Polar “Lava Tubes”

21 Responses to Polar “Lava Tubes”

1. Joe says:

   January 16, 2018 at 4:50 pm

   Ouch, a real take down

   Still it sounded to good to be true, so it should be no big surprise it turned out to be.

   An ancillary question, the article I read

   https://phys.org/news/2018-01-lava-tube-skylights-north-pole.html

   listed both SETI Institute and Mars Society as being involved in the study.

   When did they become interested in lunar activities?
   • Paul Spudis says:

     January 17, 2018 at 1:27 am

     listed both SETI Institute and Mars Society as being involved in the study.

     Not the Mars Society — the Mars Institute. Very different people and type of organization.

     When did they become interested in lunar activities?

     Perhaps when the reinstatement of the Moon as a destination for human missions suggested that there might be money forthcoming for lunar studies?
     • Joe says:

       January 17, 2018 at 10:40 am

       “Not the Mars Society — the Mars Institute. ” Sorry, should have double checked reference before typing.

       Still both organizations seem to have been uninterested in the moon until now.

       Your answer (to my admittedly leading question) seems the best explanation.

       Making as many mistakes in their initial foray would not seem to be of aid to them in that cause.
2. Gary Church says:

   January 16, 2018 at 5:26 pm

   Too bad. I was very excited. Why did they write such a flawed piece? To get more clicks I guess.
   • Paul Spudis says:

     January 17, 2018 at 1:48 am

     Why did they write such a flawed piece?

     A more pertinent question is “Why do the space-covering media unquestioningly regurgitate whatever is in a press release without investigating, questioning and vetting the assertions and conclusions of scientists/New Space promoters/NASA?” I have my own answer to that question; feel free to ponder it and come up with your own.
     • Gary Church says:

       January 17, 2018 at 3:25 pm

       I do recall when Dawn was approaching Ceres there was a media event with space journalists asking questions and one who is fairly well known asked if there was tidal heating. I certain do not identify as a space journalist and even I know something has to cause a tide to have tidal heating. No idea where he got that question. It may be this crowd is great at cutting and pasting factoids and making a piece read well- but do not necessarily know very much about, or are even very interested in, the subject matter.
3. kim holder says:

   January 16, 2018 at 5:28 pm

   This article answers a lot of my unresolved nagging questions about the dynamics of young craters. Most of this would seem to apply equally well to Lalande, my pet crater. It’s especially nice to finally understand why there are dense collections of large boulders neatly gathered on all the high points of the central peaks.

   I am surprised by the figure of -100 degrees C for the interior of lunar caves. Are you referring specifically to any that might be near the poles? I’ve had trouble getting figures on subsurface lunar temperatures, I only have one reference, and old news article on NASA’s website that mentions -30 to -40 (https://science.nasa.gov/science-news/science-at-nasa/2010/12jul_rabbithole/)
   • Paul Spudis says:

     January 17, 2018 at 1:32 am

     I am surprised by the figure of -100 degrees C for the interior of lunar caves.

     An educated guess on my part (as is the one in the link you quote). A cave at 72 degrees latitude would likely be slightly colder than one at the equator, if for no other reason that the mean surface temperatures up here are lower and thus, the passive IR from nearby surfaces would be less. In such a case, heat flow from the interior of the Moon is the only source of heat. The interior temps could be as warm as -50 C to as cold as -100 C.
4. nova9 says:

   January 17, 2018 at 10:27 am

   Since it would require less than six meters of lunar regolith to reduce lunar radiation levels within a habitat on the Moon to terrestrial levels and less than 1.5 meters of regolith to reduce radiation levels below those allowed for radiation workers on Earth (5 Rem per year), I still can’t figure out why some people are still obsessed with finding lava tubes:-)

   Marcel
5. J Fincannon says:

   January 17, 2018 at 3:23 pm

   You raised many valid points and are obviously correct.

   What I am baffled with is the picture they provide in their press release. It bears no resemblance with the other pits/caves found elsewhere on the Moon. Examination of all other images of the site show no obvious pit or cave based on other Sun angles. Am I to understand that I can simply point to any dark crater “near” the poles and claim victory for a cave/pit/tube entrance. It is very sad to see that in the pursuit for viral news, the data was not vetted/peer reviewed or checked.
6. Michael Wright says:

   January 17, 2018 at 6:00 pm

   Aw shucks, I hope this doesn’t put a damper on growing interest of lunar missions. This is also an example to not rush findings too quick, take time to peer review. What is not needed is hype and build up of excitement to only find it was no big deal. I remember after LCROSS impact, they didn’t immediately say they found water, there were indications of lots of stuff, so it took a few days to report findings in reasonable fashion.

