Planetary Defense, Space Debris and Near-Earth Objects

This manuscript proposes the Responsibility to Defend Earth (R2DE) as a core principle for planetary defense, aiming to foster international cooperation and policy changes. Despite technical advancements and creation of bodies like IAWN and SMPAG, it highlights the need for consensus on action and means.

Images collected during NASA’s DART mission of the asteroid Didymos and its moon, Dimorphos, are used to explore the origin and evolution of the binary system. Authors analysis indicate that both asteroids are weak rubble piles and that Didymos’ surface should be about 40 to 130 times older than Dimorphos.

By comparing boulders’ surface distribution and shapes on the binary asteroid system, Didymos, authors show that both bodies are rubble piles produced in their progenitor catastrophic disruption and that the secondary, Dimorphos, likely inherited its material from the primary through spin up and mass shedding.

Here, authors study boulders’ fractures on S-type asteroid, Dimorphos, and show that their size-frequency distribution and orientation are consistent with formation through thermal fatigue. Such fractures seem to propagate horizontally much faster (~kyr) than normal to the boulder’s surface (~Myr).

Bearing capacity, the ability of a surface to support applied loads, is a critical property in planetary exploration to understand a surface’s response to landing or roving. Here, the bearing capacity of the asteroid Didymos is estimated using DART images of suspected boulder tracks on its surface.

Planetary Defense efforts rely on estimates of asteroids’ mechanical properties, which are difficult to obtain accurately from Earth. Here, authors compare images from space missions to the rubble-pile asteroids Dimorphos, Itokawa, Ryugu, and Bennu and study such properties through boulders on their surface.

Atmospheric entry of asteroids or comets can cause significant damage to Earth. Two international bodies, the International Asteroid Warning Network (IAWN), and the Space Mission Planning Advisory Group (SMPAG) are working on dealing with potential threats.

The fast-spinning primary of the Didymos near-earth asteroid binary system was found to have a degraded top shape by the DART (NASA) mission. Here, authors find that these surface features observed in the asteroid are more likely to have been caused by collisional effects than by the YORP effect.

On September 26^th 2022, LICIACube monitored Double Asteroid Redirection Test (DART) mission impact on asteroid Dimorphos, which is the smaller component of a binary asteroid system. These close observations revealed the impact ejecta features of the first planetary defence test with a kinetic impactor.

NASA’s Double Asteroid Redirection Test (DART) mission intentionally impacted the asteroid Dimorphos on September 26, 2022, and this kinetic impact changed Dimorphos’ orbit around its binary companion Didymos. This first planetary defense test explored technological readiness for this method of asteroid deflection.