manned mission to Mars, favorite plans and architectures

keermalec · Oct 20, 2007

Awesome work, JWSmith, If you will allow me, I believe your habitat design can be optimised. Mass launched from Earth is what drives cost up, doesn't it? At over 10'000'000 USD a ton to LEO, we must seek to minimise as much as possible the mass transported to Mars and landed there. Current estimates show that only 20% of the mass in LEO arrives as useful payload on the martian surface. The rest is fuel, aerobrake shield, thrusters etc. That means a 30-ton habitat (good for 6 people, including life support, from Borowski) would cost 1.5 billion USD simply for transport to the martian surface. On the other hand, a re-usable lander carrying 6 people would weigh only 4 tons (without propellant). Building materials, biomass for life support, and water, should ultimately be produced on Mars and not carried from Earth. Therefore, in a long-term colonization vision, humans should be transported in a ship/habitat that stays in martian orbit and returns to Earth once it is refuelled (maybe with fuel mined on Phobos?) to gather more travellers. Re-using the same ship will certainly drive transportation costs down. Humans should land with as little mass as possible and habitats should be built from local materials, as far as possible. Being in the construction business, I see quite clearly the possibility of producing martian concrete, adapted of course to the dry and cold atmosphere of Mars. Concrete is, after all, simply an artificial stone. Many reasons call for underground habitats, unfortunately, instead of surface domes with a view (;-): - Meteorites (12 hits a day on the whole martian surface, according to recent NASA estimates). - Galactic Cosmic Rays (on the surface of Mars, these are comparable in intensity to what is found in LEO. IE: good for several month's stay but dangerous if living there your whole life). - Keeping the air pressure in. Structures can either be built from very strong tensile <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

jwsmith · Oct 20, 2007

Keermalec Wrote: Awesome work, JWSmith, If you will allow me, I believe your habitat design can be optimised. Thank You. We do not claim to have a lock on ideas or knowledge. In fact many parts of our effort has came from these forums. A bit here, a piece there and so on. We will take a serious look at what you say. There are other good observations here that I saw as I was scanning this thread. We could use a good wordsmith to put the ideas into an understandable form. Any volunteers. <div class="Discussion_UserSignature"> John Wayne Smith, CEO1000 Planets, IncHttp://www.1000Planets.com203 W.Magnolia St.Leesbutg Florida 34748Ph: 352 787 5550email jwsmith42000@aol.com </div>

spacester · Oct 20, 2007

Hehehehe been there done that. <img src="/images/icons/laugh.gif" /> It's always fun to hear from you, JWS, and I enjoy reading some of my words on your Mars Settlement pages. It's interesting to see where you depart from my thinking and where what I wrote dovetails nicely enough with your plans that you left it alone. Fun stuff, and of course you or anyone is welcome to use my sdc posts in that way: public domain, open source, etc. If I can get my Mars Cruiser built in time, you guys can catch a ride with me. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

jwsmith · Oct 20, 2007

> spacester writes: It's always fun to hear from you, JWS, and I enjoy reading some of my words on your Mars Settlement pages. It's interesting to see where you depart from my thinking and where what I wrote dovetails nicely enough with your plans that you left it alone. Fun stuff, and of course you or anyone is welcome to use my sdc posts in that way: public domain, open source, etc. < And there are shares of 1000 Planets stock sitting on my desk with your name (and others) on them. Send me a private e mail on that. I do thank you for what you have done to help solidify the rational plans for settlement of Mars. All we are waiting for is a ride. />If I can get my Mars Cruiser built in time, you guys can catch a ride with me. < Hurry up!! <div class="Discussion_UserSignature"> John Wayne Smith, CEO1000 Planets, IncHttp://www.1000Planets.com203 W.Magnolia St.Leesbutg Florida 34748Ph: 352 787 5550email jwsmith42000@aol.com </div>

