[Texascavers] Re: lunar lava tubes
I finally got hold of the original scientific journal article on that potential lunar lava tube and skylight (Geophys Res Lett 36, L21206 (2009)). I was particularly interested in how they estimated the width of the tube at a minimum of 370 m, which would dwarf any lava tube on earth. It turns out that's not very well founded. They used structural theory to calculate _maximum_ possible tube size based on purely physical data like thickness of overburden, gravity, and tensile strength and density of the rock. Ceiling thickness can be estimated from the photos and lunar gravity is known, but they really have no idea about the properties of the lava there so they used figures from terrestrial lava tubes in California. Their result was 370 m, but again, that's the maximum possible for those structural conditions and not based on anything actually observed. Then they made some arm-waving arguments about how the tube could be even larger, and suddenly 370 m became the minimum! Hogwash! Reminds me of another paper I read one time that began by saying, "Let us assume x, y, and z...". Then a few pages later they leapt to a conclusion which they justified by saying, "since we know x, y, and z...". Circular reasoning at it's best. Mark Minton At 11:54 AM 10/28/2009, Mark Minton wrote: >http://dsc.discovery.com/space/qa/lunar-moon-skylight-carolyn-van-d er-bogert.html >http://news.nationalgeographic.com/news/2009/10/091026-moon-skyligh t-lunar-base.html Did anyone else notice that they claim the lava tube associated with that skylight should be at least 370 meters wide?! That would be an unprecedentedly large lave tube. I wonder how they think they can calculate a width for the tube based on only the width and depth of the skylight, which are far smaller. I don't believe it for a minute. Mark Minton You may reply to mmin...@caver.net Permanent email address is mmin...@illinoisalumni.org - Visit our website: http://texascavers.com To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com For additional commands, e-mail: texascavers-h...@texascavers.com
[Texascavers] Re: lunar lava tubes
Don Cooper said: >I take it the nature of the "Rilles" is still a riddle? I wonder if perhaps they are collapsed lava tubes. If you read the first article, it said: >>Sinuous rilles are thought to form in two ways: (1) an open lava channel that thermally erodes into the lunar surface, or (2) subsurface lava tubes that eventually collapse. There were images of collapsed lava tubes that were discussed in the mid to late 1970's as evidence for volcanic activity and sinuous rille formation on the Moon. Mark Minton On Wed, Oct 28, 2009 at 11:54 AM, Mark Minton wrote: >http://dsc.discovery.com/space/qa/lunar-moon-skylight-carolyn-van-d er-bogert.html >http://news.nationalgeographic.com/news/2009/10/091026-moon-skyligh t-lunar-base.html Did anyone else notice that they claim the lava tube associated with that skylight should be at least 370 meters wide?! That would be an unprecedentedly large lave tube. I wonder how they think they can calculate a width for the tube based on only the width and depth of the skylight, which are far smaller. I don't believe it for a minute. Mark Minton You may reply to mmin...@caver.net Permanent email address is mmin...@illinoisalumni.org - Visit our website: http://texascavers.com To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com For additional commands, e-mail: texascavers-h...@texascavers.com
Re: [Texascavers] Re: lunar lava tubes
I take it the nature of the "Rilles" is still a riddle? I wonder if perhaps they are collapsed lava tubes. -WaV On Wed, Oct 28, 2009 at 11:54 AM, Mark Minton wrote: > > > http://dsc.discovery.com/space/qa/lunar-moon-skylight-carolyn-van-der-bogert.html > > > > http://news.nationalgeographic.com/news/2009/10/091026-moon-skylight-lunar-base.html > >Did anyone else notice that they claim the lava tube associated with > that skylight should be at least 370 meters wide?! That would be an > unprecedentedly large lave tube. I wonder how they think they can calculate > a width for the tube based on only the width and depth of the skylight, > which are far smaller. I don't believe it for a minute. > > Mark Minton > > You may reply to mmin...@caver.net > Permanent email address is mmin...@illinoisalumni.org > > - > Visit our website: http://texascavers.com > To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com > For additional commands, e-mail: texascavers-h...@texascavers.com > >
Re: [Texascavers] Re: lunar lava tubes
They were using the Missouri survey method. The cave is 370 meters wide and 10 meters long.
[Texascavers] Re: lunar lava tubes
>http://dsc.discovery.com/space/qa/lunar-moon-skylight-carolyn-van-der-bogert.html >http://news.nationalgeographic.com/news/2009/10/091026-moon-skylight-lunar-base.html Did anyone else notice that they claim the lava tube associated with that skylight should be at least 370 meters wide?! That would be an unprecedentedly large lave tube. I wonder how they think they can calculate a width for the tube based on only the width and depth of the skylight, which are far smaller. I don't believe it for a minute. Mark Minton You may reply to mmin...@caver.net Permanent email address is mmin...@illinoisalumni.org - Visit our website: http://texascavers.com To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com For additional commands, e-mail: texascavers-h...@texascavers.com
