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

[gunsandrockets]

The most recent Aviation Week & Space Technology has an article on possible drastic revision of NASA plans for reaching the moon and the requirements for the Project Constellation CEV.<br /><br />The current NASA flight architecture, and around which the current CEV requirements are based, assumes that like the Apollo mission before the CEV will use low-lunar-orbit rendezvous with a separate lunar lander which would land on the Moon and return to lunar orbit. But now NASA is considering instead direct access without using a separate lander.<br /><br />Draper has a contract with NASA to study lunar flight architecture, and considers the Apollo architecture inferior because of "new technology". After looking at thousands of different architectures, supposedly Draper is recommending a bi-conic capsule CEV, with a lift-to-drag of 0.6, which would land on the moon using a descent module and return to Earth using an ascent module. A separate habitat would provide the crew with Moon quarters (presumably landed via another descent module).<br /><br />It is already anticipated that NASA will amend the original CEV RFP with the requirement for ISS access. Depending on the final decisions NASA makes on the flight architecture, the additional requirement of landing on the moon could be added as well.<br /><br />I would certainly like more details of this supposedly superior flight architecture that Draper is pushing.

 

[larper]

Gods, it is like NASA doesn't even read its own history! When you go to the moon, you DO NOT LAND YOUR RETURN VEHICLE! You land your habitat, which stays, and your ascent vehicle.<br /><br />This is getting crazier every day. Enough is enough. Put Tom Hanks and Ron Howard in charge of NASA. At least they have researched how it was done in the past. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[adzel_3000]

Here is an image almost like what you describe. It was at the Charles Stark Draper Lab site:<br /><br />

 

[wvbraun]

This sounds very much like the First Lunar Outpost architecture (the lunar reference mission Griffin and his team designed in the early 1990s). I like it. <br /><br />larper<br /><br />It makes sense to land your return vehicle on the moon. It makes the whole operation a lot safer because you can abort to Earth at any time.

 

[wvbraun]

FLO<br />

 

[gunsandrockets]

Yikes! Big! A suped-up Saturn booster to fire a monster 95 tonne manned ship to the moon. I'm not sure that that mass cost is worth the benefit.<br /><br />From the FLO link you provided...<br /><br /><br />"FLO lunar descent. Unlike Apollo, the entire spacecraft (including Earth return capsule) is landed on the Moon. The NASA designers settled for this configuration since it would enable the lunar crew to leave from landing sites in middle latitudes. Leaving the Earth return vehicle in lunar orbit would save weight, but the lunar lander would not be able to rendezvous with the mothership on some days due to unfavorable orbital mechanics. "<br /><br />Lockheed has a different idea for their Moon plan. Rather than land several expeditions all over the Moon, they want to build up a central Moon base located in the equatorial region facing Earth and explore the rest of the Moon from the base using manned and unmanned hoppers and rovers.<br /><br />Lockheed cites several advantages for their plan, one of which is that the Moon base is a model of a plan that can be applied to Mars as well. Other advantages claimed are, using the base as a Moon safe haven instead of relying on aborts to Earth, greater mass transport from Earth to the Moon equatorial zone, constant direct communication link from Moon base to Earth, and free Earth return flight abort ability when travelling to the Moon.

 

[gunsandrockets]

Here is a link to another image of that spacecraft...<br /><br />http://www.abo.fi/~mlindroo/SpaceExp/l_phnx1.jpg<br /><br />The spacecraft is the "Phoenix" from the 1993 LUNOX plan!<br /><br /><br />"Phoenix" manned lunar spacecraft launch. After a sixth unmanned logistics cargo flight has taken place, the stage has finally been set for the first lunar outpost astronauts. The crew of four is carried into space by a "Shuttle-C" type heavy lift vehicle (HLLV). The HLLV is relatively inexpensive since it uses mostly off-the-shelf hardware from the Space Shuttle program, but it is not powerful enough to inject a fully fueled manned lunar lander. Therefore, the "Phoenix" lander only carries enough oxygen propellant to land on the Moon. Its tanks will be refueled with oxygen mined from lunar soil by the LUNOX plant. The "Phoenix" weighs only 33,684kg after the translunar injection rocket burn -- much less than the original FLO spacecraft from 1992 which weighed 95,000kg"<br /><br />Here is the link to LUNOX...<br /><br />http://www.abo.fi/~mlindroo/Station/Slides/sld051p.htm

 

[kane007]

"Space 1999" anyone?

 

[kane007]

Found it

 

[nacnud]

yep, but just because Sci-fi got there first doesn't make it any less of a good idea.

 

[starfhury]

The one problem I see with your method is that we have to build several different crafts and launch them on separate boosters. Now each of these items by themselves might be relatively cheap. In the end you will end up with several relative cheap vehicles which add up to a lot of expense. I like what they had to say about the Apollo approach. Draper claims that it was ahem "inferior." That ought to draw a lot of fire from Apollonauts. <br /><br />I think here's a perfect opportunity to go the nuclear route with the space based CEV. Launch the crew return module to space and attach it to a nuclear propulsion module which will not only be twice as efficient as any chemical rocket, but might have the ability to land and take off from the moon again due to its low gravity compared to earth. I hope Griffin has the cahones to be daring and take this approve. I think it'd be the best approach for us to take. <div class="Discussion_UserSignature"> </div>

 

[gladiator1332]

The FLO plan is rather interesting, and the pure fact that Griffin was a part of its development, leads me to believe that it will be the approach that NASA uses. This plan along with the T/Space CXV for LEO would be a great combination.

 

[grooble]

Nothing wrong with developing a specialised mars CEV lander in the 2020s right? I mean it'd only be 2 or 3 years work as the design, interface, docking is all there already. Perhaps it would just have no landing equipment and improved propulsion.<br /><br />2020s will see some awesome tech available.

 

[frodo1008]

Good Grief!! The only two ways such large amounts of material could be sent to the moon are:<br /><br />(1) In orbit assembly of such a vehicle. Even this would require many launches of either the Delta Heavy or the Atlas Heavy (could LM be interested in increased launches of the Atlas V Heavy when it becomes available??). This type of in orbit assembly is indeed possible, but brings up both safety and budget consideration. If NASA is going to even contemplate such a large program this is probably the cheapest and quickest way to go.<br /><br />(2) Launch the entire system from earth in one launch. I do not remembeer what the weight of material the Saturn V could actually get to the moon's surface but I would be willing to at least think that it was considerably less than what LM is now thinking of. THis would mean a LARGER launch vehicle than the Saturn V!! Ouch! How is NASA going to pay for the development of such a launch system, let alone have it ready in the time frame of the CEV? Even with the advances that have been made withing the space launch industry since the 1960's this would be almost impossible. It took some 400,000 of us (I was one of those, a very small frog in a very large puddly, but a frog in the puddly never the less) to develope and build and fly the Saturn V. I seriously doubt if there are 100,000 qualified people left within the industry at this time. <br /><br />No, even if this large a program could be done at all I think that door #1 is the only way it could be done!!

 

[henryhallam]

<font color="yellow"><br /> I do not remembeer what the weight of material the Saturn V could actually get to the moon's surface but I would be willing to at least think that it was considerably less than what LM is now thinking of. <br /></font><br /><br />Right - The total mass delivered to the lunar surface including the LM descent stage was ~6550kg during the Apollo missions. Using the same general Apollo architecture but some reconfiguring (minimal unmanned CM, less SPS propellant, bigger LM descent engine, very minimal LM ascent stage - just RCS + AGC) a single Saturn V could get approx. 10000 to 11000kg payload to the lunar surface if a return journey were not desired. By doing more major reconfiguration such as using a single engine for lunar orbit insertion and descent, this could be increased to perhaps 14000kg to 15000kg. But really, not much more than that is possible with a Saturn V-type vehicle. <br /><br /> I am (very slowly) working on a concept study of a nuclear-electric Earth-Moon-Earth cargo tug which can get approx. 39000kg payload to the surface on every trip. Each trip takes ~6 months and requires two ~80000kg shuttle-derived heavy lift launches (one is a propellant tank, the other is the payload and descent engine, while the nuclear reactor and ion engines are reused). I think an approach along these lines is the most economical way to get a well-equipped moonbase to the surface, since space-capable nuclear reactors are likely to be developed anyway for use on the surface.

 

[mrmorris]

<font color="yellow">"I am (very slowly) working on a concept study of a nuclear-electric Earth-Moon-Earth cargo tug which can get approx. 39000kg payload to the surface on every trip. "</font><br /><br />I should probably spend some time Googling before making this post -- but if you're much of the way along in this plan -- you may already have the figures.<br /><br />From seeing a NASA study using a similar system -- nuclear tugs aren't allowed to come below a 'nuclear-safe' orbit of ~700km. I'm wondering what the dv requirements are to get from a 700km orbit to LLO and a dv range to get from LLO to the surface (obviously highly variable depending on what part of the surface is targeted, orbit, etc.) <br /><br />The reason I ask is because I <b>think</b> that the amount of dv required to go from LLO to the surface is a good bit more than that required to go from LEO to LLO -- especially for cargos which do not have to get there in a hurry and can use low-dv trajectories. If this is true, then propellant savings from a nuclear tug that allow for increases in the payload reaching LLO are then going to be eaten back at the far end by increased propellant requirements to get that larger payload down to the surface. All things being equal -- this is still going to allow for a larger payload to the lunar surface -- but less of one than might initially seem to be the case.<br /><br />However, all is speculation, of course, since I haven't done calculation one. <img src="/images/icons/smile.gif" />

 

[henryhallam]

I haven't seen that NASA study (would love to if you have a link) but I'd assumed a nuclear-safe earth orbit altitude of 650km which is close enough that I won't bother to recalculate things for 700km right now.<br /><br />dV from a ~100km lunar orbit to surface at the equator is about 2200m/s, I would probably allocate about 2400m/s for some margin. Apollo had 2470m/s but they often finished with at least 5% propellant in the tank.<br /><br />dV from a 650km earth orbit to a 100km lunar orbit is approx. 3950m/s by my reckoning - BUT this is for what's more or less a Hohmann transfer. Using a spiral trajectory as would be necessary with ion engines is going to be different, but I don't know exactly how much and this is one of the largest unknowns in my figures at the moment. I have seen Smart-1 quoted at 3500m/s but this is from geostationary transfer orbit and I'm not sure what its lunar orbit is like. So I was conservative and assumed 4400m/s would be necessary for the calculations.<br /><br />So ion propulsion is definitely worthwhile if the development costs are cheap enough. My lunar tug also saves launch mass by reusing the engine and reactor because getting back to Earth requires only about 15 tonnes more propellant once the payload is dumped.<br />This would probably go some way towards appeasing the hippies as well, since you only launch the nuke once.<br /><br />So you're quite right that it isn't a totally revolutionary leap, but I think that a well-designed nuclear tug could deliver about 1.8 times as much payload to the lunar surface than a chemical rocket for the same launch mass. -I- think that the extra development costs would be worthwhile if a permanent moonbase is planned, but NASA may disagree.

 

[mrmorris]

<font color="yellow">"I haven't seen that NASA study (would love to if you have a link)"</font><br /><br />I haven't a clue where to find it at the moment. Ran across it several months back. I don't know if I found it while researching G-X3, or linked from an article, or was just browsing space stuff for the heck of it. It wasn't much on details -- just a Powerpoint presentation. I just remember a slide showing Earth at the bottom, the moon at the top (not pictures/circles -- just a tick mark indicating 'you are here'), with varying orbits in between. Then at varying heights on the page -- it showed the systems which would operate in that particular range of the trip (i.e. earth to LEO, LEO to LLO, LLO to surface).<br /><br />Obviously if this is under consideration, there is a reasonable amount of mass savings/advantage in using a nuclear tug. I feel reasonably confident that NASA has run the numbers, and they wouldn't consider going nuclear, with all the R&D expense and publice relations nightmares that implies unless it were. However, I wondered if the savings were really that significant for the moon, or if it was being included more as a precursor for Earth to Mars -- where the benefits of such a system are considerably more manifest.<br /><br /><font color="yellow">"3950m/s by my reckoning - BUT this is for what's more or less a Hohmann transfer."</font><br /><br />Orbital mechanics are <b>not</b> my strongpoint. However, I understood (or thought I did) that there are a couple of considerably lower-dv trajectories to the moon than a Hohmann. I did some Googling (as I said -- should have done so before -- but didn't have time right then) and found this paper on a lunar sample return mission. They have several different trajectory options described -- with TLI dv's as low as 3100m/s.<br /><br />Still not what I thought initially, though. I w

