A Violent Past Revealed

Pallas, one of the most infamous asteroids in our solar system, has been captured in stunning detail by astronomers using the SPHERE instrument at the European Southern Observatory’s Very Large Telescope. The images reveal a remarkable sight: Pallas is the most cratered object in the asteroid belt, a title it has likely earned through countless collisions with its neighbors.

“These first detailed images of Pallas suggest that the asteroid has had a violent past,” said Franck Marchis, a planetary scientist at MIT and co-author of a study published in Nature Astronomy.

An Unusual Orbit

While most asteroids in the belt travel along a similar path around the sun, Pallas takes a more rogue approach. Its tilted orbit brings it crashing through the belt at an awkward angle, increasing the likelihood of collisions.

“Pallas experiences two or three times more collisions than Ceres or Vesta,” the two largest objects in the asteroid belt, said Michaël Marsset, a planetary scientist at MIT and co-author of the study.

A Golf Ball Asteroid

The constant bombardment has left Pallas heavily pockmarked, earning it the nickname “golf ball asteroid.” An analysis of images captured by SPHERE showed that craters make up at least 10% of the asteroid’s surface.

Severe Impacts

The impacts that Pallas experiences are particularly severe. Computer simulations revealed that the impactors responsible for the craters were traveling at speeds over 25,000 miles per hour, nearly twice as fast as is typical for asteroid belt collisions.

A Family of Followers

At least 36 of the depressions on Pallas span at least 18 miles in diameter, including one massive crater that stretches 250 miles across. This crater is likely the result of a collision with an object up to 25 miles wide.

The impact that created this crater may also be responsible for the group of smaller objects that trail Pallas. After smashing into the asteroid some 1.7 billion years ago, the impactor may have shattered into fragments that drifted into space and now follow their leader.

A Window into the Past

“Because we are now able to see the surface of large asteroids in the main-belt, we have access to a fictive book on the history of our solar system,” said Marsset. “We are in the process of learning how to read it, and each page is a surprise to us, including Pallas.”

By studying Pallas and other asteroids, scientists are gaining a better understanding of the violent and chaotic early days of our solar system. These celestial bodies hold clues to the processes that shaped our planet and the potential hazards that still exist in space.

Creating an Artificial Crater

In April 2019, Japan’s Hayabusa2 spacecraft made history by creating an artificial crater on the asteroid Ryugu. The mission aimed to calculate Ryugu’s age and provide insights into its composition.

The spacecraft hurled a four-pound copper ball, known as SCI (small carry-on impactor), towards Ryugu’s surface at an astonishing speed of 4,500 miles per hour. The impact created a crater approximately 47 feet wide, larger than expected.

Calculating Ryugu’s Age

Previous estimates suggested Ryugu’s surface could be millions to hundreds of millions of years old. However, the artificial crater provided a more accurate measurement.

Researchers analyzed the size and shape of the crater, which are influenced by the asteroid’s gravity and the strength of its surface material (regolith). Using this data, they calculated Ryugu’s surface age to be between six and 11 million years old.

Microgravity Crater Formation

The Hayabusa2 mission marked the first time crater formation was observed in a microgravity environment. Unlike Earth, where gravity is strong, Ryugu’s microgravity environment significantly impacted the crater’s characteristics.

The crater’s large size and semicircular shape suggest that Ryugu has a loose top layer covering a denser core. This finding aligns with recent evidence from the Nature journal, indicating that Ryugu is primarily composed of loosely packed sand rather than solid rock.

Asteroid Composition and Evolution

While the surface of Ryugu appears to be relatively young, the asteroid itself may be significantly older. Most asteroids of similar size are estimated to be around 100 million years old.

However, Ryugu’s rapid spin rate could have eroded old craters and reset the surface’s apparent age. Landslides observed by Hayabusa2 indicate that the asteroid may have slowed down from a higher spin rate in the past.

Hayabusa2’s Return and Future Studies

Hayabusa2 left Ryugu in November 2019, carrying samples from the center of the crater. These samples will be analyzed by scientists to gain a deeper understanding of Ryugu’s composition and history.

The Hayabusa2 mission has provided valuable insights into asteroid exploration and the evolution of these celestial bodies. Future studies will continue to unravel the mysteries of Ryugu and other asteroids in our solar system.

Discovery of a Rare Aubrite Meteorite

On January 21, 2024, a three-foot-long asteroid named 2024 BX1 entered Earth’s atmosphere, creating a blazing fireball that was visible across much of Europe. The asteroid crashed to the ground near Berlin, Germany, and scientists quickly arrived on the scene to recover and classify the fragments.

To their surprise, the fragments were identified as an aubrite, a rare type of meteorite that only 80 of 70,000 previously found meteorite fragments have been classified as. Aubrites are named after the first known meteorite of this type, which fell in 1836 near the village of Aubres in France.

Challenges in Identifying Aubrites

Unlike most meteorites, which have a thin crust of black glass, aubrites do not appear glossy or dark in color. Instead, they resemble gray granite, making them difficult to detect in the field. As a result, meteorite hunters had to scour the area near Berlin for fragments of the asteroid, which proved to be a challenging task.

Importance of the Discovery

The discovery of the aubrite meteorite in Germany is significant for several reasons. First, it provides scientists with fresh material to study, which can help them better understand the origin of aubrites. Second, the accurate orbit of the asteroid 2024 BX1 can help researchers determine where it came from.

Potential Origins of Aubrites

The origin of aubrites is still a mystery, but scientists have proposed several candidates. One possibility is the Nysa asteroid family, a group of asteroids that orbit the Sun between Mars and Jupiter. Another candidate is asteroid 3103 Eger, which is located in the asteroid belt. A third possibility is the planet Mercury.

Mercury as a Potential Source

While Mercury is a potential source of aubrites, some astronomers find it unlikely in this case. The calculated orbit of 2024 BX1 suggests that it came from outside of Earth’s orbit, which would make it difficult for it to have come directly from Mercury. However, it is possible that Mercury may have indirectly projected aubrites to the asteroid belt long ago, and one of these may have made its way to Earth.

Scientific Value of the Discovery

The fragments of the 2024 BX1 aubrite meteorite will be invaluable for scientific research. By studying these fragments, scientists hope to learn more about the formation of the solar system and the origin of meteorites. The discovery of this rare meteorite is a testament to the importance of meteorite research and the potential for new discoveries to shed light on the mysteries of our universe.