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Exploration

Tweaking Inspiration Mars

By Keith Cowing
NASA Watch
March 8, 2013
Filed under , , ,

Inspiration Mars: Some Thoughts About Their Plan, Dennis Wingo, SpaceRef
“While as of yet the plan is incomplete, it is a baseline from which to build on, and most importantly it does, I think, what Mr. Tito intended, which is to change the conversation about exploring beyond Earth orbit. I am not interested in comparing the Inspiration Mars plan to NASA’s plans but to focus on what could be done to improve that mission.”

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

56 responses to “Tweaking Inspiration Mars”

  1. Andrew_M_Swallow says:
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    Any chance of a Bigelow spacestation being in orbit by  2018?

    It would allow everything to be assembled in space.  A 3 launch solution with the consumables in a Cygnus then becomes possible.

    • Ben Russell-Gough says:
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      It’s a possibility; Bigelow have long said they want to launch as soon as possible after two crew launch options are available; I would be very surprised if CST-100 and Dragonrider were not operational before then.

  2. Ben Russell-Gough says:
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    My preferred solution remains a two-launch option, either two Dragons or a Dragon and a Cygnus-derived hab and consumable store.  Bigelow’s BEAM is only an LEO technology test bed and it might not be suitable for long-duration deep space work as well as the stress dynamics of the TMI burn.

    A two launch architecture, as well as allowing more margin for stores, would also allow for various science instruments, both for crew monitoring and remote sensing during the pass through the Martian system.

    • Paul451 says:
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      “My preferred solution remains a two-launch option, either two Dragons or a Dragon and a Cygnus-derived hab and consumable store.”

      Can a capsule’s docking adaptor handle the stress of carrying the cargo-module (and tons of cargo) during TMI without warping?

      “Bigelow’s BEAM […] might not be suitable for […] the stress dynamics of the TMI burn.”

      You don’t, indeed can’t, inflate it before TMI. It would be carried in the extended trunk during both launch and TMI. After TMI, the upper stage is jettisoned, exposing the trunk. The inflatable module is unlocked and the capsule-trunk pulls away, swings 180 and docks. Only then is the inflatable inflated, and if all goes well, you open the hatch. Similar to the CM/LM manoeuvre in Apollo.

      • Steve Whitfield says:
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        Paul,

        It’s pretty much a given at this point that we’re looking at a minimum of two launches.  That being the case, if the Bigelow module is launched on a secondary LV, is there any reason it can’t be extracted, attached to the mission stack and expanded in LEO, before TMI?

        This would allow mission supplies, brought up in launch 2 and/or 3 to be transferred to the Bigelow after expansion and before TMI.  There will be some delta-V loss during cargo transfer, but I don’t see any solution where that isn’t the case.

        This, of course, assumes that the Bigelow will survive BEO for the mission duration, but that looks like it’s going to be a requirement for any architecture they choose.  They should be working on testing that now.

        If this is viable, it opens up another possibility.  If an inflated Bigelow is structurally sound enough to ride the nose of a Dragon, or whatever spacecraft is used, then what about two Bigelows, in-line, on the nose.  It gives you twice the volume; it gives you redundancy; and putting a large bladder of water in the front unit gives you a good forward primary radiation shield with a good thickness for absorbing and/or slowing secondary radiation.  It might also give you somewhere to get away from it all.

        Of course, any of this complicates the artificial gravity plan if they decide to go with a tethered system.

        Steve

        • Paul451 says:
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          Whether or not the Bigelow module is structurally sound enough to manage the TMI-burn, my question is whether a capsule docking adaptor is. It wouldn’t take much warping to prevent the hatch from opening, or to prevent the crew from jettisoning the inflatable when the time comes to prep the capsule for re-entry.

          (And the torque forces from two inflatable modules in a line would be vastly worse. And remember, it’s not just the mass of the modules, but also the tons of cargo you want to store in them.)

          This is not to say it can’t be done. But if you have to significantly redesign the docking adaptor on the capsule and inflatables to add special load-bearing mounts, you are increasing your dev costs and risking your already insanely tight schedule.

          It’s the same with any of the suggested alternatives. Tethers, solid hab-modules, orbital-assembly, pre-launched cargo, Tinker’s pressurised trunk, etc. Every step you take away from the single-stack, single-launch scenario adds much more than just the cost of an extra launch.

          If a single launch isn’t possible, then 2018 isn’t possible.

          In that case, perhaps better to skip Mars and go for a much cheaper Lunar fly-by in 2018, and maybe a landing in 2019; 50th Anniversaries of Apollo 8 and Apollo 11 respectively.

