17:15 〜 18:45
[MZZ40-P01] Science and Operation Plan of Hera TIRI Instrument to Explore Didymos Asteroid Binary System
★Invited Papers
キーワード：プラネタリ―ディフェンス、熱赤外カメラ、TIRI、ディディモス、ディモルフォス
Introduction: The thermal infrared imager TIRI for the ESA Hera mission is planned to investigate thermophysical properties and composition of the surface the S-type asteroid 65803 Didymos and its satellite Dimorphos. We introduce here the science goals and the operation plans of TIRI.
Hera Mission: The ESA Hera mission is to explore the Near-Earth asteroid Didymos and Dimorphos binary asteroids [1] in collaboration with the NASA DART (Double Asteroid Re-direction Test) mission [2], consisting of the first international planetary defense project AIDA (Asteroid Impact & Deflection Assessment). The effect of asteroid deflection by the kinetic impact of the DART spacecraft that changed the rotation period of Dimorphos around Didymos will be validated by a half year long observations of Hera during the asteroid rendezvous.
Target Asteroids:
Didymos is a potentially hazardous asteroid (PHA) with its orbit of 1.0134 x 2.2753 au, with the orbital period of 2.108 years. Didymos has the averaged size of 761 ± 26 m, and seems to be a rubble pile object. Its surface is occupied with boulders but the equatorial region is relatively smooth. Dimorphos appears to be a rubble pile, entirely covered with boulders, with the size of 151 ± 5 m [3].
TIRI Instrument:
TIRI is a thermal infrared imager, based on an uncooled micro-bolometer array of 1024 x 768 pixels. TIRI is equipped with an 8-position filter wheel for multi-band imaging, with a wide band of 8-14 µm for thermal imaging, and six narrow bands centered at 7.8, 8.6, 9.6, 10.6, 11.6, and 13.0 µm for thermal infrared multi-band imaging. Its measured FOV is 13.0° x 9.9°, and the detection range of 150-450 K.
TIRI Objectives:
Mission objectives: TIRI contributes to the Hera mission objectives with thermal infrared multi-band imaging: 1) Mass of Dimorphos and dynamics of the Didymos binary system, 2) Global feature and interior, and 3) Surface properties.
Scientific objectives: Many fundamental scientific outcomes are expected as byproducts during the Hera mission, whose primary target is planetary defense: 1) The first thermophysical properties of S-type asteroid, in comparison with those of C-type asteroid Ryugu. 2) The first thermophysical properties of small (< 200 m) asteroid Dimorphos, in comparison with Ryugu (~900 m) > Didymos (~760 m) > Bennu (~500 m) > and Itokawa (~250m). 3) Comparison of thermal properties and composition between Didymos and Dimorphos to investigate the formation of the binary. 4) Dimension of DART impact crater or remnant crop to investigate the impact scaling and the strength of the rubble pile asteroid Dimorphos. 5) Dynamics of the binary, orbital and rotation changes, by thermophysical modeling regarding Yarkovsky and YORD (B-YORP) effects. 6) Composition and space weathering process, compared between the long-exposed and the recently excavated surfaces.
TIRI Operation Plasn:
The main operation plan of TIRI is shown: 1) The health checks by deep sky imaging during the cruise and during the rendezvous phase. 2) One-rotation thermal and multi-band imaging at various distances during Early Characterization Phase (ECP, 20-30km), Detailed Characterization Phase (DCP, 8-20 km), and Close-up Operation Phase (COP, 4-22km). 3) Tracking the motion of CubeSats to inform the gravity field. 4) Close-up thermal and multi-band imaging of the geologic sites including DART crater or remnant crop during COP and Experimental Phase (EXP). 5) Construction of thermophysical model for future orbital and rotational evolution by Yarkovsky and YORP (B-YORP) effects.
Acknowledgments: This work is supported by JAXA/ISAS, as a Strategic International Joint Space Science Mission. Meisei Electric Co. is the primary manufacturer of TIRI.
