Okay, you expect to find weird stuff if you go digging on
comets.
But this weird?
(Image: Three rocks [left] and fine-grained dust [right]
from Wild 2. Credit: R. Ogliore & Z. Gainsforth.)
Geophysicist Ryan Ogliore, of the University of Hawai`i Institute
of Geophysics and Planetology, looked into the comet Wild 2, and found a bizarre assemblage of materials.
“The comet's nucleus today is made up of small rocks and
ice, separated by fractions of an inch, that originally formed billions of
miles apart. Some rocks have seen temperatures above 2500 degrees Fahrenheit,
but adjacent ice has been kept close to absolute zero for billions of years.
Every tiny grain we look at has its own fascinating story to tell.”
Here is the University of Hawai`i press release on their findings.
Ogliore and his team studied samples from the comet that
were collected by the NASA Stardust mission. Wild 2 is a comet that used to
travel outside Neptune’s orbit, but was diverted to nearer Earth’s orbit in
1974, when it got too close to Jupiter’s gravitational zone.
The team’s findings were printed in the journal Geochimica
et Cosmochimica Acta. The citation: Ogliore, R.C., Nagashima, K., Huss, G.R.,
Westphal, A.J., Gainsforth, Z., Butterworth, A.L., Oxygen Isotopic Composition
of coarse- and fine-grained material from Comet 81P/Wild 2, Geochimica et
Cosmochimica Acta (2015), doi: http://dx.doi.org/10.1016/j.gca.2015.04.028
They found both tiny dust particles and larger rock bits,
but the evidence suggest that different particles were formed in vastly
different places in the solar system. Some, as Ogliore said above, had at some
point gotten very hot. Others have been beyond icy cold for immensely long
periods of time.
Some of the larger rocks appear similar to rocks found in
primitive meteorites. But the tiny dust particles, strangely for something
orbiting out in Jupiter’s zone, looks like the dust that you’d expect from the
inner solar system.
What could be going on?
“Does the fine-grained dust from comet Wild 2 represent a
diverse sampling of many inner-solar-system objects that were transported to
the outer solar system, or in fact, the raw starting materials of the solar
system?” said Ogliore.
They’ll be looking into that. It may provide clues to how
the Solar System developed. Wild 2 has some interesting clues for us.
“The comet, in an orbit beyond Neptune since its formation,
retains an intact a record of early-Solar-System processes,” Ogliore and his
team wrote.
It may be, they write, “A window into the birth of the solar
system."
© Jan TenBruggencate 2015.
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