the case against HLV

gunsandrockets · Jan 3, 2006

Interesting article about HLV vs MLV over at the latest http://www.thespacereview.com "The case for smaller launch vehicles in human space exploration (part 1)" http://www.thespacereview.com/article/526/1 The case for greater economy based on higher launch frequency certainly seems born out in the example of the Russian Soyuz launch vehicle. Since the Soyuz rocket has now launched 1700 times, it is one of the most reliable and economical launch vehicles in the world. http://europa.eu.int/comm/space/russia/highlights/news_70_en.html Another advantage MLV have over HLV, is that MLV already support a steady market of military and commerical satellite launches. Enough of a market to support multiple types of MLV's which means the advantage of a competitive market which drives down prices. A HLV by contrast is only built for the specialized and unique NASA manned exploration market. Therefore only one HLV type is going to be to be developed and built. That is a monopoly which NASA will have to support no matter the costs or difficulties because there would be no other HLV option to turn to.

john_316 · Jan 3, 2006

But can the MLV send a crew to the moon or Mars with a lander and possible prefab shelter? Highly unlikely. MLV can continue ot service the LEO and GEO satellites and the ISS for mission requirments but to go beyond GEO will require a HLV. I hope they can also incorporate some composite technology into some of the equipment they take with them to reduce weight and add some extra's. So there shouldnt be a case against the HLV. We do actually need one.. <img src="/images/icons/smile.gif" />

mattblack · Jan 3, 2006

Grant Bonin is articulate in that he outlines why using oodles of MLVs to launch 1x 50 ton payload to Mars (6 or 7x Atlas/Deltas per payload) might, I say MIGHT make economic sense in a parallel world where the Pentagon might truly help out Nasa. BUT it does not make engineering, logistical or operational sense. Mr Bonin is truly flogging a dead horse: a horse that died years ago. Endless analysis of this issue has been done and lots of interested parties have said time and again, wearily, that you can't assemble Manned mars missions with 20-ton ELVs. I read THOUSANDS of pages of trade studies that all said nearly the same thing: Lunar missions are just BARELY possible with MLVs, but Mars missions require clustering various quantities of Atlas V and Delta IV corestages to get payloads of 40 or 50 tons. The Atlas and Delta configurations that could lift 50 metric tons are the acknowledged benchmarks for not building all-new launchpads and infrastructure. For more powerful versions that could lift 70 or more tons, billions more would have to be spent on new pads and preflight assembly infrastructure. It's been said that MLV-to-HLV conversion MIGHT take slightly less time and money than developing a 100-ton+to-LEO Shuttle-Derived HLV, but at the end of all this time and money you'd end up with rockets that could lift HALF of the SDHLV and have NO reusabilty features whatsoever. Example: Mostly unchanged launch facilities -- 3x core Delta IV 'Heavy' with 4x GEM-60 SRBs, uprated RS-68 engines and cross-fed propellants -- 40 tonnes to LEO. Impressive rocket, yes, but doesn't begin to compare to SDHLV. You'd need 7x launches of this thing to assemble a Mars mission and 3x minimum for the Moon. That's nuts!! No; although this would be a good fallback position in case Nasa has a future funding crash (God fervently forbid!) or some law is passed to ban Shuttle stuff... This ship has sailed and this Horse hide was <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

gunsandrockets · Jan 3, 2006

"...it does not make engineering, logistical or operational sense. Mr Bonin is truly flogging a dead horse: a horse that died years ago." "Endless analysis of this issue has been done and lots of interested parties have said time and again, wearily, that you can't assemble Manned mars missions with 20-ton ELVs." Well Bonin was describing the use of 25 ton payload ELVs. But that's a minor quibble. What I want to know is this. The current NASA plan for a manned Mars-Transfer-Vehicle is something that uses NTR and requires EOR of two different HLV plus one CLV payloads. This I assume is the 'sensible' 'practical' option. The architecture Bonin suggested used EOR of six flights of MLV. But Bonin's architecture used chemical propulsion for TMI. If Bonin could use NTR, just like NASA intends, then the total number of MLV launches could be cut down from six to four. So am I to understand that 3 x EOR is a sensible and practical plan, yet 4 x EOR is a ridiculous, impossible and impractical plan? Perhaps you overstate the case for HLV. Once non-chemical propulsion enters the picture the case for using common LV instead of HLV becomes even better. My greatest fear about HLV is that development will suck all the financial oxygen out of NASA, leaving hardly anything for manned exploration operational costs or development of non-chemical propulsion. My second greatest fear is that dependancy on a single launch vehicle will leave NASA stranded in LEO should the HLV fail to perform or get cancelled by future politicians.