          • Steve Whitfield says:
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            Agreed on the docking issue, but I think there’s enough time to redesign and manufacture it — if they haven’t done the redesign already, given that 1) they may have been working on this for quite a while already, and 2) Musk has been thinking Mars for quite a while now and he’ll face the same requirement.

            As far as a single launch goes, I’ve got 10 bucks that says there’s no way to do it with any single “spacecraft” that will be available, off-the-shelf or modified, by then.  An inflatable is the best looking solution, I think, which means bringing cargo, and maybe even crew, to LEO separately after inflation and before TMI.

            I wonder it a “slow” burn from LEO to TMI velocity is possible to reduce stresses.  If they’re indeed “loading up” in LEO, then fuel can be topped up as well (even if the free return doesn’t need it, extra fuel on board seems like a good idea to me, for course corrections and any unforeseen problems at either end (remember Apollo 13)).

            A tethered second Dragon would be possible for gravity, but if they’re going to stow supplies there during the trip, those supplies might as well stay on Earth, since they won’t be accessible.  So it always comes back to needing more volume in a single “vehicle,” whether it be a single capsule or a capsule with something(s) else docked to it.  Dennis suggests a hard shell volume, but how will that effect the total launch mass?  How will it stress the docking adapter?  I’m against trailing it behind if that means any breaks in the heat shield.  I think that heat shield needs to be entirely solid considering the reentry velocity, even if they do Dennis’ 10 laps around Earth braking.

            Maybe I’m short on imagination, Paul, but I see the Dragon plus Bigelow as the only starter, with a minimum of two launches.

            The other thing that occurs to me is to borrow from von Braun and wrap a doughnut-shaped storage volume (with a trapezoidal inner surface) around a Dragon that can be accessed from Dragon a side hatch, launched separately then attached and loaded in LEO.  It could be hard- or soft-shelled, but I’d ask Bigelow if they could do a rush-job special.  And I’d have them make the outer parts of the volume a water bladder, for shielding and for mass redistribution if that becomes necessary.

            My final crazy idea — a “Dragon Train” — two or more Dragons connected nose to tail (hatches open in flight after TMI), like Mir or ISS modules, with the “Caboose” having an intact heat shield for reentry.  Each “train car” is a separate launch, but they can be launched ready to go, needing only to be docked together.  Ignoring the inclination angle, this might be a good job for the ISS using Dextre.

          • Paul451 says:
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            “I wonder it a “slow” burn from LEO to TMI velocity is possible to reduce stresses.”

            If you do a “slow” chemical burn, then you lose efficiency because a significant part of your burn is not at perigee. (The further you are from perigee at burn, the less “bang for buck” you get.)

            Re: Von Braun cargo ring.
            Putting anything on the capsule rules out abort during launch. Adds another failure mode.

            Re: Stocking/fuelling.
            You are adding multiple launches, all with prox.ops, and an orbital refuelling mission, and orbital assembly of the modules, and cargo/outfitting missions…

            IMO, if you can’t figure out how to fit the supplies into the Dragon capsule to do a single stack/single launch, you can’t do a 2018 mission.

            [Okay, oaky, I’ll try one:

            Launch a full loaded hard cargo-module (ATV/HTV/Cygnus/etc) and a SEP booster. A few months later, separately launch a crewed capsule-stack directly into TMI. The capsule-stack includes the deflated inflatable in the trunk, which is deployed after TMI.

            The cargo-SEP stage starts from LEO a few weeks earlier, giving it time to get up to speed before the crew launches. The two stacks meet somewhere in BEO. (The SEP having enough spare delta-V to chase down the capsule-stack.) The cargo-module then docks to the other end of the inflatable, massively boosting your cargo volume; while the inflatable gives you a bit of open space for 500 days.

            If the SEP has any prop left, it’s possible that the thrust is low enough to shunt the whole double-stack without my dreaded torque effects, letting you eke out a few more hundred m/s delta-v. At the very least the solar panels on the SEP give an second power-supply independent from the capsule.]

          • Steve Whitfield says:
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            Reply to Paul451  Today 02:45 AM

            I like your ATV/HTV idea.  The only catch I see is that the acquisition and rendezvous software is for ISS.  Assuming that they can rewrite the software in time (which I think they could), there’s no way to test it beforehand.  It’s all or nothing, sort of like Apollo 8 and 11.

            Assuming that the delta-V can be accommodated, I’d still rather see any “assembly” done in LEO as opposed to after TMI, because:

            1) The lower velocity will make rendezvous and everything else easier and safer.
            2) Real-time control from Earth is possible, if needed, like they do for the berthing on ISS.
            3) If any problems or delays crop up, you’ve got another “window” for exit every 90 minutes.
            4) If the ISS or other facilities, like a refueling flight, are needed they’re all going to be easier, cheaper, and recoverable in LEO, but not after TMI.

