picture of the day
Sorted banding of surface materials on
Itokawa. Credit: Japan Aerospace Exploration Agency (JAXA)
Apr 29, 2008
Particle Sorting on Asteroid Itokawa
Scientists report that impact vibrations are
causing rocks and gravel on the surface to sort themselves
by size. But is the mechanical vibration theory correct?
On May 9, 2003, the Japanese space probe,
was launched from the
Kagoshima launch facility
toward the asteroid,
Its planned mission was to land on the surface of the
asteroid and return to Earth with a sample of the soil. The
spacecraft did land on the asteroid, but due to some
instrument malfunction, it was twice unable to gather
samples. Despite the loss of telemetry from the spacecraft,
however, Hayabusa did manage to take off and begin its
to Earth, due to arrive in 2010.
by a team of researchers from the University of Tokyo and
the Arizona-based Planetary Science Institute announced that
"regolith migration and sorting" is occurring on Itokawa. In
close up images
of the asteroid, the materials are aligned and segregated,
with larger rocks sitting on top of smaller gravels. The
stones and pebbles appear to congregate in
bands along the surface
as well, leaving some areas with a finer composition and
others with an accumulation of larger fragments.
cometslive their lives within the electric currents that pass
between the stars, they exhibit similar formations and
overall topography. As we have written in past Picture of
the Day articles, some have craters so large that, if formed
by impact, it is a mystery why they were not blown to
pieces. There are also gouges and groves and parallel cliffs
that defy conventional explanation.
for the granule separation effect is vibration from the
impact of small meteors. The vibrations cause the granules
to segregate from the shaking and form layers, with the
heavier material on top, gradually decreasing in diameter
and density toward the bottom and sides. Just as the raisins
will rise to the top of a box of raisin bran when you shake
it, the larger objects within Itokawa's loose surface
deposits supposedly rise to the top from the repeated
Thunderbolts Picture of the Day
analyzed images from the Hayabusa spacecraft's
high-resolution cameras and described the electrical nature
of the asteroid's surface. Itokawa's makeup surprised the
investigators, because it is far less dense than was
expected. From the
perspective of an Electric Universe model,
however, the debris that characterizes many asteroids and
comets can be easily explained.
sorting could be taking place on Itokawa - very much like
the sorting of Saturn's rings into thousands of bands. Small
rock particles can float on an ionic 'wind' that moves them
away from the area of strongest plasma flux density, so some
areas of the asteroid are covered with fine particles.
Larger pebbles and gravel could also be dragged along due to
the conductive material in them and form debris fields that
are perpendicular to the electric charges.
many common materials also possess "semi-conductor"
properties (silicon dioxide, for example), magnetic fields
will attract them differently. Therefore, because of
variations in electrical resistivity, it appears as if the
granules on Itokawa's surface are being sorted by their
ability to carry electric charges.
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