manned mission to Mars, favorite plans and architectures

[scottb50]

No matter what scheme of filling or refilling you use, or how long it takes, you must have propellant tanks large enough to hold at least 24 tonnes of liquid hydrogen and liquid oxygen. There is no escaping that fact. You can't use smaller propellant tanks than that if you want to return to Earth.....<br /><br />You also need propellant tanks to get to Mars, propellant tanks to enter orbit at Mars and as you say propellant tanks to return to Earth and with my thinking, enter orbit at Earth.<br /><br />LEO to LMO and back is a round trip and it is foolish to expect to take on propellant at Mars. Based on you 24 tonnes to leave LMO and return to Earth it would take close to 80 tonnes round trip. If you use LEO return boosters you would still need 40-45 tonnes. Enroute 5-10 tonnes would be used for electrical and environmental requirements and the amount would be ramped up to 15-20 tonnes to enter LMO. While in LMO you would only need the minimal amount and that would be increased for LMO departure, again using a minimal amount enroute and ramping that up for LEO entry, depending on mass say 20-30 tonnes.<br /><br />All I am proposing is keeping the propellant water until the Hydrogen and Oxygen are needed to reduce storage cost and complexity. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

I didn't see it mentioned that H2 engine mixture ratios are usually at 6 to 1 vs water's 8 to 1...><br /><br />How much lower would the ISP for LOX/LH2 be with a MR of 8? <br /><br />I think the SSME's intentionally run rich and the efficiency of an engine can depend on it's size and configuration. The fact Oxygen is left would allow supply to a Martian base and would not go to waste, even if that was a factor. If nothing else I would think the 6:1 mixture is probably needed for temperature control and an 8:1 ration would probably allow a higher not lower ISP.<br /><br />That's just a guess though.<br /><br />Either way people will consume Oxygen and available mass will limit how much can be recovered or how much is lost by dumping CO2. <br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

< If nothing else I would think the 6:1 mixture is probably needed for temperature control and an 8:1 ration would probably allow a higher not lower ISP.><br /><br />An oxygen+hydrogen rocket has a higher ISP with the lower mixture ratio of 6 to 1. Even though less energy is produced because not all the hydrogen is burned, the ISP is never the less even higher than when the MR is 8. This is because the excess hydrogen lowers the average molecular weight of the heated gasses. So even though the energy level is lower than it could be the exhaust velocity is higher due to the even lighter mass of the propellant.<br /><br /><All I am proposing is keeping the propellant water until the Hydrogen and Oxygen are needed to reduce storage cost and complexity. /><br /><br />I know. The problem is your concept doesn't reduce the storage cost much if at all but does add a lot of complexity. And it adds deadweight too which is even worse.<br /><br />Scottb50 I can tell you are strongly attached to your water propellant concept. And it is imaginative. But interesting and imaginitive ideas ultimately must stand the test of the cold equations. I've abandoned more than one neat concept myself because it couldn't stand up to the math. You should give this one up too.<br /><br />You don't have to take this letdown on faith in my word. Just run the numbers yourself and you will see that it's all true. The water propellant concept doesn't work.

 

[gunsandrockets]

< LEO to LMO and back is a round trip...Based on your 24 tonnes to leave LMO and return to Earth it would take close to 80 tonnes round trip. If you use LEO return boosters you would still need 40-45 tonnes. Enroute 5-10 tonnes would be used for electrical and environmental requirements and the amount would be ramped up to 15-20 tonnes to enter LMO. While in LMO you would only need the minimal amount and that would be increased for LMO departure, again using a minimal amount enroute and ramping that up for LEO entry, depending on mass say 20-30 tonnes.><br /><br />80 tonnes propellant for an all propulsive Mars mission? Not even close.<br /><br />All propulsive Mars mission designs are enormous, especially ones which rely on chemical propulsion (even LOX/LH2). An all propulsive chemical rocket Mars mission, instead of 80 tonnes of propellant, would use hundreds of tonnes of propellant, maybe even more than a thousand tonnes of propellant! See the link...<br /><br />http://www.astronautix.com/craft/nasn1971.htm<br /><br />My 24 tonne LOX/LH2 propellant figure for an ERV is a modification of the 29 tonne LOX/CH4 propellant figure of the ERV used in the NASA DRM 3.0. The NASA DRM 3.0 makes minimal use of propulsive delta-V changes. It plans for aerocapture at Mars and uses direct entry at Earth arrival instead of propulsive maneuvers.<br />

