太陽系小天体の地球衝突の回避のための活動は、プラネタリーディフェンスと呼ばれ、1990年代から本格的に始まり、30年近くが経った現在、目覚ましい進歩がある。36,000個以上の地球接近天体(NEO)が発見され、10個以上のNEOに探査機が送られ、2022年にはNASAのDARTが小惑星に衝突することでその軌道を変えるという初の試みに成功した。ESAのHeraは、DART の衝突実験結果を詳細に調査するために、2024年10月に打ち上げられた。並行してNASAのOSIRIS-APEX（OSIRIS-RExの延長）やJAXAのはやぶさ2#（はやぶさ2の延長）などのNEOミッションがそれぞれの目標に向かっている。2029年、小惑星アポフィスは地球の静止衛星軌道までの距離よりも地球に接近しするが、アポフィスはESAのRAMSEとOSIRIS-APEXの両方のターゲットとなっている。国連の下に設置されたグループでの議論や国際会議、アウトリーチ活動など幅広い活動が活発に行われている。本セッションでは、地球を天体衝撃から守るために今後どのような研究や国際協力を含めた行動をとるべきかについて議論する。

The activities that focus on the avoidance of collisions of small solar system bodies with the Earth belong to the topic called planetary defense. These activities began in earnest in the 1990s. Now, nearly 30 years later, there has been remarkable progress. More than 36,000 Near Earth Objects (NEOs) have been discovered so far, and spacecraft have been sent to more than 10 NEOs. Furthermore, in 2022, DART by NASA made the first attempt to change the orbit of an asteroid successfully. ESA Hera was also launched successfully on October 7, 2024, to investigate in detail the results of the DART impact as well as the characteristics of its target. Other NEO missions such as OSIRIS-APEX (an extended mission of OSIRIS-REx) of NASA, and Hayabusa2# (an extended mission of Hayabusa2) of JAXA are on their way to their respective target.
In 2029, the asteroid Apophis will come closer than Earth's geostationary satellite orbit to our planet, and is the target of both the RAMSES of ESA that just started officially its development until its formal approval in 2025 in order to be at Apophis a few months before its closest approach, and the OSIRIS-APEX that will visit the asteroid a few days after its closest approach to the Earth. Several concepts are also under study to visit Apophis, offering a great possible international synergy between these two missions and possibly other concepts. Internationally, a wide range of activities such as discussions in groups established under the United Nations, international conferences, and outreach activities are actively carried out. This lively situation motivates presentations on ongoing relevant activities in various areas covering ground and space based investigations, theoretical/technical research, as well as social science research on NEO and planetary defense. We will also discuss what kind of research or action, including international cooperation, should be undertaken from now on for the protection of our planet against an impact.