mattblack · Jan 3, 2006

It's true what you say about integrating nukes into smaller vehicles. And the argument about 'relying on 1 design of booster' is an old one, which is why a clustered-corestage Atlas V derivative (my choice) might be a good fallback. Apollo only had the Saturn V, yet that only ever gave minor trouble, designed from scratch with nothing similar seen before. The 'Griffin' SDHLV at least has the benefit of using mostly tried and well-understood technology -- albeit put together in a new way. 'My money' -- for the forseeable future -- is on Mike Griffin's Magnificent Flying Machine. P.S: For upgrade, the SDHLV (Nova, Hercules?) running the 5x SSMEs at 114% percent and adding a third J2S to the EDS stage (with materials improvements) should improve the payload to LEO from 125 to 140 tons. <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

mlorrey · Jan 3, 2006

"But can the MLV send a crew to the moon or Mars with a lander and possible prefab shelter? " Sure it can: 1 legless female midget to Mars, one way, with a cooler full of human embryos, a prefab shelter, MREs, seeds, and a supply of radiovoltaic batteries. It could send one person to the lunar surface and back. Why send more than one person?

nacnud · Jan 3, 2006

I though the Mars plan was for two 1+1 HLV EOR flights followed by one HVL+HVL+CEV EOR flight 18months/2yearrs later.

krrr · Jan 3, 2006

I'm neutral about the topic (HLV versus MLV), but I do have the impression that assemblophobia is a common disorder (perhaps influenced by Zubrin's strong opinions on the subject). Sticking together a spacecraft (in LEO) from a few components is a little complicated, but not really that hard. Related illness: deployophobia, the fear of deploying large structures (e.g. solar arrays). The fact that things can get stuck doesn't mean they will get stuck.

radarredux · Jan 4, 2006

I finally had a chance to read the article, and while it is good, I don't think there is anything new in it. Many of these issues were raised in early plans for the VSE, largely because NASA, in trying to please the Pentagon, tried to build and justify an architecture around the EELVs. I think to assume Griffin and his team were unaware of the benefits of this approach and did not factor them into their evaluation of probably hundreds of architecture variations is naive. Given that the ratio of Griffin knowledge of this area (not to mention politics, etc.) to my knowledge approaches infinity, I will defer to his judgement.

mattblack · Jan 4, 2006

Spot on. Couldn't have said it better myself. <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

CalliArcale · Jan 4, 2006

Assemblophobia. I like it. <img src="/images/icons/wink.gif" /> There is added mechanical complexity to it, and while you may be right that people are too paranoid about it and think it's riskier than it is, there is one unavoidable factor of it and that's that it's going to make the finished spacecraft more expensive. It might make it more practical, though, since you can use existing rockets to boost it into orbit. And you may get certain structural advantages out of it that you wouldn't otherwise. On the other hand, it will impose different constraints onto your design than single-launch from an SHLV. Skylab was positively spacious inside, but Mir was comparatively cramped, since its components all had to fit in a Proton shroud and were further constrained by the need to incorporate propulsion and all the avionics to perform automated rendezvous and docking (their preferred assembly technique; not a bad one, since it is obviously reliable, but one with its own particular constraints). I tend to be neutral too, krrr. As an engineer, I see both approaches as having their own unique constraints and challenges. In the end, I don't think either is fundamentally better; it's more a question of deciding which will be more available and more practical given the logistics of the project. Having Shuttle available hugely influenced the design of the ISS, for instance; if Shuttle had been unavailable or impractical, they would've gone a different route and probably today we'd be saying how impossible it would be to boost ISS components with Shuttle. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

spacester · Jan 4, 2006

Assemblophobia. I like it too. Isn't the idea that with large modules, you can route all or at least a lot of the plumbing internally, saving on EVAs? There is a LOT of plumbing, and a lot of EVAS are required to hook things up externally. Isn't that the lesson of the "ISS tinkertoy" argument? Almost all of the EVAs can be designed out of the construction phase if the delivered payload is massive enough? <div class="Discussion_UserSignature"> </div>

