Sep 272016

Some images copied out of the presentations today. It clearly has some heritage back to the Delta Clipper, at least in inspiration. I’m unconvinced, though, that this is a completely serious engineering concept. At the very least it seems to be jazzed up for some wow-factor; that huge window, for example, is a structural nightmare and the passenger compartment seems to be one breachable pressurized volume. Blow out one window and the whole thing will depressurize.

Still, it’s good to see big-thinkin’. But I really wish they would have somehow vetted some of the questioners after Elon’s presentation… about a third of ’em were either idiots or just there to flack some product or other.

2016-09-27-203311 2016-09-27-202604 2016-09-27-203642 spacex-interplanetary-07 spacex-interplanetary-05

 Posted by at 8:13 pm
  • MzUnGu

    Pretty low in the realism scale compared to some NASA architecture, Did he claim he can fit 100 people in there? That’s tight, considering its only 12m in dia. Aside from that, storing the PV panel that close to the engine would prob void the warranty.

    • cygnus_darkstar

      NASA’s suggested minimum volume-per-person for long-duration space flight is 25 cubic meters. Assuming we use that and a radius of 6 meters for the passenger section,the habitat space would only have to be around 30 m long (taking into account volume for structure and stores) to house that many. Indeed, that looks to be about how big it is in the proposed design taking into account that it’s not a perfect cylinder.

      The space requirements for people can seem weirdly small, but that’s because we’re used to thinking in terms of planar habitats on Earth. Of course in space you get to utilize all of the volume thanks to microgravity.

    • James

      Nah its what they “Want” to get to. That’s the eventual goal. By then hopefully we will be using nuclear rockets so the trips in space will be a bit quicker.

  • Thucydides_of_Athens

    Kudos for thinking big, but the transport ship is closer to a Saturday morning cartoon rather than serious engineering concept. To be fair, it is most analogous to a “show car” like the ones GM put out in their Motoramas in the early 1960’s.

    Now if Elon really wants to think BIG, resurrect the Sea Dragon as the first stage of the stack. Nothing like lifting 550 metric tons into LEO before setting off….

    • FooQuuxman

      Nothing like lifting 550 metric tons into LEO before setting off….

      How true, how true. Now take a look at the payload figures:

      • publiusr

        That’s Sea Dragon level all right. Still, the use of composites worry me.

        I was hoping Musk would make a giant Saturn IB type design, but using Beal BA-2s instead of Jupiters and Redstones.

        Now I imagine high-test peroxide and carbon fiber tanks might not exactly get along–but coatings/inserts could take care of that. Room temperature propellants like HTP and kero’–that’s fine for composites.

  • Bob

    Who is going to pay for all this? How much will it cost? What possible thing will these people do on Mars which will justify the horrendous cost?

    • sferrin

      I’ll bet all these questions were asked of Columbus.

      • Bob

        I have no objection to space exploration and exploitation but all such should be left to private enterprise not the government. This Marsdoggle will wind up costing far more than the Apollo Moodoggle which we are still paying for today.

        • Scottlowther

          A: Space exploration is a proper function of government. National defense and promoting the common welfare and all that.
          B: Apollo pretty much paid for itself long ago by way of economic benefits from technological advancements.

  • John Nowak

    Interesting, but yeah; there’s too much obviously wrong with it. Not a problem at this stage in the game, but it’ll be interesting to see how it develops.

  • Randino

    It’s still a chemical rocket, no matter how BIG it is. Unless Musk has planned in passenger hibernation, there’s little chance of anyone being alive (or if alive, then *sane*) after a year plus slow boat to Mars. Just saying.

    • cygnus_darkstar

      They’re aiming for a relatively hot trajectory with the proposed mission architecture, made possible by the in-orbit refueling, so only 90-150 days to Mars depending on the launch window used.

      Not sure where you’re getting the year-plus from; even a minimum-energy Hohmann transfer would get you there in a bit less than 9 months.

      • Robbie

        The advantages of orbital refueling are truly enormous. You don’t need nuclear rockets when you can just refuel and get there just as fast.

        • se jones

          “…dangerous nuclear rockets”

          Dangerous why? and to whom?

          • sferrin

            Because “nookyoular”. And dangerous to everything. Leaves will fall off trees and iphones will stop working. It would be apocalyptic.

  • cygnus_darkstar

    Yeah, I don’t know what they’re on about with all those windows either. There’s not enough to see between departure and arrival to justify a feature that so compromises structural integrity.

