1,2,8,- 1ISAS/JAXA, Department of Solar System Sciences, Sagamihara, Japan (okada.tatsuaki@jaxa.jp)
- 2University of Tokyo, Tokyo, Japan
- 3Maebashi Institute of Technology, Maebashi, Japan
- 4Chiba Institute of Technology, Narashino, Japan
- 5Univesity of Aizu, Aizu-Wakamatsu, Japan
- 6Hokkaido University of Education, Asahikawa, Japan
- 7National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
- 8Royal Observatory of Belgium, Brussels, Belgium
- 9Flemish Institute of Technology (VITO), Mol, Belgium
- 10Vrije Universiteit Brussel, Brussels, Belgium
- 11US Geological Survey, Flagstaff, USA
People worldwide are becoming aware of the necessity of Planetary Defense after the Chelyabinsk meteorite air burst event in 2013. Later, the kinetic impact experiment using the NASA Double Asteroid Redirect Test (DART) to asteroid Dimorphos was successfully performed in 2022, whose efficiency will be verified by the ESA Hera mission in 2026 to 2027. A close encounter to Earth of the asteroid Apophis in 2029, and the ESA-JAXA joint mission RAMSES (Rapid Apophis Mission for Space Safety) will continuously observe the asteroid during the flyby in 2029. A recent discovery of asteroid 2024YR4 was found, which was considered potentially impacting Earth in 2032. Therefore, physical properties of asteroids are essential for planetary defense studies concerning the nature of asteroids, the effect of asteroid deflection by a kinetic impact of spacecraft, and a degree of disaster caused by an asteroid impact to Earth.
Thermal infrared imaging of asteroids from spacecraft is a useful method to characterize the target bodies during flyby and rendezvous to provide their thermophysical and compositional properties, as was proven in the Hayabusa2 mission. Here we present the Therma InfraRed Imager (TIRI) instrument[1,2] and future observation plans in Hera and RAMSES missions. The instrument is based on an uncooled micro-bolometer array of 1024 x 768 pixels and has a field of view of 13° x 10° and an angular resolution of 0.23 mrad/pixel. It takes images at 25 Hz. In addition, an 8-position filter wheel is equipped with a wide band (8-14 µm) filter to be used for thermal imaging, and six narrow band (centered at 7.8, 8.6, 9.6, 10.6, 11.6, and 13.0 µm, with approximately 1 µm width) to be used for multi-band imaging in comparison with laboratory experiments for meteorites and rocks at thermal infrared wavelengths.
The instrument has proven its in-flight performance during the Earth-Moon system imaging just after the Hera launch in October 2024, and during the imaging of Mars and Deimos (and Phobos). The performance tested during the calibration campaign using the TIRI flight spare will be briefly shown.
References
- Okada T. et al. SSR (2025) 221, 104.
- Okada T. et al. Acta Astronautica (2026) 240, 888-892.
How to cite: Okada, T., Tanaka, S., Sakatani, N., Shimaki, Y., Arai, T., Senshu, H., Demura, H., Sekiguchi, T., Kouyama, T., Kanamaru, M., Ishizaki, T., Vilardell-Belles, R., Furukawa, S., Karatekin, O., Blommaert, J., and Titus, T.: Thermal Infrared Imaging Instruments for Planetary Defense Missions: Hera and RAMSES, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-730, https://doi.org/10.5194/epsc2026-730, 2026.
