Asteroids with a Shared Origin?

Asteroids (101955) Bennu and (162173) Ryugu, known for their missions with NASA and JAXA respectively, have sparked a new theory suggesting they may originate from a massive collisional family in the main asteroid belt, anchored by the parent asteroid (142) Polana.

Groundbreaking Observations from Webb

Using the cutting-edge James Webb Space Telescope, astronomers gathered intriguing spectroscopic data from Polana. By comparing this information with samples collected from both Bennu and Ryugu, they uncovered striking similarities in their near-infrared spectra, adding weight to the hypothesis that all three asteroids share a common ancestry.

A Shocking Cosmic Collision

According to Dr. Anicia Arredondo from the Southwest Research Institute, ancient cosmic collisions likely fragmented larger asteroids to form the Polana family. This transformative event is believed to not only have created Polana, but also to have birthed Bennu and Ryugu.

An Asteroid Family's Journey Through Space

Despite their shared origins, the three asteroids have each charted unique courses through the solar system. Bennu, roughly the size of the Empire State Building at 500 meters in diameter, and the larger Ryugu, at about 1 kilometer, orbit well inside Mars’ track. Fortunately, neither pose an imminent threat to Earth—Bennu reaches a minimum distance of 3 million kilometers (1.9 million miles) and Ryugu about 1.6 million kilometers (1 million miles) at their closest approaches.

Insights into Their Mysteries

Scientists theorize that gravitational influences from Jupiter nudged Bennu and Ryugu away from the vicinity of Polana. While they exhibit some spectral variances, these do not undermine the likelihood of a shared parent body. Dr. Tracy Becker highlights how solar radiation and micrometeoroid impacts could have shaped their surfaces differently after their formation.

A Significant Scientific Discovery

These revelations, published in the Planetary Science Journal, propel our understanding of the solar system and the origins of near-Earth asteroids. The findings underscore how historical events echo through the cosmos, linking asteroids through time and space.

The Legacy of the Polana Family

As research continues, implications of these discoveries could deepen our understanding of planetary formation and the evolution of asteroids—remnants of a time long past, still holding many secrets of our solar system’s history.