 

[scottb50]

Scottb50 I can tell you are strongly attached to your water propellant concept. And it is imaginative. But interesting and imaginitive ideas ultimately must stand the test of the cold equations. I've abandoned more than one neat concept myself because it couldn't stand up to the math. You should give this one up too.<br /><br />You don't have to take this letdown on faith in my word. Just run the numbers yourself and you will see that it's all true. The water propellant concept doesn't work...<br /><br />I think you are wrong and it does work, obviously you don't want to abandon your preconceived notions either and grasp at anything that refutes them. That there is less Oxygen used for propullsion than perfect combustion is a red herring. <br /><br />What adds dead weight is the added storage capabilities needed for any other propellant. That I am proposing a cycler system from LEO to LMO and back implies different needs. To look at it in the context of aerocapture at LMO and direct entry back at Earth you are right. I am thinking well beyond that. <br /><br />Look at what happened with Apollo. If we have a reliable means of leaving LEO, reaching and entering an orbit at a destination and getting back to LEO it opens up pretty much every destiantion in the Solar System. If you want one shot missions then you shoot the costs out the window.<br /><br /> <br /> <div class="Discussion_UserSignature"> </div>

 

[scottb50]

80 tonnes propellant for an all propulsive Mars mission? Not even close...<br /><br />I was extrapolating numbers off yours. How much it would take in reality depends on the mass of the outbound and inbound vehicles. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

<Do you have any good references on [solar thermal propulsion]?><br /><br />Aha! I've just come across some more interesting STP info, so I thought I'd share...<br /><br />http://www.boeing.com/defense-space/space/propul/SOTV.html<br /><br />http://www.astronautix.com/engines/rs77.htm<br /><br />The Boeing concept appears highly developed<br /><br />Here is a link to cancelled NASA test project...<br /><br />http://www.grc.nasa.gov/WWW/tmsb/secondaryconc/doc/rsc_sse.html<br /><br />http://adsabs.harvard.edu/abs/2002stai.conf..486T<br /><br /><br /><br /><br /><br /><br /><br /><br /><br />

 

[gunsandrockets]

<I was extrapolating numbers off yours. How much it would take in reality depends on the mass of the outbound and inbound vehicles.><br /><br />I know that. Which is why I pointed out the error of your estimate. To perform an all propulsive 6 man mission based on LOX/LH2 engines as you suggested is almost exactly like the NASA mission I linked to. And that NASA mission used over 1500 tonnes of propellant, not your 80 tonne estimate.

 

[gunsandrockets]

[Here is a thread to discuss your favorite ideas for the best ways to send men to Mars!]<br /><br />After everyone else's contribution to this thread (plus one watery detour) I guess it's time I put something forward myself!<br /><br />MARS ONE: plan for the first manned mission to Mars<br /><br />Introduction<br /><br />The problem with designing an ideal mission architecture for Mars today is the great number of unknowns, in both engineering and science, which could make a radical difference in mission design. The Mars One plan is designed to both accomodate some of those unknowns and hopefully answer some of them too.<br /><br />Primary objectives<br /><br />1) Support a crew of 2 in space and return them to Earth in healthy condition after a flight of two years.<br /><br />2) Collect samples from the Martian moon Deimos, and return them to Earth.<br /><br />Synopsis<br /><br />Mars One is a manned Mars flyby, asteroid-belt flyby and sample return mission. Mars One is launched from Earth on a two-year-long free return trajectory which will carry it by Mars and then deep into the asteroid-belt before Mars One returns to Earth.<br /><br />When Mars One flybys Mars, an impactor probe paralleling Mars One will strike the polar region of the Martian moon Deimos. Another probe following the impactor will fly through the impact plume and collect samples with aerogel. Mars One will observe the impact, help guide the probes and recover the probe sample.<br /><br />A suitable asteroid close to the free-return trajectory of Mars One will be closely observed as Mars One flybys that asteroid. If possible that asteroid will also be struck and have a plume sample collected by unmanned probes, just as Deimos was sampled.<br /><br />During the closest approach and retreat from Mars, the Mars One crew will also provide real-time control of a Mars rover previously landed on the surface of Mars.<br /><br />Rationale<br /><br />A small 2-man flyby mission can answer important questions with minimal risk an