            One thing I do like about doing it after TMI, if you’re going to send a second package to dock with, send a third one as well, flying the same trajectory separately to Mars and back.  Then if there’s any problems with #2, jettison it and dock with #3.  Or put contingency and long-shot supplies/parts/equipment in #3.  It’s money, but it’s a safety measure.

        • Paul451 says:
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          “I’d still rather see any “assembly” done in LEO as opposed to after TMI,”

          Assembly in Earth orbit means you have to carry the heavy, full-loaded cargo-module on the end of the capsule’s docking adaptor during the TMI burn. I was trying to suggest an alternative.

          “if you’re going to send a second package to dock with, send a third one as well”

          And if a third, why not a fourth. And extra crew. And…

          I’m trying to keep the costs down. The question is what’s the most spartan mission possible. If they really can’t do it with a single launch, then what’s the simplest double-launch mission.

          [Edit:
          “1) The lower velocity will make rendezvous and everything else easier and safer.”

          This I don’t get. The velocity difference between the two craft is the same, whether they’re in Earth orbit, or in Mars transit.]

    • Jeff Havens says:
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       Ok folks, ponder this — how about designing one or two inflatables that could fit into the unpressurized trunk of a Cargo Dragon (or design a Dragon trunk with a larger circumference?  Would Falcon9 v1.1 be able to handle the weight of said mission?), and send it up on one or two of the CRS runs to the ISS?  De-pallet, link to the station, inflate, and supply it before the manned capsule is launched.  Dock to the inflatables, and then head out? 

      It kinda flies in the face of this being private, but the ISS (and therefore involvement of NASA) could be minimized to a “staging point and cargo handling” scenario.. maybe pay a bit for renting the docking space?  Cargo Dragons dedicated to iMars supply runs? 

      One of the beauties I see with this scenario is that it *could* be possible to do this 1-2 years BEFORE the date of the TMI burn, so that both the time to stock up as well as the cost is spread over a longer period of time.

      Also, if packed right, you might be able to add to the structural integrity of the inflatable(s), to make it stress-tolerant to the TMI burn.

      Just burning some thought calories on a Saturday morning,

      –J

      • DTARS says:
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        Jeff
        Cool idea!!!  Lets start using ISS as a place to assemble spaceships for missions to BEO like Von Bruan intended. Lets use public space to assist in the exploration and settlement of the inner solar system. Doesn’t ISS have a robot arm to help assemble stuff??? Give those ISS astronaunts a real job! A construction job.

        Steve lolol I’m sure glad at least Mr. Tito was listioning to me when I said you just have to show them.(the public)and that pubic space needs to assist commercial space to do BEO exploration plus laying the ground work for the Inner Solar System Railroad. 

        Tick pilot
        employee of The Inner Solar System Railroad

        The idea of building an inner Solar System Railroad seems a lot more realistic today than a few weeks ago.

        Thanks Mr. Tito!!!!!

      • DTARS says:
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        Doesn’t Bigelow have a deal with NASA right now to add one of their balloons to ISS. Couldnt that BE the same balloon used on this mission?? Couldnt Bigelow send this first hab to ISS which could be tested and then used for this misson??

        Thinking about Tinkers multi floor trunk idea, from another thread with no Bigelow hab used.

        Maybe not for this mission but for Bigelow habs designs in general, What if Bigelow were to design a hab that is packed on the outside of a square 12 by 12 core/Dragon trunk and then inflates the hab which has a square shape wouldn’t that make more sense. more useful space for a spinning gravity design Couldnt you launch a bigelow hab on the outside of a dragon trunk then have a astronaunts unpack the core trunk once it iss dock to ISS or on its way to a BEO mission??

        • Andrew_M_Swallow says:
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          The balloon is called the BEAM.  You can see several references to it in this discussion.

          The BEAM has no life support or windows or cooking facilities.  It is just an empty box that blows up in space.

          So as a hab the BEAM is just a publicity stunt.  Ignore it.

          p.s. Bigelow’s original product the Sundancer will provide the needed functions.

      • Steve Whitfield says:
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        Some of us have been kicking this basic idea around, with variations.  My only comment is about the 1-2 years before idea.  Currently NASA’s prepacked astronaut food has a shelf life of 1-2 years max.  Some stuff lasts several years, but the quality (taste, texture, appearance) degrade pretty quickly after 1-2 years and you wouldn’t want to eat it.  And this brings up the question of food.  Will the IMF flight buy food from NASA or elsewhere?  I’m only aware of one US company that sells “space food” and I don’t know if it is actually packaged for use in space or if they can deliver a two-years-times-two-people sized order all at once.  So many questions; so few answers…

  3. muomega0 says:
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    “This paper is not an architecture …unknowns are large..assumptions many, many critical issues are not discussed.”