  • madoc62

    They’re gonna have to have some spin on that thing or else the astronauts are gonna be damn near useless upon reaching Mars. Even just the short hops on Mir proved that. In zero-G the human body just degrades. No one knows what the minimum threshold is for what it takes to keep the human body from doing that in space but it’s not the months of zero-G that design depicts.

    • Scottlowther

      As the saying goes, why build one when you can build two at twice the price. Adn if you have two spacecraft, somethign you *could* do s boost them simultaneously towards Mars then, after boost, rendezvous them, link them together via tethers, and tumble for gravity.

      • madoc62

        At the least it’d demonstrate just what happens to the human body after so long an exposure to less than one full G. Getting down on to Mars won’t make up for that lack.

        These are longterm things we simply won’t know until we find out.

    • se jones

      “…astronauts are gonna be damn near useless upon reaching Mars …short hops on Mir proved that”

      Noooope, Mir proved no such thing. The most famous case ‘n point was Shannon Lucid’s return to KSC on STS-79 after 6 months on orbit aboard Mir. The 53 year old biochemist & mother of three defied the flight surgeons when she stood up under her own power and walked off Atlantis. President Clinton (the 1st) called her shortly after touchdown to congratulate her, “I couldn’t believe you walked off the shuttle,” he said.

      Now, no doubt she wasn’t in the most tip-top condition and like most returning astronauts she took some time to fully adjust. Still, there’s no sound reason to exaggerate the issue of adapting to gravity, especially when Martian gravity is .38.

      I think one of the main reasons people freak out over the weightless issue is the Russian Soyuz landing ritual. Look, the Russians haven’t succeeded in their quest to breed tiny little miniature doctors who can crawl into the Soyuz in order to check the crew’s vitals after landing. The Russian flight surgeons insist on dragging the crew out and sitting them in lawn chairs because they want med data before the crew stands up to wiggle out of their suits in the tent (and…by the way, the guy in the Soyuz right seat *must* stand up in the capsule after thump-down to unlatch and open the inward opening hatch, really – they aren’t helpless as a newborn baby).

      Musk claims a four to six month trip time to Mars depending on the launch window. In my judgement, the (considerable) drawbacks to centrifuging the crew make it not worth the trouble.

      In the image below, Blofeld’s cat demonstrates that “holy f*^#* sh*^” feeling Mars colonists would have when their spaceship stops spinning around like a cheap circus ride, leaving the colonists floating around in a vomit filled cabin as everyone experiences vestibular neuronitis.

      • Scottlowther

        > the (considerable) drawbacks to centrifuging the crew

        Which are far outweighed by the *vast* drawbacks of spending decades refusing to centrifuge so much as a single crew, producing generations of no knowledge whatsoever.

        • se jones

          We don’t have *no* knowledge whatsoever Scott. We learned a lot from the RFT at Downey. I have some great movie footage that I obtained from the BBC, I interviewed some of the retired flight surgeons and read their papers. This opened my eyes to the potential flight safety hazards and lost opportunity costs.

          The Naval flight crew volunteers were able to adapt and be productive as long as they had good lighting and they moved their heads just right way.

          The serious flight safety problem arises when the lights go out and/or the cabin is filled with smoke or fog caused by a decompression. In any case, an emergency “spin down” coinciding with donning spacesuits could prove disastrous as helmets fill with vestibular neuronitis upchuck.

          Anyway; following a rapid spindown, after a few minutes the crew on the RTF were able to get “their land legs” again and press on.
          In space with NO gravity vector to tell your brain+inner ear which way is up, the lengthy disorientation from could be fatal.

          Look, *ALL* technologies have a cost, a downside, an opportunity cost, that’s the law of engineering.

          Again, centrifuging a crew for a few weeks or months to travel to Mars is not worth the cost and risk to the mission.

          BUT….I do think we (Musk) or (Musk + Bezos + NASA + esa) should build Kirk Sorensen’s Tether-Based Variable-Gravity Research Facility in LEO.

          If Musk plans to send hundreds of humans to live on Mars, we need data on human physiology in .38g as well has – – – yes, data on crew safety while dealing with flight emergencies like FIRE, explosive decompression, emergency EVAs and so on.

          If it turns out (miraculously) to not be a flight safety issue, then spin the hell up…yee ha.

          A Tether-Based Variable-Gravity Research Facility Concept
          Kirk Sorensen: NASA Marshall Space Flight Center

          • Scottlowther

            > We learned a lot from the RFT at Downey.

            Did we learn *anything* about using centrifugal force to produce *less* than 1 G?

            No. The RTF Showed that spinning at six revolutions per minute is kinda rough. But of course it is, and it’s not relevant to the discussion. 6 RPM at a radius of 78 feet produces right about 1 g… meaning the test subjects were living under 1.4 G’s or so.