keermalec · Oct 23, 2007

<blockquote>In reply to:<hr />And there are shares of 1000 Planets stock sitting on my desk with your name (and others) on them<hr /></blockquote> I am afraid private inhabited missions to Mars are still a long way off. At the moment, sending 8 tons on a trans-mars injection trajectory costs about 250'000'000 USD (cost of a Delta IV Heavy launch) and one needs 30 tons for a 6-person habitat. Thats 156'000'000 USD per person, just for launch... <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

keermalec · Oct 23, 2007

Just for fun, and assuming someone had the means to build an Earth-Mars shuttle, ie a ship that can go refuel and come back several times, I calculated the mass of such a ship: Assuming it leaves Earth with a C3 of 20.06 km2/s2 and aerobrakes for 5.4 km/s at Mars (Borowski's 120-day transfer scenario). Assuming we use nuclear thermal propulsion and that we leave from a 33'450 x 33'450 km orbit (the Gate Orbit for C3=20.06). The mass in Earth parking orbit is: Mars Transfer Vehicle ---------------------------- Delta-v: 3.17 km/s propulsive + 5.4 km/s aerobrake Structure: 3.45 tons Tanks: 3.69 tons Thrusters: 7.04 tons RCS thrusters: 0.43 tons Avionics/aux. power: 0.86 tons Main thruster propellant: 26.35 tons RCS propellant: 1.29 tons Aerobrake shell: 12.92 tons Payload: 30.00 tons Total mass: 86.14 tons You will also need an orbital transfer vehicle to go from LEO to the parking orbit. Assuming 4tons for a 6-person habitat + 500 kg / person for the 0.2 day transfer (includes food and water for the 120 day trip to Mars): Earth LEO to MGO orbital transfer vehicle ---------------------------------------------------- Delta-v: 2.61+1.48+1.48 km/s propulsive, 2.61 km/s aerobrake Structure: 1.05 tons Tanks: 1.75 tons Thrusters: 1.29 tons RCS thrusters: 0.13 tons Avionics/aux. power: 0.26 tons Main thruster propellant: 12.52 tons RCS propellant: 0.39 tons Aerobrake shell: 1.84 tons Payload: 7.00 tons Total mass: 26.26 tons Thus to set up the whole re-useable transport system one will need . One Heavy "Magnum" or Energiya launch to set the Mars vehicle in orbit (10 mio/ton = 860 million USD) . One Delta-IV Heavy launch for the orbital transfer vehicle (250 million USD) After that, operation of the system would cost 39 tons or 6.5 tons per person of H2 at the Earth end. I d <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 21, 2007

Time for a thread update! Here is a link with interesting news and links... http://chairforceengineer.blogspot.com/2007/11/marching-to-mars.html ...about a Mars plan just released by Spaceworks Engineering which uses the Ares I and Ares V launch vehicles. Enjoy!

keermalec · Nov 21, 2007

Gee Gunandrockets, do you monitor all these sites daily? You're always on top of the news! Awesome study, by the way. As is more often the case with spaceworks. I almost choked on the 96 billion USD figure at the end though... Interesting to see they favour a "payload and ERV first" approach, as did Zubrin and the previous DRMs. More interesting to see is they consider chemical propulsion and active cooling, just as we have done in our Mars discussion threads. The trip durations, though, are misleading. It says max 335 days on the Illustration but a more reasonable 205 days in the slide show text. On the interogatory side: why use two discardable interplanetary habitats and not a single one for both trips? And why not use solar electric propulsion to transfer more inert payload before sending humans? <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 21, 2007

<Gee Gunandrockets, do you monitor all these sites daily? You're always on top of the news!> Actually I find most new stuff by just monitoring a very few websites. I find a lot just by scanning the space.com discussion forums -- docm in particular is a whirlwind of production when it comes to news. But mostly I stay current via hobbyspace.com, as he is the king of spaceflight news. In fact he recently made noises about cutting back until the outcry from his grateful readers convinced him he was not toiling away in vain.

