arguing that unpiloted vehicles would be highly reliable. That’s why your belief that cargo must fly on unpiloted vehicles makes no sense.
I think you guys are looking far, far into an imagined future where spaceflight can attract investment capital on the scale of the automotive or computer industries. It cannot do so now, for what are probably sound economic reasons.
It doesn’t require investment capital on the scale of the automotive or computer industry. Again, you’re pulling numbers out of your six, and your numbers are not even close to being correct.
But this did not happen in the 60s, 70s, 80s, or 90s, and as the fundamental economics have not really changed, it almost certainly won’t happen in the 00s or the 10s.
Ah, the old standby: Mankind can never do anything in the future that was not done in the past. 🙂
Artemus, you seem to be laboring under the impression that reliability and cost have some sort of linear relationship. This is not the case, not in any system. In some cases extra reliability can require extra cost, but not always. More often than not the one key element dictating total system reliability is design. Take a look at different aircraft, for example. Say, the F-15, the A-10, and the B-1B. The A-10 is an extremely inexpensive combat aircraft (~$13 mil. per aircraft) and yet it is extremely robust and reliable, especially under fire. It’s a flying tank. The F-15 is also extraordinarily reliable and robust (an F-15 has successfully landed after having most of one wing blown off) and is moderately priced (~$43 mil. for the F-15D variant). The B-1B however is both extremely expensive (>$200 mil. per aircraft) and, at least originally, very unreliable. Even accounting for the slightly different missions of these aircraft these are still solid demonstrations that reliability doesn’t necessarily cost money and that merely spending more money does not guarantee reliability.
Similarly, if you look at something completely unrelated to the discussion at hand such as, oh, I dunno, maybe orbital launch vehicles and compare the reliability of a vehicle against its development cost you’ll find something interesting. There is essentially no correlation between development cost and reliability. On the one hand you have vehicles like Soyuz, Delta-II (7000 series), and Atlas-2 which are very reliable and relatively inexpensive, then you have vehicles like the Shuttle, Titan IV, and N-1 which are unreliable and very expensive, and then you have other vehicles like the Ariane 2/3, Saturn V, Delta IV, Atlas V, and Proton which represent various different points in the cost/reliability plane.
Let me reiterate. You can’t just throw cash at a vehicle design to get reliability, and inexpensive vehicles can quite easily have high reliability. It all depends on the fundamentals of the design. And this is not just in some future fantasy. Not just in some related enterprise. It is in orbital rocketry. In its history and its present and its future.
The absolutist, dogmatic language being used to argue these points is what is painting you into a corner.
Rand said, “Unreliability costs money”.
I simply claim that the economic returns on improved reliability are limited. If this were not true, you would have proof-tested your chair this morning before you sat down in it.
Rand said that separating crew and cargo on reliability/cost grounds is “illogical”
I stand corrected: it is illogical, provided we use the vehicles that fly through the pages of NewSpace press releases. They never have operational failures, because a failed flight is by definition a test flight. Just ask Futron!
Unfortunately, government space programs, being subject to the laws of nature, cannot achieve these reliability levels, and we still have not found the secret of free gains in reliability that you appear to have unlocked. Please don’t scold us, we’re trying our hardest.
The absolutist, dogmatic language being used to argue these points is what is painting you into a corner.
Physician, heal thyself.
I simply claim that the economic returns on improved reliability are limited. If this were not true, you would have proof-tested your chair this morning before you sat down in it.
Well, actually when I purchase a chair I do acceptance test it. I don’t buy two chairs for assured redundancy.
If you want to talk about government space programs, ask yourself it if really makes sound economic sense to develop both Ares I and Ares V. Just looking at Constellation alone, I don’t agree with developing a seperate, crew only, vehicle.
I simply claim that the economic returns on improved reliability are limited.
No, you did not simply claim that. If you had, no one would have disagreed.
All real numbers are limited (finite). They can also be measured. When reliability and cost are measured, we find that the numbers are not what you claim. The “10%” figure you keep throwing around is not based on real-world evidence.
I stand corrected: it is illogical, provided we use the vehicles that fly through the pages of NewSpace press releases. They never have operational failures, because a failed flight is by definition a test flight.