    “I am not interested in comparing to NASA’s plans but to focus on what could be done to improve that mission.”

    “Requirements: 1. Two Crew 2. As soon as Practical  3 Least Cost”

    “SpaceX Dragon does not have the volume for food and spares”

    “The 10,000 kg payload is out the door, drives you to a two launch architecture”
    ———
    Wingo concludes that the mission does not have enough mass for food, humans, and spares, higher mass is required, and an additional launch is required, even before considering all the critical issues, which just add more mass.  Many would agree.

    NASA has studied Mars architectures, and a number of launches, substantially higher, and staging are required-likely because all technology development was eliminated.  Google Mars DRM 5.

    In contrast, NASA: 1.  sends more crew 2. every other year 3. costs exceed the budget, substantially higher than Tito’s budget.

    So a comparison to NASA’s plans would be very valuable, to outline risks and to review critical issues, and perhaps identify more of the unknowns, and consider alternative architectures rather than HLV only to cut costs.  Even if this mission does not materialize, this comparison would likely be very fruitful.  Perhaps Wingo or others will provide this valuable comparison in the future.

    Why send a capsule to mars which includes the heat shield for earth?  Why does NASA *require* a HLV?  Why not stage at L2?  Where is the data to justify this architecture?  What critical issues are not being addressed in either architecture, including costs?

    Most importantly:  what critical technologies are not in place, not being funded, that could enable the mission or substantially reduce costs?

    Most feel that a depot centric architecture with EP are the key ingredients to cut the long term costs to NASA.  Yet HLV is still on the books.

    The results of architecture studies should provide the mass impacts for meeting the requirements *to various degrees” and the varying costs.  This data could help private interests design future missions.  Not paper, but test data in the appropriate environment with this technology raised to higher TRL.  the paper points out that NASA could provide a critical role here, including TPS and ECLSS.

    “I thought about an inflatable as well but the problem with an inflatable
    is that you don’t have the volume available until you are already up there and
    it inflates. Thus some type of hard module is going to be required.”

    A hard module is not required.  If one stages, more launches, one could simply fill the inflatable up later. It does not require a hard module.  Likewise for propellant tanks, launch them partially filled and fill them up later.  For radiation protection, launch the additional shielding separately, and reuse it for the trips to and from L2 to Mars.  Gather data on the radiation mitigation strategy at L2 first–much cheaper.  Even the Mars DRM included inflatable modules in the mass estimates.

    • Denniswingo says:
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      Any comparison to NASA’s plans is superfluous as the goals are completely different.  NASA’s plans, using a super rocket and a super expensive crew module are simply incompatible with a minimalist approach like this.  I think that it is doable, albeit with a mass closer to the 15-17k I mentioned.  The trajectories that I outlined will help keep the mass and C3 requirements down to two launches.

    • Denniswingo says:
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      Wingo concludes that the mission does not have enough mass for food, humans, and spares, higher mass is required, and an additional launch is required, even before considering all the critical issues, which just add more mass.  Many would agree….

      …So a comparison to NASA’s plans would be very valuable, to outline risks and to review critical issues, and perhaps identify more of the unknowns, and consider alternative architectures rather than HLV only to cut costs.  Even if this mission does not materialize, this comparison would likely be very fruitful.  Perhaps Wingo or others will provide this valuable comparison in the future.

      There is no purpose whatsoever in making this comparison.  Tito is not going to use, nor is it needed, a super heavy lift vehicle.    NASA “requires” a super heavy lift vehicle because that is what one of the NASA centers does, build launch vehicles.  A HLV has NEVER been needed for this.  If you look at Von Braun’s architectures before the Apollo era, including his project Horizon lunar base, they did not use a vehicle any larger than what a Delta IVH can put into orbit.

      IF and ONLY IF the United States had a major commitment to opening the solar system to economic development, a super heavy lift would be desirable as then you can amortize that gawdafully expensive development and operations cost.

      A hard module is not required.  If one stages, more launches, one could simply fill the inflatable up later.

      It is cheaper to just do it.  Yes there are ways to use more launches to outfit the system but that drives other complications.  It is my opinion that this can be done in two Falcon heavy or Delta IVH launches.  It is my opinion also that this is a very doable mission.  Dennis started out with a concept paper.  Things will greatly morph as the real work gets started but the  boundaries, the lift mass and the launches, are within the ball park to make this work for well less than a billion dollars.  It will be an amazing mission and it will do much for private space and to revive the interest of the American people in space.

      • muomega0 says:
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        Dennis, your looking at this from a different viewpoint.

