CEV & CLV moving target

[gunsandrockets]

"You must not have heard that EELV costs have nearly doubled, so that an EELV Heavy launch, which still isn't enough rocket to handle CEV, now costs nearly as much as the horrendously costly Titan it replaced."<br /><br /><br />As pointed out, the mass of the CEV is arbitrary and can quite easily be sized for the EELV. Costs per launch for the EELV are related to the total launch rate because most of the current costs for the EELV are fixed costs. If NASA started flying EELV missions the cost per launch would dramatically drop. And even at the current launch rate the EELV are in the same ballpark as the claimed costs of the SRB. And the cost of the SRB, as has been pointed out, keep rising. <br /><br />Can you back up your claim of Titan IV level cost for the EELV? Because the numbers I find for the Titan IV are 400 million per launch compared to Delta IV at 254 million per launch.<br /> <br /><br />"You must not have noticed that the EELV program cost the Pentagon $550 million last fiscal year, even though only ONE EELV launch was performed for the Pentagon during that time (the Delta 4 Heavy launch). The Pentagon is asking for nearly $1 billion for EELV next year, for maybe two or three launches. You must not have read the reports that Boeing and Lockheed have been losing money on their EELV efforts. You must not have noticed that both companies were eager to dump their rockets into a consortium effort in order to attempt to limit the fiscal bleeding."<br /><br /><br />That bleeding is in large part because the companies have a huge overcapacity to build and launch rockets compared to the demand for launch services. Boeing built a plant that could build 40 core boosters per year all by itself, that's a huge capacity to underutilize. <br /><br />http://www.advancedmanufacturing.com/March00/applied.htm <br /><br /><br />"You must not have read the ESAS report, which showed very clearly

 

[edkyle98]

"Can you provide the link referencing the cost of EELV ? "<br /><br />Here's one: http://www.gao.gov/htext/d04778r.html<br /><br />"BTW, the CEV launch requirement is 25 MT. That is well within the EELV (DIV-H and future Atlas V heavy) capability."<br /><br />Not for the ascent profile required for a manned spacecraft. The EELV's have underpowered upper stages that must fly lofted profiles that cannot be used for CEV because they would create excessive g-forces in the event of a launch abort. An EELV-Heavy would only be able to boost perhaps less than 15 tonnes if it had to fly a non-lofted ascent trajectory. The fix is to put a more powerful upper stage on the thing, which involves the same development effort, and cost, that NASA is applying toward CLV development. And it would create a unique, costly launcher that could would not fulfill DoD's needs.<br /><br />"BTW, if you think a single CLV launch will cost anything less than $550 million you're gravely mistaken."<br /><br />The CLV launch itself will cost less than that. The mission cost, which includes the launch, the CEV "payload", mission control, astronaut training, etc., will cost far more than the launch (my guess is that total mission costs will probably be in the $0.75-1.0 billion range), regardless of whether the launcher is a CLV or a modified EELV. The only difference is that the CLV would cost less than the EELV in the long run.<br /><br /> - Ed Kyle

 

[gunsandrockets]

Thanks for providing this link...<br /><br />http://www.gao.gov/htext/d04778r.html<br /><br />Unfortunately for you, the link does not support your claim that the launch cost of the EELV is approaching the cost of the older Titan IV, in fact just the opposite...<br /><br />"...the System Program Office, in May 2004, estimated launch cost savings of 51.4 percent over the heritage systems."<br /><br /><br />As for your other assertions...<br /><br />"The EELV's have underpowered upper stages that must fly lofted profiles that cannot be used for CEV because they would create excessive g-forces in the event of a launch abort."<br /><br />That criticism of the EELV has already been acknowledged.<br /><br />"An EELV-Heavy would only be able to boost perhaps less than 15 tonnes if it had to fly a non-lofted ascent trajectory. The fix is to put a more powerful upper stage on the thing,..."<br /><br />I doubt your estimate of the payload reduction of the EELV-heavy is correct, as that would equal a payload reduction of 40%! But as I previously pointed out the mass of the CEV is arbitrarily large and could easily be sized to fit the payload of a non-'lofting trajectory' EELV.<br /><br />"...which involves the same development effort, and cost, that NASA is applying toward CLV development. And it would create a unique, costly launcher that could would not fulfill DoD's needs."<br /><br />Hardly. Even if the EELV were 'man-rated' (whatever that means) and a new more powerful upper stage were added any changes to the EELV are minor compared to the development neccessary for an SRB derived CLV. Not only is a brand new 5-segment SRB being developed, a new upper stage engine for the SRB derived CLV is being developed as well.<br /><br />And if such a modified EELV were developed it would not be costly, as the most unique thing would be a different upper stage which most likely would amount to nothing more than a bigger tank and a greate

