The moon’s crust may have formed from a ‘slushy’ magma ocean that froze over hundreds of millions of years, studie onthul
The moon’s crust may have formed thanks to a ‘slushy’ magma ocean that froze over the course of hundreds of millions years, a new study has revealed.
An international team of scientists, led by the University of Cambridge, created a series of computer and mathematical models to examine the chemical make-up and behaviour of moon rocks, and how they’d behave in the early ‘liquid magma’ moon.
They found that as the moon cooled, after its initial explosive beginning, the freezing sea of molten rock could have led to the current lunar surface.
The moon’s crust may have formed in a similar way to crystals in a slushy machine, het die navorsers gesê, before remaining suspended in liquid magma over hundreds of millions of years as the ‘slush’ of the young moon froze and solidified.
If the crystals remain suspended as a slurry, then when the crystal content of the slurry exceeds a critical threshold, the slurry becomes thick and sticky.
This increase of crystal content occurs most dramatically near the surface, where the slushy magma ocean is cooled, resulting in a hot, well-mixed slushy interior and a slow-moving, crystal rich lunar ‘lid’ – creating the lunar surface.
The moon’s crust may have formed thanks to a ‘slushy’ magma ocean that froze over the course of hundreds of millions years, a new study has revealed
An international team of scientists, led by the University of Cambridge in England, found that freezing a sea of molten rock could have led to the current lunar surface
SCIENTISTS DON’T AGREE ON HOW THE MOON FORMED
Many researchers believe the moon formed after Earth was hit by a planet the size of Mars billions of years ago.
This is called the giant impact hypothesis.
The theory suggests the moon is made up of debris left over following a collision between our planet and a body around 4.5 billion years ago.
The colliding body is sometimes called Theia, after the mythical Greek Titan who was the mother of Selene, the goddess of the moon.
But one mystery has persisted, revealed by rocks the Apollo astronauts brought back from the moon: Why are the moon and Earth so similar in their composition?
Several different theories have emerged over the years to explain the similar fingerprints of Earth and the moon.
Perhaps the impact created a huge cloud of debris that mixed thoroughly with the Earth and then later condensed to form the moon.
Or Theia could have, coincidentally, been chemically similar to young Earth.
A third possibility is that the moon formed from Earthen materials, rather than from Theia, although this would have been a very unusual type of impact.
They used the make-up of moon rocks returned to Earth on July 24, 1969 by Neil Armstrong and Buzz Aldrin, as part of the Apollo 11 missie.
They come from the lunar Highlands, a large pale region of the moon that is visible to the naked eye, and made of relatively light rocks called anorthosites, that formed between 4.3 en 4.5 billion years ago – when the moon was very young.
Previous studies suggested that these light anorthite crystals floated to the surface of the liquid magma ocean, with heavier crystals solidifying as the ocean floor.
Egter, subsequent rock samples, from follow up lunar missions, revealed the crystals were more diverse, contradicting this floatation theory.
For this new study, die span, including Professor Jerome Neufeld from Cambridge, proposed a new model of crystallisation.
In their model the crystals remained suspended in liquid magma over hundreds of millions of years as the lunar ‘slush’ froze and solidified.
In the low lunar gravity, the settling of crystal is difficult, particularly when strongly stirred by the convecting magma ocean.
‘We believe it’s in this stagnant ‘lid’ that the lunar crust formed, as lightweight, anorthite-enriched melt percolated up from the convecting crystalline slurry below,’ said Professor Neufeld.
‘We suggest that cooling of the early magma ocean drove such vigorous convection that crystals remained suspended as a slurry, much like the crystals in a slushy machine.’
Enriched lunar surface rocks likely formed in magma chambers within the lid, which explains their diversity, het die navorsers bygevoeg.
The results suggest that the timescale of lunar crust formation is several hundreds of million years, which corresponds to the observed ages of the lunar anorthosites.
