• Andrew_M_Swallow

    Manned lunar rovers and landers will need radiation protection. The BEAM may be a good starting point for their cabins. It will also reduce the space needed on the launch vehicle.

  • Andrew Tubbiolo

    Wow, only $300 mil and the patience to see it through, he’s the perfect melding of the best of the private world and the best of the government world all rolled up into one. Impressive. Compound onto that he does not even think he’s a pioneer, he considers himself surrounded by masters of the trade as if he’s living in a zoo trying to demonstrate he can add 1+1 to the zoo spectators. I’d love to tap into his motivations. I could see all kinds of motivations from a person who thinks they are surrounded by god like beings from beyond. I would imagine motivations are quite different if you think you are alone by nature of interstellar distance, the speed of light, thermodynamics, intelligent species suicide, and the harsh logic of the drake equation, as opposed to living in a world where you consider yourself living in a zoo under constant surveillance of extra terrestrial versions of Diane Fossey (at best).

  • I think that a modest amount of polyethylene shielding of the cabin would be sufficient.

  • JamesG

    Sure, but an inflatable cabin will greatly reduce the cubic volume the rover takes up in transit.

  • Richard Malcolm

    Curious that such a lengthy piece makes no mention of the high turnover and other reports of a dysfunctional environment at the company. It would have been helpful to at least see such concerns addressed.

  • Yeah, so a chassis could be assembled, the cabin inflated and attached, and polyethylene panels inserted onto the walls of the cabin.

  • Andrew_M_Swallow

    JamesG what are you making the inflatable walls of the cabin out of?

  • JamesG

    Unobtainium.

  • JamesG

    The piece was about Bigalow hisself, not Bigalow Aerospace per se. And it’s “60 Minutes”. You are about 20 yrs. to late to expect quality journalism from them.

  • Richard Malcolm

    Yes, but the bulk of the story was about his aerospace venture. And to that extent, it felt a bit like a puff piece.

  • Tom Billings

    C’mon, James, I can think of many things to make them out of. Now, whether Mr. Bigelow would be interested in what I think is another story. He wasn’t interested at a conference 11 years ago in combining his modules with our team’s work on lunar lava tube caves as sites for settlements, but he *is* interested in lunar surface outposts using his “expandable” modules. Of course, 10 years back, there was far less evidence of lunar caverns than there is today (latest count from the Arizona LRO teams is 200+ candidate sites, plus the GRAIL data) He *is* an interesting fellow to talk to, however.

    It’s true that the video was a puff piece, but puff pieces and hit pieces are what 60 Minutes has been doing for a *long* time, as you noted. Bigelow was private enough to be different, and not a hate object for Congress, …and not as hard to get the time of as Jeff Bezos. I’m still convinced that Bigelow’s company can achieve excellent contributions to human spaceflight, whatever his motivational worldview.

    A space manufacturing facility built with his modules as the housing for riggers and teleoperators of robots, while the manufacturing is done out in the vacuum, could still be the first place truly large spaceships get built.

  • I would make the layers as such:
    – Outermost = Abrasian resistant
    – Next = Kevlar straps
    – Two air-tight layers
    – Abrasian-resistant
    – Innermost = 13-cm polyethylene panels

  • JamesG

    Well, its 60 Minutes so….

  • Mr Snarky Answer

    Are UFOs Aerospace?

  • windbourne

    I believe there is another layer that is some weird gel that will solidify upon being exposed to vacuum. Basically, designed to seal SMALL holes.
    In addition, there is a layer or more than absorbs various radiation.
    And there is insulation in there as well.
    So, there are many more layers than what you have.

  • windbourne

    surprised by a couple of things:
    1) he did not have Blair on this. It was a good way to lend some credence to her.
    2) no mention of the Genesises. You would think that he would point out that one of them has been there for 10 years. I wonder how they are doing? Are they still holding air?

  • Vladislaw

    Unless a lava cave is parked on water and has a lot of light potential for solar I would not think he would. It is my understanding Bigelow Aerospace has already has been working on a vehicle for dredging regolith and spraying it over his Habitats?

  • Tom Billings

    Yes, he has been pushing desert sandbox material around for some time in Nevada. I have not heard how well that effort goes. Still, given radiation constraints, if he doesn’t have a cave, he’ll have to build one. The latest numbers we have recommend 6-10 meters lunar regolith for covering a surface base. That’s a *lot* of tons to move, even for a 20 person Phase 1 base! We still think capital costs will be far lower in a 100m+ diameter cave.

    As for water, a cave is one possible place to look for lunar ice, as long as the entrance is pointed away from most incident sunlight. We have several ice caves in Oregon’s High Desert, East of the Cascades. With a horizontal entrance pointed at one of the poles the net radiating heat flux could be greater than solar influx, down to some very low temperatures. That would let the volatiles from comets freeze out in the cave nearly as easily as at the poles. Of course, those who find them will be those who send a little robot flyer to go look! 😉

  • JamesG

    Well the “F” stands for…

  • WhoAmI

    WRT 2, 8:38 to 9:18 discusses Genesis 1 and 2 where he names them at 9:11. HTH.