   Whatever the case may be… stop linking the Moon with Mars because people will focus and remember only the Mars aspects.
7. Gary Church says:

   January 17, 2018 at 6:14 pm

   “It is very difficult to survive the 14-day lunar night without a reliable source of electrical power. The best way to address this problem is to deploy a nuclear reactor, which can generate power continuously, but such a reactor does not now exist and we are unlikely to develop one of sufficient size any time within the next couple of decades.”

   http://www.world-nuclear-news.org/ON-NASA-to-test-prototype-Kilopower-reactor-1711174.html

   “The Kilopower reactor could produce 1-10 kilowatts of electrical power, continuously for ten years or more.”
   • Paul Spudis says:

     January 18, 2018 at 12:20 am

     “The Kilopower reactor could produce 1-10 kilowatts of electrical power, continuously for ten years or more.”

     Our lunar resources outpost architecture deploys 200 kW of solar electrical power. To survive at mid-latitudes, the need is for a 1-10 megaWatt-class reactor. This reactor is too small by 3 orders of magnitude.
     • Gary Church says:

       January 18, 2018 at 6:08 pm

       Well, unlike on Earth, the reactor can pretty much sit with no shielding in the bottom of a crater and be an arrangement of fissionable material and moderators and produce electricity and heat in a completely different manner than a reactor on Earth. When the lunar night begins the reactor would heat up and when it ends it would shut down in a day/night cycle that may work fine while such a scheme is impossible on Earth.

       The components for such a reactor design might very well be transportable with a lander like the Blue Moon in several loads. Landed in the crater and then moved with a bobcat and stacked together.
8. J Fincannon says:

   January 18, 2018 at 9:21 am

   In your SPACE 2016 paper, I could find the 200 kW for your LLO and LEO orbital hab-depots, but it lists only a total of 125 kW for the polar outpost (75 kW for the surface “power plant” and 50 kW from the “mobile power package”). Is there another paper you wrote that updates these values?

   I don’t understand why you need a 1-10 megawatt reactor. If your outpost can operate with 200 kW solar power (near continuous during the polar day time), then assuming a nuclear system providing 10 kW each, you need 20. Developers/funders do not want to build giant nuclear reactors due to high costs, so, while the smaller reactors may not be mass optimized, they meet other programmatic needs. The reactor based power level/outpost is then site independent. Does it take a lot more power to acquire water/ice elsewhere on the Moon? Do you have a paper documenting this analysis?
   • Paul Spudis says:

     January 18, 2018 at 9:30 am

     Is there another paper you wrote that updates these values?

     No. I assumed that we would continue to expand power generation as the outpost grows. There’s no significant qualitative difference between 125 and 200 kW — you can still do it all with steerable solar arrays.

     I don’t understand why you need a 1-10 megawatt reactor.

     Because 1) you have to survive the 14-days of continuous lunar nighttime; and 2) it requires at least 1-2 orders of magnitude more power to extract implanted solar wind hydrogen from “dry” regolith than it does to melt and collect the water in ice-laden polar regolith.
     • J Fincannon says:

       January 18, 2018 at 9:53 am

       >Because 1) you have to survive the 14-days of continuous lunar nighttime; …

       But doesn’t that only pertain to a solar based power system? The day/night cycle only affects the reactor radiator sink temperature (thus power production) slightly and in the opposite direction anyway.

       In any event, as you imply, it makes no sense to extract hydrogen from dry regolith. Yet, outposts at non-polar sites might still have valid uses for other resource extraction/science.
       • Paul Spudis says:

         January 18, 2018 at 11:47 am

         In any event, as you imply, it makes no sense to extract hydrogen from dry regolith

         I didn’t say that and don’t believe it. You simply require much more power to do it.
         • J Fincannon says:

           January 18, 2018 at 12:13 pm

           Sorry that I mis-inferred that you were implying this.

           However, needing megawatts of power to do resources extraction like this, in my opinion, cannot possibly have a viable cost/benefits ratio.
         • Joe says:

           January 18, 2018 at 12:36 pm

           “However, needing megawatts of power to do resources extraction like this, in my opinion, cannot possibly have a viable cost/benefits ratio.”

           If I might suggest, the immediate goal should be utilization of the water at the lunar poles and beginning to utilize other lunar resources for structures (etc.).

           There will be plenty of time later to decide the proper course of expansion to other lunar regions (with more data upon which to make informed decisions) at that point.
       • nova9 says:

         January 18, 2018 at 9:27 pm

         Once polar outpost are fully established (I assume by multiple nations and corporations), they will inherently produce a valuable commodity in the form of biowaste. This valuable hydrocarbon resource could be easily exported by electric vehicles to lunar outpost at non polar sites on the lunar surface.

         I assume that non polar sites will be focused on the extraction of oxygen from lunar regolith using both solar and nuclear power.

         The electric power used for the plasma arc pyrolysis of biowaste produces more than six times as much electric power in the form of syngas (hydrogen and carbon monoxide) as is put into it.

         The combustion of syngas with oxygen to produce electric power during the lunar night would, of course, produce water and carbon dioxide as a byproduct.

         Marcel

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