References: [1] Michel, P. et al. (2022) Planet. Sci. J., 3, 160. [2] Cheng A.F. et al. (2018) PSS 157, 104-115. [3] Daly, R.T. et al. (2023) Nature 616, 443-447.
Hera Mission: The ESA Hera mission is to explore the Near-Earth asteroid Didymos and Dimorphos binary asteroids [1] in collaboration with the NASA DART (Double Asteroid Re-direction Test) mission [2], consisting of the first international planetary defense project AIDA (Asteroid Impact & Deflection Assessment). The effect of asteroid deflection by the kinetic impact of the DART spacecraft that changed the rotation period of Dimorphos around Didymos will be validated by a half year long observations of Hera during the asteroid rendezvous.
Target Asteroids:
Didymos is a potentially hazardous asteroid (PHA) with its orbit of 1.0134 x 2.2753 au, with the orbital period of 2.108 years. Didymos has the averaged size of 761 ± 26 m, and seems to be a rubble pile object. Its surface is occupied with boulders but the equatorial region is relatively smooth. Dimorphos appears to be a rubble pile, entirely covered with boulders, with the size of 151 ± 5 m [3].
TIRI Instrument:
TIRI is a thermal infrared imager, based on an uncooled micro-bolometer array of 1024 x 768 pixels. TIRI is equipped with an 8-position filter wheel for multi-band imaging, with a wide band of 8-14 µm for thermal imaging, and six narrow bands centered at 7.8, 8.6, 9.6, 10.6, 11.6, and 13.0 µm for thermal infrared multi-band imaging. Its measured FOV is 13.0° x 9.9°, and the detection range of 150-450 K.
TIRI Objectives:
Mission objectives: TIRI contributes to the Hera mission objectives with thermal infrared multi-band imaging: 1) Mass of Dimorphos and dynamics of the Didymos binary system, 2) Global feature and interior, and 3) Surface properties.
Scientific objectives: Many fundamental scientific outcomes are expected as byproducts during the Hera mission, whose primary target is planetary defense: 1) The first thermophysical properties of S-type asteroid, in comparison with those of C-type asteroid Ryugu. 2) The first thermophysical properties of small (< 200 m) asteroid Dimorphos, in comparison with Ryugu (~900 m) > Didymos (~760 m) > Bennu (~500 m) > and Itokawa (~250m). 3) Comparison of thermal properties and composition between Didymos and Dimorphos to investigate the formation of the binary. 4) Dimension of DART impact crater or remnant crop to investigate the impact scaling and the strength of the rubble pile asteroid Dimorphos. 5) Dynamics of the binary, orbital and rotation changes, by thermophysical modeling regarding Yarkovsky and YORD (B-YORP) effects. 6) Composition and space weathering process, compared between the long-exposed and the recently excavated surfaces.
TIRI Operation Plasn:
The main operation plan of TIRI is shown: 1) The health checks by deep sky imaging during the cruise and during the rendezvous phase. 2) One-rotation thermal and multi-band imaging at various distances during Early Characterization Phase (ECP, 20-30km), Detailed Characterization Phase (DCP, 8-20 km), and Close-up Operation Phase (COP, 4-22km). 3) Tracking the motion of CubeSats to inform the gravity field. 4) Close-up thermal and multi-band imaging of the geologic sites including DART crater or remnant crop during COP and Experimental Phase (EXP). 5) Construction of thermophysical model for future orbital and rotational evolution by Yarkovsky and YORP (B-YORP) effects.
Acknowledgments: This work is supported by JAXA/ISAS, as a Strategic International Joint Space Science Mission. Meisei Electric Co. is the primary manufacturer of TIRI.
References: [1] Michel, P. et al. (2022) Planet. Sci. J., 3, 160. [2] Cheng A.F. et al. (2018) PSS 157, 104-115. [3] Daly, R.T. et al. (2023) Nature 616, 443-447.