News on Euro-Russian CSTS

[PistolPete]

A lot of the numbers that I stated in my example have very very narrow margins of error, some with absolutely no margins. 200kg of propellant could mean the difference between having a flawless mission and not getting home.<br /><br />While Murphy does throw monkey wrenches in every plan, the thing that he loves to wreck the most are plans that require precise timing and coordination. Rocket don't blow up as much as they used to, but one thing that does happen more than a lot is that launch schedules tend to slip for various reasons (take the current STS mission for example). Windows to Lunar orbit don't come around every day and sometimes it may be a month or more before the next launch window opens up. If you plan a mission that requires precise timing with little to no margin for error then it will fail virtually every time.<br /><br />Ok, so you need to plan a little bit of redundancy into the system, this means extra weight. The TLI stages are already at the maximum for the booster that they will be launched on (actually the Angara KVRB stage already weighs a little bit more than what can be carried by a Proton M). So the logical answer would be to split the TLI stage into two separate loads launched on two separate rockets. Now we've gone from 4 to 6 boosters. Because of the time it takes to turn around a launch pad it may be several months between the launch of the lander and the launch of the crew.<br /><br />But bear in mind that the original LK lander was designed to take only one cosmonaut to the lunar surface for a few hours. Using modern technology you might get the crew size up to two, but I doubt that you could make it last much longer. For anything longer than the stereotypical "flags and footprints" mission you need either a bigger lander, or a separate cargo lander. Either way you work it this means that you now need anywhere from 2 to 4 more launch vehicles. Now you've gone from 6 to either 8 to 10 Proton launches.<br /><br />Now let's assume t <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[MeteorWayne]

PistolPete<br />While I agree with the gist of your post, I have one question. You said:<br />"Windows to Lunar orbit don't come around every day and sometimes it may be a month or more before the next launch window opens up."<br /><br />I don't see why. Lunar mission begin with a launch into near equatorial LEO. You can leave that orbit at the proper spot on any orbit., since the moon is "roughly" in the same plane, unless your propellant margins are too tight.<br /><br />Still plenty of room for Murphy Wrenches, though. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[ckikilwai]

ok, all the engineering stuff is a bit over my head <img src="/images/icons/laugh.gif" /><br />I also see that launching so many rockets isn't the solution for real lunar exploration on the long term.<br />But it would be useless that engineers start talking how they would really take a spaceship to the moon, while they have only limited funds for studying the spaceship only.<br />And that's the problem ofcourse, in Europe we can't start a whole moon program, because it would never be approved by the European ministers.<br /><br />So we are doing it step by step, first the ATV and the Columbus module, maybe a manned spaceship that has the capability to be flown to the moon, and later on, when Europe and Russia are ready for it, build bigger rockets and lunar landers and join the Americans in building a lunar base.<br /><br />and just a thought: the reason why multiple launches are mentioned by ESA, could it just be to "fool" Europe's ministers, because if they said that they actually need new heavy rockets, the ministers would never approve the plans for the CSTS?

 

[PistolPete]

I had to search the Internet a little bit to find the answer. Below is a link that details the launch windows of the Soviet Zond missions.<br /><br />http://www.svengrahn.pp.se/histind/Zondmiss/Zondmiss.htm<br /><br />Basically the problem revolves around the fact that the orbital plane of the moon needs to match as closely as possible the plane of the parking orbit of the spacecraft around the Earth. This occurs once every sidereal month (27.32 days). Because an exact match is not possible from Bailonur, extra fuel has to be spent to make a plane change. Timing it so that the planes are closest to each other reduces the amount of fuel that has to be consumed in the plane change.<br /><br />This also has to do with the reason that Cape Canaveral was chosen. It's latitude of 28 degrees 28 minutes N almost precisely matches the orbital inclination of the moon which is 28 degrees 34 minutes. This means that once every sidereal month the Moon is directly overhead meaning that absolutely no plane change is required to get to the moon. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[PistolPete]

It's not that using a multiple launch scheme is impossible, it's just that running the numbers myself I found that the current LVs are just a tad bit understrength to accomplish the task. LVs such as the Ariane 5 and Proton M would have to be enlarged to to increase the payload to LEO to somewhere around 25-30 metric tonnes. A couple of Angara 5 pads at Kourou might help solve this problem. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[PistolPete]