Incorrect. That definition may be true for missiles, but transport vehicles like aircraft, a failed flight is simply “ops normal.” You may not know it, but you’ve probably flown on airliners that had multiple failures. The reason you didn’t become a flaming datum is because airliners have greater redundancy than missiles and pilots who are able to switch between systems.
Airliners will even take off with systems that have failed on the ground. They are not designed to need “all systems go” to operate safely. Instead, safety is ensured by minimum equipment lists.
Unfortunately, government space programs, being subject to the laws of nature, cannot achieve these reliability levels,
Again, you are incorrect. The X-15 was a government space program, and it obtained the 99% level of reliability that you think is impossible. It did not require carbon nanotubes or violate any laws of physics, and apples-to-apples comparisons showed that it was cheaper to develop than missiles with comparable performance.
Military aircraft achieve reliability levels far in excess of 99%. They are more reliable than UAVs or missiles, by orders of magnitude, in every flight regime. And contrary to UAV marketing hype, they are also cheaper to develop (in an apples-to-apples comparison). In fact, many of the larger UAVs are actually piloted during early stages of flight test, for safety and reliability reasons.
It is not impossible for government programs to achieve high levels of reliability. It is impossible for missile programs to achieve high levels of reliability.
That’s why it is illogical to keep throwing astronauts into space on “vehicles” that are designed like missiles rather than transportation systems. It was a bad idea when Von Braun had it, and it’s a bad idea today.
Clearly I am not going to convince you. You seem to envision something like an orbital airliner: best of luck with that.
It’s interesting you mention von Braun. I take it that had you been in his shoes in 1961, you’d have told Kennedy to forget about the moon by 1970, because to do that we’d need an unsustainable crash program, with systems that would ultimately prove inadequate for the goal of making mankind a spacefaring people. All true, yet von Braun decided to endorse the moon mission anyway, much to his credit and the betterment of mankind (disagree with that if you like, but you’ll find yourself in a tiny minority.) I believe that there have been no fundamental technological advancements to change that calculation. So I come down with von Braun, and Mike Griffin. You do what you can with what you’ve got, or you give up and become a sheep rancher in Australia.
It’s interesting you mention von Braun. I take it that had you been in his shoes in 1961, you’d have told Kennedy to forget about the moon by 1970, because to do that we’d need an unsustainable crash program, with systems that would ultimately prove inadequate for the goal of making mankind a spacefaring people. All true, yet von Braun decided to endorse the moon mission anyway, much to his credit and the betterment of mankind (disagree with that if you like, but you’ll find yourself in a tiny minority.) I believe that there have been no fundamental technological advancements to change that calculation. So I come down with von Braun, and Mike Griffin.
I would have come down with von Braun, because Kennedy’s goal was not to build a sustainable and affordable space transportation infrastructure–it was to beat the friggin’ Russkies to the moon.
It was a good way to help win the Cold War, but as a means to open up space, it has proven a disaster. Tragically, despite the forty years of technological advances, and different national goals, NASA is determined to repeat it. Which is why, ten years from now, the agency will be largely irrelevant.
All true, yet von Braun decided to endorse the moon mission anyway,
Yes, and he also decided to build ballistic missiles to bomb London. I wouldn’t have agreed with that decision, either.
much to his credit and the betterment of mankind
How did Apollo “better” mankind?
By collecting a few rocks, which Americans aren’t even allowed to touch?
By preventing any serious attempt to develop affordable space transportation for 40 years?
By killing off DynaSoar and other military space programs, giving Communist China the forty years they needed to catch up?
I don’t consider those to be good things.
you’ll find yourself in a tiny minority
So says the Greek goddess. 🙂
Sorry, Artemis, but every poll I’ve seen says you’re wrong. A majority of Americans say that they would like to go into space. Many would spend significant sums of money for such a trip. They do not believe it should be a private club for a tiny handful of civil servants.
If you do, then you are the one who’s part of a tiny minority.
By collecting a few rocks, which Americans aren’t even allowed to touch?
Well, I’m an American, and I’ve touched one. I fairly certain many other Americans have touched one. I must admit that touching one is really anti-climatic. It certainly isn’t worth the cost of admission or obtaining one, if all you want to do is touch it.