        Your assessment appears valid:  the flyby needs two launches, and the inflatable may not be ready.  Implicitly, LOC should decrease significantly with more food, spares, etc versus one launch.

        The comparison is not to reflect NASA’s approach into Tito’s flyby, but to update NASA’s architecture, which you and most everyone else agree does not need a HLV.  And also to highlight key technologies that need to be worked rather than engine development.

        Sorry for the confusion.

        • Denniswingo says:
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          The comparison is not to reflect NASA’s approach into Tito’s flyby, but to update NASA’s architecture, which you and most everyone else agree does not need a HLV.

          Ah, I see.

          Well that is pretty much a religious discussion.  The problem is that NASA does not have a concise reason for doing Mars.  During the Apollo era the goal was very clear cut.  I spoke to some of the old Marshall Spaceflight Center hands and they told me that their requirements document from headquarters had two bullets.

          Get the crew to TLI alive.

          90,000 lbs to TLI

          That’s it.  Everything else was left to MSFC.

          The SLS has no requirements wrapped around it and it has no mission.

          Any proper mission development begins with a level zero requirement about what they are going to do.  Then you can start to do the mission analysis, which feeds back to determine what kind of launcher you need, and then everything starts to fill in.

          NASA has the heroic scientist/astronaut vision for government employees walking around, picking up rocks, and answering the questions about life on Mars.  

          What if that idea was instead colonization?  A completely different architecture would be used.

          Until we figure out what people are going to be doing on Mars it is impossible to develop system to do it!!

          The assumption is that we need a heavy lift vehicle to do it.  However, that was not Von Braun’s assumption, especially after the demise of the NERVA program.  I did the last video interview of Ernst Stuhlinger about a year before he died.  In that Dr. Stuhlinger related to me that Von Braun told him in 1972 that ion propulsion was the only way to do the Mars mission.

          So, who do you believe?

          This is why it is not really worth wasting time on developing a NASA architecture when NASA has no idea what they are going to do when they get there.

          To me, I really like the idea of the buildup of a colony and send people there one way.  It makes a lot of sense and with our modern technology and the new revolution in 3D printing I now think that it is possible to do so.

          • Steve Whitfield says:
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            Dennis,

            I agree with you whole-heatedly on the one way trip plan.  However, the first few trips would have to be two way, in case things don’t work out for some unforeseen reason.  When push comes to shove, I don’t think the world will let it happen any other way, even though there’ll be thousands of volunteers.

            I think we need to prove that the spacecraft can go two way, even if they come back with no people in them.  We want these spacecraft to be reusable, not a new one every trip out.  There’ll be a lot of value in that aspect alone.  There have been all kinds of railroad, conveyor, whatever-you-want-to call-it systems proposed, and once we get one running between Earth and Mars, the asteroid belt is almost right next door.  And then a little farther down the road, instead of sending one back to Earth, we send it farther out.  Hello moons of Saturn.

    • Steve Whitfield says:
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      muomega0,

      I don’t follow the logic in your heat shield comment.  Even if you’re staging at L2, or anywhere else, you still need to slow down from interplanetary velocity and “stop.”  So if you’re not going straight to Earth landing, which requires the heat shield, you’re going to need considerably more fuel/oxidizer, which will mass considerably more than the heat shield, and you have no choice but to carry it the whole trip.

      Also, re: your comments on Dennis’ assessment, I think volume is more the issue he was initially pointing to than mass, although mass obviously has to be considered at every step in the design.

      Steve

  4. Brian_M2525 says:
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    What everyone seems to just now be coming to the realization, just as was discovered back in the 1960s with the Skylab wet workshop, unless all you need is pressurized volume, having a collapsed inflatable really is of little use as you really need a lot of stuff to go into it, and then the logistics costs are prohibitive. Why not just launch the stuff in the volume you intend to use from the outset? NASA’s Transhab discovered this prior to selling out to Bigelow; they figured out a way to pack everything into a center core and then it would all deploy after inflation.   

    Another thing that people tend to forget or not realize is that in the Apollo era, we did not start out by trying to have all of the pieces required for the ultimate mission ready at once, and ready in time for the first flight. Initially we were launching Saturn 1s and command modules, and later came Saturn Vs and lunar modules and rovers. Everyone, including NASA itself, seems to think that NASA cannot just develop the initial elements first; this was a critical error in Constellation-we needed the Mars mission capsule from the outset; we had to start working on Altair landers immediately; for some reason everything has to be ready to send a total crew to land on Mars the first time. It was all for nothing. Tito’s mission is what NASA would need to do as a first step, too, just to test out systems, trajectories, etc.

