New AW&ST CEV article [Pow! Zoom! Straight to the Moon!]

[starfhury]

From what I am reading here, the assumption is that the CEV will be cable of at least two things. A return to earths surface from LEO or lunar orbit or even more radical, a return to earth after landing on the moon! That might explain the additional mass requirement Griffin wants. Is 30 - 40 tons enough to allow the CEV to land on the moon, boost back to orbit and then aerobrake and land again on the earth? Looked at long term, that might not be such a bad idea. Sure it makes the CEV heavier and possible bigger than it really could have been, but it would also eliminate developing a separate lunar lander. Right there is a cost reduction they can achieve by parts reduction and integration of functionality. <br /><br />This allows the option of a TLI stage to which the CEV attaches itself. The TLI stage will also return the CEV to earth orbit and partially slow it down for a combined rocket/aerobrake manuever back to earth. This only requires us to have a barebones TLI stage of nothing more than prop tanks and motors. This will allow NASA to sort of go the Shuttle route again. They would build 4 or 5 resuable CEVs to establish a fleet of them so that the core parts are not thrown away. This brings up an another interesting question. Would a stick launched CEV be able to achieve LEO with a rocket motor also capable of ascending from the lunar surface? It seems to me they might be going for a lot of integration. If that's the case the CEV might be more intersting that I originally thought. Could a second stage rocket motor attached to the CEV achieve earth orbit, and if it can can it not also achieve lunar orbit after landing on the moon? If both are true then NASA has a potential winner in my book. With this new insight, I have to go rethink what I thought about CEV, but the plans I've seen so far don't actually support it. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

"Is 30 - 40 tons enough to allow the CEV to land on the moon, boost back to orbit and then aerobrake and land again on the earth? Looked at long term, that might not be such a bad idea. Sure it makes the CEV heavier and possible bigger than it really could have been, but it would also eliminate developing a separate lunar lander. Right there is a cost reduction they can achieve by parts reduction and integration of functionality."<br /><br /><br />The mass of a vehicle that can do what you describe is 93.5 tonnes. It's very much like the First Lunar Outpost plan of 1992.<br />See this link for details and illustrations galore...<br /><br />www.abo.fi/~mlindroo/Station/Slides/sld051f.htm<br /><br /><br />"This allows the option of a TLI stage to which the CEV attaches itself. The TLI stage will also return the CEV to earth orbit and partially slow it down for a combined rocket/aerobrake manuever back to earth. This only requires us to have a barebones TLI stage of nothing more than prop tanks and motors. This will allow NASA to sort of go the Shuttle route again."<br /><br /><br />Oh heck no! Even the 93.5 tonne monster two-stage lander leaves most of it's mass behind and only returns a 6.5 tonne 4 man capsule back to the Earth's surface. The TLI stage alone needed to boost the lander towards the moon has a dry mass of 22 tonnes compared to the lander dry mass of 31 tonnes!<br /><br />The are only two ways to achieve your goal of a reusable moon lander which can travel from LEO to the lunar surface and back again.<br /><br />(1) Use Nuclear Thermal Rocket engines instead of chemical engines. Only a nuclear rocket has enough ISP to travel to the moon and back and carry a complete load of fuel.<br /><br />(2) With chemical rocket engines the only solution is to refuel from lunar derived materials after landing on the moon. A one stage chemical rocket is only capable of a one-way trip.<br /><br />Even

 

[starfhury]

Nice link. Truly the math sucks when it comes to this. If we can't exploit other options such as nuclear rockets, we are left in a pretty tight straight jacket. <div class="Discussion_UserSignature"> </div>

 

[vogon13]

Sounds like a job for Orion.<br /><br />Orion could deliver 10 million tons of shopping mall to lunar orbit.<br /><br /><img src="/images/icons/wink.gif" /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[starfhury]

ROFL. Orion is so dangerous, I don't know how anyone can even consider that monster any more. I doubt you'd survive watching that beasty launch from twenty miles away. <div class="Discussion_UserSignature"> </div>

 

[vogon13]

Put boron in radiation channel of directed energy effect nukes, put on some sunscreen, and watch Ishtar 2 at the Luna 20 Cineplex.<br /><br /><img src="/images/icons/smile.gif" /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[spacester]