 

[frodo1008]

Also using EELV's does bring up a slightly out of the box kind of thought. That is such a system would also give the US military the capability of getting into LEO with its own people in a big way.<br /><br />Heck, under that proposition NASA might even be able to get the military to help with the bill for such a CEV!<br /><br />Another plus would be the possibility of two systems instead of just one, a system based on the Delta IV Heavy, and a separate system based on the Atlas V Heavy.<br /><br />NASA would still have more than enough on its own hand with the development of the CALV.<br /><br />Even a smaller CEV would still be far larger than the Apllo command module was, and the EELV is a far more expandible system for the future. This could be relatively simple in increasing the number of Common Booster Cores (CBC's) from three to four or more, or increasing the thrust of the engines, or even both.<br /><br />I personally think that the so called man-rating is way over-rated at best. If you look at history, all the first launchers for NASA were either shorter range ballistic missiles (the redstone Mercury) or direct ICBM's (the Alas Mercury, or the Titan Gemini)! They had no man-rating about them at all!<br /><br />I too, originally thought that using shuttle derived hardware was a good idea, but that was until ATK decided that it was going to cost some three times more to develope the 5 segment SRB. <br /><br />Besides I personally think that using mass produced CBC's along with using only liquid engines (where the actual engines to be used can be hot fired) is a very good idea! Besides with Mike Griffin's justifyable anger at the cost increases of ATK, the chances of using another system just got far better!

 

[gunsandrockets]

"Another plus would be the possibility of two systems instead of just one, a system based on the Delta IV Heavy, and a separate system based on the Atlas V Heavy." <br /><br /><br /><br />Before NASA revealed the 'Apollo on steroids' plan, I started a thread promoting the idea of a high-low two spacecraft mix for the NASA CEV program. Developing in parallel a small lightweight manned vehicle (like a t/Space CXV capsule) and a larger more capable manned vehicle (something like the Lockheed proposed lifting-body).<br /><br />NASA today is sort-of following my scheme but in a much more subdued and less formal sense with the small budget COTS program. But I had something different in mind, I envisioned the low-end of the CEV mix as an inexpensive backup to the high-end CEV, one that was small enough to launch on a variety of launch vehicles and that way ensure that no matter what future problems developed that the U.S. would never again find itself in the situation of the Space Shuttle groundings of the past. Just as the USAF deliberatly developed two different launch vehicles with the EELV program to guarantee access to space, NASA should have two different manned spacecraft to guarantee access too.

 

[edkyle98]

"Thanks for providing this link...<br /><br />http://www.gao.gov/htext/d04778r.html<br /><br />Unfortunately for you, the link does not support your claim that the launch cost of the EELV is approaching the cost of the older Titan IV, in fact just the opposite...<br /><br />"...the System Program Office, in May 2004, estimated launch cost savings of 51.4 percent over the heritage systems." "<br /><br /><br />Read the entire quote. It says that the estimate was "according to the EELV System Program Office" and that <br />the GAO was "unable to verify the statements or projections".<br /><br />Read the cost details. It says that the original EELV program was projected to cost $18.8 billion for 187 launches. The new projection ballooned up to $32 billion for only *137* launches. That is a 132% increase on a per-launch basis, up to an average $234 million each for all EELV types including Mediums and Heavies. Since the original EELV-Heavy estimate was $150 million, it stands to reason that the revised Heavy cost is now $349 million, and probably still rising, which is getting close to the Titan 4 range. If you think that is costly, imagine how much a NASA-modified and operated EELV would cost!<br /><br />As for the lightweight CEV idea, the final Apollo CSM weighed more than 30 tonnes, and that only supported a few days on the Moon. NASA has already trimmed CEV down to 25-ish tonnes - for a longer mission. CEV, and CLV, are being developed for lunar missions. ISS is an afterthought, as CEV will only run there a few times before NASA backs out of the project.<br /><br /> - Ed Kyle

 

[propforce]