 

[JonClarke]

I have toyed with the idea of a 2 man flyby lander mission, which could be possible with a singel launch of an Ares V. See the reference to FLEM on the same astronautix site. I can't see any government program doing something so risky, but I can just imagine a trillionaire adventurer doing it.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[scottb50]

I think that wastes a lot of money. There is no technical reason we can't land and take-off from Mars. Why not just do it instead of putting up another hurdle.<br /><br />I would say a basic Cycler would use 13 identical Modules. Two of the outer and the central Module being half livable space and half water, the other ten Modules could be partitioned as needed with floating or lockable, pistons. You could even use multiple pistons in the same tube.<br /><br />The core could support a crew of 4-5 and 10- 15 passengers and it becomes a simple task to add other cores as required. Cores would use spent Upper Stages. Engine Modules would be removed for use as Tugs or Cycler engines.<br /><br />I would think a single launch could carry enough hardware to outfit two or three Modules for other missions.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

<I have toyed with the idea of a 2 man flyby lander mission, which could be possible with a single launch of an Ares V. See the reference to FLEM on the same astronautix site.><br /><br />I like to describe missions like FLEM as 'flyby rendezvous' to avoid confusion with pure flyby missions, such as Mars One.<br /><br />< I can't see any government program doing something so risky, but I can just imagine a trillionaire adventurer doing it. /><br /><br />You and I are of one mind here. Flyby rendezvous is risky (though you never hear the cycler proponents describe it as risky) but could provide the cheapest means of mounting a manned mission to the Martian surface. Taking that kind of risk seems beyond the reach of western governments anymore. Though I wouldn't be surprised if some future day China takes a risky method to beat the rest of the world to Mars.<br /><br /><br /><br />

 

[JonClarke]

Yep, all the flyby rendzvous missions scare me. Not only is it rendzvous or die, but the launch window must be very small.<br /><br />But in a space race situation, or for a private mission, where people are very confident in the technology. It becomes very attractive.<br /><br />It would be interesting to see how small a mission you could actually get away with using this mode and accepting only a two man crew.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[j05h]

My favorite Mars architecture, by far, is the James Cameron reference mission.<br /><br />Article: <br /><br />http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=813&mode=thread&order=0&thold=0<br /><br />Gallery: <br /><br />http://www.astrobio.net/news/modules.php?set_albumName=marsdrm&op=modload&name=gallery&file=index&include=view_album.php<br /><br />The rover and EDL method are wicked cool.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[tsilatipac]

<Here is a thread to discuss your favorite ideas for the best ways to send men to Mars!><br /><br />Technical considerations aside for a moment, the best way to send men/women to Mars is to select a primary path forward: direct, lunar, capture, etc and then execute! Proceed with the vigor and determination of the lunar space race! Not because it is a race but because it is human destiny, because it is there, because if we don't push ourselves and grow--we die.<br /><br />Since when did we become so risk adverse? If we fail on the first attempt, debrief, build another and go again.

 

[j05h]

<i>> Since when did we become so risk adverse? If we fail on the first attempt, debrief, build another and go again.</i><br /><br />The problem is who is "we"?<br /><br />If we is the US govt, then Mars is not neccessarily the current goal. If it's we-the-world, look how schlerotic ISS construction has been. If it is "we" in the sense of an entreprenurial or established company, there are massive monetary hurdles to be overcome, but not much else in the way. <br /><br />If you want, I can go start "HydroAres, Inc." tomorrow, but I need to borrow $1 billion from you to do it. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[qso1]

