Learn about the earliest ages of the solar system

Scientists have used meteorite data from Vesta to address the "missing mantle problem" and delay our understanding of the solar system to just a few million years after it began to form.

The dwarf planet Vesta is helping scientists better understand the earliest times when the solar system formed.

Two recent articles used meteorite data from Vesta to address the "missing mantle problem" and delay our understanding of the solar system to just a few million years after it began to form.

The papers were published in Nature Communications and Nature Astronomy on September 14 and September 30, respectively.

Vesta

Vesta was the fourth asteroid discovered on March 29, 1807, by Dr. Obers, a member of the Sky Patrol who also discovered Ceres and Wisdom.

Vesta completed its accretion between 2 million and 3 million years. Between 4 million and 5 million years, it was heated and melted by the energy of radioactive decay, causing the separation of the metal nuclei.

After 6-7 million years, after 80% of the material has crystallized, convection will stop. The remaining material was squeezed to form star crusts, basalt lava during explosions, or short-lived magma seas.

When older lava is deformed by the pressure of the newer surface layers, the deeper layers of the star's core crystallize into deep rock. Finally, Vesta's interior slowly cooled and became what it is now.

It's big enough to evolve like rocky Earth-like objects like Earth, the Moon, and Mars. It is the second largest object in the asteroid belt after Ceres, accounting for 9% of the total mass of the main asteroid belt.

Like Ceres, Vesta orbits in the main asteroid belt between Jupiter and Mars. But could it be classified as a dwarf planet?

After many measurements, Vesta has only 25% of the mass of Pallas and is an oblate spheroid with a density much less than that of Pallas, and there is not enough mass to overcome the solid stress to reach a shape in hydrostatic equilibrium.

Therefore, at the 26th International Astronomical Union Congress, delegates felt that it was too early to talk about whether Vesta could be classified as a dwarf planet and should continue to be called a small body in the solar system.

Like other small celestial bodies in the solar system, it does not emit light by itself but emits light by reflecting sunlight. Its brightness is related to its distance from the sun and Earth, and also to the ability of its surface to reflect sunlight.

Vesta is closer to the sun than Ceres. Its orbit is still in the orbit of Ceres, and Vesta's surface is more able to reflect sunlight. As a result, Vesta is the brightest small object in the solar system, with an average brightness of magnitude ooooooo6.5. f f f f f f f

These asteroids are preserved in the impact environment of the solar system and have everything intact since their formation.

Among the asteroids in the solar system, the two "big brothers" that are m concerned scientists are Vesta and Ceres. he he ost

In the past ten years, scientists have also gained some new understanding of the structure of the solar system in the observation and theoretical research of the solar system, especially asteroids.

new understanding

In a recent Nature Astronomy paper, Qingzhu Yin, professor of Earth and Planetary Sciences in the UC Davis College of Arts and Sciences, and UC Davis graduate students Supratim Dey and Audrey Miller, in collaboration with lead author Zoltan Vaci of the University of New Mexico, describe the recent discovery Three of the meteorites that do contain mantle rocks, called ultrabasic meteorites, include the mineral olivine as a major component.

Scientists now know that Vesta's structure, like Earth's, can be divided into three layers: a core composed of metallic iron and nickel. The core is covered by an olivine mantle, and the outer mantle is the star's crust.

Most a planet like Earth has a mantle. But mantle-type rocks are rare in asteroids and meteorites.

In 2011, NASA's Dawn mission, which remotely observed rocks from Vesta's largest south pole impact crater, found no mantle rocks.

"This is the first time we have been able to sample Vesta's mantle," said Yoon Kyung-J. "If we look at meteorites, we have core material, we have we can't see the mantle." Planetary scientists call this the "missing mantle problem." oo crustbout

Early on, these were lava balls heated by collisions. Iron and o, or "iron-loving" elements, such as rhenium, osmium, iridium, platinum, and palladium, sink to the center to form a metallic core that deprives the mantle of these elements. organophilic

As the planet cooled, a thin solid crust formed on the mantle. Later, meteorites brought iron and other elements to the crust.

Vesta formed a solid crust long before larger bodies like Earth, the Moon, and Mars.

Because it is so small, the accumulation of m in the crust and mantle forms the core and also the r for the very early solar system. onopiless record

Over time, the collisions caused debris from Vesta to sometimes fall to Earth as meteorites.

The study found

Yin Qingzhu's lab at UC Davis previously worked with an international team studying elements in the lunar crust to probe the early solar system.

Now the UC Davis team has performed a precise analysis of the isotopes, creating a fingerprint that allows them to identify the meteorite from Vesta or a very similar object.

This work was partially supported by the Macau Science and Technology Development Fund, the Deutsches Research Instit, ute, and NASA.

Zhu Menghua of Macau University of Science and Technology and his colleagues extended this work using Vesta.

Yin Qingzhu said. "This pushes us back to two million years after the formation of the solar system began." "Because Vesta formed so early, this is a good template for understanding the entire history of the solar system."

Vesta and the larger inner planets were once thought to get most of the material from the asteroid belt.

But a key finding of the study is that most of the mass of the inner planets (Mercury, Venus, Earth and Moon, M,s and inner dwarf planets) comes from collisions and mergers with other large molten bodies in the early solar system. ars

That is, the asteroid belt itself represents the leftover material from planet formation, but contributes little to the larger world.

These features suggest that it and Ceres have different evolutionary paths. If it is studied together with Ceres and compared with each other, it will be able to reveal the evolution process of the solar system more clearly.