Major changes of NASA's exploration plans

[gunsandrockets]

"Well, when you turn it into the Shuttle-C you do eliminate some of the workforce, but your also creating a vehicle a lot cheaper then starting from scratch. This thing can put 100-tonnes into orbit if I remember correctly - thats a lot of stuff for one launch. I think the shuttle-C concept will save money in the end because its already half developed and the trainned workforce is already on hand. To me, it will finally make the shuttle system economical. "<br /><br /><br />I side with Rand Simberg (of transterrestrial.com) on the issue of heavy lift. The main arguement in favor of heavy lift is avoiding the hassle of LEO rendevous and construction. But if we are going to become a spacefaring civilization learning how to cope with LEO rendevous and construction is unavoidable. Even using heavy lift, multiple launches would be needed for just a single manned mission to Mars. And if instead of spending billions on developing a heavy launch vehicle we spent that money on building more of an existing medium lift vehicle, costs could be brought down due to scale of production efficiencies. The main reason the Russian Soyuz launch vehicle is so cheap is because they have built and flown hundreds of them, they crank them out like sausages.

 

[mrmorris]

<font color="yellow">"I can give you a reasonable estimate of the Lockheed CEV length and width just from the artwork in Popular Mechanics which describes the CM+MM+PS as 70 feet long. So the Lockheed CEV is 10 meters long and 6 meters wide. See how easy that is? <br /><br />I can't give an estimate yet for the overall dimensions of the Grumman CEV yet. But I will estimate the Grumman re-entry module has a habitable space of 8 cubic meters based on the Grumman artwork which shows (contrary to the Soyuz) an apparently larger re-entry module than the orbital module. These dimensions also nicely fit in with a re-entry module that could squeeze in six people (as opposed to only 4) with some minor redesign, and with an orbital module that matches up nicely with the Grumman Spiral Two design for using the transferred orbital module as the habitable space of a lunar lander. <br /><br />From this I felt pretty safe in saying the Grumman re-entry module (with 8 cubic meters) would be smaller than the Lockheed crew module (with 14 cubic meters). "</font><br /><br />You seem to have a great deal of difficulty separating estimates from statements of fact. You're indicating that you feel fully justified making a statement of fact (namely that the LM CEV is larger than the Grumman CEV) based on estimates generated from conceptual graphics. I wonder -- while you were basing your size estimates from the Grumman graphic -- based on your extensive knowledge of the Soyuz -- did you take into account the difference in launch vehicle sizes? The Soyuz ST has a diameter of 2.68 meters. By contrast -- the Delta-V Heavy which is the intended launch vehicle for the Boeing/Grumman CEV has a diameter of 5 meters. Since the Grumman graphic shows the vehicle using pretty much the full diameter of the core -- that would mean its diameter is ~180%

 

[mrmorris]

<font color="yellow">"How is that much different than for the Apollo CSM?..."</font><br /><br />OK -- one of us (or both) isn't understanding the other. You'd indicated in your previous post that much of the mass 'of the CEV' would be taken up by propellant for Lunar return. Specifically:<br /><br /><font color="yellow">"e) TEI burn from LLO (which is about a delta vee of 1 km/s) <br /><br />...calculate how much of the resulting vehicle's mass must be propellent to achieve a delta vee of 1 km/s."</font><br /><br />I don't believe the requirement in question meant that the <b>CEV</b> must have this level of delta-v. If the CEV does not have to have it (i.e. the dv can be supplied by the EDS), then it's not part of the 20-ton limit. The EDS is launched on a separate booster. This in turn means the volume of the CEV should indeed be a multiple of the Soyuz. As I indicated before 250% of the mass returns much more than 250% of the volume. Even if were assumed only 200% of the mass -- the habitable volume would triple or better.

 

[gunsandrockets]

"for the grammatically challenged"<br /><br />I had a feeling things would eventually devolve to the level of challenging my grammar. What's next, spelling?