  • Mr Snarky Answer

    I thought you had switched to Wishalloy

  • Mr Snarky Answer

    Why carry useless panels on the walls rather than just store supplies (food, water, tools, etc. in bags on the wall)? Kill two birds with one radiation shield.

  • windbourne

    wow. I missed that.
    Thanx.

  • duheagle

    I’m inclined to cut billionaires willing to pay to get the species into space a fair amount of slack anent peculiar (by my standards) beliefs. I don’t think Bob Bigelow’s belief in space aliens in any way compromises what he’s trying to do. The same is true, IMHO, of Elon Musk’s frequently professed belief in Anthropogenic Global Warming (aka “Climate Change”). UFO’s and AGW are roughly tied, in my view, anent objective evidence for the veracity of either hypothesis.

  • To explore a new, distant area you would have to use a refueled lander to hop the crew rover to the new location. Given the rocket equation, modest increases in mass means significant increases in propellant needed vs shortened distances traveled or fewer locations per refueling. Polyethylene is noticably better radiation shield than water-bearing provisions so it is inaccurate to call it useless. And, one cannot consume that amount of shielding during a set of distant EVAs.

  • End-to-end sandbags is Bigelow’s preferred solution. I prefer flat-roofed inflatable habitat so that you don’t have to package the regolith to keep it from sloughing off.

  • 6-10 meters of regolith is more than what is necessary. One needs to keep crew within their career limits. Given the ability to rotate crew, one wouldn’t need very much shielding. Certainly we don’t need to have crew at sea-level radiation levels because certain populations live out their lives at nearly 1/2 atmospheres (18,000 ft).

  • Tom Billings

    “6-10 meters of regolith is more than what is necessary.”

    For temporarily occupied outposts that are not made into settlements, you are correct. For even the Phase 1 of beginning a lunar settlement, the secondary radiation from primary cosmic rays creates substantial hazards, and the acceptable dosages from the Health Physics community keeps dropping. Lunar settlement, at many sites, is what we are interested in. That is what attracted us to lunar lava tube cave study as early as 1987.

    The robotic components of a lunar settlement will also benefit from a lava tube cave site. They will not be subjected, once inside the cave, to the extremely abrasive dust that covers everything on the surface because of static charge levitation of the dust. The short history we have with that dust (specifically including Apollo 17) still makes us very cautious over the need for large numbers of replacement parts in lunar dust environments. Since we know of no transport mechanism that will move the surface dust inside the caves beyond the first 100m or so, we believe the caves will be the only clean places on or near the lunar surface. That is where, among other things, we hope to make as many of those replacement parts as possible for robots that must operate on the surface.

    Add that to radiation protection, consistent temperatures instead of the vast variations of the lunar surface, and the cave walls as supporting structure, and we believe the caverns of the Moon to be very attractive settlement sites. (OK, …sales pitch over now, … 😉

  • Hi Tom. When you Google Images “GCR shielding” most all of the graphs look like this:
    http://selenianboondocks.com/wp-content/uploads/2015/09/Material-shielding-comparisons1-Rapp2006-edited2.png

    Can you therefore explain how the radiation effect (mSv) goes up with regolith thickness?

    We don’t know of lava tube skylights near the poles where there are the Peaks of Persusyent Illumination or the large quantities of volatiles. So, if the graphs are to be believed then starting with a modest amount of regolith pushed on top of a flat-roofed habitat would reduce mSv levels thereby buying crew enough time to maintain telerobots which would increase the amount of regolith cover until the crew can remain indefinitely and still remain within their career limits (eh 1,000 mSv for a 47 year-old male).

  • Tom Billings

    “Can you therefore explain how the radiation effect (mSv) goes up with regolith thickness?”

    Fairly simple, if depressing, Doug. Lunar Mare Basalts, like most basalts, have lots of Iron in them. The large nuclei of Iron, when struck by GCRs, shatter into lots and lots of secondary particles. They turn a rifle bullet into a shotgun blast. In the past we had been told that the secondaries’ contribution to REMs from GCRs peaked at about 2m
    thickness of regolith. However, there is recent work showing that the less common heavy nuclei, sometimes included in GCRs, contribute far larger numbers of secondaries per primary when striking heavy metallic nuclei, and will increase the thickness estimated to give the peak REM.

    So, that, combined with the Health Physics community’s growing conservatism
    about lifetime dosage, has us putting the thickness we would use at 6-10m of regolith for lunar settlement work that has to include permanent surface habitation. Of course, with lava tubes hundreds of meters across, the roof thickness will be substantially
    greater than this, making them a very low radiation environment.

    “We don’t know of lava tube skylights near the poles where there are the Peaks of Persusyent Illumination or the large quantities of volatiles.”