CalliArcale · Jan 4, 2006

That's most of the headache at install time, but you need plumbing either way. Whether it's on the inside or outside doesn't really matter -- you put it wherever it fits. A single-launch space station might still have a lot of external plumbing just to make more habitable volume with the same hull. Mainly you'll be adding doohickeys to connect it up. The plus side, of course, is that if the plumbing goes bad, the problem will likely be confined to that one module, which can be sealed off if the damage is bad enough, allowing you to keep using the rest of the station until you've got an opportunity to fix the problem. One good argument for modularity is actually safety. Consider Mir. When the Spektr module was punctured, they ended up sealing its hatch and never using it again. But Mir itself stayed in operation. It's a little like the reason ships are sometimes built with separate compartment separated by watertight bulkheads that can be sealed at a moment's notice to keep flooding contained. There's also a redundancy argument; some systems must neccesarily be duplicated between modules. If that includes propulsion, that can be useful down the road, giving you extra flexibility. (Mir modules were relocated a number of times, using their own internal propulsion systems.) But that adds cost too. But there are drawbacks. No only do you have to build in all the connectors for your plumbing, ventiliation, power, and data, but you also have to build in hooks and latches and hatches and things like that to structurally connect the modules. If they're delivered on ELVs, like Russian modules, you also have to build in propulsion and navigational systems which end up being a very large percentage of the cost and a significant design constraint. And then of course there are all the EVAs and all the manual work to hook everything up, like you said. Pros and cons. Nothing in engineering comes free. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

soyuztma · Jan 5, 2006

<blockquote>In reply to:<hr />Isn't the idea that with large modules, you can route all or at least a lot of the plumbing internally, saving on EVAs? There is a LOT of plumbing, and a lot of EVAS are required to hook things up externally. <hr /></blockquote> They did most of the plumbing in Mir internally. But when the progress crashed into Mir they found out this had a large drawback: they had problems sealing off Spektr module because there were a lot of cables running through the hatch. So now most of the plumming of the ISS is done externally. The drawback of external plumbing is that you have to perform a lot of EVA's. <div class="Discussion_UserSignature"> </div>

spacester · Jan 5, 2006

Obviously I didn't make my point very well. Sure you need plumbing either way, and of course nothing comes for free. The job of an Engineer isn't just to randomly choose <img src="/images/icons/wink.gif" /> but to find the optimum solution. Beyond that, the job of the systems architect is to make big-picture decisions that fully account for the engineering ramifications of the systems design options. Fortunately for NASA, we have message boards in place to figure these things out. <img src="/images/icons/wink.gif" /> <img src="/images/icons/wink.gif" /> <img src="/images/icons/wink.gif" /> My point is that when you do the trade study on external plumbing versus internal plumbing, I gotta believe that the costs of EVAs are such that internal wins the day easily as long as you have room to do it that way. IOW if you spend all the money for an HLV, one of the main things you get in return is the ability to find room for all your plumbing AND your hatches in the end of your larger diameter module. This lets you connect the plumbing between modules without an EVA, as well as lets you access all the internal plumbing in shirtsleeves. Without running ductwork thru safety bulkheads and hatches. <img src="/images/icons/laugh.gif" /> In the extreme case, you could design your space station such that EVAs are never required except in the most extreme contingency. Bad for space walk fans, good for stretching our space dollars. I doubt that Bigelow is designing his stations with EVAs assumed. In fact the cost of EVAs may be so high that if one was required to repair a Bigelow module, the unit might be abandoned and replaced instead. <div class="Discussion_UserSignature"> </div>

gunsandrockets · Jan 6, 2006

"...assemblophobia is a common disorder ..."! "...Related illness: deployophobia, the fear of deploying large structures..."! I salute your wit! Well done.

gunsandrockets · Jan 6, 2006

"I finally had a chance to read the article, and while it is good, I don't think there is anything new in it. Many of these issues were raised in early plans for the VSE...Given that the ratio of Griffin knowledge of this area (not to mention politics, etc.) to my knowledge approaches infinity, I will defer to his judgement." I suspect no-one will be happy with everything that the ESAS plan contains. Some don't like the return to Apollo-style capsules, some don't like the return to Saturn-sized boosters, and some don't like the endorsement of nuclear power. Engineering wise I have nothing to complain about. Money wise...that's something else. "I think to assume Griffin and his team were unaware of the benefits of this approach and did not factor them into their evaluation of probably hundreds of architecture variations is naive." I think to assume that critics made the assumption you describe is unfair to the critics. And reasoned criticism, as is the Bonin paper, is deserving of reasoned response. Griffin, as respected as he is, is not a pope, Griffin is not infallible. For example the accelerated timetable that Griffin has decided to pursue is making the NASA budget crunch even worse than it was before. Griffin is certainly a better 'Spock', but former administrator O'Keefe I suspect is better at managing large expensive projects and clumsy bureaucracies.

