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Earth Moon Space Science Technology

Glass From Nuclear Test Site Shows the Moon Was Born Dry (newscientist.com) 48

An anonymous reader quotes a report from New Scientist: We can't recreate the giant impact that led to the moon's formation in a lab, but humans have made some other big explosions. By examining residue from the first detonation of a nuclear weapon, researchers have cracked a window into the moon's past. On 16 July 1945, the U.S. army detonated a nuclear weapon for the first time in an operation codenamed Trinity (see photo, above). As the bomb exploded with an energy equivalent to 20 kilotons of TNT, the sand underneath it melted, producing a thin sheet of mostly green glass dubbed trinitite. The explosion brought the area around the bomb to temperatures over 8000 C and pressures nearing 80,000 atmospheres. These extreme conditions are similar to those created as the moon formed in a colossal collision between Earth and another rock, probably about the size of Mars. Fortunately for planetary science, scientists meticulously measured and recorded the details of the Trinity detonation, so there is plenty of information to work with. Day and his colleagues took advantage of that past precision to investigate why the moon has surprisingly little water and other volatiles with a relatively low boiling point -- much less than Earth. To do so, they studied the distribution of one volatile element, zinc, in trinitite collected at different distances out from the explosion's center. They found that the closer to the explosion the trinitite formed, the less zinc it had, especially when it came to zinc's lighter isotopes. That's because these evaporated in the intense heat of the explosion, while the heavier isotopes didn't and so remained in the trinitite. The ratios of different forms of zinc left behind in trinitite showed remarkable parallels to what was observed in the moon rocks retrieved in the Apollo missions. This means that zinc and other volatile elements, most notably water, probably evaporated off the moon while it was being formed in a violent collision or soon afterward, while its surface was still incredibly hot. The study has been published in Science Advances.
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Glass From Nuclear Test Site Shows the Moon Was Born Dry

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  • by SensitiveMale ( 155605 ) on Thursday February 09, 2017 @03:13AM (#53831195)

    I always assumed it had a placenta.

  • by mmell ( 832646 ) on Thursday February 09, 2017 @03:20AM (#53831217)
    It simply makes sense to assume that what we now call the Earth was subjected to intense heating by the impact which was violent enough to form the moon, tilt the planet's axis and accelerate planetary rotation so radically that despite billions of years of slowing it's still slightly over 365 times as fast as it was before the impact. It was one helluva bang. It makes sense to assume that nearly all (if not all) of the water now present on the Earth originated elsewhere.

    I've often heard that colonists to the Moon or Mars could generate much of the energy and oxygen they need if they can find water present. How much water is still present in the interplanetary environment, and is it enough to consider using it to augment the fuel/oxygen supply on an interplanetary rocket?

    • by Hylandr ( 813770 )

      I keep hearing comets being described as mostly rock and ice. I think there's water on these celestial bodies, but we aren't finding it on the surface for obvious reasons stated above.

      Most places on Earth require drilling at least 100ft before finding fresh useable water where there's not natural springs. Lets send a serious drill to some of these celestial bodies and do some real digging to find out what's below. Blowing craters in the surface will just melt, then disperse water as ice, recreating the envi

      • This is about water, not fresh water, in the majority of cases your drill will sink in the stuff. Earth is not short of water.

        A lot of the times for fesh water it depends when you drill and in the far north and south it's 0.0000001 inches always. The rest, depends on the last time it rained.

  • by Anonymous Coward

    Did part of the mantle get blown off to make the moon or it all crust?

  • Nuclear explosions on the moon... Inherit the Stars explains it well. :)

  • by rickyslashdot ( 2870609 ) on Thursday February 09, 2017 @04:29AM (#53831369)

    Good Grief. Talk about a bit of over-simplification - - -
    article quote - probably evaporated off the moon while it was being formed in a violent collision or soon afterward, while its surface was still incredibly hot.

    There WASN'T any MOON surface to evaporate from - it was the multi-quadrillion PIECES that got thermally blasted, and lost all of their volatiles.

    Because the major mass-locus was earth, the free-floating material preferentially 'gravitated' here, leaving the particulate residue to accumulate into our moon, with the majority of it's material probably being from the crustal region of the earth and the colliding planetoid (Theia).

    With the earth being more massive, and presumably less heated by the collision, the lighter materials would eventually either be 'lost in space' or captured by earth, while the nascent moon cloud, still in it's infancy and HOT, and in FRAGMENTS, continued to out-gas. Even with thermal equivalence of the two bodies, the higher gravitational tug of earth would have preferentially attracted - and kept - the lighter volatiles blown off by the collision. (Yep, I'm agreeing with the author, except on the point of "the moon's surface").

    OK, so I'm knit-picking, but please keep your presentation straight, as there was NOT any definable 'surface' of the moon at that period, just a LOT of really hot pieces that thermally expelled all low-temp volatiles as they circled earth and eventually coalesced into our moon.

    Still, overall, a very good piece, and worthy of inclusion under the 'real science' category of slashdot's potpourri - unfortunately a small and decreasing category of material on this site.

    cheers . . .

    • Good comment; agree.

