News on Euro-Russian CSTS

[gunsandrockets]

"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?...I'm not sure why, but that comes in at 20-25 tonnes to LEO, excluding that prelaunched habitat. Did I get something horrably wrong with that?"<br /><br />Total mass budget for a 3 man lunar mission of only 20-25 tonnes payload to LEO? Yeah, I think your math is off. <br /><br />A 1.5 tonne 3-man crew module is unrealistic. The very cramped Soyuz reentry module is double that mass. Then you have two other capsule flights up to LEO, the first to ferry the crew up, then the second flight to recover them upon return from the moon. Even the lightweight t/Space capsule system would mass 5 tonnes, so twice that is a total of 10 tonnes into LEO just for the crew ferrying portion of your total mass budget.<br /><br />Otherwise your basic mission design is mostly okay. The biggest flaw is during lunar-return of the crew module, as multiple-pass aerobraking into LEO could take days or weeks.<br /><br />In many ways your mission design is similar to the current NASA ESAS plan to reach the moon, except your plan uses three men instead of four and uses a more bare bones lunar lander. Keep in mind the NASA plan places about 155 tonnes into LEO to accomplish the mission, or about 39 tonnes per man. The Apollo mission put two men on the moon using 60 tonnes per man. Even cutting to the bone there is no way you can reduce the mass down to 8 tonnes per man as you concluded.<br /><br />I think the best one can hope for in a mission as small as 25 tonnes is limited to a one man lunar mission, as outlined in the Lunar Millenium plan... <br /><br />http://www.retro.com/employees/gherbert/Space/LunMil/Moon2k5.21 <br /><br />

 

[solarspot]

"A 1.5 tonne 3-man crew module is unrealistic. The very cramped Soyuz reentry module is double that mass."<br /><br />Okay, but isn't the orbital module around 1.5 tonnes? Maby I will still figure the fuel weights out again with a 3 or 4 tonne module instead<br /><br />"Then you have two other capsule flights up to LEO, the first to ferry the crew up, then the second flight to recover them upon return from the moon. Even the lightweight t/Space capsule system would mass 5 tonnes, so twice that is a total of 10 tonnes into LEO just for the crew ferrying portion of your total mass budget."<br /><br />I excluded that from the 25 tonne number... was in a rush when I wrote that post. I was planning to use the same capsule for both ascent and decent, how this would be done I have yet to figure out.

 

[gunsandrockets]

"Okay, but isn't the orbital module around 1.5 tonnes?"<br /><br />True. But the reason the Orbital Module is so lightweight is because all of the heavy systems needed by a reentry module are stripped out.<br /><br />A reentry module needs a heatshield, parachutes, soft-touchdown landing rockets, and a structure able to stand up to sustained 10+g during a ballistic reentry and even higher accelerations for a very short shock during a rough touchdown.<br /><br />"...I excluded that from the 25 tonne number... was in a rush when I wrote that post..."<br /><br />Okay. With the three launches you have excluded even your own mission numbers are getting into the range of 53 tonnes payload into LEO, or 18 tonnes per man.<br /><br />I think at a minimum you are facing a total requirement of 85 tonnes in LEO divided into 4 launches. (about 29 tonnes per man) <br /><br />One Delta IV heavy class launch to put a ~4 tonne payload on the lunar surface. <br /><br />One Delta IV heavy class launch to put a lunar lander into low-lunar orbit. <br /><br />One Delta IV heavy class launch to put a propulsion module of 25 tonnes into LEO. <br /><br />And one Atlas V medium class mission to put a crew capsule into LEO.