Actually, now that I think about it, an equatorial launch site such as Kourou would be an ideal launch place for a multiple launch scheme because launch windows would open up twice every sidereal month instead of just once. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[themanwithoutapast]

As PistolPete and I have outlined, the current CSTS approach will not lead to lunar orbital missions or even a lunar landing due to the complexity of a multiple launch scenario unless ESA/RSA develop a larger launch vehicle.<br /><br />However, if ESA/RSA would develop a more capable heavy lift rocket, the current CSTS approach (that is use a Soyuz 2-3 as the crew launcher and other heavy lift launchers for propulsion stages and for the lunar lander) appears to be even more at odds with reality. Here is why:<br /><br />1. If the CSTS approach is kept, that is the crew vehicle is launched on a Soyuz-2-3 rocket, the smallest number of launches for a single mission is 2. That is, you use an Ares V/Energia class rocket for cargo (EDS stage, lander) and a Soyuz 2-3 for the crew launcher. In essence this is what NASA is doing with Ares I and Ares V. I think most people understand that 10-20 billion EUR in development for such a large vehicle render this an unrealistic proposal, especially because such a large rocket does not serve any apparent commercial purpose outside lunar (or Mars) missions.<br /><br />2. Second possible solution for the CSTS approach is to minimize the launches that are required for one mission. If however the concept of launching the crew vehicle on a Soyuz-2-3 should be kept, this would require at a minimum a rocket capable of 50t to LEO in a three launch scenario or 30-35t in a 4 launch scenario. The problems any scenario that use more than two launchers docking together in LEO have been outlined above. I note that I deem it possible to have a feasible 4 launch scenario involving a lunar rendezvous, that is, you launch 1. the lunar lander into LEO 2. a propulsion stage on your newly developed 40t vehicle and propel those two modules to lunar orbit then 3. you launch a secon propulsion stage into LEO on the new 40t vehicle and 4. you launch the CSTS craft on Soyuz-2-3 and propel it to lunar orbit and 5. dock the CSTS craft and lunar lander in lunar orbit

 

[neviden]

To get to the moon and back you need around 150 MT in LEO. But since most of it is fuel, it can be split into multiple launches. About half of that fuel will be spent on TEI (3 km/s) to get near close to the moon, so that lends itself to practical split. One rocket (Proton, Arian 5) sends TEI stage (Block DM?) another sends actual payload. Meet in LEO, do TEI and your payload is on the way to the moon.<br /><br />The problem is that to get from TEI to LLO you need a lot of delta-v (1,4 km/s). That’s why you need extra Block DM to get Soyuz into/out of lunar orbit. But, if you do lunar fly-by and go to L2 instead, you can do it with only one Block DM. It takes longer to get there, but it’s simpler (2 launches instead of 3). L2 rendezvous would mean bigger lunar lander, but since this lander needs to be designed and built new anyway it doesn’t really matter, especially if it was designed to be reusable and refueled with LUX (or even hydrogen if there is any at the poles) from the start. That way you would start with 6 launches (1 lander, 1 payload, 1 Soyuz, 3 Block DM) and that would drop to only 2 launches (1 Soyuz, 1 Proton/Ariane 5 with Block DM) with occasional Hydrogen resuplies (or not even that if there is extractable water).<br /><br />That way the only thing ESA/Russians would need to develop is a Soyuz with better shield and better life support (= CSTS) and reusable/refillable lander that could get from moon to L2 and back. I think even ESA with it's small manned budget could do that..

 

[holmec]

"The main problem with a multiple launch lunar system is that it requires a great deal of timing to get all of the various windows to align. If there is bad weather over an extended period over the launch site or a technical problem with one of the LVs midway through the sequence, then the fuel in one of the upper stages may boil off below the critical level to continue with the mission. You then either waste several million dollars on a failed mission or spend several million more to rescue it. "<br /><br />If you add orbital fueling into the equation, then it just might be a robust enough process. So the idea is that you launch different parts, lander, lunar transfer booster. And do this in advance without the fuel for the mission. Then later launch the crew int he Soyuz capsule, and also launch the fuel needed for the mission. The crew dock, fuel up and go to the moon.<br /><br />Maybe that could be a viable piece of the puzzle. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[rocketman5000]

That's a lot of ducks to get in a row...

