Space
Iron Rain May Have Fallen on Early Earth
Catherine Griffin
First Posted: Mar 20, 2015 09:28 AM EDT
Iron rain may have poured down on our early Earth. Scientists have found that at pressures rivaling those when worlds collide, iron vaporizes at far lower pressures than assumed. This may explain why the element is distributed in Earth's mantle rather than collected at its core.
Researchers have long wondered why the moon proportionately has much less iron in its mantle than Earth. The moon would have undergone the same extraterrestrial bombardment as its neighbor, so why is our planet iron-rich and the moon is not?
In order to find out, the researchers decided to investigate the vaporization point of iron under high pressures. If vaporization occurred at lower pressures than assumed, a solid piece of iron after impact might disperse into an iron vapor that would blanket the forming Earth instead of puncturing through it.
The scientists turned to Sandia's Z machine to find out the experimental value for the vaporization threshold of iron. Z accelerated metals to extreme speeds using high magnetic fields. More specifically, the researchers created a target that consisted of an iron plate 5 millimeters square and 200 microns thick, against which they launched aluminum flyer plates travel at up to 25 kilometers per second. At this impact pressure, the powerful shock waves created in the iron caused it to compress, heat up and then vaporize.
"Because planetary scientists always thought it was difficult to vaporize iron, they never thought of vaporization as an important process during the formation of Earth and its core," said Rick Kraus, one of the researchers, in a news release. "But with our experiments, we showed that it's very easy to impact-vaporize iron."
The findings are published in the journal Nature Geoscience.
For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).
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First Posted: Mar 20, 2015 09:28 AM EDT
Iron rain may have poured down on our early Earth. Scientists have found that at pressures rivaling those when worlds collide, iron vaporizes at far lower pressures than assumed. This may explain why the element is distributed in Earth's mantle rather than collected at its core.
Researchers have long wondered why the moon proportionately has much less iron in its mantle than Earth. The moon would have undergone the same extraterrestrial bombardment as its neighbor, so why is our planet iron-rich and the moon is not?
In order to find out, the researchers decided to investigate the vaporization point of iron under high pressures. If vaporization occurred at lower pressures than assumed, a solid piece of iron after impact might disperse into an iron vapor that would blanket the forming Earth instead of puncturing through it.
The scientists turned to Sandia's Z machine to find out the experimental value for the vaporization threshold of iron. Z accelerated metals to extreme speeds using high magnetic fields. More specifically, the researchers created a target that consisted of an iron plate 5 millimeters square and 200 microns thick, against which they launched aluminum flyer plates travel at up to 25 kilometers per second. At this impact pressure, the powerful shock waves created in the iron caused it to compress, heat up and then vaporize.
"Because planetary scientists always thought it was difficult to vaporize iron, they never thought of vaporization as an important process during the formation of Earth and its core," said Rick Kraus, one of the researchers, in a news release. "But with our experiments, we showed that it's very easy to impact-vaporize iron."
The findings are published in the journal Nature Geoscience.
For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone