ESAS UPDATE SPACECRAFT FEATURES DISCUSS. PART #1

mattblack · Oct 5, 2005

I'd like to start a discussion about the features of the proposed CEV, CLV, Lunar Landing Module & Heavy Lift Booster. We all know basically what they're to look like, but I'm intrigued as to how they'll compare with the specs of the Apollo craft we know so well. **NOTE: The names and some of the specs I want to use are provisional for the sake of this discussion and are subject to updates as I get them. C.E.V. "ARTEMIS", Command & Service Modules: CM: Mass -- 9 tons. Diameter -- 5.5 meters. Habitable Volume -- 386 cubic ft. (10.9 cubic m). (Apollo -- 5.9 tons, 3.9 meters, 210 cubic ft.) SM: Mass -- 6.5 tons, Propellant load 7 tons of Lox/Methane. Power Source -- 2x Gallium Arsenide 4.5kw Solar Arrays . Propulsion -- 1x RL-10 15,000lb thrust engine (6,600 kg) (Apollo -- 6 tons, 18 tons of Hypergolic fuels, 9,300 kg thrust SM Engine, Fuel Cells). Total "Artemis" Mass -- 23 tons. Independant Mission Endurance with a crew of 4 -- 21 or 30 days(?), Unmanned Loiter -- 6 months (Apollo/Skylab -- 3 months). "ATHENA" Lunar Surface Access Module: Total Mass -- 30 tons(?), Descent Stage Propellants -- 14 tons of LOX/LH2. ASCENT STAGE: Propellants -- LOX/Methane, Habitable Volume -- 350 cubic ft (10.5 cubic m). Descent Stage Propulsion -- 4x RL-10 engines at 15,000 lb thrust each (6,700 kg). Ascent Stage Propulsion -- 1x RL-10 6,700 kg thrust. Mission Endurance -- 12+days with a crew of 4. Power Source -- Fuel Cells. (Apollo LM: Total weight of 16 tons, Total Propellants -- 11 tons of hypergolics, Power Source -- Batteries, giving a mission endurance of 3.5 days with a crew of 2. Habitable Volume -- 160 cubic ft [4.65 cubic m]). Crew Launch Vehicle (CLV) "CAESAR", 5-Segment SRB Version: Payload to LEO -- 29 tons to 28.5 degree inclination orbit. "HERCULES" Heavy Lift Booster. Liftoff Thrust -- 9.28 million pounds (4.18 million kg) Payload to 28.5 degree LEO -- 125 tons. Ea <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>

tomnackid · Oct 5, 2005

I don't really like the idea of giving the spacecraft arbitrary names at this point. It will only cause confusion and contention and since these names almost certainly will NOT be used by NASA anyway what's the point? (I also don't like naming the CLV after an ancient Roman dictator--or is it the salad?)

mattblack · Oct 5, 2005

Well, perhaps I should name it "One Ring To Rule Them All" or something. Sheesh. Salad indeed. You've lived too long in some sort of politically correct dreamland. Still, point reluctantly taken. But the object was to discuss the upcoming engineering figures, not to get into the type of argument that seems to pass for discussion on parts of this forum these days... <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>

mattblack · Oct 7, 2005

Besides, which Caesar were you referring to? Julius, Augustus, Nero, Claudius or Caligula? Caesar was a title, not one man, in spite of what the tv show "Xena" might have told you. They weren't all dictators. <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>

nexium · Oct 7, 2005

Hi mattblack: You lost me at ESAS and every other line thereafter. Are you thinking the possesive of European Space Agency? To get more participation you need to explain repeatedly the abreviations. There are hundreds of them used each week in the missions and launch threads with one or two explained. Neil

mattblack · Oct 7, 2005

ESAS: Exploration Systems Architecture Study. http://www.nasa.gov/missions/solarsystem/explore_main.html You're right about acronyms; which is why I started to use provisional names after the establishment of what the acronyms meant -- CEV; Crew Exploration Vehicle. LLM; Lunar Landing Module etc. See the original post itself and the link for Nasa's details and pictures. <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>

mattblack · Oct 7, 2005

5.5 meters. Okay, Got it! Thanks, shuttle_guy. <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>

tomnackid · Oct 7, 2005

Yes, Ceasar is a title, its also where Czar is derived from--I didn't learn that on "Xena" either. If you want serious discussions then stop making snide, obnoxious comments.