 

[gunsandrockets]

"I think here's a perfect opportunity to go the nuclear route with the space based CEV. Launch the crew return module to space and attach it to a nuclear propulsion module which will not only be twice as efficient as any chemical rocket, but might have the ability to land and take off from the moon again due to its low gravity compared to earth. I hope Griffin has the cahones to be daring and take this approve. I think it'd be the best approach for us to take. "<br /><br />I fully agree about deep space propulsion, it's the key to everything including reducing the total mass needed in LEO which in turn reduces the need for massive numbers of massive boosters.<br /><br />"The one problem I see with your method is that we have to build several different crafts and launch them on separate boosters. Now each of these items by themselves might be relatively cheap. In the end you will end up with several relative cheap vehicles which add up to a lot of expense."<br /><br />Here I disagree. Specialization is what allows you to reduce the total number of booster you need to accomplish the mission. The bulk of space mission costs are from the massive rockets needed to lift payloads up from the Earth's surface. The payloads themselves once they are securely in orbit are tiny and cheap in comparison.<br /><br />It was the multiple specialized spacecraft of Apollo that allowed a trip to the moon and back while only using a single Saturn V booster for the job. Until the radical plan of lunar-orbit-rendezvous with a specialized lunar lander was accepted it was going to take two or more Saturn V rockets to do the same job.<br /><br /><br />And there is another type of specialization aside from purpose designed landers. The different qualities of the types of propulsion systems and the different needs of manned vs cargo deep space missions are so radical it begs for purpose designed separate spacecraft. Manned craft need short flight times, cargo flights don't. High thrust propulsion

 

[gunsandrockets]

"The way it sounds is that the CEV is being design to specifically for the moon."<br /><br /><br />Not really.<br /><br /><br /><br /><br />"Someone mentioned a lot of vehicles... well i don't want a CEV for the moon and then a CEV for mars and then a CEV for the ashtroid belt."<br /> <br /><br />It all depends on what we mean by CEV of course. The general understanding is the CEV will be the manned spacecraft for leaving the Earth's surface and for returning to the Earth's surface after accomplishing some LEO or deep space mission.<br /><br />So, with this understanding, the CEV is a specialized vehicle. The CEV is the specialized 'Earth lander' of Project Constellation. So long as the original CEV design is able to land on Earth after returning from a mission to Mars, the same CEV should also be capable of moon return or LEO reentry without any changes.

 

[gunsandrockets]

"Good Grief!!"<br /><br /><br />Yep. The 1992 FLO plan Moon Direct spacecraft is pretty massive at 95 tonnes.<br /><br /><br />"The only two ways such large amounts of material could be sent to the moon are: <br /><br />(1) In orbit assembly of such a vehicle...<br /><br />(2) Launch the entire system from earth in one launch. I do not remembeer what the weight of material the Saturn V could actually get to the moon's surface but I would be willing to at least think that it was considerably less than what LM is now thinking of. [side note: this isn't the LM plan, it's (possibly) the new NASA plan] THis would mean a LARGER launch vehicle than the Saturn V!! Ouch! How is NASA going to pay for the development of such a launch system, let alone have it ready in the time frame of the CEV?... "<br /><br /><br />Well as we can see from the news since the time you posted, it seems the answer from NASA is in-orbit assembly combined with super-boosters! And yes, the cost of such a super-booster could very well break the bank of NASA.<br />

 