danwoodard · Jan 6, 2006

It's essential to consider development cost, development risk, and the vast uncertainties in both development and operating cost. If the HLV makes only a few flights, it will be more costly and less reliable than making more flights with a smaller vehicle. We have to remember that during Apollo we had unlimited funding. We don't have it now. SRBs have failure modes that are not easily mitigated. I have seen a fair number blow up over the years. In addition, the assembly of the shuttle SRBs is both hazardous and expensive. The problems are not as severe with smaller nonsegmented, nonsteerable SRBs such as those on the Atlas V and Delta IV, though the all-liquid systems (Soyuz and Delta IV Heavy) have the least frightening failure modes. But the biggest problem is development risk. With no commercial or military application, the HLV will be a huge budget target with almost no constituency. With a small number of actual flights it will never attain the level of experience that allows accurate predictions of reliability. With a design that, like the shuttle, is a substantial departure from the past, there is no way to accurately predict operating or development cost. Yet paradoxically it provides no technological benefits because the basic technology is 30 years old. The smaller CEV Launch Vehicle has performance and even dimensions almost identical to those of the EELVs except that they have flown and it hasn't even been designed. The only rationale that have been provided for designing yet another launcher in the same crowded class are catch-phrases like "Man-rating should be designed in, not added on", which are presented as facts without any supporting evidence whatsoever. I guess this means the Soyuz, which was originally an ICBM, is to unreliable. Let's face facts. The cost of human spaceflight is to high to be practical except for a few billionaire tourists, and even they can't afford US launch costs. Why not con

najab · Jan 6, 2006

>SRBs have failure modes that are not easily mitigated.Such as?

josh_simonson · Jan 6, 2006

Launch vehicles cost less than the payloads they carry, so even if they were nearly free, you'd still be paying 2/3 of the current price. There's no point in being able to launch once a week if you can't afford to build the payloads to keep the launcher busy. To increase the flight rate and decrease costs, you need demand as well as supply for launch services.

josh_simonson · Jan 7, 2006

Yes, but folks like GT would still complain about the CEV even if the CLV were free. Now tourism can hopefully turn that around. Tourism supplies it's own paying cargo for free. As long as the price is low enough to keep the thing almost fully booked it'll do well. After that, standardization, mass production and re-use of in-space components are the only ways to bring costs down.

gunsandrockets · Jan 9, 2006

http://www.thespacereview.com/article/529/1 Part 2 of the Bonin article is out in today's Space Review, "The case for smaller launch vehicles in human space exploration (part 2)" Bonin hammers home the reliability benefit MLV gains over HLV because of redundant vehicles and the economic advantages MLV have from increased flight rates compared to HLV. Good stuff!

josh_simonson · Jan 9, 2006

He does mistakenly quote 1 in 2000 as the failure rate of the CLV, when it's actually 1 in 460. He quoted the loss of crew number, which is inappropriate since most of the flights are cargo only. The biggest concern I would have would be in landing a modular vehicle on the moon or mars. He claims on-orbit assembly is well understood, this is true for non-mobile structures that don't bear a load. Entry to Mars' atmosphere will make assembly significantly more complex. Interestingly, the price of the EELVs went up by 2/3 due to demand being less than anticipated. Given a higher flight rate their price should drop back to baseline. SpaceX may also enter the fray and embarass folks into a re-evaluation of things. It's good we have a couple years to mull things over on the HLV.

cuddlyrocket · Jan 9, 2006

I want to see some actual calculations that I can verify rather than assertions that I can't. Granted it makes an articles less readable <img src="/images/icons/smile.gif" />, but it's the only way any of us can really decide who's right (unless you base it on 'who you trust' or other popularity contest). Generally speaking, I tend to take the attitude that NASA and other organisations that actually have to launch things and carry out other-than-paper missions tend to get it right. So, I need some actual evidence that they are wrong. And by get it right, I include financial and political considerations, which are valid concerns to the pragmatic rather than the idealistic.

JonClarke · Jan 9, 2006

Orbital assembly has yet to be tested under 10Gs! Bonin has tried to rerecreate Mars direct using assembly of 20-25 tonne units. It might be better to adapt the architecture to better utilise the smaller units. For example, have several small landers. A spacecraft surface mass is just over half its earth departure mass, Twenty five tonnes in LEO equates to 13 tonnes on Mars. One lander would supply the lander and ISRU plant, a second the power source and assorted cargo, a third the surface laboratory, the fourth a crew lander and rover. Twenty 50 tonnes in LEO would need two 25 tonne LOX-LH2 earth departure stages, docking three spacecraft is much simpler than docking six, especially when most are carrying liquid hydrogen. Travelling to and from Mars could be done differently. The crew would travel to Mars in the lander/rover with some additional living space and storage in a module that would be dumped before a direct landing. This would require four docked spacecraft in LEO. The return could be best done after a Mars orbit rendezvous, rather than directly. This means a much smaller return vehicle and less hydrogen feed stock taken to Mars. The return craft could travel to Mars in two three element components, also docking in Mars orbit. Note this is all for a 4 man crew. if you want to send 6 men multiply everything by 1.5. To me it shows while a Mars mission is possible without a HLV it is very complex and ugly business. Some orbital assembly will probably be neccessary for a Mars mission, but the bigger the building blocks the easier it is. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

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