mattblack · Oct 8, 2005

Sorry, but you're the one who came across as snide when you took me to task over using provisional names. I made abundantly clear why I was using provisional names, because a number of people have told me to resist using excessive acronyms, as if I INVENTED those acronyms!! And I DID say that your point was taken, albeit reluctantly. However, you must realise that I am quite within my rights to provisionally name these things, within the context of this discussion, just as you are within your rights to disagree with me. Now, as a bit sarcastic as my reply WAS (can't deny it) if you'd remonstrated several other characters on this forum, telling them what they can and can't do, you'd expect, clearer than you are sitting there reading this, a somewhat more hostile response than what you got from me. I've been on this forum for 5 years and I have NO desire to get into petty arguments of this type. That happens too much round here. Objecting to a roman term because it has something to do with millenia-old Imperialism and colonialism is far outside the context of my post. PLEASE accept my original post in the spirit and function it was designed in. Anything else and you'd be missing the point. Truce? Now; does anyone know if the combined CEV and er, LLM will enter lunar orbit together with a burn of the SM engine, like Apollo, or will the crew enter the LLM and make a direct descent to the surface, leaving the CEV to enter lunar orbit alone? The reason I ask is that the combined CEV & LLM mass is much higher than Apollo and I wondered if the CEV's engine would have enough delta-V to handle their combined mass, despite the increased power of Lox/Methane over hypergolics (Apollo). <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>

mattblack · Oct 8, 2005

By the way, tomnackid, your posts in the "liquid engines for CEV" discussion are quite good. <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>

mattblack · Oct 8, 2005

>>long burn & short burn<< True enough! <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>

darkenfast · Oct 9, 2005

I'm still not convinced that the payload capability of the CEV launcher is enough to loft both a 5.5m diameter capsule and a Service Module that has enough propellant to carry out all the burns neccessary for a lunar mission. This is based on the weights of the old Apollo. 25 tonnes is less than the Apollo CM/SM weighed. I realize that the Methane/LOX choice will give a nice improvement, but that lander is going to have to be a lot bigger as well. One possibility would be to use the descent stage of the lander, with its very efficient LH/LOX engines for the lunar orbit insertion burn. The provisional artist's conceptions seem to show a lot of tankage, although the LH is very bulky. Another possiblity would be retaining the Earth Departure Stage, although I think that is a much less desirable solution. Whatcha all think?

mattblack · Oct 9, 2005

No, the EDS wouldn't be retained, and the Nasa animations have shown that. The isp rating for Lox/Methane is about 20% percent better than Nitrogen Tetroxide and Di-Methyl Hydrazine, but even so as you pointed out, the CEV Service Module might not have enough propellant to insert into lunar orbit the CEV and 30+plus ton LLM and still have enough left for Trans-Earth Injection. Your idea about using the LLM's engines for LOI is a logical one with the CEV probably performing circularisation and plane-change burns. Perhaps the lunar missions might use the 5-segment SRB crew launcher to deploy a 29 ton CEV, not a 25 ton version. <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>

tap_sa · Oct 9, 2005

I believe S_G said in some other thread that five segment version is probable in the lunar missions. And NASA fact sheet about ESAS says the fifth segment adds seven tonnes to the payload capability giving total of 32t.

