NASA’s Double Asteroid Redirection Test (DART) mission has yielded a wealth of new insights into the nature and formation of near-Earth asteroids. Five recently published papers in Nature Communications reveal fascinating details about the Didymos-Dimorphos binary asteroid system, shedding light on their origins and physical properties.
A Tale of Two Asteroids: Didymos and Dimorphos
The DART mission, which successfully altered the orbit of the asteroid moonlet Dimorphos by intentionally crashing a spacecraft into it, provided researchers with an unprecedented close-up look at a binary asteroid system. Scientists from the Johns Hopkins Applied Physics Laboratory (APL) and international partners analyzed images and data from the mission to piece together the geological history of both Didymos and its smaller companion, Dimorphos.
Olivier Barnouin, an APL scientist who led one of the studies, explained: “The images and data that DART collected at the Didymos system provided a unique opportunity for a close-up geological look at a near-Earth asteroid binary system. From these images alone, we were able to infer a great deal of information on geophysical properties of both Didymos and Dimorphos, and expand our understanding of the formation of these two asteroids.”
The researchers found striking differences between the two asteroids. Dimorphos is covered in boulders of various sizes, while Didymos has a smoother surface at lower elevations and more craters overall. This led the team to conclude that Dimorphos likely formed from material spun off from Didymos in a “large mass shedding event.”
Unveiling the Secrets of Asteroid Formation and Evolution
One of the most intriguing findings is the age disparity between Didymos and Dimorphos. Analysis suggests that Didymos’ surface is 40-130 times older than Dimorphos, with estimated ages of 12.5 million years and less than 300,000 years, respectively. This significant age difference provides valuable insights into the formation and evolution of binary asteroid systems.
The studies also revealed surprising details about the physical properties of these asteroids:
1. Weak surface characteristics: Both Didymos and Dimorphos have remarkably weak surfaces, which likely contributed to DART’s significant impact on Dimorphos’ orbit.
2. Rapid boulder breakdown: Thermal fatigue can cause boulders on Dimorphos’ surface to break apart much faster than previously thought, altering the asteroid’s physical characteristics.
3. Extremely low bearing capacity: Didymos’ surface has a bearing capacity at least 1,000 times lower than dry sand on Earth or lunar soil, making it incredibly fragile.
4. Similar boulder characteristics: The surface boulders on Dimorphos share similarities with those on other rubble pile asteroids like Itokawa, Ryugu, and Bennu, suggesting a common formation process.
Why it matters: These findings are crucial for improving our understanding of near-Earth asteroids and developing effective planetary defense strategies. The insights gained from the DART mission will inform future asteroid deflection techniques and help scientists better predict how different types of asteroids might respond to impact events.
The research also has implications for future space exploration missions. Understanding the physical properties of asteroids is essential for designing spacecraft and instruments capable of landing on or interacting with these celestial bodies.
As the European Space Agency’s Hera mission prepares to revisit the DART impact site in 2026, these studies provide a baseline for what to expect and will help guide further investigations. The continued analysis of the Didymos-Dimorphos system will undoubtedly yield more surprises and advance our knowledge of asteroid formation, evolution, and behavior.
The DART mission and subsequent research represent a significant step forward in planetary defense capabilities. By demonstrating the effectiveness of kinetic impact as a deflection technique and providing detailed insights into asteroid properties, these studies contribute to humanity’s ability to protect Earth from potential asteroid threats in the future.