gunsandrockets · Nov 21, 2007

<On the interogatory side: why use two discardable interplanetary habitats and not a single one for both trips?> I haven't read though the documents yet, I've only skimmed them. But I can make a guess. The 10.9 ton inflatable habitats seem very much like the Bigelow Aerospace inflatable Sundancer module which masses 10 tonnes and is designed to support 3 people for six months. So limited life support consumables could be the answer. <And why not use solar electric propulsion to transfer more inert payload before sending humans? /> Or use gravity assist? Or use ISRU? Ah, now those are the big questions. The mission is interesting as a baseline, but I think it is bloated and much of it's mass could be trimmed off by clever use of some the very techniques we have been discussing.

gunsandrockets · Nov 23, 2007

Okay, I've had a chance to go through the SpaceWorks plan more closely and there are a couple odd things that jump right out. First off, the plan is very conservative in terms of new tech, for example it makes no use of ISRU technology. Yet the plan assumes a closed ECLSS with seemingly 100% efficiency! Even for the 500 day stay on Mars! Fully closed ECLSS seems like a much greater leap in technology than ISRU. Secondly the Ares V utilization for the ERV launch seems odd. Two Ares V launches are used, complete with the Ares V third stage commonly called the EDS. The first Ares V launches into LEO the SpaceWorks 126 tonne TMI stage. The second Ares V launches into LEO the SpaceWorks 72 tonne ERV. The TMI stage then mates with the ERV in LEO and boosts the ERV on a trajectory towards Mars. But why use a complete 3-stage Ares V just to place a modest sized ERV into LEO? The SpaceWorks ERV only masses 72 tonnes which is less than the payload of even a 2-stage Ares V. I believe the payload of a 2-stage Ares V is around 109 tonnes! But with that much unused payload capacity an even better question is why use the SpaceWorks 126 tonne TMI stage at all when the Ares V EDS stages are already in play? Here is how an alternative plan could work... Alternative Plan #1 Use an Ares V to launch into LEO a payload of it's 3rd-stage EDS with a remaining propellant load of 132 tonnes. Then use a second launch of an Ares V with a payload of the ERV + the EDS with 60 tonnes of remaining propellant. That ERV + EDS stack then mates with the solitary EDS, leaving the ERV sandwiched in-line between the two EDS stages. The two EDS stages should have a total remaining combined propellant load of 192 tonnes. Then one EDS fires providing part of the Mars trajectory delta-V, and when empty is jettisoned from the stack. The remaining stack then pivots 180 degrees and the second EDS then fires to complete the delta-V needed t

JonClarke · Nov 23, 2007

Good points I think. Obviously the aim is to have a minimum mass and minimum development mission but still have a long stay. I am more interested in what happens on the surface. A three person crew is not a good number for exploration, however you look at if. If there are two engineers and one scientist it means that the scientist had a disproportionate share of the EVA risk as they will do amost everyone everyone. Regardless of the crew make up, if something catastrophic happens to the EVA crew you are left with one person to complete the entire mission on their own, possibly over a two year period. While inclusion of a pressurised rover is good (and the size is about right), the lack of any backup means it cannot centurer further from the landing site than the safe walkback distance, <10 km. So the presurised rover is wasted. It would be better to send two unpressurised rovers and give the EVA crew the ability to travel ~50 km from the landing site. The lack of ISRU means that power options are very limited. If relying on imported propellants then range will be very limited, if using batteries then it is reliant on the rare the very limited recharge rate. On the subject of power why DIPS? It seems a very inefficient and limited power source for a crewed mission. At least the crew will be warm.... Jon <div class="Discussion_UserSignature"> 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 Arthur Clarke </div>

