Once again, I suspect that rocky
planets such as Earth and Mars are produced as ejects from Jupiter which does
the heavy lifting in terms of accumulating the mass and clearing out the Solar
System. Jupiter is close by the point of
rotational instability and a mass the size of Earth rapidly acquired would be
spun up and ejected back out.
I go further than that and
propose Venus is a recent addition to the Solar System and that its scar on
Jupiter is the Red Spot. However most of
the planet making activity took place during the early years of the formation
of the Solar system and we have a very good explanation for the formation of a
solar system. The late arrival of Venus
is plausibly caused by deliberate intervention as was the crustal shift that
ended the Great Ice Age here on Earth.
Thus discovering a much smaller
ejecta body such as Vesta is actually to be expected.
Vesta
Dec 9, 2011: NASA's Dawn spacecraft spent the last four years
voyaging to asteroid Vesta – and may have found a planet.
Vesta was discovered over two hundred years ago but, until Dawn, has
been seen only as an indistinct blur and considered little more than a large,
rocky body. Now the spacecraft's instruments are revealing the true complexity
of this ancient world.
"We're seeing enormous mountains, valleys, hills, cliffs, troughs,
ridges, craters of all sizes, and plains," says Chris Russell, Dawn
principal investigator from UCLA. "Vestais not a simple ball of rock.
This is a world with a rich geochemical history. It has quite a story to
tell!"
Like Earth and other terrestrial planets, Vesta has ancient basaltic
lava flows on the surface and a large iron core. It also has tectonic
features, troughs, ridges, cliffs, hills and a giant mountain. False colors in
this montage represent different rock and mineral types.
In fact, the asteroid is so complex that Russell and members of his
team are calling it the "smallest terrestrial planet."
Vesta has an iron core, notes Russell, and its surface features
indicate that the asteroid is "differentiated" like the terrestrial
planets Earth, Mercury, Mars, and Venus.
Differentiation is what happens when the interior of an active planet
gets hot enough to melt, separating its materials into layers. The light
material floats to the top while the heavy elements, such as iron and nickel,
sink to the center of the planet.
Researchers believe this process also happened to Vesta.
The story begins about 4.57 billion years ago, when the planets of the
Solar System started forming from the primordial solar nebula. As Jupiter
gathered itself together, its powerful gravity stirred up the material in the
asteroid belt so objects there could no longer coalesce. Vesta was in the
process of growing into a full-fledged planet when Jupiter interrupted the
process.
Like Earth and other terrestrial planets, Vesta is differentiated into
layers.
Although Vesta’s growth was stunted, it is still differentiated like a
true planet.
"We believe that the Solar System received an extra slug of
radioactive aluminum and iron from a nearby supernova explosion at the time
Vesta was forming," explains Russell.
?deis ex machina? The ejecta model sends out a molten body of
material that will obviously differentiate as it also cools down. Please note that the surface temperature of
the rock on Venus is still close to the temperature at which it is molten as
may be expected from a recent ejection event.
This needs to be counteracted with a cometary bombardment that delivers
methane and water and accelerates the cooling and recycling of the near crust.
It is my conjecture that once
Earth is fully terraformed, our next task will be the terraforming of Venus
ultimately providing Earth with a back up.
"These materials decay and give off heat. As the asteroid was
gathering material up into a big ball of rock, it was also trapping the heat
inside itself."
As Vesta’s core melted, lighter materials rose to the surface, forming
volcanoes and mountains and lava flows.
"We think Vesta had volcanoes and flowing lava at one time,
although we've not yet found any ancient volcanoes there," says Russell.
"We're still looking. Vesta's plains seem similar to Hawaii's surface,
which is basaltic lava solidified after flowing onto the surface.
Vesta has so much in common with the terrestrial planets, should it be
formally reclassified from "asteroid" to "dwarf planet"?
"That's up to the International Astronomical Union ,
but at least on the inside, Vesta is doing all the things a planet does."
If anyone asks Russell, he knows how he would vote.
New NASA Dawn Visuals Show Vesta's 'Color Palette'
Image Advisory: 2011-375
This image using color data obtained by the framing camera aboard
NASA's Dawn spacecraft shows Vesta's southern hemisphere in color, centered on
the Rheasilvia formation.
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
December 5, 2011 - PASADENA, Calif.
In images from Dawn's framing camera, the colors reveal differences in
the rock composition associated with material ejected by impacts and geologic
processes, such as slumping, that have modified the asteroid's surface. Images
from the visible and infrared mapping spectrometer reveal that the surface
materials contain the iron-bearing mineral pyroxene and are a mixture of
rapidly cooled surface rocks and a deeper layer that cooled more slowly. The
relative amounts of the different materials mimic the topographic variations
derived from stereo camera images, indicating a layered structure that has been
excavated by impacts. The rugged surface of Vesta is prone to slumping of
debris on steep slopes.
Dawn scientists presented the new images at the American Geophysical
Union meeting in San Francisco
"Vesta's iron core makes it special and more like terrestrial
planets than a garden-variety asteroid," said Carol Raymond, Dawn's deputy
principal investigator at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"The distinct compositional variation and layering that we see at Vesta
appear to derive from internal melting of the body shortly after formation, which
separated Vesta into crust, mantle and core." The presentation also
included a new movie, created by David O'Brien of the Planetary Science
Institute, Tucson , Ariz.
Dawn launched in September 2007 and arrived at Vesta on July 15, 2011.
Following a year at Vesta, the spacecraft will depart in July 2012 for the
dwarf planet Ceres, where it will arrive in 2015.
Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science
Mission Directorate in Washington Pasadena Ala. Dulles , Va. German Aerospace
Center
More information about the Dawn mission is online at: http://www.nasa.gov/dawn.
To follow the mission on Twitter, visit: http://www.twitter.com/NASA_Dawn.
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