            Nobody is suggesting using such a small radius and such a high g load. Instead… call it a radius of 100 meters to produce 1/3 g: about 1.7 RPM. What experience do we have with that?

            From an RTF report:
            The influence of rotational rates produced significantly poorer performance at 6 rpm than at either 4 or 5 rpm, for WOFEO, WOFEC, SREC, and SO LEG, with the results of SOLEO and SREO, although not statistically significant, tending in that direction (see Tables 14 and 15). It may be seen that performance at 4 or 5 rpm did not differ appreciably, but the 6 rpm rate seemed to be a critical point, resulting in marked performance deterioration, even with eyes open.

          • se jones

            “Did we learn *anything* about using centrifugal force to produce *less* than 1 G?”
            Errr no, that would raise the crackpot index.

            Your pitching strawmen by insinuating ludicrous g levels and RPMs.

            I’m not talking about “performance levels” at various RPMs, I’m talking about performance when the merry-go-round stops, i.e. Postrotation Ataxia.

            In aerospace human factors, no matter how painful it is to one’s pet technology or project budget, you must plan for contingencies, you know… IN CASE SHIT.

            “It also appears that the loss of postural equilibrium is significant and
            could be important to performance in some operational situations. The
            results of these evaluations appear then to suggest that the more body
            movements (and perhaps head movements) that are made following rotation, the more rapid the recovery of postural equilibrium.” – Green et al..

            The RTF studies went into all sorts of prescribed head movement exercises to try to reduce postrotation ataxia. That’s all well and fine, except in a real, worst case spacecraft emergency (fire in the s/c being #ONE), leading to an emergency de-spin to weightlessness and with possible loss of visual cues (you know thick smoke / fog) there won’t be much opportunity for choreographed head-bobs and such.

            It’s a classic human factors trade-off. Yes, some centrifugal gravity in transit will buy you some fitness benefits, but it could also kill you IN CASE SHIT.

            The RTF study authors think “transition between a rotating and nonrotating environment” in one g is the “worse case scenario”.
            I disagree. I think common sense dictates that going from rotation to NO rotation (especially in the dark) just has-to-be the worse case.
            But I can’t prove it, and you can’t prove the opposite. We need a few $billion to build, test, launch and operate Sorenson’s “Gravity Lab” in LEO. However, that takes us back to the problem of “opportunity cost”.

            There is opportunity cost to the money & time spent on the R&D plus the mass penalty & complexity rotation adds to the mission.
            In the case of the initial NASA led expeditions, with public funding and short attention spans, there will be limited funding and schedules to keep. We can assume the crew on the “exploratory” missions will be steely-eyed missile men. I’m satisfied that after 30 years of experience in LEO, our steely-eyed missile men can take 4 to 6 months in zero gravity then land on Mars and wander about. In my judgement (at this time), it is better to save the R&D + mass of tethers, oversized momentum wheels, fluidic mass transfer systems, beefed-up solar panels & radiators and – so – forth and just give the guys some more TV dinners, spare parts, medkits and cool sciency stuff instead.

  • se jones

    President Clinton (the 1st).
    God I can’t believe I typed that. Talk about “vestibular neuronitis”

    • publiusr

      This thing looks like it will have submerged tanks–but they’d be at lower pressure, right?

      I might want a giant Saturn IB design–but with Beal BA-2s instead of jupiters and redstones:

      Keep propellants room temperature.

      • se jones

        submerged tanks?

        You might want? It’s what Elon Musk wants (and what engineering dictates) that matters. Sorry.

        propellants room temperature?
        Kerosine + hydrogen peroxide has horrible performance, plus the pressure feed scheme needs extremely heavy tankage, otherwise what’s not to like?

        • publiusr

          Turbopumps might lighten things up some. Musk seems to have that down. I wonder what went with the Beal filament winding machine–someone bought that out some time back.

          This explains the big composite buy from Japan recently

  • madoc62

    Oh, and as to how the hardware is depicted….

    If we’ve learned anything from reading all those issues of APR it’s that the initial appearance of hardware in early press releases can bear little to no resemblance of the actual hardware that actually completes a mission. Right now this is just a graphic artist’s dream – and Elon’s approval as he insists that anything and everything which SpaceX does must look cool doing it.

    • HyperJ

      True, but there is an awful lot of detail in those cross-sections. Much more detail than in previous SpaceX presentations of years past. Note how the full size prototype LOX tank seems to match the one in the schematic.

      The big front window is likely the most ‘artistic licensy’ element.