[radarredux]

> <i><font color="yellow">The general understanding is the CEV will be the manned spacecraft for leaving the Earth's surface and for returning to the Earth's surface after accomplishing some LEO or deep space mission</font>/i><br /><br />More recent words from Griffin is that he wants to the CEV to go from Earth surface to Lunar surface and back to Earth surface. No rendezvous, no docking, no crew exchange. I don't think I have heard of anything regarding the CEV's role with respect to Mars missions.</i>

 

[gunsandrockets]

"More recent words from Griffin is that he wants to the CEV to go from Earth surface to Lunar surface and back to Earth surface."<br /><br />Well there is the AW&ST article I refered to at the very start of this thread. If you have some other news about statements Griffin has made supporting Moon Direct flight architecture please share it and post a link.

 

[gunsandrockets]

"The CEV is an earth lander. That is inefficent. Why am I going to return to earth in a 30 tonne vehicle when a private group like t/space can return me to earth using the CXV."<br /><br /><br /><br />Assuming it ever flies the t/Space CXV is only capable of reentry from LEO. The NASA CEV is supposed to be capable of Earth reentry while returning from the moon or Mars as well as LEO. Reentry velocities are much higher from beyond the top of Earth's gravity well than from only 2/3 of the way up. <br /><br /><br /><br /> "The advantage is that I dont have to launch a 30 tonne vehicle into LEO to begin another mission because its already waiting for me in LEO."<br /><br /><br />We don't know if the mass of the CEV will be as high as 30 tonnes, or how much would be dry mass, that's very speculative at this point. The best evidence still suggests the CEV will gross less than 20 tonnes. <br /><br /><br /><br />"The CEV should specialize in deep space missions, not landing on earth. Why do we need a 30 tonne vehicle just made for returning astronauts to earth, thats a waste of to many things to list here."<br /><br /><br />The NASA CEV is intended for Earth reentry from deep space. The alternative of using rocket engines to slow a spacecraft down for capture into LEO is much less efficient and uses much more mass than simple atmospheric reentry.<br /><br /><br /><br /><br />"But I do agree that we need specilized vehicle for each mission. The CEV's mission is to travel deep space. It shouldn't be a one size fits all by landing and taking off from planets, it should carry the people and the equipment saftly from point A to point B."<br /><br /><br />An orbital transfer spacecraft is a completely different issue and the NASA CEV does not conflict with it, in fact it complements it. The CEV is the way an orbital transfer spacecraft can receive and send crew back to Earth similar to the way an orbital transfer spacecraft would use a Mars Lander to access the surface of Mars.<br /><br />Finally I do

 

[henryhallam]

<font color="yellow"><br />The NASA CEV is intended for Earth reentry from deep space. The alternative of using rocket engines to slow a spacecraft down for capture into LEO is much less efficient and uses much more mass than simple atmospheric reentry.<br /></font><br /><br />I would like to emphasise this point because I'm not sure how well it's understood by everyone on this board. To slow a spacecraft returning from the Moon or Mars back to LEO without aerobraking requires a rocket almost as large as that used for the Earth Departure Stage - as a rough rule-of-thumb you can multiply the spacecraft mass by about 1.3 and that is the ADDITIONAL mass of the rocket required to slow you into LEO. Of course this means that the Earth Departure Stage now has to be MUCH BIGGER in order to accelerate both the spacecraft and its braking rocket out to the Moon, Mars or wherever. Furthermore, this braking rocket HAS TO WORK on time,or you go flying off into interplanetary space with pretty much no hope of return! Overall atmospheric braking is pretty much vital for manned missions. You could use just enough atmospheric braking to return you to LEO, but the heatshield required for that is nearly as heavy as one required to completely re-enter so you may as well go all the way to the ground.<br /><br />Unmanned spacecraft returning from the moon (Mars, less so) have a couple more options: they can either use an ion drive to brake into orbit much more efficiently (but taking months to do it) or a small rocket burn at perigee combined with repeated passes through the very high upper atmosphere to slowly aerobrake to LEO - without a heavy heatshield, but again taking months.