The reason CEV will not be a true space vehicle is to have continuous abort modes. NASA cannot count on having the ability to rendezvous and transfer crew to CXV every time.<br /><br />A lot of mission architecture derives from that IMO.<br /><br />Later when CXV and / or orbital tourism is developed (using whatever financing), along with orbital refueling, the logistics of safe human space flight will allow true space vehicles. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

" Orion is so dangerous, I don't know how anyone can even consider that monster any more. I doubt you'd survive watching that beasty launch from twenty miles away. "<br /><br /><br />Ah Orion. The choice that was not taken. Sigh.<br /><br />In defense of the marvelous Orion drive, the liftoff from Earth involved very small atomic bombs of only 0.15 kiloton yield while inside the atmosphere. Outside the atmosphere the standard cruising bomb was only 5 kilotons yield. Hardly the kind of power to fry you from twenty miles away. Remember that the bombs are detonating only a couple hundred feet from the Orion spaceship itself. There's no point in frying the ship or it's crew!

 

[vogon13]

Great efficiency of Orion concept is due to the directional nature of the nuke blast. IIRC, a solid angle of 30 or 45 degrees is acheivable. Bomb detonates and radiation channel design 'focuses' blast at pusher plate. Putting boron in the radiation channel soaks up neutrons and couples the blast more efficiently to spacecraft. High efficiency of nukes is due to subcritical PU or U235 being maximally compressed by convential explosive lenses.<br /><br />One of the funny problems with Orion is the large size of the smallest practical ship.<br /><br />Around 4000 tons.<br /><br />Orion does scale up very nicely. Math has been done on 25 <i>million</i> ton designs. These ships would be assembled in orbit and propelled with multi megaton H bombs. In space, radioactive debris less of a problem, next solar storm to come by is worse than anything we can do. Flight times of less than 200 years to the nearest stars are possible.<br /><br />I can't take credit for this, but a staged Orion second generation concept would probably get you out to 20 lightyears in under 300 years. For a spacecraft with a launch mass of 50,000,000,000 pounds, this doesn't seem unreasonable. <br /><br />Orion is such a good idea, I would not be surprised if the first one mankind encounters is crewed by alien colonists headed towards us. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[skywalker01]

An interesting discussion with much food for thought.<br /><br />Regarding FLO<br />Since the SDHLLV being proposed has a payload capacity to LEO of 120 tonnes it would appear that FLO as shown is not an option.<br /><br />Regarding all the Lunar Exploration options/ideas that have been mentioned, I have yet to find one that makes use of any Lunar derived propellants.<br />Since one of the goals of this whole program is to make space exploration affordable and sustainable by using Lunar materials, it seems to me that we should be designing with that in mind from the beginning. For example, should we plan on designing the Lunar landing and return vehicles with LOX/RP so that we can use the same engines when Lunar LOX becomes available?<br /><br />And how soon in the program should we plan on having Lunar LOX available? ASAP? After an initial outpost is in place? Only after we have found a source of Lunar water so we can use LOX/LH2 engines?<br /><br />And what about LOX/Alum engines? <br />According to the Lunar samples returned by the Apollo program LOX/Alum is available just about anywhere on the Moon. <br />Should that be the Lunar operations propellant combination that we initially design for?<br /><br />The amount of Earth departing mass that will be required for a sustained program of space exploration of the Moon, Mars, and the asteroids and the resulting cost will be significantly reduced with an easy supply of Lunar derived propellant, but which one? <br />Is it a decision we should be making now as we design our first Earth/Moon transportation system or should we wait until we have explored the Moon enough to see if there is enough Lunar ice available to make Lunar supplied LOX/LH2 a reality. <br />But if Lunar LOX is a certainty wouldn't it be smart to at least plan on having that available ASAP in order to save money on launch vehicle development and mission costs in order to have a higher flight rate for exploration within what ever budget is going to be availa

 

[crix]

There's no way the first missions would rely upon lunar oxygen to get our astronauts back home. BUT, I do think that trying out ISRU technologies will have a high and very immediate priority. We're not going back to do pure science research. We're going there to test our ability to live permanently out of the cradle.