      But while we're picking nits....

      https://en.wikipedia.org/wiki/... [wikipedia.org]

      • lol - been there, done that. My niece brought home some of these 'guests' from school, and we bought the local family pharmacy out of RID to clean the house (and us) - - - NOT a fun day.

        • Re: (Score:2, Informative)

          by Anonymous Coward

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          5% benzyl alcohol lotion is available under the brand name Ulesfia (and maybe some other names, not sure?) in the USA, but requires a prescription. However, it is basically just benzyl alcohol mixed with creamy baby oil. (CREAMY baby oil, the t

    • true. It's not like water evaporated from the moon "while cooling". How would the water beat the gravity of the moon? It must have escaped before the moon was formed.
    • There WASN'T any MOON surface to evaporate from - it was the multi-quadrillion PIECES that got thermally blasted, and lost all of their volatiles.

      Wouldn't there necessarily have to have been some larger chunks that didn't get pulled into Earth? Fragments of Earth or the impactor itself?

      There had to have been something fairly substantial around which Luna could coalesce. Otherwise Earth would have (a) ring(s), and not a moon. This seems to follow because Luna really is too big for its planet in the first place. Everywhere else in the solar system where moons coalesced out of a cloud of relatively small particles, those moons are considerably small

  • .. just so happened to just release a very interesting video on this topic.

    https://www.youtube.com/watch?v=hbXDLKFkjm0
  • And ice can also quickly sublimate in a vacuum depending on the temperature, and during the day the Moon temperature rises above the boiling, let alone melting point of water. The Moon's gravity is too low to retain water vapor, so as soon as you get liquid water it disappears within minutes. Meters of ice would sublimate in a day. If the Moon had a 3 km thick layer of ice, like we do, it would sublimate in 10 years.
    You don't need heat or impacts, just some basic knowledge of thermodynamics.These well-known

  • Elements (Score:5, Funny)

    by Muros ( 1167213 ) on Thursday February 09, 2017 @05:52AM (#53831499)

    This means that zinc and other volatile elements, most notably water, probably evaporated off the moon while it was being formed in a violent collision or soon afterward, while its surface was still incredibly hot.

    Ok, we all know water is an element, but isn't zinc a compound of earth and air?

    • by fnj ( 64210 )

      What are you taking about? Zn is a metallic element with an atomic number of 30; the first element in group 12. Didn't you ever take a carbon-zinc battery apart? You get a zinc can (anode), a carbon rod (cathode), and a bunch of yucky pasty electrolyte.

  • Water came to Earth after the Moon formed. Remember it was 4.5 billion years ago when the solar system hadn't yet been formed and stable and it had a lot of dust.

    Or maybe there was no collision at all, and Moon and Earth formed independently from the same rocks orbiting the Sun.

  • At a nuclear test site, volatiles boil off and condense farther away from the center of the explosion. Fine.

    However, this has basically zilch to do with the formation of the moon. *That* impact literally knocked the earth into pieces. Likely there really was no more "center" of the impact. Also, note the quality of the science reporting: "volatile elements, most notably water". Who knew that water was an element?

    The actual article [sciencemag.org] is basically only about isotope separation of Zinc, and admits repeatedly dur

    • Also, note the quality of the science reporting: "volatile elements, most notably water". Who knew that water was an element?

      Some words have more than one meaning. When we say the stranded hikers were exposed to the elements we don't mean they were visible to lanthanum or that silicon was dropping on their heads.

      Having said that, the author is an absolute 'dromie for not using substances in the context.

    • by Opyros ( 1153335 )

      Who knew that water was an element?

      Empedocles?

  • Come on, first of all the bone is not all that dry.

    Second, when the Moon was formed there were not even single celled organisms either on Earth or the nascent Moon. Boned animals did not appear till very recently, just 500 million years ago.

  • Time to take time out from bashing Slashdot and its paid staff (yes, these editors actually get paid, I hear) to remind ourselves of some of its goodness. In this case, it's that fact that Slashdot thankfully still doesn't include images with summaries - that makes the content much easier to scan.
  • The thousands of degrees of heat created by the impact, "boiled off" any water?
    Well fuck me. I never would have guessed.

    How much time and money did they use on this study?
  • by jimbob6 ( 3996847 ) on Thursday February 09, 2017 @10:59AM (#53832493)

    Sir Bedevere: ...and that, my liege, is how we know the Earth to be banana-shaped.
    King Arthur : This new learning amazes me, Sir Bedevere. Explain again how sheep's bladders may be employed to prevent earthquakes.

  • If it evaporated, wouldn't it have stuck around as part of the atmosphere? Where would it have gone, carried off on fragments doesn't sound so likely?

    • Solar particle radiation knocks hydrogen out of the earth's gravitational field. That is, hydrogen atoms achieve escape velocity of 11.186 km/s or more. I guess they mean that the Earth and Moon remained sufficiently hot for sufficiently long.

      I thought that Earth was already largely devoid of water since its creation. The creation of Earth amounted to a large mass (one earth mass) falling freely from large distances into the center of the cloud from which the Earth formed, and so hitting the proto-Earth at

  • "Glass From Nuclear Test Site Shows the Moon Was Born Dry "

    Empty beer bottles on the moon could mean that, but nuclear glass on earth ...

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