Scientists studying samples of lunar rock retrieved during the 1972 Apollo 17 mission have found that the Moon’s interior may be far wetter than previously believed, according to an article recently published in the journal Science Express.
The samples, ejected by lunar volcanic eruptions billions of years ago, are windows into the Moon’s mantle. The eruptions hurled crystals containing microscopic beads of magma to the surface. The crystals prevent water in the magma from escaping into space, preserving samples of the inaccessible lunar interior.
Scientists have been measuring water content in these rocks for decades, but “the data that came out of those analyses was some combination of laboratory air contamination and solar wind”, says Erik Hauri, staff scientist of geochemistry at the Carnegie Institution of Washington and the article’s lead author.
Hauri’s team used an untried technique, secondary ion mass spectrometry (SIMS), to get more accurate results. The method focuses a 10 micron-thick beam of charged ions onto the globules of magma, removing bits for analysis in a mass spectrometer to determine chemical composition. The results showed a water density of 1 400 parts per million.
Nasa recently confi rmed the presence of study supports the idea that at least some of the water is native to the Moon. The abundance of water is prompting a reappraisal of a leading lunar formation theory (see left). – Steve Rousseau
Where does the moon come from? Two theories have already come and gone. Now, just when scientists were in agreement on an answer, a 2011 study is causing some head scratching.
Theory 1: Condensed?
The Moon and Earth condensed at the same time from the original nebula that formed the solar system. CONSENSUS: Disproved. The Moon and Earth do have similar compositions, but the theory does not explain the Moon’s size and orbit.
Theory 2: Captured?
The Earth’s gravity ensnared the Moon, which was formed elsewhere. CONSENSUS: Not likely. A wandering moon, with a composition very similar to Earth’s, would have to slow down at just the right time to be captured – an unlikely cosmic coincidence.
Theory 3: Ejected?
A Mars-sized body collided with Earth 4,5 billion years ago, and the Moon formed from a resultant cloud of magma. CONSENSUS: Popular, but now in question. If true, the Moon would have lost water to heat and into space. However, evidence of elevated water casts doubt on the theory.