The chemical traces of water have been found in this moon rock, called the Genesis Rock. The moon rock was collected by astronauts during the Apollo 15 mission in 1971 and is thought to be a piece of the moon's primordial crust.
Image: NASA/Johnson Space Center
The discovery of "significant amounts" of water in moon rock samples collected by NASA's Apollo astronauts is challenging a longstanding theory about how the moon formed, scientists say.
Since the Apollo era, scientists have thought the moon came to be after a Mars-size object smashed into Earth early in the planet's history, generating a ring of debris that slowly coalesced over millions of years.
That process, scientists have said, should have flung away the water-forming element hydrogen into space.
But a new study suggests the accepted scenario is not possible given the amount of water found in moon rocks collected from the lunar surface in the early 1970s during the Apollo 15, 16 and 17 missions. By "water," the researchers don't mean liquid water, but hydroxyl, a chemical that includes the hydrogen and oxygen ingredients of water.
Those water-forming elements would have been on the moon all along, the scientist said. [Water on the Moon: The Search in Photos]
"I still think the impact scenario is the best formation scenario for the moon, but we need to reconcile the theory of hydrogen," study leader Hejiu Hui, an engineering researcher at the University of Notre Dame, told SPACE.com.
The results were published in Nature Geoscienceon Sunday (Feb. 17).
Water in moon's 'Genesis Rock'
Past studies have suggested water-forming elements came to the moon from outside sources long after the moon's crust cooled. The solar wind — a stream of particles emanating from the sun — as well as meteorites and comets were pegged as possible sources ofwater depositson the moon in recent studies.
But that explanation does not account for the amount of water found in the Apollo samples, the researchers stated in the new study.
Because they found hydroxyl deep inside each sampled rock, the scientists say they have eliminated the solar wind moon water explanation, because those particles can penetrate the surface only slightly. An impact from an asteroid or comet could push the hydrogen in further, but it would not be as pristine as the samples the researchers observed, because it would have melted from the heat of the asteroid collision.
Researchers probed samples from the late Apollo missions, including the famous "Genesis Rock" that was named for its advanced age of 4.5 billion years, about the same time the moon is thought to have formed.
Using an infrared spectrometer, the researchers found water embedded in the Genesis Rock, as well as all the Apollo samples they studied. This implies that the various landing sites of Apollo 15, 16 and 17 each had water present.
Hui's research flies in the face of past analyses of Apollo rocks that found they were very dry, except for a small bit of water attributed to the rock containers leaking when they were returned to Earth.
Past instruments that analyzed these samples, however, were not very sensitive. Hui said those older spectrometers had a sensitivity of around 50 parts per million (ppm), while his instruments were able to detect water at concentrations of about 6 ppm in anorthosites and 2.7 ppm in troctolites, which are both igneous rocks found in the moon's crust.
Troctolites form in the highlands as part of the moon's highland upper crust, and anorthosites are believed to be a part of the moon's "primary" crust, which solidified around the same time as other bodies in the solar system.
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5 Comments
Add CommentIf I recall correctly, the moon is thought to be composed mostly of material that once formed the Earth's crust. How much water or hydrogen and oxygen was sequestered within the Earth's ancient crust - enough to account for the amount of hydroxyl found in moon rocks? If so, there'd be no mystery presented by the moon rock hydroxyl or conflict with established moon formation theory...
Reply | Report Abuse | Link to thisElizabeth Howell and SPACE.com did not say what the alleged "process" is... or why the cataclysmic impact as described should have flung the water-forming element hydrogen away into space, unless all of the ejected material was broken down to the molecular level.
Reply | Report Abuse | Link to thisMy personal thoughts are that we are solid into plurality of ideas on the origins of the Moon. The 'Trillion-to-one Hit-and-Run' construct is fascinating, but I do not think it is probable. I envision a teapot floating by right after that collision occurred.
Reply | Report Abuse | Link to thisPerhaps it is time to add, not prove mind you, but add to the discussion, the idea that the Moon is simply a dessicated relic (in comparison to what it used to be) Oort Cloud object which was trapped by the Earth's gravity. This object would have been rife with oxygen, water, hydrogen, nitrogen, salts, etc. All the things which are less commonly found near a star, and would have rained that elemental makeup down in substantial quantity onto the surface of the proto Earth, thereby accelerating the appearance of life very soon after Earth's formation.
Thereafter solar photons would have sputtered (solid or liquid to ion) and dessicated the remaining ice/water on the surface of the Moon into space, but in the mean time the water would tidally accrue on ONE side of the Moon facing the earth and eventually through friction, lock the water side of the Moon permanently facing the earth so that the facing ocean/silty (Mares) side is smooth in comparison to the far side which is craggy - and had no erosion in comparison.
And then we would have a thousand to one probability construct and would not have to look for teapots between Jupiter and Mars. So, you see - it is not that the Moon is similar to the Earth - rather it is the Earth possibly, which is similar to the Moon.
- TES
Doesn't work, the oxygen isotope ratio of the Moon is ALMOST exactly the same as the Earth's, so it originated in the same area of the solar nebula, most likely as a single body.
Reply | Report Abuse | Link to thisThe question is just what conditions was the material that now makes up the Lunar crust subjected to? If it was limited heating then some water would have persisted. Given the isotopic and dynamical evidence for the collision theory IMHO we'll find that the material making up the crust simply wasn't so heated that all hydrogen was driven off, and there is plenty of oxygen, no issue explaining that.
In other words the issues are more with the details and not with the general big picture of the formation. There could be other variations we haven't quite worked out yet too. Perhaps there was already a decent sized satellite which was subsumed into the forming Moon, etc.
Изменилась форма Земли и изменились скорость вращения Земли вокруг своей оси и угловой наклон.Эти изменения нарушили равновесие в системе Земля-Луна и Луна приблизилась к Земле,попала в сферу тяготения Земли (не путать с притяжением).Не дойдя до точки Лагранжа она пролетела вокруг Земли создав на Земле апокалипсис а после этого обменявшись С Землей мощнейшими приливными воздействиями и метеоритными ударами,захватила часть земной атмосферы вместе с земными выбросами,сменила географические полюса(смену географических полюсов Луны доказали сотрудники парижского Института Физики Земли Mark Wieczorek and matthien Le Feuvere)одновременно с Землей и отошла от Земли.Это произойдет снова во время лунного затмения в северном полушарии.Форма Земли меняется смотрите в интернете картинки "Земля как картошка".Внимательно прочитайте то,что об этом написали библейские пророки.
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