 

[gunsandrockets]

"Since the SDHLLV being proposed has a payload capacity to LEO of 120 tonnes it would appear that FLO as shown is not an option."<br /><br />Not true. If you go and reread the FLO link...<br /><br /> http://www.abo.fi/~mlindroo/Station/Slides/sld051f.htm<br /><br />...you will see, "(early FLO trade studies also investigated a dual-launch scheme where the spacecraft and translunar injection rocket stage would have been launched separately into Earth orbit on Saturn V-class rockets; the vehicles would then rendezvous and dock, and then the TLI stage launches the spacecraft toward the moon)."<br /><br /><br />You also said...<br /><br />"Regarding all the Lunar Exploration options/ideas that have been mentioned, I have yet to find one that makes use of any Lunar derived propellants."<br /><br />Earlier in the thread were links and images from LUNOX...<br /><br />http://www.abo.fi/~mlindroo/Station/Slides/sld051p.htm<br /><br /><br />You also said...<br /><br />"For example, should we plan on designing the Lunar landing and return vehicles with LOX/RP so that we can use the same engines when Lunar LOX becomes available?"<br /><br /><br />Most lunar derived lox plans involve rocket engines burning liquid hydrogen fuel. XCOR has proposed use of methane instead of hydrogen.<br /><br /><br />You also said...<br /><br />"And what about LOX/Alum engines? <br />According to the Lunar samples returned by the Apollo program LOX/Alum is available just about anywhere on the Moon. <br />Should that be the Lunar operations propellant combination that we initially design for?"<br /><br />XCOR during the 2004 LOSCON convention presented a fascinating proposal for using lunar derived aluminum and oxygen as rocket propellants. The unique thing about the proposal was the rocket engine would use liquid fuel. That's right, liquid aluminum as fuel!<br />

 

[skywalker01]

<<There's no way the first missions would rely upon lunar oxygen to get our astronauts back home.>><br /><br />No argument there. <br />But if affordability and sustainability are key issues it might drive us to select LOX and some storable fuel for our 'beyond Earth orbit' transportation system so that we don't have to redesign our vehicle propulsion systems when Lunar LOX does become available.<br /><br />Also, since Lunar LOX appears to be available anywhere on the Lunar surface, it does simplify site selection for the initial Lunar outpost. Designing for early availability of Lunar LOX would also allow us to return to an Apollo style mission arrangement versus the Earth Orbit direct method shown in the FLO concept as our initial base could be located on the Lunar equator. That alone would reduce the amount of mass needed to be launched from Earth by half, which would mean twice as many flights for a given budget.

 

[skywalker01]

I am sorry I missed the link to the LUNOX plan before. When I downloaded it the first time the top of the screen looked the same as the FLO plan and I jumped to the conclusion that it was another link to FLO.<br /><br />The LUNOX plan looks really good to me.<br />I like the use of Lunar LOX (right from the beginning (something I didn't think possible)).<br />I like the use of exploration tractors right from the very beginning. <br />I like the fact that it is a basic exploration plan that could also be used for exploring Mars.<br />I like the fact that it uses a 'Shuttle-C' type of launcher which is a lower cost to develop vehicle then the inline version. <br /><br />Congratulations to the people who came up with it. <br />This appears to be the plan to beat if anyone is to come up with something better.<br /><br /><br />Regarding LOX/Alum rocket engines.<br />I have a report in my files somewhere that tells about the building and test firing of a LOX/powdered alum rocket motor where the LOX and powdered alum were mixed together and stored in a single tank. According to the report it worked great.<br /><br />Regarding the dual launch FLO concept. Yes I saw that but it seemed to negate so many of the reliability advantages of the single launch FLO that my first blush assessment of it was to want to return to the Apollo concept for half the price.<br /><br />Looking beyond the initial Lunar exploration plan to when a permanent base/outpost for Lunar LOX production is being planned (along with the production of any other worthwhile Lunar derived exports), that might be the time to start thinking about the building of an Earth Orbiting Elevator as shown at<br />http://www.affordablespaceflight.com<br />for an even lower cost Earth-Moon transportation system.