    From Dennis’ analysis, It unfortunately looks like the Tito mission cannot be accomplished in five years. It was a nice idea but… If SLS were on a slightly more advanced schedule, perhaps it would have better mass margins than a Falcon? Having any other manned vehicle ready prior to Dragon, which of course is already flying in prototype form with several successful missions-not likely.

      

    • Denniswingo says:
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      From Dennis’ analysis, It unfortunately looks like the Tito mission cannot be accomplished in five years. It was a nice idea but… If SLS were on a slightly more advanced schedule, perhaps it would have better mass margins than a Falcon? Having any other manned vehicle ready prior to Dragon, which of course is already flying in prototype form with several successful missions-not likely.

      Funny, I have come to the opposite conclusion that it is absolutely doable.  In just doing my bit of research the delta V can be brought down significantly and with the added benefit of more flybys.  It is MORE doable today than before in my opinion.  You just can’t do it on one launch.

      • Steve Whitfield says:
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        Without going into details, I believe that NASA, should  they ever get that far, is going to find out that even with their BFR they still can’t do it with a single launch.

        Once again, go back to von Braun; he’s already worked out these issues, in detail, over years, and I don’t recall ever seeing a first mission to any destination that von Braun proposed to do with a single launch.

      • muomega0 says:
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        Project Gemini- objective was to develop space travel techniques in support of Apollo, which had the goal of landing men on the Moon

        Project Mercury – two goals: putting a human in orbit around the Earth, and doing it before the Soviet Union

        Each lasted a few days. 

        Doable–  Gravity assist and flybys already demonstrated.  Plus is bone loss, radiation, ECLSS, TPS data for the mission.  Lack of mass budget adds much risk, including lack or crew health technology.

        Alternative:  Tito’s misson could be tested at ISS/L2 with substantially less risk–it just  skips the already demonstrated flyby demo.  Reduced testing reduces costs with sometimes higher risk (e.g. hubble mirror).

        Inspirational?  Perhaps, depending on level of success. 

        This mission and the NASA DRM or tech plans fail to flexible paths to demonstrate the sustainable key technologies required for Mars.

        Staging is required to lower costs and allow flexible mission paths.

        Depots, a much higher priority than this mission IMHO, are not in NASA’s plans to reduce the number one cost driver:  HLV.

        • Denniswingo says:
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          Alternative:  Tito’s misson could be tested at ISS/L2 with substantially less risk–it just  skips the already demonstrated flyby demo.  Reduced testing reduces costs with sometimes higher risk (e.g. hubble mirror).

          Technically maybe.  However, there is little inspiration there.  I give you an example.  Warren Buffett and Bill Gates have $200 BILLION dollars in pledges for their do gooder ideas from rich people.  What if, in answer to what Inspiration Mars does, that we get even a fraction of that pledged to support private space.

          Technical progress is at the mercy of financial support.  We have all the technology that we need to explore and develop the solar system, we just don’t have the financial resources to support it.

          You don’t know what will result from the Inspiration part of Inspiration Mars, even if the crew don’t make it back alive.

    • mattmcc80 says:
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      But for a long duration flight, you really do want a decent amount of pressurized volume to occupy, so that you don’t kill your crewmates before reaching your destination.  Inflatable modules are an economical way to accomplish that.  It doesn’t have to be stuffed to the gills with supplies to justify its presence on a long-range spacecraft. 

      • JimNobles says:
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         There’s going to be times when crew members will really, really feel the need to get out of each others sight. I mean really. And preferably out of conversation range as well. 500 days is a long goddam time to look at the same person.

    • Steve Whitfield says:
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      Brian,

      I understand what you’re saying about the inflatable, but your analysis, I think, reflects single-mission thinking, and to an extent short-mission thinking — NASA thinking.  What if your goal is colonizing, in-space manufacturing or processing, resource acquisition, etc., anything that’s more involved than just going somewhere and coming back?  Looked at that way, I don’t think working with Bigelow inflatables is selling out.  Hopefully there will be lots of uses easily-delivered storage/working/living volume in the not too distant future.

      • Joe Cooper says:
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        Single mission thinking is certainly relevant to a single mission project. It’s probably going to be a long time before there’s colony-scale funding.

        • Steve Whitfield says:
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          You may be right.  But two months ago we were all saying it’s probably going to be a long time before anyone flies to Mars.

          The sort of projects that are not single mission 1) are not limited to colony stuff (and more likely to generate revenue), and 2) need to have planning start years before they do get funded.  Single-mission and short-term thinking seem to go together, but I think we’re at the point where we need to start thinking more in terms of multi-mission and long-term.

    • Paul451 says:
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      “unless all you need is pressurized volume, having a collapsed inflatable really is of little use as you really need a lot of stuff to go into it,”

      I may be reading it wrong, but I think the idea is precisely pressurised volume. You’ve seen the Soyuz packed for launch/return? Three crew jammed into the tiniest space possible. Picture the much larger Dragon packed out like that for launch, with barely enough space for the two crew to wedge in.