Your right about "Proceed with the vigor and determination of the lunar space race!". However, if we wait till the right combination of events set up the goal...we may be in for a very long wait. When I began learning about NASA, spaceflight etc. I was around 12-13 and knew almost nothing about the cold war.<br /><br />I was too young to recall the JFK speech. I was under the impression we went to the moon in part for the reasons you mentioned...human destiny. When I was maybe 15 or so, I began to learn the politics behind the moon race and as a story writer/illustrator...I figured it would take some similar reasoning to get humans to mars.<br /><br />I thought we would have made mars by 1986 earliest, late 1990s at the outside. Here were still waiting and I'm 51 now.<br /><br />As for risk aversion, I'm not that certain its risk aversion...more like cost aversion. Once it sank in that the moon race was really about beating the Russians, the public, press, and politicians turned against the idea of future space expansion as proposed by Von Braun in 1969. By 1970, the familiar argument we still hear today was prevalent then.<br /><br />"If we can land man on the moon, why can't we cure cancer?" or do whatever critics were advocating. And its not that the argument is not a good one. But almost four decades later, with NASA at around 50% of budget levels of the pre 1973-74 era...its obvious the money saved from those draconian cuts never went to the causes that needed the money. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[JonClarke]

<i>If it's we-the-world, look how schlerotic ISS construction has been.</i><br /><br />Construction rate has not been a function of the international nature of the program. Without international participation there probably would not have been a space station and, if it had, it would have been abandoned after Columbia.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[j05h]

<i>> Construction rate has not been a function of the international nature of the program. Without international participation there probably would not have been a space station and, if it had, it would have been abandoned after Columbia. </i><br /><br />I was being somewhat rhetorical. International cooperation through ISS has been both boon and bane. Station wouldn't have survived after the early 90s without becoming ISS. US and Russian space policy are joined at the hip, at least from an outsider's perspective. The rest of the partners have even more delays. ATV was supposed to fly years ago. <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

<What is the purpose for NASA going to Mars? ><br /><br />Exploration. <br /><br />I should point out this thread is intended to discuss the 'how to' rather than the 'reason why' for going to Mars. <br />

 

[JonClarke]

The ATV and Columbia delays illsutrate the strengths of multilateral partnerships, other other partners were able to pick up some of the slack caused by these delays which would have been crippling if not fatal.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[nrrusher]

<br />Considering the implications of failure, I believe they should send ahead all equipment, remotely or automatically assembled. The habitats should be self deploying, or nearly so, and setup and fully functional and tested before we even send off our people.<br /><br />Granted, the units would be minimal, enough for basic survival if something failed on the primary systems, and the there would be additional stuff coming along with the human explorers, 6 months later, to add to everything.<br /><br />Wouldn't it be nice to know there is a warm place with air sitting there ready for you to open the air lock and sit down and have a cup of Joe?<br /><br />External Sensors could measure radiation levels, damage, and penetration so we would have a better idea of how well everything will hold up.<br /><br />Also of importance, this would help ensure a successful mission.<br /><br />NR

 

[j05h]

<i>> The ATV and Columbia delays illsutrate the strengths of multilateral partnerships, other other partners were able to pick up some of the slack caused by these delays which would have been crippling if not fatal.</i><br /><br />Interesting. All I know is that everything has taken twice as long as projected or more, for the whole ISS project. <br /><br />Jon, can we discuss the best part of your Mars Mission here or in "9 tons"? I'm heading off for the weekend, but will reply after.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[sirius_1113310]

I think once they finish the ISS thing, they'll work on possibly going back to the Moon and then Mars. I've heard that NASA will do something similar to what they did in the Apollo missions for Mars and that they'll spend a year going there, a year on Mars, and a year coming back. I don't know if that is entirely true though.

 

[jwsmith]

I no longer stop by here much because I am not much into just talking. <br />My favorite plan is still the one we are working on over at 1000 Planets, Inc. <br />We still are looking for people in all areas of knowledge but we have most of the things decided. <br />1000 Planets had it's start on these forums back in 2000. <br /><br />We are still looking for people knowledgeable in agriculture. Someone active in the field would be usefull. <br /><br /> <div class="Discussion_UserSignature"> <p><font size="2">John Wayne Smith, CEO</font></p><p><font size="2">1000 Planets, Inc</font></p><p><font size="2">Http://www.1000Planets.com</font></p><p><font size="2">203 W.Magnolia St.</font></p><p><font size="2">Leesbutg Florida 34748</font></p><p><font size="2">Ph: 352 787 5550</font></p><p><font size="2">email jwsmith42000@aol.com</font></p> </div>