 

[gunsandrockets]

"Regarding the dual launch FLO concept. Yes I saw that but it seemed to negate so many of the reliability advantages of the single launch FLO that my first blush assessment of it was to want to return to the Apollo concept for half the price."<br /><br />I think many people overestimate the difficulty of orbital assembly and underestimate the difficulty of flying giant rockets. And it's even more puzzling to me considering the extensive flight experience over the last 45 years.<br /><br />In a recent editorial by Zubrin he advocated going with a small CEV in order to use Moon Direct. What I found pretty odd is that he advocated the Moon Direct 'small CEV' in conjuction with the proposed Saturn V class Shuttle Derived Heavy Lift Vehicle. But the SDHLV using Moon Direct only has enough capacity for a two man CEV at best, not a four man CEV! That's one small CEV.

 

[skywalker01]

<<I think many people overestimate the difficulty of orbital assembly and underestimate the difficulty of flying giant rockets. And it's even more puzzling to me considering the extensive flight experience over the last 45 years. >><br /><br />I agree. I have been a proponent of small payloads, small launch vehicles, high payload fractions, high flight rates, and orbital assembly for quite some time as a way of getting the cost of manned space travel/exploration down to a reasonable cost. <br />The dual FLO launch looks to be the worst of all worlds when it comes to cost -- very large launch vehicles, with very low flight rates, with low payload fractions, and with orbital assembly. That is not a path that leads to a sustainable and affordable program of manned space exploration.<br /><br />The best concept I have seen for a sustainable program of affordable manned space flight/exploration for the Earth surface to Earth escape portion of the flight, based on existing technology, is the Earth Orbiting Elevator shown at<br />http://www.affordablespaceflight.com<br /><br />Use that to boost the LUNOX vehicles to Earth orbit and then to escape velocity for their trip to the Moon and watch what happens to the cost per flight.<br /><br />It also works for Mars exploration. Combine the Earth Orbiting Elevator with the Earth/Mars cycler spacecraft concept and the LUNOX concept adjusted for Mars orbit to Mars surface operations.<br />

 

[gunsandrockets]

"The best concept I have seen for a sustainable program of affordable manned space flight/exploration for the Earth surface to Earth escape portion of the flight, based on existing technology, is the Earth Orbiting Elevator"<br /><br />Sorry, a 300 km plus long spacestation is bit too much science fiction instead of near term 'existing technology'. But since you are so keen on the topic perhaps you should start a brand new thread with the Earth Orbiting Elevator as the subject.<br /><br />I've got nothing against exotic methods of space travel, some of them I am even quite favorable towards. But I prefer examining systems which are real world solutions and near term applications.

 

[skywalker01]

<< Sorry, a 300 km plus long spacestation is bit too much science fiction instead of near term 'existing technology'. But since you are so keen on the topic perhaps you should start a brand new thread with the Earth Orbiting Elevator as the subject. <br /><br />I've got nothing against exotic methods of space travel, some of them I am even quite favorable towards. But I prefer examining systems which are real world solutions and near term applications. />><br /> <br />Sorry to see you are so closed minded. <br />I was enjoying the discussion up to now. <br />Nor do I view hanging both an upward and a downward pointing graphite rope from the ISS as beyond the realm of existing technology -- but then I used to build tree houses when I was a kid that included a rope for climbing up to it.<br />But hey, if a long piece of graphite rope is too high tech for you, so be it.<br /><br />As to my reference to the Earth Orbiting Elevator being off-topic, considering this thread was all the way back on page 7 when I first posted on it due to inactivity I think you are stretching a bit with the territorial nonsense. But if that is the way you want to play it that is fine with me. <br />For myself I see your close mindedness and need to control as just another example of why NASA has become such a great example of 'not invented here' and 'no progress allowed' over the last 30 years.<br /><br />Good Luck to you.<br /> <br /> <br /><br />

 

[gunsandrockets]

"Sorry to see you are so closed minded. "<br /><br />"But if that is the way you want to play it that is fine with me. "<br /><br />Yikes! Touchy touchy touchy. I meant no offense and I was genuinely trying to be helpful not dismissive when I suggested you might want to start a new thread. I think the Earth Orbiting Elevator is a new idea deserving of a new thread that many would be interested in, but it is rather off topic for this thread about NASA moon plans.<br /><br /> <br />I've seen more than enough ill will in the space forums already. I'd hate to see more especially if it stems from misunderstanding.