      After TMI, you deploy the inflatable, move some of the packed supplies into the inflatable, but otherwise leave the Dragon packed tight to use as a radiation storm-shelter.

      If you can fit a core-equipped version of an inflatable (like BA-330) into the extended trunk, then you might be able to add some supplies or systems to the inflatable. But I suspect it’s just about having room to move during the 501 days.

      People keep trying to picture the inflatable into a storage module, and it doesn’t work and they get angry and confused. Think of the inflatable purely as room-to-move. It still may not work, as a mission, but at least it is clearer what they are trying to do, and what the actual issues are.

  5. cuibono1969 says:
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    Great article! Love the Lunar and Venus options.

    My main concern is the re-entry. It would be less than inspirational if, after 500 days of getting to know (and love?) the brave crew, they were then frazzled at the last hurdle, or succumb to the G-force strain.

    Dragon (if they use it) is supposed to already be designed for Mars-return velocities, but it hasn’t been tested. Then again, I believe Apollo 8 was the first test of lunar re-entry velocity for the CM.

    They definitely need an mini exercise machine to prepare for multiple Gs.

    • Steve Whitfield says:
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      In another thread we talked about the possibility of tethering to a Dragon trunk or a spent second stage and spinning them around their common center of gravity to provide an artificial gravity.  This is proven technology; they would simply have to use a tether long enough that the Coriolis effect wouldn’t affect their inner ears.  Although they haven’t proposed this that I’ve seen, neither has it been ruled out.

      • cuibono1969 says:
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        Great idea, and ground-breaking.

        As an aside, isn’t this the sort of research that should be part of the ISS program? Inflatables, new propulsion ideas (VASIMR and others), tethers, long-term life support, active and passive radiation shields, etc, etc. Things we need for Mars flights. Despite some announcements (eg: Bigelow) it seems badly underused.

      • Ben Russell-Gough says:
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        IIRC, this is in conflict with their current preferred use for the spent TMI stage – namely as extra solar radiation shielding.

        • Paul451 says:
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          Okay, now I’m stumped. How the hell can they deploy the inflatable module if the trunk is still mated to the TMI booster?

          • Ben Russell-Gough says:
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            That, Paul, is one of the many things that remains ‘TBC’ in this. 

            However, my favoured solution is to have the inflatable secured to the propulsion stage rather than the Dragon (much as the ORBCOMM prototype satellite was on the SpX-CRS-1 mission).  The Dragon detaches, translates clear, waits until the module has inflated and then docks nose-to-nose with the hab.  This means that you can use the propulsion stage’s batteries to power the hab until the Dragon is docked again.

  6. tejasmojo says:
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    Would there be enough space under the Dragon nose cap (maybe a special nose cap design) to stuff a small packed inflatable (how big) under the cap. If one could stuff everything in the capsule, then one could transfer some consumables into the deployed inflatable later to make room for the crew to exercise, perform hygiene and give more living space.

  7. John Gardi says:
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    Dennis:

    Any good solutions for a mission like this? What if the outgoing leg to the Moon was a minimum energy transfer, a sort of shakedown cruise, as it were. Couldn’t you then use the Moon and the Earth for two gravity assists? Could the shakedown cruise days be made up for by getting a faster Mars (or Venus) transfer? If the shakedown to the Moon went badly, you could abort to Earth re-entry. This might take two burns instead of one, wouldn’t it?

    tinker

    BTW: Have you calculated just Venus flybys? As a consolation prize, it’s not bad. It’s another planet, we have no intention to land there and the trip would probably be shorter as well.

    [Edit]

    Geez, there’s a Wikipedia page on crewed Venus fly bys! One paper from the ’60’s showed some promising numbers:

    http://ntrs.nasa.gov/archiv… (pdf)

    [/Edit]

    • Denniswingo says:
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      Tinker

      The problem is that it takes too much time to do the minimum energy transfer and you need a lot of delta V to get to Mars without taking three years.

      The Venus flybys do look interesting and some of them can be done in a year. However, Mars is the one that fires the imagination, I get that. If we can get both, that is historic.

  8. Saturn1300 says:
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     I checked this mission with NASA Trajectory Browser. 96 days to Mars. This sounds like the Pluto mission. It is a free orbit. Mars does not change the orbit.  A no return takes a lot longer, but the Delta V is less. I guess all of the ways have been calculated. I wish that a slingshot at Mars would work. I guess not. Falcon Heavy and Delta 4H are not comparable. FH lifts 2X as D-4H. The largest amount ever claimed for Dragon is 12,000lb. For ISS they claim 3500lb. internal. They are only bringing 1500Lb. now.Shotwelll thinks it is full.No room for people. Unless they will lease one of the used Dragons,SpaceX can build a new design. A biconic would be very good. How could they afford to test it? I still like my idea of extending the trunk and using it. A hatch through the heatshield would work. The heatshield is already in pieces. They use calk in between the sections.