<font color="yellow">"Can you provide the link referencing the cost of EELV ? " <br /><br />Here's one: http://www.gao.gov/htext/d04778r.html </font><br /><br />Thanks. Interesting read. The article supports what I said about the cost ($550M last year for only one DIV-H launch). That figure includes infrastructure "fixed cost" as well as the launch itself.<br /><br />The report summaries the reason for the cost growth very well and I find it fair and balanced. It attributes to both the failure of the commercial market as well as the satellite weight growth and an increase of "mission assurance activities" initiated by the EELV program office that required additional fundings. <br /><br />It also credited the EELV for achieving "... met projected program cost savings of 25 percent to 50 percent-.." in both 2003 and 2004 "... over heritage launch systems...".<br /><br />Overall, if you look at historical large scale system develoopment programs, you'd find the cost increase in the EELV program is very minor compare to other large scale systems. Someone should pull out the initial projected Space Shuttle development cost estimate and compare that with the actual !! <img src="/images/icons/laugh.gif" /><br /><br /><font color="yellow">"BTW, if you think a single CLV launch will cost anything less than $550 million you're gravely mistaken." <br /><br />The CLV launch itself will cost less than that..... regardless of whether the launcher is a CLV or a modified EELV. The only difference is that the CLV would cost less than the EELV in the long run. ...</font><br /><br />Oh boy, if you believe that I have some condo space to sell you up in the L1 orbit <img src="/images/icons/laugh.gif" />.<br /><br />You must amortize the cost of development, including the vehicle itself plus any facility upgrade & mission control & people training into the cost of vehicle. Otherwise you are not compare apple <div class="Discussion_UserSignature"> </div>

 

[propforce]

After reading the report, I came to realize that Lockheed is *smarter* than Boeing. Afterall, they <br /><br />1) Buy an existing foreign rocket engine without spending their own money to develop a brand new engine, and then managed to convince the Air Force to let them do so.<br /><br />2) Initially they *promised* that they will build a RD-180 co-production facility in the U.S. Now looks like they will have the EELV program office to pay for that co-production facility and all the learning curve cost !!<br /><br />3) They get paid by the EELV program office to build a west coast launch pad in VAFB, whereas Boeing paid for upgrading SLC6 with its own money.<br /><br />4) They will get paid by the EELV program office to develop a Atlas V Heavy, again Boeing paid for its own Heavy development.<br /><br />5) Claimed that Boeing has gained an unfair advantage by having illegal access to its proprietary information, even though I doubt that really change both companies' development strategies on the EELV program, and have more launch missions transferred to them instead, then followed up with a law suit to Boeing.<br /><br /><br />I think the Boeing senior managment can learn a few things from Lockheed on this "government acquisition process" ! <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

 

[geminivi]

Let me ask this question, if the 5 seg SRB is going to cost an extra $2 billion over the 4 seg just so the J2x's can be used over the SSME, then I believe NASA must be looking at 2 or more decades of flying the CLV before they will break even.<br />I understand the SSME's can be produced optimally around 6 per year and the CLV is supposed to fly about 3 times a year.<br />I understand the SSME's cost about $50 million each but I don't know the cost of a J2X. For the sake of argument, lets say $10 million each. So the 2 billion spread over a 40 million differntial means about 50 launches before breaking even. At 3 launches per year, that is about 17 years of flying before the costs are recouped.<br /><br />That is nuts. I admit my accounting skills are atrophied from college, maybe I'm missing something. But it seems to me that NASA's rationale of saving operational money over R&D is pure hog wash.<br /><br />Now I understand that the SSME was also targetted to the HLV and RS-68's will replace them too. But I don't see why the powerplant on the HLV is related to the CLV unless its purely a preference.<br />

 

[edkyle98]

""CLV would cost less than the EELV [derived] in the long run. ..."<br /><br />Oh boy, if you believe that I have some condo space to sell you up in the L1 orbit "<br /><br />It says so right here: <br />http://www.nasa.gov/mission_pages/exploration/news/ESAS_report.html<br /><br />I haven't seen an equivalent in-depth, published study that claims otherwise.<br /><br /> - Ed Kyle

 

[edkyle98]

"if the 5 seg SRB is going to cost an extra $2 billion over the 4 seg just so the J2x's can be used over the SSME, then I believe NASA must be looking at 2 or more decades of flying the CLV before they will break even." <br /><br />The 5-segment is going to be needed for CaLV anyway, so NASA is actually *saving* money by developing only one SRB-based booster for both CLV and CaLV now, rather than developing a 4-segment for CLV now and a 5-segment for CaLV later. Using the 5-segment for CLV also allows NASA to save big bucks by dropping SSME now, rather than later, in favor of the less-costly J-2X and RS-68 engines. In order to understand what NASA is doing, you have to look at the big picture, keeping both launch vehicles in mind. <br /><br /> - Ed Kyle

