Jupiter's Influence on Asteroid Bennu's Hybrid Origin

• Analysis of samples from asteroid (101955) Bennu, collected by the OSIRIS-REx mission, reveals an unexpected chemical signature that blends characteristics of both inner and outer solar system materials.
• Researchers at ETH Zurich and Lawrence Livermore National Laboratory identified this dual origin, suggesting a complex formation history involving Jupiter.

Isotopic Evidence

• Isotopes serve as markers of the early solar system, where distribution was uneven due to varying neutron counts in elements like iron, titanium, and chromium.
• While Bennu’s titanium and chromium matched expectations for Carbonaceous (CC) asteroids formed in the outer solar system, its iron isotopes resembled Non-Carbonaceous (NC) asteroids from the inner solar system.
• Radioactive manganese-53 decay dating indicates Bennu formed about 2 million years after the first solid rocks appeared in the solar system, earlier than expected for outer-system bodies.

The Role of Jupiter

• As Jupiter grew to 23 times Earth's mass, it carved paths in the protoplanetary disk, creating pressure ridges that acted as filters.
• These ridges trapped larger molten droplets (chondrules) outside its orbit while allowing smaller dust grains to migrate inward.
• The location of these pressure ridges coincided with the 'ice line,' where temperatures were low enough for water to freeze.
• Bennu originated in this transition zone, where the 'traffic jam' of trapped outer-system material and inward-drifting inner-system dust blended together to form the asteroid's building blocks.
• Over billions of years, orbital shifts and collisions moved the body into its current position as a Near-Earth Asteroid (NEA).