keermalec · Nov 25, 2007

<blockquote>In reply to:<hr />...the plan assumes a closed ECLSS with seemingly 100% efficiency<hr /></blockquote> Analysing the difference between inert transhab and total transhab mass from table 1 page 14, and assuming each astronaut (+suit) weighs 144 kg (from Apollo data), I get 2.2 kg per person per day of consumables. According to this source a human requires 4.5 kg/day (1 kg O2, 2 kg water, 1.5 kg food) without recycling. Assuming an 80% air recycling efficiency and a 97% water recycling efficiency (VPCAR) the mission will need to provide "only" 1.8 kg/day of consumables per person. This mission provides 2.2 kg and is therefore credible in my opinion. Note the air and water recycling technique here is not 100% closed loop as the CH4 resulting from reacting CO2 and H2 in a Sabatier reactor is vented into space. The technology seems to be identical to that already developed today but not yet implemented in the ISS transhab module. Most suprising though is that a sabatier reactor is used on board but not on the martian surface for ISRU... <blockquote>In reply to:<hr />I believe the payload of the Ares V without the EDS is around 109 tonnes! <hr /></blockquote> Isn't the LEO payload capacity of the Ares V 130 tons ?(figure 13 page 14). I don't understand exactly what the term EDS (Earth Departure Stage) corresponds to in this study. In some cases it is the third stage used to place the payload in LEO, THEN inject it on a TMI course; in other cases it is the payload itself. <blockquote>In reply to:<hr />Use an Ares V to launch an EDS stage with a remaining propellant load of 132 tonnes into LEO. Then use a second launch of an Ares V + EDS to launch the ERV into LEO. The ERV + EDS stack then mates with the first EDS, leaving the ERV sandwiched in</blockquote> <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 26, 2007

<Analysing the difference between inert transhab and total transhab mass from table 1 page 14,> I can't find the table you are talking about. There must be some problem with the documents I downloaded since they don't seem to contain the depth of information you are refering to. Okay. <According to this source a human requires 4.5 kg/day (1 kg O2, 2 kg water, 1.5 kg food) without recycling. /> That sounds like survival level reflecting only consumption of drinking water. Normal water consumption levels are usually much higher because of washing and cleaning. <Assuming an 80% air recycling efficiency and a 97% water recycling efficiency (VPCAR) the mission will need to provide "only" 1.8 kg/day of consumables per person. /> What is the longest a recycling system has operated between breakdowns? The water recycling system for the ISS hasn't even been installed yet (as far as I know) let alone tested to the point of supporting a crew continuously over a period of 500 days, which would equal the time spent in the Mars surface habitat. <This mission provides 2.2 kg and is therefore credible in my opinion. /> For the reasons noted above, I have to disagree. I don't think the life-support system assumptions in the plan are credible. <Most suprising though is that a sabatier reactor is used on board but not on the martian surface for ISRU... /> No kidding. That's just loopy. <Isn't the LEO payload capacity of the Ares V 130 tons ? /> Estimates are as high as 133 tonnes, but that is only for a complete Ares V including EDS. The EDS is the Ares V third stage, of Shuttle external tank diameter, propelled by a single J-2X engine. Without the third stage, the Ares V is supposed to exceed a payload of 100 tonnes, the estimate I've seen lists it at 109 tonnes. <I d

keermalec · Nov 26, 2007

<blockquote>In reply to:<hr /><Analysing the difference between inert transhab and total transhab mass from table 1 page 14,> I can't find the table you are talking about. There must be some problem with the documents I downloaded since they don't seem to contain the depth of information you are refering to.<hr /></blockquote> This is the document I am referring to <blockquote>In reply to:<hr />What is the longest a recycling system has operated between breakdowns? The water recycling system for the ISS hasn't even been installed yet (as far as I know) let alone tested to the point of supporting a crew continuously over a period of 500 days, which would equal the time spent in the Mars surface habitat. <hr /></blockquote> Perfectly agree. I would feel safer if the crew took along all 4.5 kg/person/day and did not rely on a life support system that has not at this day proven its reliability. I suppose the authors think in 25 years time the technology will be reliable. In this context I believe the mission is credible. However, were it my own design, I think I would prefer to use only proven technologies. <blockquote>In reply to:<hr /><I don't understand exactly what the term EDS (Earth Departure Stage) corresponds to in this study. In some cases it is the third stage used to place the payload in LEO, THEN inject it on a TMI course; in other cases it is the payload itself.> Okay I'm having pronoun trouble understanding you. Are you refering to the SpaceWorks study or my suggested improvement of the SpaceWorks plan? <hr /></blockquote> The spaceworks study. <blockquote>In reply to:<hr /><If the ship then has to rotate and fire again, it is probable the second burn will occure sever</blockquote> <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 28, 2007