 

[gunsandrockets]

"As for the lightweight CEV idea, the final Apollo CSM weighed more than 30 tonnes, and that only supported a few days on the Moon. NASA has already trimmed CEV down to 25-ish tonnes - for a longer mission."<br /><br />Well that's a rookie level mistake. You are comparing apples to oranges just like the mistaken comparison of the total mass of Big Gemini to Apollo.<br /><br />Let's refresh your memory...<br /><br />http://www.astronautix.com/craft/apolocsm.htm<br /><br />http://images.spaceref.com/news/2005/nas.esas.16.l.jpg<br /><br />...as anyone can see the 3.9m Apollo command module only has a mass of 5.8 tonnes, wheras the 5.5m CEV crew module has a mass of 9.5 tonnes. It's true the 30 tonne Apollo CSM outmasses the entire 23 tonne CEV, but that's a function of the huge amount of propellant the Apollo service module carries (18.5 tonnes!). The Apollo has enough propellant for 2.8 km/s of delta vee wheras the CEV only has enough propellant for 1.7 km/s of delta vee. If the Apollo service module was proportionate to the CEV service module and used the same type propellants as the CEV, then the Apollo would only have 2/3 the total mass of the CEV.<br /><br />So as I have pointed out before, the CEV is an enormous beast, much bigger than it needs to be and could easily be scaled down to fit the payload of the EELV or a 4-segment SRB version of the CLV.

 

[gunsandrockets]

"The 5-segment is going to be needed for CaLV anyway, so NASA is actually *saving* money by developing only one SRB-based booster for both CLV and CaLV now, rather than developing a 4-segment for CLV now and a 5-segment for CaLV later."<br /><br />Not true. The 5-segment SRB was only neccessary for the SSME version of the HLV. Now that NASA has switched to a 10m tank core stage powered by 5 x RS-68, the HLV could make do with the original 4-segment SRB and still achieve the original 125 tonne payload requirement. Adding the 5-segment SRB now is overkill and is estimated to increase the payload of the HLV by 10% or more.<br /><br />The only reason to continue with the 5-segment SRB project is to allow the CLV to put up an overweight CEV. The more logical and much much less expensive design choice is to shrink the CEV to match the CLV.

 

[gunsandrockets]

"Let me ask this question, if the 5 seg SRB is going to cost an extra $2 billion over the 4 seg just so the J2x's can be used over the SSME, then I believe NASA must be looking at 2 or more decades of flying the CLV before they will break even... I admit my accounting skills are atrophied from college, maybe I'm missing something. But it seems to me that NASA's rationale of saving operational money over R&D is pure hog wash."<br /><br />To be fair to NASA the one element your are overlooking is the development cost of an air-starting SSME. You see NASA couldn't use an off the shelf SSME for the upper stage of the crew launch vehicle as the SSME was never designed to function that way. So not only would an air-startable SSME be more expensive to produce it would also be more expensive to develop than the J-2X as well.<br /><br />Where NASA really screws up is substituting the 5-segment SRB for the 4-segment SRB in the CLV to make up for the performance differences between the SSME and the J-2X. That choice at best will delay the availability of the CEV years beyond the date administrator Griffin wanted.<br /><br />A much better choice is to shrink the CEV to fit the expected lift of the CLV. NASA has already started down that path by shrinking the CEV from a 5.5m capsule down to a 5m capsule. With any luck NASA will go down to a 4.5m capsule.<br /><br />

 

[gunsandrockets]

"Read the entire quote..."<br /><br />Oh, boy. I am reminded of that old refrain, "Who are you going to believe? Me? Or your lying eyes?" Heh.<br /><br />I read the report. In many places the report states the goal of the EELV program of 25% to 50% cost savings compared to legacy systems was met, and not just the sentence I excerpted. You certainly aren't convincing me otherwise, and if you hope other people might believe I am cherry picking the report anyone can check out your link and read the report for themselves, which I recommend.<br /><br />http://www.gao.gov/htext/d04778r.html<br /><br /> <br />Of course the EELV program as the report states has suffered cost problems due to low launch demand, as I have acknowledged previously. But the fact remains even with the current cost problems the EELV is a bargain compared to legacy systems. <br />As a point of comparison look at the price in 1999 dollars of the Titan IV, a launch cost of $432 million!<br /><br />http://www.astronautix.com/lvs/titan4b.htm<br /><br />And as I have already pointed out in a previous post, the launch demand problems of the EELV would obviously evaporate if NASA used the EELV. It really doesn't make sense for NASA to spend 15 billion dollars developing two new launch vehicles while the EELV are just sitting there underutilized. NASA should take advantage of the existing huge capacity for producing EELV. <br /><br />

 

[gunsandrockets]

"It says so right here:...I haven't seen an equivalent in-depth, published study that claims otherwise. "<br /><br />Resort to authority? Gee than what's wrong with NASA considering NASA is not following the original ESAS gameplan anymore! Maybe that report is as mistaken about EELV estimates as it has proven to about SSME estimates and SRB estimates.