mattblack · Oct 9, 2005

Well then, things must have changed as several tables I've seen list the 5-segment launcher with SSME upper stage as being a 29.6 ton capable launcher. <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>

barrykirk · Oct 9, 2005

Mattblack, Wow, where did you find that data? That is so cool!!! I've never seen a table with that mixture of data. It even includes Max Q psf. I've heard the term before and talked posted about it and asked questions about it. But I've never seen a table listing Max-Q in actual pressure. I had no idea even the magnitude of it was. Thank you

ace5 · Oct 9, 2005

http://homepage.mac.com/karsten/Tech%20Ramblings/C105171974/E20050803223507/ http://www.spaceref.com/news/viewnews.html?id=1055 As far as I know, NASA is still trying to kill people using SRBs in manned spaceflight. Or, do they believe that just putting a LES launch escape system atop the CEV will save the astronauts from a catastrophic SRB launch failure? Sorry for the enthusiasts of theses SRB plans, but I find hard to believe that SRBs are safe for manned spaceflight as a whole.

henryhallam · Oct 9, 2005

The NASA requirement for the delta V capability is 1740 Meters a second. The Apollo capability SM was 2400 meters a second. I will be interested to see the details of the mission architecture, because this would leave VERY little margin for error if done using the same modules for the same burns as during Apollo. IMO, either the trajectory will be a low-energy one, requiring longer to get to the moon, or the LM DPS will be used for at least part of the LOI burn. I suppose another option is to enter a much higher lunar orbit than the ~60 nm of apollo. This would require less energy to get into and out of, allowing some of the dV burden to be transferred from SM/CEV to LM. (more efficient since you are only moving the mass of the LM, not the whole stack) This also makes the necessary plane change for long-duration landings less expensive. Dave, those figures are for the SM with CEV and LM attached, right?

darkenfast · Oct 9, 2005

"As far as I know, NASA is still trying to kill people using SRBs in manned spaceflight. " The SRB's have proven themselves. The SAIC report I refered to above analyzes that and other factors in regards to the CEV. The biggest potential problem I can see with SRB's on the Shuttle is if one were to light off and the other one didn't. This won't be an issue with the CEV. Statistically, just going from two SRB's down to one makes a big improvement in the numbers. No, I don't think NASA is trying to "kill" anybody.

ace5 · Oct 9, 2005

Look at what one of these boosters did with Challenger. You just need *one* to explode to really turn things into a complete mess. No, using liquid fuelled boosters are the right way to put men aloft. They´re safer.

mattblack · Oct 9, 2005

The Challenger SRB didn't explode, it 'sprang a leak' that torched the side of the E.T. for about 70 seconds. If the crew had had an escape system and the vehicle monitoring capability, they'd have had plenty of time to get clear. Even a serious leak on the Crew Launch Vehicle SRB would give the crew time to thrust away on the escape tower. <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>

barrykirk · Oct 9, 2005

I thought that the leak torched the side of the external fuel tank and that was what exploded.

spacester · Oct 9, 2005

Putting people on solid rockets is an idea that takes some getting used to. But all things considered, I think it makes sense. I suspect many of us will never be truly comfortable with the concept, but if it gets us to the moon, and it looks like it will, we'll just have to deal with it. <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

darkenfast · Oct 9, 2005

Ace5, this has been brought up many times, and again, it has been addressed in the SAIC report. Once again, for everybody, the propellant in both the SRB's and the ET will NOT detonate. In fact, solid rocket fuel can be shipped a lot easier, because it is classed as a flammable, not as an explosive. In the event of a burst casing, the CEV escape sytem would be able to pull the capsule away. In the event of an upper stage catastrophic failure, the escape system would be able to pull the capsule away. The Challenger disaster was caused by a jet of flame though a leaking seal (caused by freezing weather the night before) that impinged on the External Tank until the tank ruptured. The Orbiter was destroyed by aerodynamic forces when it swung sideways at supersonic speeds. This is exactly the kind of thing that a capsule is better at handling. But the odds are greatly against having to, because this problem was fixed years ago. There is nothing inherently safer about liquid-fueled rockets at this stage of development.

kane007 · Oct 10, 2005

Exactly. Re the Inline CEV SRB launcher. And to further emphasis there won't be a big heefer of an ET along side for a jet of flame from a broken seal to burn into. If it were to break AGAIN?!?

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