 

[no_way]

Thats called the dry launch option, and is very doable. Like already stated elsewher, if you have a stack on LEO, that is going to soft land on lunar surface and come back to LEO, at least 5/6ths of it is inevitably going to be propellant.<br />Building a new launcher from scratch to just lob up tons of propellant.. is pretty braindead. <br /><br />EDIT: Bytheway. If you are a space organization that is incapable of arranging a few launchers to meet up on LEO .. what the f**k are you going to the moon for anyway ?

 

[holmec]

Absolutely,<br /><br />I'm glad Orbital is doing research into "inflight?" or "inorbit?" fueling.<br />http://www.space.com/missionlaunches/070308_atlas5_stp1_launch.html <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[themanwithoutapast]

"...5/6ths of it is inevitably going to be propellant"<br /><br />That might be the case if you are doing a moon mission that returns to Earth via direct landing, if you are talking about a roundtrip LEO-LLO-Lander to Lunar Surface-Lander to LLO and THEN get back to LEO again (+3300 m/S for the breaking into LEO) your propellant mass ratio becomes a bit more in the range of 14/15 or 19/20. I am not sure it is worth to double or tripple the amount of mass required to get to LEO for a mission just to save a fraction of the total mass (the spacecraft and lander) for the next mission.

 

[rocketman5000]

Why try to reuse of mass is a point that many people argue. One pound of computer chips, or advanced composites cost a lot more than one pound of fuel. The cost of launching one pound of payload into orbit isn't all of the mission cost. If you have a spacecraft that could make 5 or 10 trips to the moon because you use more fuel it will be orders of magnitude lower recurring cost. <br /><br />It goes back to the same problem that the shuttle expirenced in its operational life. It went for lower development cost and led to much higher operating cost.<br /><br />Your 14/15ths and 19/20 seem to be pulled out of thin are. At least use the rocket equation to come up with something a little more substantial. <br /><br />But it all comes down to this. You can't make broad generalizations about what is the most cost effective way of getting to the moon without doing design studies and figuring out the development cost and operational costs. <br /><br />We are all intelligent lets actually take the time to put some thought into what we post.

 

[themanwithoutapast]

<blockquote><font class="small">In reply to:</font><hr /><p><br />Your 14/15ths and 19/20 seem to be pulled out of thin are. At least use the rocket equation to come up with something a little more substantial.<br /><p><hr /></p></p></blockquote><br /><br />LEO to LLO is 4100 m/s minimum. Let's disregard the lunar lander and just say we want to make a round trip from LEO to LLO back to LEO with storable propellants. That's 8200 m/s + 10% margin = 9000 m/s. If we are generous our storable propellant will give us an Isp of 320sec. That means that if our spacecraft weighs 1000t in LEO, it will have to burn appr. 940t of fuel for the round trip leaving us with 60t for the tank structure and spacecraft. That's fuel/mass ratio of 94%. I suggested it to be between 14/15 and 19/20, which is between 93% to 95%. <br /><br />Even if we would use LH2/LOX and assuming an Isp of 450sec (which would lead to heavy insulation to prevent boil-off and therefore a higher required mass of the tank structure) a 1000t vehicle would require 880t of propellant. A lot of the 120t that is not fuel would need to be used for the insulation or a system to reliquify the LH2 and LOX.

 

[rocketman5000]

great reply

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>LEO to LLO is 4100 m/s minimum. Let's disregard the lunar lander and just say we want to make a round trip from LEO to LLO back to LEO with sortable propellants. That's 8200 m/s + 10% margin = 9000 m/s. <p><hr /></p></p></blockquote><br />Actually, that's incorrect. The 4,100 m/s delta v to LLO consists of at least two burns: one to send the craft towards the Moon, the second to brake the spacecraft into a Lunar orbit. For the trip back all you need is a 1,100 m/sec burn to break the craft from the Moon's gravitational pull. The rest of the speed can be dissipated in the Earth's atmosphere, either as an aerobraking maneuver into LEO or during re-entry. This means that the total delta V expenditure for the mission is just 5,200 m/sec.<br /><br />BTW, for my sample mission, I got a mass fraction of 7/11 fuel and 4/11 dry mass which is a ~2.75:1 ratio. With a single launch, ie. a Saturn V, the ratio would probably be higher but with a lower gross mass for the same payload because there is a lot of dead weight inherent in a multi-launch system. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[themanwithoutapast]