 

[josh_simonson]

>Adding the 5-segment SRB now is overkill and is estimated to increase the payload of the HLV by 10% or more. <br /><br />So HLV payload goes up by 12.5t, at an (unprecidented in the us) $1500/lb, that's worth $41M. <br /><br />And from geminiVI's analysis, the 5 seg SRB also saves about $40m/launch of the CLV. <br /><br />Assuming 3 launches per year of each craft, it'll then only take a little over 8 years to recoup the $2B cost of the 5 seg SRB over the 4 seg. The shuttle program lasted over 25 years, so if the aries program has a similar run, by the end we'll be ahead to the tune of 4 billion in cost savings and added utility. <br /><br />To put it another way, that $2b is basically earning 5% compounded interest. Considering all the cash that's basically been flushed down the toilet in stillborn NASA programs over the last decade, that's not that bad.

 

[gunsandrockets]

"And from geminiVI's analysis, the 5 seg SRB also saves about $40m/launch of the CLV."<br /><br />No, the 5-segment SRB doesn't save anything. The savings come from replacing an air-startable SSME with a cheaper J-2X. The only thing the 5-segment SRB does in this case is allow the same oversized CEV to be launched with the J-2X as with the SSME.<br /><br />"Assuming 3 launches per year of each craft, it'll then only take a little over 8 years to recoup the $2B cost of the 5 seg SRB over the 4 seg. The shuttle program lasted over 25 years, so if the aries program has a similar run, by the end we'll be ahead to the tune of 4 billion in cost savings and added utility."<br /><br />That amount of benefit for the investment is highly speculative. It's always possible to spend more in development in the hope of gaining returns in the long run, but there is a practical limitation to this game.<br /><br />NASA's budget is already stretched to the breaking point by financing the Shuttle, the ISS, the CEV, the CLV and the HLV. Cutting costs whever possible is the only way NASA can survive this budget crunch, so right now is the worst possible time to pour money into developing a 5-segment SRB. At this stage I am surprised NASA is still pursuiing development of the J-2X when a cluster of the existing RL-10b would work just as well. <br /> <br /><br />

 

[edkyle98]

"You are comparing apples to oranges just like the mistaken comparison of the total mass of Big Gemini to Apollo."<br /><br /><br />Well of course NASA shaved spacecraft mass (Apollo versus CEV) by moving the lunar insertion burn to another module. That is how CEV will weigh less, but still support a longer mission. My point was to show that these lunar spacecraft weigh a lot more than 15-ish tonnes.<br /><br /><br />"the CEV is an enormous beast, much bigger than it needs to be and could easily be scaled down to fit the payload of the EELV or a 4-segment SRB version of the CLV."<br /><br /><br />I don't see how. CEV is designed to carry 4-6 crewmembers. Apollo only handled three, and they had very little room to move around. Your tiny CEV would probably force astronauts to remain immobile for long periods of time. Like Gemini 7, it would be a miserable ride for the crew. <br /><br /> - Ed Kyle

 

[edkyle98]

""It says so right here:...I haven't seen an equivalent in-depth, published study that claims otherwise. ""<br /><br />"Resort to authority? Gee than what's wrong with NASA considering NASA is not following the original ESAS gameplan anymore! Maybe that report is as mistaken about EELV estimates as it has proven to about SSME estimates and SRB estimates."<br /><br /><br />NASA *is* following the ESAS plan. The study seriously considered the five-segment RSRB with J2S option, which was actually predicted to be cheaper than the four-segment with SSME design (both were less costly on a per-flight basis, and provided less loss-of-crew risk, than Delta IV). The two designs were nearly tied, but four-segment won out due to the desire to get CLV flying as fast as possible. When detailed engineering work began post-ESAS, the five-segment option was reconsidered.<br /><br />I would love to read an authoritative, well-researched paper that reaches a different (perhaps pro-EELV type) conclusion than ESAS, but I have yet to see one. <br /><br /> - Ed Kyle

 

[edkyle98]

