Dwarf planet Vesta a window to the early solar system

Date:
October 6, 2021
Source:
University of California - Davis
Summary:
The dwarf planet Vesta is helping scientists better understand
the earliest era in the formation of our solar system. Two recent
articles use data from meteorites derived from Vesta to resolve the
'missing mantle problem' and push back our knowledge of the solar
system to just a couple of million years after it began to form.



FULL STORY ==========================================================================
The dwarf planet Vesta is helping scientists better understand the
earliest era in the formation of our solar system. Two recent papers
involving scientists from the University of California, Davis, use
data from meteorites derived from Vesta to resolve the "missing mantle
problem" and push back our knowledge of the solar system to just a couple
of million years after it began to form. The papers were published in
Nature Communications Sept. 14 and Nature Astronomy Sept. 30.


========================================================================== Vesta is the second-largest body in the asteroid belt at 500 kilometers
across.

It's big enough to have evolved in the same way as rocky, terrestrial
bodies like the Earth, moon and Mars. Early on, these were balls of molten
rock heated by collisions. Iron and the siderophiles, or 'iron-loving'
elements such as rhenium, osmium, iridium, platinum and palladium sank
to the center to form a metallic core, leaving the mantle poor in these elements. As the planet cooled, a thin solid crust formed over the
mantle. Later, meteorites brought iron and other elements to the crust.

Most of the bulk of a planet like Earth is mantle. But mantle-type rocks
are rare among asteroids and meteorites.

"If we look at meteorites, we have core material, we have crust, but we
don't see mantle," said Qing-Zhu Yin, professor of earth and planetary
sciences in the UC Davis College of Letters and Science. Planetary
scientists have called this the "missing mantle problem." In the
recent Nature Communications paper, Yin and UC Davis graduate students
Supratim Dey and Audrey Miller worked with first author Zoltan Vaci
at the University of New Mexico to describe three recently discovered meteorites that do include mantle rock, called ultramafics that include
mineral olivine as a major component. The UC Davis team contributed
precise analysis of isotopes, creating a fingerprint that allowed them
to identify the meteorites as coming from Vesta or a very similar body.

"This is the first time we've been able to sample the mantle of Vesta,"
Yin said. NASA's Dawn mission remotely observed rocks from the largest
south pole impact crater on Vesta in 2011 but did not find mantle rock.



========================================================================== Probing the early solar system Because it is so small, Vesta formed a
solid crust long before larger bodies like the Earth, moon and Mars. So
the siderophile elements that accumulated in its crust and mantle form a
record of the very early solar system after core formation. Over time, collisions have broken pieces off Vesta that sometimes fall to Earth
as meteorites.

Yin's lab at UC Davis had previously collaborated with an international
team looking at elements in lunar crust to probe the early solar
system. In the second paper, published in Nature Astronomy, Meng-Hua Zhu
at the Macau University of Science and Technology, Yin and colleagues
extended this work using Vesta.

"Because Vesta formed very early, it's a good template to look at the
entire history of the Solar System," Yin said. "This pushes us back
to two million years after the beginning of solar system formation."
It had been thought that Vesta and the larger inner planets could have
got much of their material from the asteroid belt. But a key finding from
the study was that the inner planets (Mercury, Venus, Earth and moon,
Mars and inner dwarf planets) got most of their mass from colliding and
merging with other large, molten bodies early in the solar system. The
asteroid belt itself represents the leftover material of planet formation,
but did not contribute much to the larger worlds.

Additional coauthors on the Nature Communications paper are: James Day
and Marine Paquet, Scripps Institute of Oceanography, UC San Diego; Karen Ziegler and Carl Agee, University of New Mexico; Rainer Bartoschewitz, Bartoschewitz Meteorite Laboratory, Gifhorn, Germany; and Andreas Pack, Georg-August- Universita"t, Go"ttingen, Germany. Yin's other coauthors
on the Nature Astronomy paper are: Alessandro Morbidelli, University of Nice-Sophia Antipolis, France; Wladimir Neumann, Universita"t Heidelberg, Germany; James Day, Scripps Institute of Oceanography, UCSD; David Rubie, University of Bayreuth, Germany; Gregory Archer, University of Mu"nster, Germany; Natalia Artemieva, Planetary Science Institute, Tucson; Harry
Becker and Kai Wu"nnemann, Freie Universita"t Berlin.

The work was partly supported by the Science and Technology Development
Fund, Macau, the Deutsche Forschungsgemeinschaft and NASA.

========================================================================== Story Source: Materials provided by
University_of_California_-_Davis. Original written by Andy Fell. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zoltan Vaci, James M. D. Day, Marine Paquet, Karen Ziegler,
Qing-Zhu Yin,
Supratim Dey, Audrey Miller, Carl Agee, Rainer Bartoschewitz,
Andreas Pack. Olivine-rich achondrites from Vesta and the missing
mantle problem.

Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-25808-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211006143439.htm

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