<This is the document I am referring to> That's what I thought. In my case that document doesn't seem to contain any text, just some images and graphs. Dangit! <...it is the duration from start of first burn to end of second burn which entails gravity losses. To give you an idea, in Borowski's Mars Mission Design, a 38 minute burn in LEO for a total delta-v of 4.21 km/s has a gravity loss of 0.362 km/s. This gravity loss and the additional propellant mass it requires represents a payload mass loss of 12%... Assuming similar thrust/ship mass as in the Borowski example (it works out to aroudn 2 N/kg) two burns would take about 2 x 38 minutes. Gravity losses would be something like 0.35 + 0.45 km/s, as they scale with duration. /> Ah, but the thrust to weight is not the same, not even close. The J-2X engine of the EDS stage has something like 290,000 lbf of thrust! The nuclear engines of the Borowski design only have around 45,000 lbf total thrust. With an estimated average mass of less than 210 tonnes during the burn, the burn time of a two-ended EDS Mars mission stack is likely to be much much briefer than 38 minutes. EDS #1: 25(?) tonnes dry mass + 132 tonnes propellant EDS #2: 25(?) tonnes dry mass + 60 tonnes propellant ERV : 72 tonnes Total stack : 314 tonnes beginning of TMI burn @ Earth departure Total stack : 97 tonnes at end of TMI burn <But your idea is actually a valid one: use two half-spent EDS to save one complete Ares V launch. /> I wish it would save one complete Ares V launch! Instead it just saves placing into orbit the specialized 126 tonne TMI stage of the SpaceWorks plan. <I would go in your direction but would prefer a solution whereby propellant is routed from one EDS to the other via the ERV. In this manner no turning is needed and only one set of engines (expensive things) is used. /> Ah, orbital refueling.

keermalec · Nov 28, 2007

OK, that's where my miscomprehension of what was meant by EDS created an error. I was using 4 RL-10B engines for thrust, as found on the spaceworks TMI stage, and these only deliver a total of 441'600N, not 1'290'000N like the J-2X. Considering an average acceleration of 1'290'000/((314'000+97'000/2) = 6.3 m/s/s and a final velocity of 4.2 km/s (for a C3 of 19.37 km2/s2 as indicated in the spaceworks proposal), the burn duration is indeed only about 12 minutes. Gravity losses are only around 0.12 km/s! I believe there is however, a third solution for using 2 EDS stages as you propose, without rotation: simply stack them: ERV EDS #2 EDS #1 In this way we create a two stage TMI vehicle. No need to turn around in mid-burn. <blockquote>In reply to:<hr />I wish it would save one complete Ares V launch! Instead it just saves placing into orbit the specialized 126 tonne TMI stage of the SpaceWorks plan. <hr /></blockquote> By eliminating the TMI stage you really do eliminate one whole Ares V launch, or is there something I missed? <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 29, 2007

In this way we create a two stage TMI vehicle. No need to turn around in mid-burn. /> That might make for a tricky docking operation in LEO. And how complicated and heavy would the docking collar be that links the two EDS together? It would be interesting to find another mission architecture that considered a similar layout and compare it to your concept. <By eliminating the TMI stage you really do eliminate one whole Ares V launch, or is there something I missed? /> I re-edited my 11-23 post, and hopefully it is now a little more clear. My alternate plan #1 still uses two Ares V launches to get the Spaceworks ERV to Mars. One Ares V launch to place an EDS into LEO. The second Ares V launch to place the ERV plus another EDS into LEO. The Spaceworks plan is wasteful of the full capability of the Ares V launch vehicle. The Spaceworks plan to use a complete Ares V just to launch into orbit a 72 tonne "ERV", wastes 60 tonnes of Ares V payload!