"In many places the report states the goal of the EELV program of 25% to 50% cost savings compared to legacy systems was met, and not just the sentence I excerpted. You certainly aren't convincing me otherwise, and if you hope other people might believe I am cherry picking the report anyone can check out your link and read the report for themselves, which I recommend. "<br /><br />I haven't said that EELV doesn't cost less than Titan IV. I said that EELV costs are "approaching" those of Titan IV. At $350 million and climbing (more than twice the original estimate) EELV-Heavy is clearly doing just that. The program has begun the predictable Pentagon program high-cost spiral, with high costs forcing launch numbers to be cut, which forces costs up more, which will force more launches to be cut, etc.. Just like B-2, F-22, etc...<br /><br /> - Ed Kyle

 

[gunsandrockets]

"I haven't said that EELV doesn't cost less than Titan IV. I said that EELV costs are "approaching" those of Titan IV. "<br /><br />Well it's good you no longer dispute that EELV launch costs remain 25% to 50% lower than Titan IV, as I claimed the report said.<br /><br /><br />"... The [EELV] program has begun the predictable Pentagon program high-cost spiral, with high costs forcing launch numbers to be cut,..."<br /><br />You have that exactly backwards, for it is the lower launch numbers which are the main reason for the increase of per launch costs.

 

[josh_simonson]

>No, the 5-segment SRB doesn't save anything. The savings come from replacing an air-startable SSME with a cheaper J-2X. The only thing the 5-segment SRB does in this case is allow the same oversized CEV to be launched with the J-2X as with the SSME. <br /><br />You do the same job as a 4 seg SRB and a SSME with a 5 seg SRB and J2X for less cost. That's cost savings in anyone's book. You propose doing less FOR less. How does that reflect on $/lb to orbit? That's the most important metric. <br /><br />The larger CEV will be able to return ISS science materials to earth, and bring enough lunar samples back that NASA doesn't have to guard them like the crown jewels. That's not a trivial capability.

 

[themanwithoutapast]

I don't see how. CEV is designed to carry 4-6 crewmembers. Apollo only handled three, and they had very little room to move around. Your tiny CEV would probably force astronauts to remain immobile for long periods of time. Like Gemini 7, it would be a miserable ride for the crew. <br />----------------<br />While I don't think it makes much sense practically to strip down the size of the 4-crew CEV to less than the size of Apollo, your argument of 'astronauts would not have a convenient ride' actually is not very convincing - space exploration is not about keeping astronauts comfortable and especially if the period of being uncomfortable only endures for a certain short period of time (a few days) I don't (and I think astronauts do not either) have a problem with that. Especially in light of saving thousands if not millions of dollars by each kilogram that the CEV is lighter than is planned now.

 

[gunsandrockets]

"Well of course NASA shaved spacecraft mass (Apollo versus CEV) by moving the lunar insertion burn to another module. That is how CEV will weigh less, but still support a longer mission. My point was to show that these lunar spacecraft weigh a lot more than 15-ish tonnes."<br /><br />I recommend you stop digging the hole you are in. The mass of the CEV vs Apollo CSM has almost nothing to do with life support consumables. The mass of consumables is inconsequential compared to reentry capsule mass and rocket propellant mass. And as I have shown multiple times now, the CEV is much more massive than the Apollo where it really counts which is in the mass of the reentry capsule.<br /><br /><br />"I don't see how [the CEV is too big]. CEV is designed to carry 4-6 crewmembers. Apollo only handled three, and they had very little room to move around. Your tiny CEV would probably force astronauts to remain immobile for long periods of time. Like Gemini 7, it would be a miserable ride for the crew."<br /><br />Actually Apollo had plenty of room to move around in, enough room for a galley, a toilet and to put on or take off a pressure suit. As befitting the Apollo capsules orginal purpose, which was to land on the moon! The Apollo capsule design remained the same despite the later addition of a separate LM lunar lander spacecraft to the lunar flight plan.<br /><br />The CEV capsule is too big, way too big. A CEV crew only spends 4 days out of a three week lunar journey living in the CEV by itself. On lunar missions a CEV crew will spend most of the time either in the LSAM lunar lander by itself, or while the LSAM is docked to the CEV. And the LSAM cabin is huge, even compared to the overlarge CEV capsule. Since all the volume of the LSAM is available to the crew for almost the whole mission, a CEV capsule can afford to be as small as possible. <br /><br />So there is no good reason for the CEV capsule to have three times(!) the internal volume of the Apollo capsule. Even NASA ha