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>I'm not sure why, but that comes in at 20-25 tonnes to LEO, excluding that prelaunched habitat. Did I get something horrably wrong with that? I know my math can be off haha. <p><hr /></p></p></blockquote><br />Yes, your math is very off.<br /><br />First, as mentioned before, the Soyuz TMA re-entry module has a mass of 2,950 kg. This is about the smallest you can make a three man re-entry module. However, the re-entry module was not designed for flights longer than a few hours. There is simply not enough room for a crew of three and all of the extra equipment needed for a long duration flight. In the Soyuz, that equipment is in two other modules. The first is known as the orbital module which has extra space for the cosmonauts to move as well as storage space for consumables such as food, water, and air. The orbital module has a mass of 1,370 kg. The second module is known as the propulsion module. This 2,900 kg module houses 880 kg of fuel and a 3.92 kN engine with an Isp of 305 sec. as well as the solar power cells, batteries, heat radiators and other electronic equipment. All total, the mass of the Soyuz TMA is 7,220 kg and can produce a delta v of 390 m/sec.<br /><br />The second thing that caught my eye was the fact that you failed to mention the mass of the lander. NASA’s Langley Research Center designed a one man lander similar to the one you described. It had a gross mass of 4,372 kg including the astronaut and 3,500 kg of N2O4/UDMH propellant with an Isp of 311 sec. If you increase the crew size to two space suited astronauts at 150 kg each, then I would estimate a gross mass of 6,250 kg with 4,000 kg of propellant and can produce a delta v of ~4,900 m/sec.<br /><br />However, your plan also calls for the lander to brake the re-entry module/lander stack into LLO. This means an added delta v of 1,100 m/sec., not an inconsequential number. Let’s say that somehow you managed to build a re-entry module weig <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]

Also, I doubt that an open cockpit lander could realistically support a long-term lunar program. I know that there are people who would disagree with me, but I just don’t see it. <br />--------------<br />Pistol, any bare-bones lunar mission would only make sense if you already have a lunar outpost and the only thing you want to do is get people to that outpost and from it. In that case a two-crew lunar mission to that outpost may be possible with a two-launch strategy with a larger yet-to-be developed rocket such as Angara-5 or any other heavy-lift rocket between 25t-30t to LEO capacity.

 

[daniko]

Sorry if it was allready dicussed, but was it mentioned that there were plans for electro-propulsion cargo vehicles to cover Earth-Moon-Earth cargo transfers.<br />Something like SMART-1 mission but with engines 10 to 20 times the thrust.

 

[ckikilwai]

<blockquote><font class="small">In reply to:</font><hr /><p>Sorry if it was allready dicussed, but was it mentioned that there were plans for electro-propulsion cargo vehicles to cover Earth-Moon-Earth cargo transfers.<br />Something like SMART-1 mission but with engines 10 to 20 times the thrust.<p><hr /></p></p></blockquote><br /><br />I thought I've read somewhere that ion engines are only useful to interplanetary missions, and that the moon is too close for such engines, and that chemical engines are cheaper to use.<br /><br />And I have another question on my own, couldn't the Russians (together with the Europeans if they want) modernize their plans of the Energia Rocket?<br />IRC the Russians still have at least 1 launchpad where it could be launched (after some repairs ofcourse).<br />(this question was probably asked a 100 times, but I could find an answer after searching the forum for it for 5 min).<br />

 

[dreada5]

<blockquote><font class="small">In reply to:</font><hr /><p>I thought I've read somewhere that ion engines are only useful to interplanetary missions, and that the moon is too close for such engines, and that chemical engines are cheaper to use. <p><hr /></p></p></blockquote><br /><br />I seriously doubt the technology would have developed sufficiently circa 2020 to transport several tons of esa spacecraft through cislunar space with similar technology to Smart-1 and within a reasonable length of time.