    • Denniswingo says:
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      The FH does not lift 2X of the DIVH to escape trajectories.  The Centaur performance is much higher than the Falcon H upper stage.

      • John Gardi says:
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        Dennis:

        How about a liquid Methane/LOX upper stage for the Falcon Heavy. It’s a likely choice for SpaceX’s initial test of the so far mythical Raptor engine.

        tinker

        • Denniswingo says:
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          There are plenty of options to uprate the upper stage of the Falcon system.  I am sure that one day SpaceX will do them.  However, the Inspiration Mars folks only have about 24 months before their launch vehicle choice has to be set in stone.

      • Steve Whitfield says:
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        How much will launch site location and inclination angle affect the delta-V requirement for a given mass to TMI?  I’m not looking for a number; just whether they’re particularly important.

      • Saturn1300 says:
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          The Centaur has 25,000lb thrust. The new Merlin 161,000lb. vacuum. How do they get better performance,run longer? FH can lift 6 Dragons to LEO at once, by weight. 117,000lbs. LEO 160mi. 28 deg. Launch 2  used Dragons at once. Join together at nose like L-M Orion suggested. There are 2 prices,by weight,93m and 123m. A D4-H 400m?
         Biconic is the best. Internal layout is anyway you want,except for balance. Make a huge volume. Light weight. Might have to detach the front end for reentry. NASA says a capsule is best for BEO. They may know that a biconic would not work. Take a look at the FH fairing. Huge. 16’D. A biconic would be about the same.

        • Denniswingo says:
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          Isp Merlin 1D = 311

          Isp RL-10-4-B2 = 455

          • Ben Russell-Gough says:
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            It would be better to compare the RL-10B-2 to the Merlin-1D-VAC (the upper stage version).  That has an Isp in the 350 range.

          • Anonymous says:
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            Where do you get that number?

            Their Wikipedia page says 311 for the 1D-Vac

            http://en.wikipedia.org/wik

          • Ben Russell-Gough says:
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            http://www.spacelaunchrepor… – The tables at the bottom of the page, which are based on official SpaceX data sheets.

            Sorry, I overestimated. The Merlin-1c-VAC provides about 336s. The Merlin-1d-VAC will certainly have improved performance – a specific impulse of 340s or more is a reasonable assumption.

          • Anonymous says:
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            Sorry Ben, threading died, have to reply this way…

            Sorry, I overestimated. The Merlin-1c-VAC provides about 336s. The Merlin-1d-VAC will certainly have improved performance – a specific impulse of 340s or more is a reasonable assumption.

            The 336 has a question mark beside it.  The Merlin 1D Stage 1 has an Isp of 311. Until they get a lot closer to making the stage 2 work I am going to go with what is a more reasonable Isp out of a Lox/Kero engine.

            Lets see what the real numbers are when it flies.

        • chriswilson68 says:
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          “The Centaur has 25,000lb thrust. The new Merlin 161,000lb. vacuum. How do they get better performance,run longer?”

          Essentially, yes, the Centaur can run longer.  The Centaur gets more thrust per pound of propellant.  So, for a given mass of propellant, the Centaur can run enough longer that it gets more change in velocity from the same propellant mass.  This is called specific impulse.  Centaur can do this because it uses liquid hydrogen as a fuel.  Liquid hydrogen engines get better specific impulse than those that use any other fuel, but liquid hydrogen has to be kept colder than any other fuel and is more difficult to deal with in other ways, too (the molecules are small and tend to leak more easily, they cause damage to some materials, etc.).

  9. chriswilson68 says:
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    “That part of the team has a good grasp on their requirements and what
    needs to be done, though the notion that consumables and spare parts for
    a 501 day mission can be stored in the Dragon is a non starter. The
    team understands this and their revised graphics show an inflatable
    module, though an inflatable module really does not solve the storage
    problem.”

    Of course an inflatable doesn’t solve the storage problem.  It makes the storage problem worse, if anything.  Denis Tito and his team are smart people, and surely they know this.  Whatever their reason for showing an inflatable on their revised graphics, I find it hard to believe this is because they think this will help them with a storage problem.

    Tito and his team have spent a lot of time studying this, and they explicitly claim that all the consumables and spare parts do fit in a single Dragon along with the crew.

    I think we need to see the detailed analysis by Tito and his team before we so quickly dismiss it as a “non starter”.