 

[gunsandrockets]

"I don't believe the requirement in question meant that the CEV must have this level of delta-v. "<br /><br />Well so be it. Lockheed certainly thought NASA required TEI burn on the CEV. As shown in this document...<br /><br />Lockheed Martin's<br />System-of-Systems<br />Lunar Architecture<br />Point-of-Departure Concept<br /><br />CE&R BAA Open Forum<br />CA-1 (Basic Period)<br />Final Briefing<br /><br />01 March 2005<br /><br />On page 30 of the document "Key features differing from EMSD's POD" under the heading "Key LMC architecture feature" it lists "unified approach to upper stage and two transfer stages (no TEI on CEV)" . And under the heading "Resulting benefits if adapted by NASA" it states "Uses existing RL-10 engine, single production line, up to $1B program savings".<br /><br />In other words, instead of following the NASA requirement of TEI burn on the CEV, LM wants to separate that function out into a separate propulsion module. The LM plan is to use identical modules for a launch vehicle upper stage and for two propulsion modules for the CEV (one of which is for TEI). <br /><br /> <br /><br /><br /><br /><br />

 

[gunsandrockets]

"I agree. But the same goes for the shuttle, we've been flying it for decades and the proposed system is still going to resemble the same architecture (SP) as the STS system, just in a different format. If we're learning to become a spaceflaring civilization then 100 tones to LEO is going to be the future's light lift vehicle. In order to sustain an extended presence in space we are eventually going to need to develop heavy lift vehicles. If we can develop these vehicles for a lot cheaper and from exisiting hardware, then why should we scrub the opportunity. Besides this could be just the thing that will get the United States larger market share in launching payloads. "<br /><br />Unfortunately NASA's resources are limited. And I believe developing the HLV at this point would bankrupt NASA. I believe the shorter term (as in next 20 years) savings and greatest economy means forgoing HLV for now and focusing on MLV.<br /><br />It's unrealistic to expect in the near term the kind of numbers of HLV produced and flown that would generate economies of scale. How many years might it be before a Shutte C would even fly the first time? Then how long would it take for the flight rates to even equal 10 missions? 10 years combined? After all in the last 33 years there have been little more than 100 STS missions, and for part of that time all American missions of all sizes were forced to fly on the STS rather than use another booster.<br /><br />In that 10 years and with the billions used to develop HLV, we could mass produce MLV. And the MLV is available now, not several years from now.<br /><br />Now don't get me wrong, the case of HLV vs MLV isn't black and white. And who knows? Maybe a Shuttle C development would really turn out to be cheap and easy. That would be great. But in my opinion it would be taking a gamble. The question is can NASA afford to lose that bet?

 

[gunsandrockets]

" Since the Grumman graphic shows the vehicle using pretty much the full diameter of the core"<br /><br />Really? That's very interesting. So tell me where is the core shown in the artwork? At least you're trying now!<br /><br />As for your other comments, since we can't even seem to agree on the basic NASA RFP for the CEV I see little point in trying to reason with you. I have the feeling that if I said the sun sets in the west you would pounce to disagree!<br /><br />

 

[mrmorris]

<font color="yellow">"...challenging my grammar"</font><br /><br />Um yes. When you're claiming that I stated something that I clearly didn't. When you're unable to understand the difference between a statement and an estimate -- then I'll explain that difference to you... which I have. All part of the service. You're welcome.

 

[mrmorris]

<font color="yellow">" I see little point in trying to reason with you."</font><br /><br />I agree -- subject dropped.

 

[gunsandrockets]

As for your other comments, since we can't even seem to agree on the basic NASA RFP for the CEV I see little point in trying to reason with you. I have the feeling that if I said the sun sets in the west you would pounce to disagree!<br /><br /> "I agree -- subject dropped."<br /><br /> Well at least we agree on one thing, that you're unreasonable!

 

[alokmohan]

Peace,peace.