Speaker
Description
The planetary defense is an important activity for humankind. JAXA has been involved in this activity for long time, and recently Planetary Defense Team has been established and started to work.
The first thing to do for the planetary defense is to discover celestial bodies that will collide with the Earth and to estimate their orbits accurately. We carry out observations of Near-Earth objects (NEO) as well as space debris at Bisei Spaceguard Center. We also developed a method for discovering fast-moving objects that are approaching the Earth, and successfully discovered approximately 10 small NEOs using a small telescope with a diameter of about 20 cm.
If a celestial body that will collide with the Earth is discovered, we will try to avoid the collision. In order to do so, we need to know the physical properties of NEOs. We investigated physical properties of two NEOs, (25143) Itokawa and (162173) Ryugu by Hayabusa and Hayabusa 2 missions. Hayabusa2 mission has been extended after the Earth return, and it will explore two more NEOs, (98943) Torifune and 1998 KY26. Hayabusa2 will flyby Torifune in July 2026, and arrive at 1998 KY26 in July 2031. Torifune flyby has a planetary defense purpose in engineering as well. We will try to make Hayabusa2 approach very closely to Torifune in the relative velocity of 5km/s. If we can perform the spacecraft navigation very precisely, we can have ability to collide spacecraft to a small asteroid. The exploration of 1998 KY26 is also very important for the planetary defense because it is very tiny asteroid (size is estimated as 30m). Such kind of asteroids have the Earth collision probability of once in 100 or 200 years. In addition, we are collaborating with ESA's Hera mission, which will explore Dimorphos, the satellite of (65803) Dydimos, that NASA's DART collided with and successfully changed its orbit. We provided Infrared camera (TIRI) to Hera. We are also working for ESA's RAMSES mission to explore asteroid Apophis, which will approach the Earth in 2029.
Other activities related to the planetary defense in JAXA include orbit analysis of NEOs, participation in international conferences, and outreach activities. Collisions of celestial bodies that cause major damage will happen once every few decades, and such disasters can be predictable and avoidable if we can find celestial bodies colliding with the Earth in advance. We will continue our activities that will contribute to the planetary defense.