keermalec · Nov 29, 2007

<blockquote>In reply to:<hr />The original SpaceWorks plan uses a total of one Ares I, four Ares V and four EDS stages plus one specialized TMI stage to launch the mission payloads. Our system could cut that down to one Ares I, three Ares V and one EDS stage plus one specialzed SEP-TMI stage! <hr /></blockquote> if I summarize the spaceworks proposal we have: 1st Ares V launch: TMI 2nd Ares V launch: ISPS + return Hab 3rd Ares V launch: ERV 4th Ares V launch: Crew MEV + Hab Your suggestion, if understand it right: 1st Ares V launch: EDS # 1 2nd Ares V launch: ISPS + return Hab 3rd Ares V launch: EDS #2 + ERV 4th Ares V launch: Crew MEV + Hab So, if I get it, you are replacing the TMI stage by an EDS, and adding a second EDS to the 3rd launch. You are effectively optimising the mission by using two EDS to obtain a higher delta-v at departure? If this is the case we may have to consider the implications in arrival delta-v (faster departure means faster arrival). The aeroshell should be designed for a higher aerobrake delta-v. <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Nov 30, 2007

[The original SpaceWorks plan uses a total of one Ares I, four Ares V and four EDS stages plus one specialized TMI stage to launch the mission payloads. Our system could cut that down to one Ares I, three Ares V and one EDS stage plus one specialzed SEP-TMI stage!] Okay, I think the confusion comes from the fact my 11-23 post listed two different alternatives to the SpaceWorks Engineering plan. The alternative you have just referred to does indeed only use a total of three Ares V launches to complete the mission. I'll reedit my 11-23 post again and try to clear up any remaining confusion.

solarspot · Dec 2, 2007

Actually, aren't gravity losses when boosting the apogee of an orbit dependent on how long you run your engine away from the perigee of the orbit? If that is the case, then burn the first EDS on your first orbit, then use the second one on your next pass through the orbit's perigee. I think that may reduce gravity losses suffered compared to burning the second EDS mid-way between perigee and apogee.

keermalec · Dec 4, 2007

You are right Solarspot, but in the spaceworks proposal there is only one perigee, as the vehicle goes directly into a hyperbolic escape trajectory. <div class="Discussion_UserSignature"> “An error does not become a mistake until you refuse to correct it.” John F. Kennedy </div>

gunsandrockets · Dec 15, 2007

<Good points I think.> Thanks! <Obviously the aim is to have a minimum mass and minimum development mission but still have a long stay. /> Well, I would say more minimum development rather than minimum mass. The tonnes per crew is a lot higher than Zubrin's Mars Direct. I don't agree. Three is the perfect size for surface exploration, consisting of a two-man team in EVA suits plus one person in the habitat handling any remote control robot. As is typical with ISS EVA missions where one person inside the ISS controls the robot arm. <If there are two engineers and one scientist it means that the scientist had a disproportionate share of the EVA risk as they will do amost [every one]. /> Any reasonably sized crew (6 or less) will be composed of cross-trained generalists rather than pure specialists. Every person will share the burden of EVA. <Regardless of the crew make up, if something catastrophic happens to the EVA crew you are left with one person to complete the entire mission on their own, possibly over a two year period. /> Any resonably sized crew to Mars could be subject to catastrophic loss from a variety of causes. A crew of 3 is not especially more vulnerable than a crew of six. <While inclusion of a pressurised rover is good (and the size is about right), the lack of any backup means it cannot centurer further from the landing site than the safe walkback distance, <10 km. So the presurised rover is wasted. It would be better to send two unpressurised rovers and give the EVA crew the ability to travel ~50 km from the landing site. /> There very well may be an upressurized rover to serve as an emergency back-up to the pressurized rover, therby permitting surface exploration beyond walk-back

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