Similar anorthosites, formed through the crystallisation of magma, can be found in fossilised magma chambers on Earth.
Egter, producing the large volumes of anorthosite found on the moon however, would have required a huge global magma ocean.
Scientists believe that the moon formed when two protoplanets, or embryonic worlds, collided.
The larger of these two protoplanets became the Earth, and the smaller became the Moon. One of the outcomes of this collision was that the moon was very hot – so hot that its entire mantle was molten magma, or a magma ocean.
They found that the moon’s crust may have been formed similar to crystals found in a slushy machine, where the crystals remain suspended in liquid magma over hundreds of millions of years, as the ‘slush’ of the young moon froze and solidified
‘Since the Apollo era, it has been thought that the lunar crust was formed by light anorthite crystals floating at the surface of the liquid magma ocean, with heavier crystals solidifying at the ocean floor,’ said co-author Chloé Michaut from Ecole normale supérieure de Lyon.
‘This ‘flotation’ model explains how the lunar Highlands may have formed.’
Egter, since the Apollo missions many lunar meteorites have been analysed and the surface of the moon has been extensively studied.
‘Given the range of ages and compositions of the anorthosites on the moon, and what we know about how crystals settle in solidifying magma, the lunar crust must have formed through some other mechanism,’ said co-author Professor Neufeld.
Die bevindinge is in die tydskrif gepubliseer Geophysical Research Letters.
WHAT WAS THE APOLLO PROGRAM?
NASA-foto geneem op Julie 16, 1969 toon die groot, 363-voet lank Apollo 11 Ruimtetuig 107 / Lunar Module S / Saturnus 506) ruimtevoertuig vanaf Pad A gelanseer, Begin kompleks 39. Kennedy-ruimtesentrum (KSC), by 9:32 am. (EDT).
Apollo was die NASA-program wat in 1961 en het agt jaar later die eerste man op die maan gekry.
Die eerste vier vlugte het die toerusting vir die Apollo-program getoets en ses van die ander sewe vlugte het daarin geslaag om op die maan te land.
Die eerste bemande sending na die maan was Apollo 8 wat dit op Oukersaand in sirkel 1968 maar nie geland het nie.
Die bemanning van Apollo 9 tien dae deurgebring en die eerste bemande vlug van die maanmodule voltooi - die gedeelte van die Apollo-vuurpyl wat Neil Armstrong later op die maan sou laat beland.
Die Apollo 11 missie was die eerste een wat op die maan geland het 20 Julie 1969.
Die kapsule het op die See van rustigheid beland, die sendingbevelvoerder Neil Armstrong en die vlieënier Buzz Aldrin.
Armstrong en Aldrin het op die maanoppervlak geloop terwyl Michael Collins in 'n wentelbaan om die maan gebly het.
Toe Armstrong die eerste persoon word wat op die maan loop, hy het gesê, 'Dit is een klein stap vir (a) man; een reuse sprong vir die mensdom.’
Apollo 12 later daardie jaar geland 19 November op die oseaan van storms, skryf NASA.
Apollo 13 sou die derde sending wees om op die maan te land, maar net onder 56 ure in vlug, 'n ontploffing van die suurstoftenk het die bemanning genoop om die maanlanding te kanselleer en na die Waterman-maanmodule te beweeg om terug te keer na die aarde.
Apollo 15 was die negende bemande maansending in die Apollo-ruimteprogram, en destyds beskou as die suksesvolste bemande ruimtevlug tot op daardie oomblik vanweë sy lang duur en groter klem op wetenskaplike verkenning as wat moontlik was op vorige missies.
Die laaste maanlanding van Apollo het plaasgevind in 1972 na 'n totaal van 12 ruimtevaarders het die maanoppervlak aangeraak.
Ruimtevaarder Edwin ‘Buzz’ Aldrin pak eksperimente uit die Lunar Module op die maan tydens die Apollo uit 11 missie. Gefotografeer deur Neil Armstrong, 20 Julie 1969