 

[gunsandrockets]

"Saturn V had 120 tons ( OK 118 ) Only 47 Tons went TLI, the rest got burned up in order to get them there. I would expect similar numbers since we still burn the same stuff and physics have not changed recently."<br /><br /><br />Consider this, without propellant the combined mass of the Saturn V third stage and the CSM and the LM is only 30 tonnes. The combined mass of the propellant carried by those vehicles is 134 tonnes. If you used a nuclear thermal rocket just for the Saturn stage you could cut 60 tonnes out of that weight.<br /><br />

 

[tap_sa]

<font color="yellow">" If you used a nuclear thermal rocket just for the Saturn stage you could cut 60 tonnes out of that weight. "</font><br /><br />And if you use solar thermal you could cut another 10 tonnes and get the environuts off your back.

 

[skywalker01]

<<I meant no offense and I was genuinely trying to be helpful not dismissive >><br /><br />You were being closed minded and dismissive but I'll let it go.<br /><br />And no I do not see the Earth Orbiting Elevator concept as being off-topic in this discussion. It is simply another way of going from Earth orbit to TLI at a very low cost, and it works with existing materials and technology.<br />(Note: The Earth Orbiting Elevator is not the same as a Space Elevator)<br />And since it does effectivly eliminate the need for an expendable TLI stage, notice how much mass no longer needs to be lifted to Earth orbit for going to the Moon.<br />With the Earth Orbiting Elevator and a reusable Lunar Lander that uses Lunar supplied propellants that is based at the Lunar Outpost, all you need to go to the Moon from Earth orbit is the modern day equivalent of an Apollo Command Module and Service Module.<br />That is sure a lot more affordable and sustainable then either FLO or LUNOX by themselves.<br /><br />And please be clear that I am not proposing that we hold off on returning to the Moon while an Earth Orbiting Elevator is built. <br />What I am proposing is that people start thinking about what can be done to reduce the cost of going to the moon once a Lunar Outpost has been established so that we end up with an affordable and sustainable space program and not another defunct Apollo program once the excitment wears off with the general public.<br />

 

[gunsandrockets]

Latest Developments on NASA Plans for Return to the Moon<br /><br />According to this article from thespacereview.com...<br /><br />http://www.thespacereview.com/article/418/1<br /><br />...the Moon Direct plan hinted at in the earlier AW&ST article appears to be dead. Here is the relevant text...<br /><br />"...After 2010, the focus of the exploration plan would shift towards human missions to the Moon, with the development of a heavy-lift launch vehicle, Earth departure stage, lunar lander, and other systems needed for human crews to live and work on the lunar surface... "<br /><br />"...The technical details of those human lunar missions will not be surprising to those who have either followed the debate on the topic in recent months, or who remember Apollo. “One of the lessons that we’ve had from this exploration systems architecture study, at the large level, is, ‘Boy, those guys from Apollo were really smart,’” Shank said. “The physics hasn’t changed, and the orbital mechanics hasn’t changed.” As a result, the general mission architecture has a number of similarities to Apollo, including the use of the lunar orbit rendezvous approach, where the lunar lander ferries crews between the CEV, in lunar orbit, and the surface of the Moon..."<br />

 

[gunsandrockets]

"And if you use solar thermal you could cut another 10 tonnes and get the environuts off your back. "<br /><br />I don't think solar thermal has a thrust to weight that comes anywhere near NTR, so I think solar thermal is out for a launch vehicle. An orbital transfer vehicle on the other hand is something else. Do you have any performance numbers on solar thermal to share? ISP? Thrust to weight?

 

[skywalker01]

That is a very interesting article.<br />I found the comments about not being able to afford MtM unless costs can be reduced in such activities as ISS resupply especially revealing.<br />Hopefully this will give some of the small launch vehicle start-ups a chance to show what they can do and will open up the field to some of the untried ideas that have been floating around for years but never tried.<br /><br />