DESTINY ⁺搭載カメラMCAP EMの光学校正試験とPFM試験に向けた課題整理

A ground-based optical calibration test of the multiband camera MCAP (Multiband Camera for Phaethon) onboard the DESTINY⁺ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) spacecraft was conducted using the Engineering Model (EM). This test aimed to verify the validity of data acquisition methods corresponding to various calibration processes, including bias correction, dark correction, linearity correction, flat-field correction, radiometric sensitivity correction, and distortion correction. In addition, the measured signal levels obtained from the test images were compared with theoretical estimates based on the camera specifications, and their consistency was evaluated. The results demonstrated that the acquired calibration data were valid for most items, as confirmed through the evaluation of various aspects of camera performance using the acquired images. However, several issues were identified, including stray light caused by out-of-field illumination, radiometric calibration errors due to spectral mismatch between the integrating sphere and the observation target, and methodological uncertainties in conversion gain estimation. To address these issues, countermeasures were implemented for the upcoming calibration test of the Proto Flight Model (PFM), including a modification of MCAP, improvements to the optical measurement system, and the introduction of statistically robust analysis methods. The findings obtained in this study will be incorporated into the preparation and execution of the optical calibration tests for the MCAP PFM.