<blockquote><font class="small">In reply to:</font><hr /><p>This means that the total delta V expenditure for the mission is just 5,200 m/sec. <p><hr /></p></p></blockquote><br /><br />Pistolpeat, try aerobracking with a massive empty tankstructure, you will see that does not work unless you have a heatshield massive enough to cover a really, really large tank (that needs a rather robust structure as well). My assumption was LEO to LLO and then back to LEO and stay in LEO. If you want to minimize mass, you rather go by doing another 3km/s burn to get back to LEO.

 

[scottb50]

It makes sense to pre-position propellant in LLO. With solar power Hydrogen and Oxygen could be kept liquid with very little if any lose.<br /><br />It also makes sense to base a surface lander at a facility on the moon, refueling in LLO before it returns to the surface. If we use the tanks we take to LLO to build the surface structures, after the propellants are transfered, costs could be kept fairly reasonable.<br /><br />Once in operation a dedicated cycler could take a large number of people, or a substantial load of propellant to LLO, transfer propellant and return to LLO. It then become a matter of getting the propellant and people to LEO and the people back to the surface. With solar power in LEO Hydrogen and Oxygen could be maintained quite easily and expendable launch containers might make sense. Maybe it would take 5-6 Falcon1's to upload enough for a lunar mission, but just the volume of launches would lower costs substanially. <div class="Discussion_UserSignature"> </div>

 

[nyarlathotep]

<font color="yellow">Pistolpeat, try aerobracking with a massive empty tankstructure, you will see that does not work unless you have a heatshield massive enough to cover a really, really large tank</font><br /><br />Aerobraking tanks and transfer stages is idiotic, they're the cheapest part of the vehicle. Simply set up an assembly line and launch another. What we are really interested in aerobraking is the expensive biological cargo.

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>Pistolpeat, try aerobracking with a massive empty tankstructure, you will see that does not work unless you have a heatshield massive enough to cover a really, really large tank (that needs a rather robust structure as well). My assumption was LEO to LLO and then back to LEO and stay in LEO. If you want to minimize mass, you rather go by doing another 3km/s burn to get back to LEO. <p><hr /></p></p></blockquote><br />?<br /><br />Huh?<br /><br />Who said anything about trying to aerobrake tanks? I think you are confused about what I meant. In my reference mission, Once the final 1,100 m/s burn to TEI is completed, the Block D-1 is jettisoned, it's fuel expended. There are no other burns required after that. Once the Soyuz TMA (with extra thick heat shield) is near Earth, it jettisons its service and orbital modules and re-enters the Earth's atmosphere. This is exactly how it was done in the Apollo program, except that the CSM's main engine conducted the final 1,100 m/s burn.<br /><br />The aerobraking maneuver that I was talking about was for a vehicle purpose built for such a task with all associated tankage built internally. It would be a large vehicle, but NASA did studies on aerobraking large vehicles in the late 80's-early 90's. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[rocketman5000]

When you initially posted about aerobraking tanks I didn't think you were talking internal tanks. If you have a large craft. With a very small L/D (wide and not very tall) wouldn't it be possible to have a lighter heat sheild (wrt vehicle mass) than a smaller dense craft? If you have a large and lite vehicle it should be able to break more in the upper atmosphere right? and since the upper atmosphere is much cooler than down low

 

[themanwithoutapast]

<blockquote><font class="small">In reply to:</font><hr /><p>Who said anything about trying to aerobrake tanks? I think you are confused about what I meant. In my reference mission, Once the final 1,100 m/s burn to TEI is completed, the Block D-1 is jettisoned, it's fuel expended. There are no other burns required after that. Once the Soyuz TMA (with extra thick heat shield) is near Earth, it jettisons its service and orbital modules and re-enters the Earth's atmosphere. This is exactly how it was done in the Apollo program, except that the CSM's main engine conducted the final 1,100 m/s burn.<p><hr /></p></p></blockquote><br /><br />Pistol, I think there is some confusion. I originally replied to another post that said a "Cylcler" between LEO and LLO would make sense. In my reply I noted that it would require (with margins) 9000 m/s of delta-v to do that and obviously if you want to redo the whole procedure of going from LEO to LLO and back in the same vehicle and just retank your vehicle in LEO you have to get the whole spacecraft including tanks back to LEO - which is not possible by aerobreaking unless you also find a way to do aerobreaking with a large tank structure without adding a massive heatshield.<br /><br />I am totally aware of the fact that for a realistic, "normal" lunar mission (as you outlined previously) a Soyuz-based spacecraft would aerobreak into Earth's atmosphere without another burn.