    True, but no one has yet done the large aperture orbiting ground-penetrating radar work of the sort Sood, Melosh and Howell from Purdue have proposed:

    https://www.researchgate.net/publication/298529224_Lunar_Advanced_Radar_Orbiter_for_Subsurface_Sounding_LAROSS_Lava_Tube_Exploration_mission

    That would bring us conclusive data about any tubes. Until that is done, we cannot tell what’s there from the GRAIL data alone, because its gravitometers’ data, even with the best processing, don’t give resolutions much below 1km. We are hoping for ice caves at lower latitudes, as I noted to Vladislaw, above. If those are not available, then we will have to settle for the 8/9ths of water that the metal oxides in the rocks can give us. Otherwise, water from the polar regions will be one of the first big imports for Lunar Caverns settlements. See? Yet another argument that industrializing the Solar System will require *many* nodes in the trade network!

  • Thanks Tom for that explanation. Can you explain the many graphs (as I linked above) that show the mSv going down even with modest amounts of regolith?

  • Tom Billings

    My guess, …because I am *not* a Health Physics expert, …is that they are counting the straight primary radiation effects. The secondary radiation from the shielding structure being bombarded may not be counted here. That can end up contributing more REMs than the primaries in the case of heavy metal nuclei, like Iron, being in the structure, being struck, and contributing far larger numbers of secondary particles, because those secondaries larger numbers have more chances of interacting with human tissue. This is why high Hydrogen mass percentages in shielding materials are good, even into the problematic materials like Lithium Hydride, that must be pressurized to hold together. Light nuclei=good shield!

    As shield thickness continues to increase, even with heavy metal nuclei in the shield, those secondary particles are also absorbed, and their cascade sequences die out as particle energies become lower at each succeeding level of the secondary cascade started by the primary particle. Eventually the secondary particle has insufficient energy to do anything but bang around till it’s captured. But as I said, the net radiation lifetime doses we want to make things attractive for settlers, start appearing in the 6-10m basalt regolith shield thickness range.

  • The problem is that none of us are radiation health experts and so we are left guessing why some say that multiple meters of regolith are needed. But again, if you Google Images “GCR shielding”, the large majority of graphs show decreasing, not increasing mSv with increasing regolith depth. Perhaps all of those graphs only calculate the decreased energy in the primary GCRs and not the total energy including the secondaries. However, there is one graph that shows increasing mSv to about 2 meters of regolith. Yet, it starts at 0 mSv at zero depth so we can conclude that it isn’t the total mSv including the mSv of the primaries. So, are all graphs only calculated and has no one ever measured the radiation after a GCR-like beam has passed through different lengths of regolith stimulant with both the primaries and the secondaries? It seems like someone would have done that study long before now. Ideas?

    http://www.projectrho.com/public_html/rocket/radiation.php
    – 75% of the way down the page.

  • Tom Billings

    ” However, there is one graph that shows increasing mSv to about 2 meters
    of regolith. Yet, it starts at 0 mSv at zero depth so we can conclude
    that it isn’t the total mSv including the mSv of the primaries.”

    Indeed, my *suspicion* is that it is a graph of secondary radiation, which would be zero at the surface of the shield, because the particulate collision cascades that produce secondaries would not yet have started at its surface.

    “So, are all graphs only calculated and has no one ever measured the
    radiation after a GCR-like beam has passed through different lengths of
    regolith stimulant with both the primaries and the secondaries? It
    seems like someone would have done that study long before now.”

    We received several research proposal requests on a NASA list for exactly such human factors work in the last 10 years. Bother!, …I cannot now find my only reference to work done for that, …IIRC, at Brookhaven National Labs. Their accelerators could do good work there. I am sorry I cannot say more clearly what their results were, beyond that they were done on heavy ion bombardment.

    “It seems like someone would have done that study long before now. Ideas?”

    My speculation about the work being done so recently is that it is the usual reason. This is work you do when you are thinking of getting serious about settling someplace in the Solar System. Until recently, NASA was not encouraged, since 1965, to be serious about settlement, or even about long-term bases, because no one thought the political combination of political costs and political profit could be made to balance. However, this *may* be changing, IMHO, if and only if, NASA is allowed to slip into the slot of NACA, but with regards to spaceflight.

    If NASA can be allowed to support lower capital cost/lower agency cost private settlement of the Solar System, in the same way that NACA supported aviation and airlines between 1915 and 1958, then this sort of thing may get done more promptly. It won’t be in demand, if we have to ask for congressional political majorities to support foundation of every node in a market network stretching from LEO to the Moon to Mars, to Ceres, to Saturn and beyond, because those majorities will not be forthcoming.

    Sorry for being a gloomy gus on this. It’s probably my rhino-virus/sore throat coming out.

  • redneck

    It would seem that an early investigation should involve a 10 meter deep drill hole with sensors every few centimeters dropped in. A few months of real data at all levels from 0-10 meters of depth should resolve this issue. Multiple locations with different regolith mixtures and different latitudes should nail down minimum requirements fairly rapidly.

    Though well located tubes with 50 meters of rock would make that investigation less urgent.

  • Really one of my favorite guys. But I’m biased.

  • Mr Snarky Answer

    Yea…except the thread was about a Lunar Rover so stop carrying goal posts on our back.