11:00 〜 13:00
[PPS03-P02] Optical Calibration Plan for DESTINY+ on-board Cameras, TCAP and MCAP
キーワード：カメラ、光学校正、DESTINY+ mission
DESTINY+ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) onboard cameras, TCAP (Telescopic Camera for Phaethon), and MCAP (Multi-band Camera for Phaethon) will observe the asteroid (3200) Phaethon [1]. The following four scientific objectives will be achieved by the cameras depending on the distance between the spacecraft and the asteroid: (1) Obtaining the global shape of Phaethon; the outline and the light curve, (2) Obtaining the semi-global features of Phaethon; the 3-D topographic model, (3) Observing the local features of Phaethon; topography of the surface such as dust ejection, (4) Observing the material distribution on Phaethon [2]. Optical performance evaluation of the sensors and calibration of the cameras must be conducted to extract the correct signal and convert it into scientifically valuable data for achieving the objectives. We are planning to conduct both the ground-based optical calibration and the in-flight calibration of TCAP and MCAP.
Data acquisition for calibrating the two cameras in ground-based optical calibration is classified into the following three categories: (a) performance evaluation for understanding the characteristics of the image sensors, (b) sensitivity calibration for converting the digital number on the pixels into scientifically valuable data, and (c) geometric calibration for correcting the measurement position captured by the cameras into the accurate position. (a) will be carried out before installing the optical system, including the examination of the temperature dependence. We will obtain the data for evaluating dark current, dark-shot noise, read-out noise, dead pixel, fixed-pattern noise, linearity, conversion gain, full-well capacity, and obtain dark images for subtracting dark component. The calibration data, including the optical system, is obtained in (b) and (c), which will be conducted in the final phase after various environmental tests using EM (Engineering Model) and FM (Flight Model) of the cameras. Data required for flat-field correction, sensitivity correction, and stray light evaluation will be obtained in (b). Data required for evaluating spatial resolution, distortion, field-of-view (FOV), and instantaneous field of view (IFOV) will be obtained in (c). Before conducting this ground-based optical calibration, we are also preparing simulated calibration in advance, assuming the actual calibration tests of (a–c) to identify problems and study analysis methods of the obtained calibration data.
In-flight calibration is required because the performance of the cameras can be changed or degraded after the launch. Calibration data will be obtained several times during the cruise to check the change in performance. We plan to use the Earth, the Moon, stars as the natural light source and deep space as dark for the calibration. In particular, the Moon can be regarded as a stable surface-light source in space. It is possible to calibrate the sensitivity of the sensors with high accuracy by comparing the lunar reflectance models, such as ROLO (RObotic Lunar Observatory) model and SP (Spectral Profiler) model, with the images captured by TCAP and MCAP. In addition, we are considering cross-calibration using imaging data of the Moon. In cross-calibration, the Moon images taken by pre-calibrated cameras on satellites at a specific solar phase angle are compared with the Moon images taken by TCAP and MCAP under the same conditions.
We will report the detailed methods and considerations of ground-based optical calibration and the in-flight calibration in the presentation.
References: [1] Arai, T. et al., (2021), LPSC 52, Abstract #1896. [2] Ishibashi, K. et al., (2022), LPSC 53, Abstract #1729.
Data acquisition for calibrating the two cameras in ground-based optical calibration is classified into the following three categories: (a) performance evaluation for understanding the characteristics of the image sensors, (b) sensitivity calibration for converting the digital number on the pixels into scientifically valuable data, and (c) geometric calibration for correcting the measurement position captured by the cameras into the accurate position. (a) will be carried out before installing the optical system, including the examination of the temperature dependence. We will obtain the data for evaluating dark current, dark-shot noise, read-out noise, dead pixel, fixed-pattern noise, linearity, conversion gain, full-well capacity, and obtain dark images for subtracting dark component. The calibration data, including the optical system, is obtained in (b) and (c), which will be conducted in the final phase after various environmental tests using EM (Engineering Model) and FM (Flight Model) of the cameras. Data required for flat-field correction, sensitivity correction, and stray light evaluation will be obtained in (b). Data required for evaluating spatial resolution, distortion, field-of-view (FOV), and instantaneous field of view (IFOV) will be obtained in (c). Before conducting this ground-based optical calibration, we are also preparing simulated calibration in advance, assuming the actual calibration tests of (a–c) to identify problems and study analysis methods of the obtained calibration data.
In-flight calibration is required because the performance of the cameras can be changed or degraded after the launch. Calibration data will be obtained several times during the cruise to check the change in performance. We plan to use the Earth, the Moon, stars as the natural light source and deep space as dark for the calibration. In particular, the Moon can be regarded as a stable surface-light source in space. It is possible to calibrate the sensitivity of the sensors with high accuracy by comparing the lunar reflectance models, such as ROLO (RObotic Lunar Observatory) model and SP (Spectral Profiler) model, with the images captured by TCAP and MCAP. In addition, we are considering cross-calibration using imaging data of the Moon. In cross-calibration, the Moon images taken by pre-calibrated cameras on satellites at a specific solar phase angle are compared with the Moon images taken by TCAP and MCAP under the same conditions.
We will report the detailed methods and considerations of ground-based optical calibration and the in-flight calibration in the presentation.
References: [1] Arai, T. et al., (2021), LPSC 52, Abstract #1896. [2] Ishibashi, K. et al., (2022), LPSC 53, Abstract #1729.