 

[daniko]

For electric propulsion system I had in mind this:<br />http://www.esa.int/esaCP/SEMOSTG23IE_index_0.html<br />http://www.newscientist.com/article.ns?id=dn8599<br /><br /><b>" ... This system allows voltage differences of up to 30,000 V between the two grid sets, producing much faster ion exhaust plumes than previously possible, and without damage to the engine. <br /><br />Given sufficient electrical power, a cluster of DS4G engines could take a crew to Mars and back, says ESA. Alternatively, the design could be used to slash the time of longer missions to Pluto, or the Kuiper belt.<br /><br />But given the extensive testing required of a new ion engine design, it could be a decade before DS4G engines make their debut in a space mission, Sutherland says."</b><br /><br />but recently I haven't found any news - may be another stranded or underfunded idea !!! <img src="/images/icons/frown.gif" />

 

[rocketman5000]

couldn't the testing be simultaneous with a planned probe? validate the enging in parallel with the validation of the probes systems? It would raise the risk to the probes success as a program, but too often today aerospace is risk adverse.

 

[ckikilwai]

<blockquote><font class="small">In reply to:</font><hr /><p>couldn't the testing be simultaneous with a planned probe? validate the enging in parallel with the validation of the probes systems? It would raise the risk to the probes success as a program, but too often today aerospace is risk adverse. <p><hr /></p></p></blockquote><br /><br />This is actually the reason why ion engines haven't been tested much earlier, nobody wanted to put their probe at such a risk.<br />But now, when smart 1 and deep space 1 have proven that these engines work, ESA is planning to use them for their mission to Mercury. (in combination with chemical engines ofcourse)<br /><br />Here is the link about ESA's BepiColombo mission.<br />http://www.esa.int/esaSC/SEMLN5T1VED_index_0.html

 

[no_way]

why not send just a barebones spacecraft with engines and guidance basically, on any small comsat bus out as a test ? <br />why does it have to be a planetary probe mission that takes several years to put together<br />Small launchers come pretty cheap so even the Planetary Society could afford testing their solar sail. Why wait decades and not test and improve this thing now with frequent test flights ? <br /><br />Stagnation ... <br /><br />EDIT: ESA Smart-1 cost around 110 Mil euros over its lifetime, including launch. Ditch the science part of it entirely, use the existing spacecraft design with only the improved engines. how much would a program with a few test flights to Mars for instance cost ?<br /><br />The trouble is, nobody is thinking like that any more. In the early days of space flight the whole series of continously improved spacecraft were sent out to get to the results. (Venera, Mariner, Pioneer, Viking etc ) Now it takes ages to put together a mission.<br />Because everyone is afraid of failure and big launch costs ?

 

[rocketman5000]

I think the stigma is launch costs and development costs. When it really comes down to it however is the high development cost.<br /><br />And despite the fact that we have 40 years of rocketry expirence we still are not perfect at building long range spacecraft, and landing them on other planetary bodies.<br /><br />I ofter feel that if we got lower cost access to LEO then we would be able build more reliable probs because we could afford the extra weight that a standardized craft would cost. <br /><br />You could build a standard cruise stage, and a standard desent stage and mix and match till your hearts content.<br /><br />

 

[no_way]

"When it really comes down to it however is the high development cost. "<br /><br />Thats the thing. For testing and developing a new type of deep-space engine, you should really be concerned with the development of the engine to keep the costs and schedule manageable.<br /><br />Pick a working satellite bus, send all the scientist asking for piggybacking the payloads straight to hell and just launch a engine testing flight. You dont even have to wait for any special launch windows or planetary alignments, simply send it straight out or if you want to test maneuvering, go to the moon and back ten times or whatever.<br />Predictable costs, predictable schedule.<br /><br />get the engine working and tested and THEN let the scientists plan their new cool missions around it. serial produce the design or something.

 

[daniko]

I think the difference comes from the different approach:<br /><br />From one side:<br />- military/political approach = military/political goals are chased<br />they are ambient; it's difficult to say what is a failure even a long time after; lesser control of funding (you only need to prove political righteousness);<br /><br />From other side:<br />- scientifical/commercial approach = scientifical/commercial goals are chased<br />they are precisely specified in time, money, people; you can say a project is a failure even far before its end;<br /><br />So depending on which approach is applied you see different outcomes . . .