 

[solarspot]

Not overly related to the discussion at the moment, but I think this fits in this thread more than anywhere else...<br /><br />The mission archetecture I've come up with seems strangely smaller than the ones people here have quoted / shown. Can you show me where my math / logic is off here?<br /><br />1: The crew launches into LEO on a current vehicle (SpaceX Dragon or whatever) 2: A larger launch vehicle sends a LOX/LH2 booster (10-15 tonnes) , a small 3-man crew module (1-1.5 tonne) , and a small lunar lander ( (open ascent stage using storable propellants, with the crew wearing spacesuits practically sitting on the tanks. Descent drop stage uses LOX/LH2 and might weigh around a tonne to carry the ascent stage.)<br /><br />3: the crew from the manned capsule transpher (??) to the crew module, then undocks so the Booster can do the TLI burn.<br /><br />4: The lunar lander's decent stage engine burns to slow the remainder of the stack into lunar orbit, then then the crew don spacesuits and get into the open-style lander.<br /><br />5: The descent stage carries the crew in the ascent stage down to the surface (Lox/LH2 drop stage takes ascent stage to near 0 velocity, monopropellent thrusters or ascent engines do the soft touchdown) where the crew continues to a small pre-landed habitat (used solar-thermal propultion to get to Lunar orbit?? Not sertain)<br /><br />6: After a week or two (partial or full lunar day desirable?) on the surface, the crew return to the open lander (using storable propellents for added reliablity and to avoid excessive boil-off), and return to the orbiting crew module.<br /><br />7: The crew module uses it's own storable propellant engines for the TEI burn, then uses areobreaking (multiple passes?) to return to LEO where the crew transphers back to the capsule (same one they launched in?) for return to earth's surface.<br /><br />I'm not sure why, but that comes in at 20-25 tonnes to LEO, excluding that prelaunched habitat. Did I get something horrably wro

 

[scottb50]

1: The crew launches into LEO on a current vehicle (SpaceX Dragon or whatever) 2: A larger launch vehicle sends a LOX/LH2 booster (10-15 tonnes) , a small 3-man crew module (1-1.5 tonne) , and a small lunar lander ( (open ascent stage using storable propellants, with the crew wearing spacesuits practically sitting on the tanks. Descent drop stage uses LOX/LH2 and might weigh around a tonne to carry the ascent stage.)<br /><br />If you use a cycler you only have to send up one lander/ascender then take up the propellant to fuel it by a cheaper launcher. If the crew module just goes from LEO to LLO and back to LEO, it could be rather simple. Since you already postulate a SpaceX Dragon to bring the crew up why not use it to take the crew back to the surface?<br /><br />2:?<br /><br />3: the crew from the manned capsule transpher (??) to the crew module, then undocks so the Booster can do the TLI burn....<br /><br />That make sense.<br /><br />4: The lunar lander's decent stage engine burns to slow the remainder of the stack into lunar orbit, then then the crew don spacesuits and get into the open-style lander....<br /><br />I would think it would be much simpler to have the lander come up from the moon and dock to the cycler, transfering cargo, people and propellant before it returns to the surface. I don't see a need for an Apollo type lander/ascender that has to be replaced for the next mission. That only means more mass that has to get from the surface to LEO then to LLO. Rather than vehicles I would rather take propellant and spare parts for existing equipment.<br /><br />5: The descent stage carries the crew in the ascent stage down to the surface (Lox/LH2 drop stage takes ascent stage to near 0 velocity, monopropellent thrusters or ascent engines do the soft touchdown) where the crew continues to a small pre-landed habitat (used solar-thermal propultion to get to Lunar orbit?? Not sertain) />>><br /><br />I would think it much simpler to take a vehicle from LLO to a mobil <div class="Discussion_UserSignature"> </div>